Site 231

2. SITE 231 The Shipboard Scientific Party1 SITE DATA Date Occupied: 5 May 1972 Date Departed: 8 May 1972 Time on Site: 95 hours, 40 minutes Position: Latitude: ll°53.4l'N Longitude: 48°14.7l'E Water Depth: 2152 corrected meters (echo sounding) Bottom Felt At: 2161 meters (drill pipe) Penetration: 584.0 meters Holes Drilled: 1 Number of Cores: 64 Total Length of Cored Section: 584.0 meters Total Core Recovered: 424.9 meters Acoustic Basement: Depth: 566.5 meters Nature: Basalt and nanno chalk Inferred vertical velocity to basement: 1.9 km/sec Age of Oldest Sediment: Middle Miocene Basement: Middle Miocene (intercalated sediments) Principal Results: This site, in the Gulf of Aden south of the Sheba Ridge and 70 km north of the Somalia Coast, was drilled and cored continuously to a depth of 584 meters, and 424.9 meters of sediment were obtained. These are hemipelagic with sands at intervals in the upper 220 meters; the remainder is acoustically transparent, consisting of nanno clay and nanno ooze as follows: Pleistocene 0-102 meters; upper Pliocene 102-178 meters; lower Pliocene 178-254 meters; upper Miocene 254-482 meters; and middle Miocene 482-566.5 meters (base of sediments). Sediments intercalated with basement are middle Miocene. There is little evidence for sediments being baked above the basaltic basement. Robert L. Fisher, Geological Research Division, Scripps Institution of Oceanography, La Jolla, California (Co-chief scientist); Elizabeth T. Bunce, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts (Cochief scientist); Paul J. Cernock, Producing Department, Texaco Inc., New Orleans, Louisiana; David C. Clegg, Scripps Institution of Oceanography, La Jolla, California; David S. Cronan, Department of Geology, University of Ottawa, Ottawa, Ontario, Canada (Present address: Department of Geology, Imperial College, London SWT, England); Vincenzo Damiani, Instituto Italiano de Idrobiologia, Italy (Present address: Canada Centre for Inland Waters, Burlington, Ontario, Canada); Leonid V. Dmitriev, Institute of Geochemistry, Academy of Sciences of the USSR, Moscow, USSR; David J. J. Kinsman, Department of Geological and Geophysical Sciences, Princeton University, Princeton, New Jersey; Peter H. Roth, Geological Research Division, Scripps Institution of Oceanography, La Jolla, California; Jörn Thiede, Universitet I Bergen, Geologisk Institut, Bergen, Norway (Present address: School of Oceanography, Oregon State University, Corvallis, Oregon); Edith Vincent, Department of Geological Sciences, University of Southern California, Los Angeles, California. 55' Basement was drilled to 17.5 meters with 7.5 meters recovered. BACKGROUND AND OBJECTIVES Site 231 was the first of three localities accepted for drilling the Gulf of Aden in order to investigate this apparently young oceanic area and to elucidate sedimentary processes in the earliest stages of ocean development by rifting. Situated between southern Arabia and the Horn of Africa, the gulf is at the focus of a topographically and tectonically complex and mobile region. Southeast of Socotra the axis of the northwest-trending Carlsberg Ridge, part of the seismically active mid-ocean ridge system, is offset right laterally at Owen Fracture Zone (a transform fault) for a distance of 310 km. West of Owen Fracture Zone the active ridge crest, there termed Sheba Ridge, continues along the axis of the gulf and into the East African rift system at a triple junction located in the Afar Depression. Sheba Ridge is offset by several minor transform faults within the gulf and by one major one, the linear 5360-meter-deep Alula-Fartak Trench, that extends across the mouth of the gulf. Geophysical evidence suggests that the Gulf of Aden is a young oceanic area with new mafic crust forming the central region (Sheba Ridge) for the past 10 m.y. as Arabia has moved away from Somalia. South of the complex, deformed, and active central ridge, the magnetic anomaly amplitudes, basement relief, and sea-floor topography itself all become subdued; an acoustically transparent layer overlies smooth basement and underlies turbidites of variable thickness. 17 SITE 231 Site 231 lies in the "Half- Degree Square", which is south seawater was pumped down the drill pipe to keep the bit of West Sheba Ridge and was the object of an intensive clean and to prevent the drill from torquing. From 160 to geophysical survey by R.R.S.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Discovery in 1967 (Laughton 567 meters (top of basalt), the pipe was rotated at 30 to 35 et al., 1970). Our stated objectives in drilling here were to rpm and with 150 psi of pump pressure and 20,000 pounds date and determine the composition of the smooth of weight on the bit. The basalt was cored with 30,000 basement that seems to correlate acoustically with volcanic pounds of bit weight and 150 to 200 psi of pump pressure. igneous material at Sheba Ridge, but in the southern region, A total of 64 cores was taken at Site 231. Each core was does not have a marked magnetic signature; to determine checked for the presence of gas. The methane- ethane ratio the age, lithology, and, perhaps, origin of the transparent was monitored from Cores 13 to 62. Before leaving the site, layer (evaporites?); to examine the time and extent of the hole was filled with 190 barrels of heavy (12.5 PPG) changes in level and sedimentary regime in the Somalia drilling mud. continental margin, which presumably is the source area for the upper turbidites. LITHOLOGIC SUM M ARY Hence, it was obvious that we should core the Hole 231 was continuously cored from the sediment hemipelagic sediment section continuously, penetrate the surface down to basalt at a depth of 566.5 meters and then acoustic basement as far as necessary to establish it as true 17.5 meters into the basalt. The sedimentary sequence can basement, not a sill, and obtain unweathered igneous rock, be divided into five units (Table 2), with the underlying expectably basalt, for petrologic analysis and possible basalt constituting a sixth unit. dating. Unit 1 (0.0- 7.0 m; Cores 1- 2) OPERATIONS Near- Site Activities Site 231, in the "H alf Degree Square" of Laughton et al. (1970), was approached on a course of 079° followed by a westerly run a few miles southward to provide two nearly east- west bathymetric, reflection, and magnetic lines to complement the closely spaced north- south dan- buoy controlled sounding and magnetic lines run by R.R.S. Discovery in 1967. Upon heading for, and surveying near, the proposed locality ("24- 1" on Figure la), it was learned that more favorable structure was present somewhat to the south, and a spar buoy was dropped to mark the new locality. Glomar Challenger continued her traverse south- southeast to provide equally good reflection context south of the site. Upon doubling north- northwest, the hydrophone streamers were retrieved and the beacon was dropped (1956Z) at a point, very near the buoy drop, marked 231 on Figure lb, with a water depth of 2146 meters (corrected) by sounder. It is 3.6 miles south of the proposed 24- 1, at the southwest extremity of a small transform fault zone offsetting Sheba Ridge and just north of the continental slope off Somalia. Figure la incorporates the sounding data of Discovery and Glomar Challenger. At the close of the drilling program, Glomar Challenger streamed gear, passed northerly through both 231 and 24- 1 to the vicinity of 12°10'N , 48°lθ 'E and then easterly en route to Sites 232 and 233. The latter two runs provide reflection data to supplement—by two crossings—a seismic refraction profile (N o. 6228) reported by Laughton and Tramontini(1969). Drilling Program Water depth was established at 2161 meters by drill pipe measurements. A total penetration of 584 meters was reached. Basalt was cored from 566.5 to 584 meters, and 7.7 meters was recovered (Table 1). The first 50 meters of sediment was cored without pumping water or rotating the drill pipe. From 50 to 160 meters the drill pipe was rotated at 30 rpm and some 18 Unit 1 is a light gray nanno ooze. It contains up to 70 percent calcareous nannoplankton, together with minor quantities of foraminifera, radiolarians, and diatoms. Inorganic constituents include quartz, feldspar, volcanic glass, dolomite, calcite, and mica. Unit 2 (7.0- 64.0 m; Cores 3- 8) This unit consists of light olive- gray nanno ooze with intercalated sandy horizons. The ooze contains more than 60 percent calcareous nannoplankton together with some foraminifera. The sandy layers are somewhat variable in composition and some contain materials of reef origin (including Acropora fragments). The first 11 meters contains 50 percent sand- sized material of which 50 percent is quartz, and the remainder detrital and biogenous carbonate together with minor constituents. Other sandy layers with their principal characteristics are as follows: (a) 18 meters, nanno- rich foraminiferal sand"; (b) 28 meters, quartz- rich shelly sand; (c) 34 meters, shelly sand; (d) 38 meters, shelly sand; (e) 48 meters, shelly sand; and (f) 59 meters quartz- rich shelly sand. Minor constituents in this unit include pyrite 1 to 5 percent, mica 1 to 5 percent, feldspar, dolomite, calcite, and quartz. Unit 3 (64.0- 121.0 m; Cores 9- 14) Unit 3 consists of a rather uniform nanno ooze predominantly light olive gray in color. Burrow mottling is common in this unit but does not attain the intensity found lower in the section. Some of the burrows are filled with mud, others with sand. Between 92 and 102 meters, a nanno clay with somewhat less than 60 percent nannos was recovered. One striking characteristic of this unit is that between 73 and 83 meters there are a number of reworked shallow- water fossils which indicate slumping. These include a gastropod, a scaphopod, a cerithid, and several foraminiferal limestone fragments. A sandstone fragment was also found in this interval. Minor constituents in this unit include pyrite, dolomite rhombs, detrital calcite, mica, quartz, foraminifera, radiolarians, and sponge spicules. To^ wards the base of the unit there is a thin sand layer. SITE 231 48°20' 48°10'E 48°30' 12°10 12°OO'N n°50 Nautical Miles Contours in Matthews corrected meters 11° 40' Figure la. Site survey track of Glomar Challenger showing proposed Site 24­1 and Site 231. Contours in Matthews­corrected meters. 231 3 SEC ....... • . . . . . .- . ..... Figure lb. iVo^/e showing location of Site 231. 19 SITE 231 TABLE 1 Coring Summary-Site 231 20 Date Core (May 1972) Time Depth Below Sea Floor (m) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 0.0-0.5 0.5-7.0 7.0-16.5 16.5-26.0 26.0-35.5 35.5-45.0 45.0-54.5 54.5-64.0 64.0-73.5 73.5-83.0 83.0-92.5 92.5-102.0 102.0-111.5 111.5-121.0 121.0-130.5 130.5-140.0 140.0-149.5 149.5-159.0 159.0-168.5 168.5-178.0 178.0-187.5 187.5-197.0 197.0-206.5 206.5-216.0 216.0-225.5 225.5-235.0 235.0-244.5 244.5-254.0 254.0-263.5 263.5-273.0 273.0-282.5 282.5-292.0 292.0-301.5 301.5-311.0 311.0-320.5 320.5-330.0 330.0-339.5 339.5-349.0 349.0-358.5 358.5-368.0 368.0-367.5 377.5-387.0 387.0-396.5 396.5-406.0 406.0-415.5 415.5-425.0 425.0-434.5 434.5-444.0 444.0-453.5 453.5-463.0 463.0-472.5 472.5-482.0 482.0-491.5 491.5-501.0 501.0-509.5 509.5-519.0 519.0-528.5 528.5-538.0 538.0-547.5 547.5-557.0 557.0-566.5 566.5-568.5 568.5-574.5 574.5-584.0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 0753 0830 0925 1015 1102 1201 1310 1410 1507 1609 1715 1819 1926 2030 2147 2247 2347 0052 0150 0249 0346 0442 0537 0647 0738 0833 0938 1041 1140 1246 1345 1452 1605 1705 1813 1922 2040 2213 2331 0047 0200 0318 0434 0601 0720 0833 0950 1122 1313 1429 1605 1729 1912 2102 2245 0006 0145 0326 0500 0618 0753 0905 1158 1551 Depth From Drill Floor (m) 2161.0-2161.5 2161.5-2168.5 2168.5-2177.5 2177.5-2187.0 2187.0-2196.5 2196.5-2206.0 2206.0-2215.5 2215.5-2225.0 2225.0-2234.5 2234.5-2244.0 2244.0-2253.5 2253.5-2263.0 2263.0-2272.5 2272.5-2282.0 2282.0-2291.5 2291.5-2301.0 2301.0-2310.5 2310.5-2320.0 2320.0-2329.5 2329.5-2339.0 2339.0-2348.5 2348.5-2358.0 2358.0-2367.5 2367.5-2377.0 2377.0-2386.5 2386.5-2396.0 2396.0-2405.5 2405.5-2415.0 2415.0-2424.5 2424.5-2434.0 2434.0-2443.5 2443.5-2453.0 2453.0-2462.5 2462.5-2472.0 2472.0-2481.5 2481.5-2491.0 2491.0-2500.5 2500.5-2510.0 2510.0-2519.5 2519.5-2529.0 2529.0-2538.5 2538.5-2548.0 2548.0-2557.5 2557.5-2567.0 2567.0-2576.5 2576.5-2586.0 2586.0-2595.5 2595.5-2605.0 2605.0-2614.5 2614.5-2624.0 2624.0-2633.5 2633.5-2643.0 2643.0-2652.5 2652.5-2662.0 2662.0-2670.5 2670.5-2680.0 2680.0-2689.5 2689.5-2699.0 2699.0-2708.5 2708.5-2718.0 2718.0-2727.5 2727.5-2729.5 2729.5-2735.5 2735.5-2745.0 Cored (m) Recovered (m) 0.5 6.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 8.5 9.5 9.5 9.5 9.5 9.5 9.5 2.0 6.0 9.5 0.5 1.6 5.5+ 4.5 9.0+ 8.6+ 3.7+ 9.7 8.8 6.7 3.9 5.8 7.7 7.2 3.7 7.7 7.0+ 4.0± 5.5 8.8 8.7+ 6.7+ 7.89.0 8.7 7.9 7.8+ 9.0 9.1 7.8 6.3 8.7 7.2+ 9.2 4.5 8.2 7.2 5.3+ 6.0 6.4 7,3 7.8 9.5 2.3 9.3 9.5 8.9 4.2 3.5 8.3+ 9.4+ 7.6 8.5 4.0 4.5 7.7 3.7 8.8 9.5 3.9+ 8.31.0 2.2 4.5 Recovered (%) 100 24 58 47 94 91 39 96 92 70 41 61 81 76 39 81 74 42 58 93 91 70 82 94 91 83 82 94 96 82 66 91 76 97 47 86 76 56 63 67 77 82 100 24 97 100 94 44 37 87 99 80 90 42 53 81 39 93 100 41 86 50 36 47 SITE 231 TABLE 2 Lithologic Units - Site 231 Depth Below Sea Floor (m) Thickness Unit Lithology (m) Cores 7 1- 2 1 Nanno ooze 2 Nanno ooze intercalated sandy horizons 57 3- 8 3 Nanno ooze 57 9- 14 4 Nanno ooze with intercalated horizons 114 15- 26 5 Uniform grayish- olive nanno ooze 331.5 27- 61 6 Volcanic basement with thin nanno chalk layers 7n 61 0 1 I n Λ 62- 64 584.0 Unit 4 (121.0- 235.0 m; Cores 15- 26) This unit consists predominantly of grayish- olive to light olive- gray nanno ooze and nanno clay with intercalated coarse sediments, some of them volcanic ash deposits. The coarse horizons are as follows: (a) 123 meters, quartz- rich nanno ooze; (b) 142 meters, nanno dolomitic clayey silt; (c) 161 meters, foram- rich nanno ooze; (d) 170 meters, volcanic ash; (e) 180 meters, volcanic ash;(f) 181 meters, nanno- and foram- rich silty quartz sand; (g) 188.5 meters, volcanic ash; (h) 203 meters, volcanic ash;(i) 208 meters, nanno detrital silty sand; (j) 231 meters, nanno detrital silty sand. Within this unit, the calcareous nannofossils vary from about 40 percent up to about 90 percent. Other constituents are foraminifera, radiolarians, dolomite rhombs, detrital calcite, quartz, feldspar, and pyrite, all usually in minor quantities. Unit 5 (235.0- 566.5 m; Cores 27- 61) Unit 5, lowest in the sediment column, consists of a fairly uniform grayish- olive nanno ooze. Burrow mottling becomes increasingly apparent down the unit. The degree of lithification also increases downwards. Gas was evident in most of the cores, and bitumen occurs at 397 meters. At 425 meters, there is a thin layer consisting of quartz nanno ooze containing 30 percent quartz, 5 percent feldspar, 5 percent shell, and 50 percent nannos. Towards the bottom of the unit, color variation between grayish olive and light olive gray becomes common. Calcareous nannoplankton commonly comprise between 80 and 90 percent of the sediment. H 2 S was detected throughout much of the lower part of the unit. Unit 6 (Below 566.5 m; Cores 62- 64) This unit consists of volcanic rocks, principally basalt and volcanic glass, together with layers and veins of lithified nanno chalk. The volcanics are discussed in Appendix A and the sediments enclosed in them have not been examined in detail. Conclusions 1. The gross characteristics of the entire sediment section are surprisingly uniform, the sediments being nannoplankton- rich hemipelagic ooze. There is little or no variation even close to the basalt basement. This uniformity suggests near constant conditions of water depth, pelagic carbonate production, and detrital sediment input. 2. Reef and other very shallow- water carbonate grains are largely limited to Units 1 and 2. The accession of shelf facies sediments to deep water may be related to Pleistocene low sea level periods, when the outer shelf edge became the reef growth locale. 3. The fairly abundant very fine and silt- sized quartz, dolomite, calcite, and other detrital mineral grains found dispersed throughout the section may well be of eolian origin. Aridity in the potential detrital sediment source area of Somalia probably precluded large inputs of waterborne terrigenous sediment. 4. In the basalt unit, nanno chalk layers are generally associated with chilled basaltic glass and may be indicative of continued sediment deposition between eruptive events or represent xenoliths. BIOSTRATIGRAPHIC SUMMARY Introduction The 567.6 meters of sediments continuously cored at Site 231 represents an apparently uninterrupted sequence from Quaternary to middle Miocene. Sediments at 567.4 meters (Sample 62- 1, 85- 90 cm), above the basalt, and below the altered volcanic ash, are approximately 12.5 to 12.8 m.y. old (foraminiferal Zone N .12), and the nanno 21 SITE 231 chalk inclusions in the basalt at 567.8 and 569.4 meters with assemblages including common Reticulofenestra (Samples 62- 1, 130 cm and 63- 1, 90 cm) indicate an age of pseudoumbilica and Sphenolithus abies. Cores 23 through approximately 13 to 14 m.y.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (Sphenolithus heteromorphus 27 contain reworked Miocene discoasters and placoliths in nannofossil zone). These dates permit a reliable age small numbers. Core 28 yielded Ceratolithus acutus assignment of approximately 13 m.y. for the basalt/ together with rare C tricorniculatus, which indicates the sediment contact. basal Pliocene Ceratolithus acutus Zone. The Ceratolithus rugosus Zone was not found in any of the samples studied. Calcareous nannofossils are common and slightly etched throughout the sedimentary sequence and considerably The Pliocene/ Miocene boundary, based on calcareous altered in the basalt inclusions. Planktonic foraminifera are nannofossils, would fall between Cores 28 and 29. Core 29 common and moderately well preserved throughout most belongs to the upper Miocene Ceratolithus tricorniculatus of the upper 225 meters of the section but are less common Zone and contains an assemblage including Ceratolithus and poorly preserved in the lower 342.6 meters (below tricorniculatus and C primus. The Ceratolithus primus Core 25). Radiolarians are abundant and well preserved Zone is quite thick at this site and occurs in Cores 30 only in the uppermost core and are present but poorly through 42. Ceratolithus primus, C. amplificus, and preserved throughout the remainder of the hole. Discoaster quinqueramus are characteristic for this interval. The zonation of the various fossil groups are summarized Cores 43 through 46 are assigned to the Discoaster on the site summary form at the end of this chapter. berggrenii Zone based on assemblages including Discoaster Because of the uncertainty of the position in the section of berggrenii, D. quinqueramus, andZλ surculus. Cores 47 and the evolutionary appearance of the foraminiferal 48 contain Discoaster sp. cf. D. neorectus (somewhat Quaternary index species Globorotalia truncatulinoides, the smaller), D. bellus, D. neohamatus, and D. pseudovariabilis Pleistocene / Pliocene boundary was placed on the basis of and is thus assigned to the Discoaster neohamatus Zone. nannofossil data. This boundary, placed at the highest Cores 49 through 52 yield assemblages typical of the occurrence of Discoaster brouweri (Pseudo emiliania Discoaster bellus Zone including Discoaster neohamatus, D. lacunosa/ Cyclococcolithina macintyrei zonal boundary), bellus, D. calcaris, and D. pseudovariabilis. The boundary lies at 102 meters, between Cores 12 and 13. The between the upper and the middle Miocene, based on late / middle Miocene boundary was placed on the basis of nannofossils, lies between Cores 52 and 53. Cores 53 nannofossil data at 482 meters (between Cores 52 and 53 at through 56 contain rich assemblages characteristic of the the Discoaster neohamatus/ Discoaster bellus zonal Discoaster hamatus Zone with Discoaster hamatus, D. boundary), although the foraminiferal zonation indicates a neohamatus, D. calcaris, rare Discoaster bollii, Catinaster higher position for the boundary (between Core 46, Section coalitus, and C. mexicanus. The next lower zone present at 5 and Core 48, Section 3). this site is the Discoaster kugleri Zone, recovered in Cores 57 through 60, with assemblages including Discoaster Calcareous N annoplankton kugleri, D. exilis, and Coccolithus eopelagicus. Cores 61 and the top of 62 contain impoverished assemblages with Nannofossils are common throughout the sedimentary Discoaster exilis and Coccolithus eopelagicus, which are section. assigned to the Discoaster exilis Zone. N annoplankton Core 1 contains an assemblage consisting of Gephyrochalk layers interbedded with basalt in Cores 62 and 63 capsa oceanica and many small placoliths which belong, yield moderately recrystallized assemblages including early most probably, to Emiliania huxleyi. This core is forms of Cyclococcolithina macintyrei (slightly elliptical), tentatively assigned to the Emiliania huxleyi Zone, but only Coccolithus eopelagicus, Cyclicargolithus floridanus, electron microscopy could give definitive proof of this age Discoaster deflandrei, and Reticulofenestra pseudoumbilica assignment. Cores 2 through 9 recovered the Gephyrocapsa (with covered central areas). This assemblage is typical of oceanica Zone with common G. oceanica and G. the Discoaster exilis to Sphenolithus heteromorphus Zone. caribbeanica. The last occurrence of Pseudo emiliania lacunosa in Core 4 could be used to further subdivide this Preservation: All the assemblages recovered from soft interval. The Gephyrocapsa caribbeanica Zone is thin and sediments at this site show slight etching resulting in serrate was recovered only in Core 10. Crenalithus doronicoides margins of coccoliths and sometimes destruction of central and Gephyrocapsa caribbeanica overlap in that interval. The area elements. Delicate forms like Pontosphaera and Pseudoemiliania lacunosa Zone is present in Cores 11 and Scyphosphaera are preserved. The sediment interbedded 12 with assemblages including common Crenalithus with basalt contains highly overgrown nannofossils with doronicoides and Pseudoemiliania lacunosa; Ceratolithus almost unrecognizable discoasters and considerably altered cristatus and C. rugosus occur in the lower part of this placoliths. Reticulofenestra pseudoumbilica has a strongly zone, and Cyclococcolithina macintyrei ranges throughout overgrown central area, giving it an appearance similar to this interval. Reworked Discoaster brouweri is present in Reticulofenestra bisecta. small numbers throughout this zone. The upper Pliocene Cyclococcolithina macintyrei Zone was found in Cores 13 Foraminifera through 16 with assemblages including Cyclococcolithina macintyrei and Discoaster brouweri. Cores 17 through 19 Abundance and Preservation yield assemblages belonging to the Discoaster pentaradiatus Zone with Discoaster brouweri, D. pentaradiatus, and, in Moderately to poorly preserved foraminifera are the the lower part, D. surculus. The Discoaster tamalis Zone dominant component of the coarse fraction (>63µ ) occurs in Core 20 only. The Reticulofenestra throughout the sediments recovered at Site 231 except in pseudoumbilica Zone was recovered in Cores 21 through 27 the interval between Cores 47 and 57 in Unit 5. Terrigenous 22 SITE 231 components are common throughout the section and increase in relative percentage down the hole; they are abundant in some sandy horizons and dominate the coarse fraction between Cores 47 and 57. Pyrite is rare to common below Core 9 and abundant in some horizons. Skeletal debris of pelecypods, gastropods, pteropods, and echinoderms are rare throughout the section. These are common in the sandy horizons of Unit 2 together with bryozoan and coral debris and transported shallow-water benthic foraminifera. Foraminiferal faunas exhibit signs of dissolution, especially below Core 15. Planktonic faunas show an increasingly high degree of fragmentation below Core 8, and in many horizons, the planktonic species are predominantly forms with robust solution-resistant tests. Dissolution of planktonic foraminifera is also reflected by the high relative frequency of benthic species, which are more resistant to solution and which sometimes dominate the assemblages. Planktonic foraminifera are dominant in Cores 1 to 25; they constitute from 80 to over 99 percent of the total foraminiferal fauna in Cores 1 to 15, and 50 to 80 percent of the fauna in Cores 16 to 25. Below Core 25, relative proportions of planktonics and benthics are variable. Planktonic species make up 30 to 80 percent of the fauna, and are very rare in some intervals (especially in Core 47 and in the interval between Cores 50 and 57). Planktonic Foraminiferal Zonation The interval Core 1 to Core 6, Section 5 is assigned to the Quaternary (Zones N.23 and N.22) as indicated by the common presence of Globorotalia truncatulinoides. The N.23/N.22 zonal boundary is tentatively drawn between Sections 2 and 3 of Core 3, at the lowest occurrence of Globigerinella adamsi. Specimens of pink colored Globigerina mbescens occur commonly above this level in the interval Core 1 to Core 3, Section 2, rarely in the interval between Core 3, Section 3 to Core 5, Section 3, and they were not found below. The N.22/N.21 zonal limit (Pleistocene/Pliocene boundary) is placed in Core 6, Section 5 at the base of the common occurrence of G. truncatulinoides. The exact level of the evolutionary appearance of this species from its direct ancestor Globorotalia tosaensis cannot be easily determined. Specimens intermediate between G. truncatuli­ noides and G. tosaensis (with a rounded edge but with an imperforate band) occur occasionally throughout the interval between Core 3, Section 4 and Core 12, Section 1. The highest occurrence of G. tosaensis (specimens with a perforate rounded edge) is in Core 5, Section 2. The latter species occurs rarely in the interval between Core 5, Section 2 and Core 6, Section 1, commonly between Core 6, Section 3 and Core 9, Section 4, and rarely below. The base of the common occurrence of G. truncatulinoides (in Core 6, Section 5) approximates the highest occurrence of Globigerinoides quadrilobatus fistulosus, the lowest appearance of Globigerina tenella (in Core 6, Section 4), and the highest occurrence of Globigerinoides obliquus extremus (in Core 6, Section 6). An interval with dextrally coiled Globorotalia tumida tumida was found between Core 9, Section 4 and Core 10, CC. A horizon containing Globoquadrina sp. A (a new species to be described in a subsequent paper) occurs in Sample 12, CC, slightly above the highest occurrence of Globorotalia limbata and Turborotalia humerosa in Core 13, Section 3. The N.21/N.20-N.19 zonal limit is drawn between Cores 19 and 20 at the lowest occurrence of G. tosaensis. The N.19/N.18 boundary is placed between Cores 27 and 28, at the lowest occurrence of Sphaeroidinella dehiscens, although the scarcity of this species at this site makes it an unreliable biostratigraphic indicator for the Gulf of Aden. The N.18/N.17 limit (Pliocene/Miocene boundary), based on the lowest occurrence of Globorotalia tumida tumida, lies between Cores 28 and 29. Cores 30 to 46 are assigned to the late Miocene Zones N.I7 to N.I5. The N.17/N.16 boundary is placed at the base of Globorotalia tumida plesiotumida, between Cores 34 and 35, and Zones N.I6 and N.I5 were not differentiated. The lowest occurrence of Turborotalia acostaensis lies in Core 43, but Globorotalia merotumida ranges lower; as low as Core 46, Section 5. Preservation of planktonic foraminifera is inadequate between Core 46, Section 5 and Core 48, Section 3, and no biostratigraphic data was obtained from this interval. The lower part of the section from Core 48, Section 3 to the bottom of the hole contains common Turborotalia siakensis and is assigned to middle Miocene Zones N.I4 to N.I2. In this interval, many horizons did not yield biostratigraphically valuable data because of the poor preservation of planktonic foraminifera, especially in Core 49 and between Cores 51 and 57. The N.14/N.13 boundary was not determined. Rare forms referable to Globigerina nepenthes, which is known to define the base of N.14, occur as far down as Core 59, Section 2; however, forms known to become extinct within N.I3 are present higher in the section. The highest occurrences of Globigerinoides subquadratus and Turborotalia mayeri lie, respectively, in Core 50, Section 6 and Core 58, Section 2. The N.13/N.12 boundary is placed at the lowest occurrence of Sphaeroidinellopsis subdehiscens in Cofe 61, Section 2, which is also the level of highest appearance of Globorotalia fohsi fohsi and Globorotalia peripheroacuta. The lowest sample, just above the basalt and below the altered volcanic ash (Sample 62-1, 85-90 cm), contains a rich but altered planktonic fauna including Globorotalia fohsi fohsi, G. fohsi lobata, G. fohsi robusta, Globorotalia peripheroacuta, Globorotalia peripheroronda, and Globorotalia praefohsi. This assemblage belongs to the faunal Zone N.I2 and is 12.5 to 12.8 m.y. old according to the Berggren scale. Benthic Foraminifera Benthic foraminifera are common throughout the section, but their relative frequency varies. In the Pleistocene sediments, they constitute from less than 1 to 20 percent of the total foraminiferal fauna and are especially common in the sandy layers of Unit 2 because of dilution of planktonic foraminifera by displaced elements of shallow origin. In Pliocene sediments, benthic foraminifera comprise 20 to 50 percent of the foraminiferal fauna and in the Miocene 20 to 70 percent. They are especially abundant in the lower part of the section where they often dominate the foraminiferal assemblages because of dissolution of planktonic foraminiferal tests. 23 SITE 231 Benthic foraminiferal assemblages in most cores are characteristic of deep water; however, mixing with displaced shallower water elements was observed in various horizons. The assemblages commonly include deep-water species characteristic of a lower bathyal, or deeper, environment, such as Cibicides wuellerstorfi, Epistominella exigua, Gyroidina soldanii, Laticarinina pauperata, Melonis pompiliodes, and Pullenia quinqueloba. Species usually found at upper to middle bathyal depths, such as Chilostomella oolina, Eggerella bradyi, Globocassidutina subglobosa, Hoeglundina elegans, Melonis barleeanus, and Sphaeroidina bulloides, were also found associated with the deep-water fauna. Some horizons include species typical of outer neritic to upper bathyal depth, such as Cassidulina carinata, Hyalinea balthica, and Textularia spp., which have probably been transported downslope. Shallow-water species with abraded tests, such as Amphistegina lessonii, Asterigerina sp., Ammonia gaimardii compressiuscula, and Elphidium spp., are common in the sandy layers of Unit 2 (upper Pleistocene) and in some lower Pleistocene and upper Pliocene horizons (especially in Core-Sections 9-3 to 9-5; 13-3 to 13-5, 15-3, 17-1 to 17-3, 18-3). These are frequently associated with skeletal debris of pelecypods, gastropods, bryozoans, echinoderms, and corals, suggesting slumping from shelf areas. Radiolarians The only sample with abundant well-preserved radiolarians is 231-1-1, 145-147 cm, which is Quaternary in age. Below that, most of the samples from Cores 2 to 16 contain radiolarians, which are, however, somewhat dissolved and therefore inadequate for biostratigraphic interpretation. Radiolarian abundances and preservation in all samples examined from Site 231 are as follows: 1-1, 145-147 cm (A, G); 2-2, 49-51 cm (R, M); 3-1, 58-60 cm (R, M); 3-4, 53-55 cm (R, M); 4-1, 50-52 cm (R, M);4-3,50-52 cm (R, M); 5-1, 49-51 cm (C, M); 5-6, 50-52 cm (F, M); 5-6, 115-117 cm (None); 6-1, 50-52 cm (R, M); 6-6, 50-52 cm (F, M); 7-3, 130-132 cm (None); 8-1, 59-61 cm (F, M); 8-6, 110-112 cm (C, M); 9-1,49-51 cm (C, M); 9-6, 120-122 cm (None); 10-3, 29-31 cm (C, M); 10-5, 130-132 cm (C, M); 11-2, 50-52 cm (C, M); 11-3, 110-112 cm (C, M); 12-1, 50-52 cm (R, M); 12-4, 130-132 cm (F, M); 13-2, 30-32 cm (F, M); 13-6, 108-110 cm (F, M); 14-1, 49-51 cm (F, M); 14-5, 118-120 cm (F, M); 15-2, 83-85 cm (R, M); 16-2, 19-21 cm (R, M); 16-6,119-121 cm (None); 17-1, 58-60 cm (None); 17-5, 119-121 cm (None); 18-2, 29-31 cm (None); 19-2, 29-31 cm (F, M); 194, 110-112 cm (None); 20-1, 44-46 cm (None); 20-6, 119-121 cm (None); 21-1, 59-61 cm (None); 21-6, 109-111 cm (None); 22-1, 84-86 cm (+, M); 23-6, 119-121 cm (None); 24-5, 119-120 cm (None); 25-6, 120-122 cm (None); 26-6, 110-112 cm (None); 27-6, 110-112 cm (R, pyritized); 28-6, 110-112 cm (R, pyritized); 29-6, 110-112 cm (+, pyritized); 30-6, 110-112 cm (None); 31-5, 110-112 cm (None); 32-6, 110-112 cm (None); 33-5, 110-112 cm (None); 34-6, 110-112 cm (None); 35-2, 50-52 cm (None); 36-6, 100-102 cm (None); 37-5, 100-102 cm (None); 384, 60-62 cm (None); 394, 100-102 cm (None); 40-5, 104-106 cm (None); 41-5, 120-122 cm (None); 42-6, 120-122 cm (None); 43-6, 120-122 cm (None); 44-2, 110-112 cm (None); 45-6, 4042 24 cm (None); 47-1, 60-62 cm (None); 47-6, 120-122 cm (None); 48-1, 119-121 cm (None); 49-2, 4042 cm (None); 50-6, 110-112 cm (None); 51-6, 110-112 cm (None); 52-5, 130-132 cm (R, M); 53-6, 120-122 cm (R, M); 54-2, 56-58 cm (None); 55-1, 70-72 cm (R, P); 56-2, 30-32 cm (None); 57-1, 107-109 cm (None); 58-6, 50-52 cm (None); 59-6, 102-104 cm (None); 60-2, 70-72 cm (R, pyritized); 61-6, 117-119 cm (None); and 62-1,85-90 cm (None). SEDIMENT ACCUMULATION RATES Average accumulation rates were calculated as follows: Series Thickness (m) Average Accumulation Rate (m/m.y.) Pleistocene Upper Pliocene Lower Pliocene Upper Miocene Middle Miocene 102.0 76.0 76.0 228.0 85.6 56.7 63.3 38.0 38.0 47.8 The average accumulation rate for the entire sedimentary sequence is 43.7 m/m.y. The higher rate for the Pleistocene and upper Pliocene series (average of 59.3 m/m.y.) probably reflects the input of coarse shell and skeletal debris slumped from shelf areas in Unit 2 and the upper part of Unit 4. PHYSICAL PROPERTIES Bulk Density and Porosity Only one slight variation in bulk density and porosity occurs in the 566.5 meters of nanno ooze overlying the basaltic basement. In Core 5, a 0.21 g/cm3 increase in bulk density and a corresponding 13 percent decrease in porosity is attributed to the quartz-rich shell sand layer at 28 meters which is described in the section on lithology (see also Core 5, physical property data). The various sandy layers described in Unit 2 (7-64 m) of the lithologic description are grossly reflected in the density and porosity data in Figure 2. The plots of bulk density and porosity are remarkably smooth, the former showing a steady increase from 1.64 g/cm3 near the surface to 1.97 g/cm3 near 550 meters while over the same interval, the porosity generally decreases from approximately 63 to 44 percent. The trends of these properties are attributed to normal consolidation of the sediments, i.e., an escape of pore water in an upward direction due to an increasing overburden pressure by sedimentation. Bulk densities of the basaltic basement rocks were obtained by the GRAPE device on block samples approximately 1.5 cm × 1.5 cm X 2.5 cm. Bulk densities measured in the vertical direction (long axis) ranged from 2.67 to 2.86 g/cm3 and those measured in the horizontal direction from 2.72 to 2.86 g/cm3 (See Table 3). Sonic Velocity The velocity profile of the nanno ooze in Figure 2 shows a smooth increase from 1.50 km/sec near the surface to 1.80 km/sec just above the basaltic basement. Lithologic Unit 2 is represented by a velocity of 1.66 km/sec for the SITE 231 DSDPLEG24 SITE 231 BARREL NO. BULK DENSITY 3, (gm/ cm") POROSITY 70 60 1.5 2.0 2.5 3 . T ~ π 1 r ACOUSTIC IMPEDANCE 5 2 (10 x gm/ cm sec) VELOCITY (%) (km/ sec) 50 40 ~ T . O 2.0 3.0 4.0 5.0 6.0 2.0 4 . 0 6.0 8.0 10.0 12.0 14.0 izyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA a, i 1 1 1 r π 1 1 1 r 16.0 SEC SEAFLOOR- 100 • "• ' i i Wl • i i PPPWf • • ' • 200 AC O US TI C BASEMENT : • • • • • • • . : • • : : zyxwvutsrqponmlkjihgfedc \ ^ iisisiii E - 300 400 - ® 500 - VIA "GRAPE DEVICE © % POROSITY = 161.7- 59.9 (BULK DENSITY) VERTICAL VELOCITY ® HORIZONTAL VELOCITY © VERTICAL ACOUSTIC IMPEDANCE Figure 2.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Physical properties, Site 231. 25 SITE 231 TABLE 3 Bulk Density of Basalt­Site 231 Sample^ 62-1 (CC) 63-1 (1) 64-1 (2) 64-2 (2) 64-2 (4) 64-3 (3) Velocity (km/sec) Bulk Density (g/cm3) Vertical Horizontal Vertical Horizontal 2.67 2.81 2.79 2.83 2.86 2.72 2.84 2.82 2.86 2.86 4.37 5.21 5.12 4.78 5.54 Rock Description Vesicular basalt Basalt Basalt Oxidated basalt Basalt Basalt 3.74 4.13 5.28 5.22 5.17 5.49 a Figures in parentheses are sequence numbers of basalt pieces in the section. sandy interval in Core 5. Other sandy layers within Unit 2 were not measured for sonic velocities because of the degree of disturbance of the layers and the high attenuation of the received measuring signal. Although attempts were made to calculate velocities for Cores 12 through 41, few reliable values were obtained. Core disturbance, gas bubbles, and cracks caused by the expanding gases precluded accurate measurements. However, the smoothness of both the bulk density and porosity curves over this depth interval suggests that no significant velocity changes have occurred. Ideally, horizontal and vertical velocity values should be obtained for the sediments for application to, and interpretation of, seismic refraction and reflection measurements. The upper 430± meters of sediments were measured only for horizontal velocities due to the consistency of the sediment. However, the small degree of velocity anisotropism in Cores 48 and 50 suggests that the measured horizontal velocities are also valid representations of the vertical velocities. Velocity anisotropism increases from 0.09 km/sec near 440 meters to approximately 0.58 km/sec at about 505 meters. Therefore, horizontal velocities are plotted above 430 meters and vertical velocities from 430 meters to basement contact. It must be emphasized at this time that all sediment velocity measurements are probably minimum values due to: (1) release of overburden pressure, (2) release of hydrostatic pressure, and (3) changes of temperature from in situ values (see Hamilton, 1965 or Cernock, 1970 for a detailed explanation). The major velocity change occurs at 566.5 meters (Unit 6) where basaltic basement is encountered. An altered, fractured, vesicular basalt sample from the core catcher of Core 62 has a horizontal sonic velocity of 3.74 km/sec (Table 3). A more homogeneous basalt sample from Core 63 has a vertical velocity of 4.37 km/sec and a horizontal velocity of 4.13 km/sec. The deepest basalt samples measured are from Sections 1, 2, and 3 of Core 64. These samples have velocities of 5.12 to 5.54 km/sec in the vertical direction and 5.22 to 5.49 km/sec in the horizontal direction. These samples appear to be the most homogeneous tested and best represent basaltic velocities at this site. A maximum one-way travel time for seismic energy traveling from the sediment/water interface to the basalt basement can be calculated as follows: 26 Depth Interval (m) Average Velocity (km/sec) Travel Time (sec) 0-25 25-70 70-150 150-480 480-566 1.50 1.58 1.54 1.70 1.80 0.017 0.028 0.052 0.194 0.048 0.339 Thus maximum one-way travel time at Site 231 for the basement reflection should be 0.339 seconds. Acoustic Impedance The reflection coefficient is inherently related to the acoustic impedance. Thus, sharp acoustic impedance changes should be associated with the major reflectors. The acoustic impedance profile is smooth throughout the 566.5 meters of nanno chalk mud, increasing from 2.5 × I0 5 g/cm2 sec near the surface to 3.5 × g/cm2 sec directly above the basaltic basement. Unit 2 has an acoustic impedance increase from 2.64 to 3.25 × I0 5 g/cm2 sec. Due to the small thickness of the included sandy layers, it is doubtful that a reflection would be observed from these horizons in recordings made with normal seismic frequency bandwidths. However, individual sandy layers within Unit 2 could be observed if high frequency-short pulses were employed. The only major reflector observed on the acoustic impedance profile is Unit 6 (basaltic basement). The basalt has a velocity of approximately 5.3 km/sec and a bulk density of about 2.8 g/cm2. Thus, the acoustic impedance is about 14.8 X I0 5 g/cm2 sec or 4 times that of the overlying sediment layer. The previously calculated travel time for the basement reflection (0.34 seconds one-way travel time) agrees well with the ±0.60 seconds two-way travel time determined from the seismic reflection profiles in Figure 2. INTERSTITIAL WATER CHEMISTRY Salinity: Gulf of Aden bottom water at this site has a salinity close to 35 % o (Wyrtki, 1971). Pore waters show a fairly rapid decrease in salinity from 35.5 °/ oo at 5 meters to 32 %o at 60 meters; values between 60 and 550 meters are in the range 32.5 ± 1 o / o o (Table 4 and Figure 3). Depletion of SO4~ by sulfate reducing bacteria could account entirely for this salinity trend. SITE 231 TABLE 4 Interstitial Water Chemistry- S ite 231 Depth Below Sea Floor (m) Salinity Alkalinity (meq/ kg) (%o) Surface seawater 5 20 45 63 80 110 123 150 175 194 215 243 262 299 329 365 405 436 479 495 551 36.2 35.5 35.2 34.6 32.2 32.2 32.2 32.2 32.2 31.6 31.6 b 33.8 31.4 32.2 31.9 31.9 31.6 31.6 32.4 32.4 33.5 32.7 pH and Alkalinity: pH measurements are recorded in Table 4 and were made with a combination electrode; values in parentheses were made with a punch- in electrode. Values between 5 and 400 meters are 7.6 ± 0.2, but between 400 and 500 meters they decrease to 6.9 (Figure 4). These are fairly typical ranges of values found in marine sediment pore waters and are indicative of equilibration r essu r es greater than atmospheric, the excess with CO2 P CO2 being a by product of bacterial metabolism. Alkalinities are given in Table 4 and the data plotted versus depth in Figure 4. A fairly rapid increase occurs between 5 and 60 meters, followed by a fairly rapid decrease from 60 to 215 meters; from 215 to 550 meters a further small decrease occurs. Below 205 meters, alkalinities are lower than that of seawater. The great increase in alkalinity below the sediment- water interface is presumably related to bacterial C O 2 production; the deeper decrease in alkalinity may reflect cessation of bacterial activity and slow consumption of the alkalinity by mineral- pore water reactions. Water Content, Porosity, and Bulk D ensity: These data comprise Table 5. Water content decreases from 35 to 40 weight percent in the upper core sections to 20- 25 weight percent near the base of the cored sequence. Porosity and bulk density data are only available for the interval 0- 90 meters and show little trend in their variation. 7.55(7.54) 7.51(7.39) 7.53(7.34) 7.62 7.50 7.49 7.48 7.39 7.40 7.51 7.94 7.47 7.54 7.66 7.57 7.89 7.80 7.39 7.36 7.14 6.85 2.09 2.71 4.62 6.54 6.05 5.96 4.90 3.54 2.90 2.44 1.35 1.43 1.36 1.50 1.11 0.95 0.95 1.04 0.81 0.86 0.35 a pH values in parentheses are corrected, (see Chapter 1, Explanatory Notes). ^Contaminated. / "~ ~ - — - _ β _ — """ ? SEA WATER CONTAMINATION X punch- in elec t rod e INTERSTITIAL PORE WATER pH and s.w. - 1 1 29 I 30 .5 31 32 33 34 35 36 7.0 PH 7.5 1 ALKALINITY S.W. I L_ 2 3 4 ALKALINITY 5 6 7 8 9 (m eq / kg ) SALINITY [ " / . „ ) Figure 4. Interstitial pore water pH and alkalinity, Site Figure 3.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Interstitial pore water salinity, Site 231. 231. 27 SITE 231 TABLE 5 Water Content, Porosity, and Bulk Density of Sediments-Site 231 Core, Section, Top of Interval Water (cm) (%) 1-1,137 2-2, 34 2-2, 72 2-2, 100 2-2,127 3-1,141 3-2, 20 3-2, 53 3-2, 74 3-2, 95 3-2,115 3-2, 132 3-2,144 3-3, 24 3-4,48 3-3, 66 3-3, 89 3-3,109 3-3, 132 3-4,113 3-4,139 3-4,146 4-1, 34 4-1,73 4-1,102 4-1,126 4-2,17 4-2, 88 4-2,111 4-2, 134 5-4,132 4-3, 37 4-3, 63 4-3, 88 4-3,112 4-3, 133 5-2, 46 5-2, 77 54,80 5-2, 109 5-3, 127 5-4,35 5-5,26 5-5, 72 5-5, 132 5-6,47 5-6,86 5-6,112 6-1, 120 6-3,72 6-3,127 6-4, 30 6-4,83 6-4,142 6-5,61 6-5, 138 6-6, 28 7-3, 98 7-3,134 8-1, 77 8-2,42 8-3, 133 84,46 8-4,122 8-6, 65 9-3, 77 28 46.31 35.22 37.32 35.37 38.46 38.15 35.44 38.59 38.06 36.39 38.86 38.83 36.13 37.29 37.28 32.38 35.06 38.29 29.08 40.13 35.45 31.79 35.78 36.74 35.66 36.66 37.11 37.23 33.05 34.04 34.96 38.33 40.22 39.96 39.91 37.31 42.75 40.01 41.33 36.78 38.80 40.39 37.81 36.98 36.94 41.55 38.91 34.55 38.93 36.94 36.90 38.34 38.96 36.25 36.49 35.27 39.05 34.12 34.59 35.71 35.52 35.01 32.66 33.39 43.41 38.03 Porosity (%) Density (g/cm3) 66.50 53.06 56.93 54.21 58.61 57.65 54.50 59.68 58.98 57.76 58.56 58.48 55.76 58.18 57.17 50.96 54.96 56.85 48.02 61.06 54.85 1.4359 1.5065 1.5254 1.5326 1.5239 1.5111 1.5378 1.5465 1.5496 1.5872 1.5069 1.5060 1.5433 1.5596 1.5335 1.5738 1.5675 1.4847 1.6513 1.5215 1.5472 56.61 57.62 54.58 57.76 57.04 55.52 52,66 54.88 55.12 64.96 65.33 65.30 65.62 64.93 70.77 66.88 68.16 64.82 68.93 68.37 66.61 66.88 66.42 71.22 69.14 64.10 67.54 102.71 66.63 69.32 69.12 57.97 65.87 64.72 80.26 53.88 64.80 64.43 66.00 63.93 57.23 63.46 72.73 67.63 1.5821 1.5683 1.5305 1.5755 1.5370 1.4912 1.5933 1.6122 1.5766 1.6947 1.6243 1.6341 1.6441 1.7402 1.6554 1.6715 1.6491 1.7623 1.7765 1.6927 1.7617 1.8085 1.7980 1.7140 1.7769 1.8552 1.7349 2.7804 1.8056 1.8080 1.7741 1.5991 1.8051 1.8349 2.0553 1.5791 1.8733 1.8042 1.8581 1.8260 1.7522 1.9005 1.6754 1.7783 TABLE 5 ­Continued Core, Section Top of Interval Water (cm) (%) 9-4,100 11-2,83 5-2,140 5-3,31 5-3,58 5-6, 24 5-6, 69 6-2, 14 6-2, 139 7-3,143 8-5, 33 9-3, 138 9-4, 14 9-5, 99 10-3, 142 10-4,127 11-3,92 12-4,118 13-5,135 13-6, 84 14-4,67 14-5,128 15-1, 126 15-2,130 16-6,58 17-2, 72 17-4,100 17-5,55 18-3, 142 19-2, 84 19-4,77 20-2, 92 20-4,117 20-6,113 21-2, 136 214,124 21-6,98 22-2, 84 22-4,124 23-2,108 234, 66 23-6, 82 244,105 24-6, 78 25-2, 100 254, 76 25-6, 79 26-2,106 264, 122 26-6, 82 27-2, 55 274,104 27-6, 96 28-2, 86 28-4,104 28-6, 82 29-2, 114 29-5,112 30-2, 84 30-5, 76 31-2,75 32-2, 50 32-3, 80 33-2, 86 33-3,75 34-2, 114 34-3,110 35-1,98 35-3,103 34.39 34.62 31.39 17.36 26.14 38.73 35.84 28.44 36.30 23.06 31.85 36.42 40.06 35.00 35.97 31.31 37.00 35.78 19.45 34.73 34.72 33.15 37.34 30.97 37.95 26.98 33.37 32.18 33.76 33.39 35.77 36.62 32.03 31.66 31.04 28.68 30.06 30.73 29.36 28.66 32.97 30.61 31.05 31.02 32.30 33.91 30.85 32.69 30.75 33.29 32.41 29.27 32.32 34.15 33.69 31.55 31.09 29.47 31.97 28.12 31.35 32.93 27.08 30.54 29.97 29.32 27.00 27.96 30.58 Porosity (%) Density (g/cm3) 61.70 68.03 1.7941 1.9650 SITE 231 TABLE 5 ­Continued Core, Section, Top of Interval Water (cm) (%) 36-3, 94 36-4, 106 37-2, 78 38-2, 90 39-2, 90 41-4, 100 42-2, 4 42-5, 86 43-2, 70 43-2,4 43-2, 84 43.5,95 45-2, 71 45-2,148 46-2, 52 46-5,81 47-3,128 48-2, 95 50-2,118 51-4,94 51-6,48 51-6,59 52-2, 119 54-2, 93 55-3, 134 57-2,111 58-5, 37 59-3,94 60-2, 141 61-6,95 Porosity (%) Density (g/cm3) 27.76 28.17 27.87 31.48 24.57 24.87 23.77 32.94 28.89 32.11 29.64 25.78 25.93 25.00 24.07 23.45 22.59 27.84 22.83 22.37 24.27 24.25 26.70 28.46 22.91 23.35 22.08 20.83 23.36 21.20 CORRELATION OF REFLECTION PROFILES AND LITHOLOGIES The characteristics of the reflection profiles obtained in the near-site area and onsite can be summarized rather briefly. The sequence observed consists of three units: (1) possibly stratified or layered sediments of variable thickness resting on (2) acoustically transparent material also of variable thickness which in turn overlies (3) acoustic basement. The thickness of the stratified sediments ranges between 0.1 and 0.4 sec (two-way travel time); the thicker sections apparently are ponded in the acoustically transparent layer by basement hills. The description of stratified or layered sediments is not wholly based on these particular records (Figure 5) where the reflected source pulse obscures any such character, but on other observations from R.R.S. Discovery; R/V Chain, and R/V Conrad (unpublished data). Since the total depth to basement surface varies between 0.35 and 0.60 sec, and the base of the transparent layer is conformable with it (as are all but the uppermost sediments), the thickness of this intermediate depth material depends on the surface relief of the basement, being roughly between 0.25 and 0.55 sec. The basement topography is subdued by comparison with that of the nearby West Sheba Ridge; the relief is on the order of 0.05 sec. While this is not a large change in absolute depth, it amounts to about 130 meters of surface relief. (This is calculated using the velocity value reported by Laughton and Tramontini [1969, Sta. 6228], of 5.22 km/sec for the Layer 2 basement material.) Laughton and Tramontini (1969) described the stratified sediments as turbidites and further suggested that the transparent layer might be of evaporitic composition. These are questions that should be resolved by the drilling. In this light, it seemed expedient to attempt continuous coring of this site. Figure 5 shows the relation between the recorded reflection profile and the generalized lithology; the relation to physical properties is shown in Figure 2. The sediment sequence that extends to the acoustic basement surface is acoustically transparent except in the upper 0.3 sec portion, where the source pulse appears. This pulse is here elongated enough to suggest that some part might represent a reflecting horizon within the layer. The remainder of the acoustically transparent material appears to be represented by the nanno chalk mud. The acoustic and the volcanic basement depths are in excellent agreement. SUMMARY, CONCLUSIONS, AND SPECULATIONS The single hole drilled at Site 231 was continuously cored through 566.5 meters of sediment extending down to middle Miocene in age, and into 17.5 meters of basalt basement. The Pleistocene and Pliocene parts of the section are more variable in lithology than is the Miocene. From 0 to 7 meters the sediment is a light olive-gray nanno ooze. Between 7 and 64 meters, the sediment is a nanno ooze with intercalated sandy horizons. The sands are variable in composition, and some include material of reef origin, possibly as a result of the erosion of reefs on the continental shelf during periods of lowered sea level during the Pleistocene. From 64 to 121 meters, the sediment consists of a relatively uniform nanno ooze. Some derived shallow-water fossils were obtained between these depths, indicating slumping of material down the continental slope. Within this interval, the Pliocene/Pleistocene boundary has been placed at 102 meters at the highest occurrence of Discoaster brouweri. Below 121 meters and down to a depth of 236 meters, nanno oozes contain more layers of intercalated coarse sediments, including four volcanic ash layers associated with the eruption of Pliocene rhyolites. The base of the Pliocene is at approximately 254 meters. Lithologically, the lower Pliocene sediments are very similar to the upper Miocene deposits below. The Miocene sediments between 254 meters and basement consist of a very uniform grayish-olive nanno ooze. The monotony of this sequence is broken only by patches of bitumen and a shelly quartzose sand layer at 425 meters. Hydrogen sulphide was detected throughout much of this section. Throughout the section, calcareous plankton is common, with calcareous nannoplankton slightly etched and planktonic foraminifera moderately to poorly preserved. Radiolarians are abundant and well preserved in the uppermost core only; they are present but poorly preserved throughout the remainder of the section. The sedimentary sequence is apparently uninterrupted from middle Miocene to Quaternary and the average sediment accumulation rate for the entire series is 43.7 m/m.y. Pleistocene and upper Pliocene sediments accumulate with a rate higher than the other series, averaging 59.3 m/m.y., reflecting slumping of coarse elements from shelf areas during these epochs. 29 SITE 231 iNanno-marl--muc Nanno ooze, sandy horizons Nanno ooze 100 Nanno ooze 200 — Sandy horizons Nanno ooze 300 (b) LU Q 400 (a) 500 600 Basement Figure 5. Generalized lithology and seismic sections; core length is in meters, the seismic section in seconds of two­way travel time. In the delayed sweep recording the outgoing pulse obscures the transparent layer, center of record (a). The physical properties of the sediments are, like the lithology, fairly uniform throughout the section. Only one slight variation in bulk density and porosity occurs; it is associated with a sandy layer in Core 5. Overall trends in both these properties can be attributed to normal consolidation of the sediment. The sonic velocity profile of the section shows a smooth increase from 1.50 km/sec near the surface to 1.80 km/sec just above basement, also reflecting the uniformity of the sediment throughout the section. Basalt basement was reached at a depth of 566.5 meters, the basalt being similar to standard oceanic tholeiite and extrusive in origin. 30 In summary, the gross characteristics of the entire section, excluding the basalt, are very uniform. This suggests near constant conditions of depth, carbonate productivity, and detrital input in this area since the inception of deposition in middle Miocene times. Some of the fine-grained detrital material in the sediments may be eolian in origin; aridity in the potential source areas of Somalia probably precluding a large input of water transported sediment. Most of the principal aims of this site were met. The age and lithology of the entire sedimentary sequence has been established, but the speculation that the basal transparent layer might be evaporites has proved to be false. The age SITE 231 and lithology of the basement have been established. The inhomogeneities in the upper part of the section result from the intercalation of coarse sediment, as suggested from the seismic profiles. REFERENCES Cernock, P. J., 1970. Sound velocities in Gulf of Mexico sediments as related to physical properties and simulated overburden pressures: Texas A&M Univ. Tech. Rept. 70-5-T, Naval Res. Contract N000 14-68-A-0308 (0002) Oceanography, 114 p. Hamilton, E. L., 1965. Sound speed and related physical properties of sediments from Experimental Mohole (Guadalupe Site): Geophysics, v. 30, p. 257-261. Laughton, A. S. and Tramontini, G., 1969. Recent studies of the crustal structure in the Gulf of Aden: Tectonophysics, v. 8, p.359-375. Laughton, A. S., Whitmarsh, R. B., and Jones, M. T., 1970. The evolution of the Gulf of Aden, Roy. Soc. London Phil. Trans., v. 267, p. 227-266. Wyrtki, K., 1971. Oceanographic Atlas of the International Indian Ocean Expedition: Washington, (U.S. Government Printing Office), 531 p. ADDITIONAL SELECTED REFERENCES Bennett, R. H., and Keller, G. H., 1973. Initial Reports of the Deep Sea Drilling Project, Volume XVI: Washington (U. S. Government Printing Office). Peterson, M. N. A., Edgar, N.T. et. al., 1970. Initial Reports of the Deep Sea Drilling Project, Volume II: Washington (U. S. Government Printing Office). Whitmarsh, R. B., 1972. Initial Reports of the Deep Sea Drilling Project, Volume XII: Washington (U. S. Government Printing Office). APPENDIX A PRELIMINARY OBSERVATIONS ON THE IGNEOUS ROCKS SAMPLED AT SITE 231 Leonid V. Dmitriev, Vernadsky Institute of Geochemistry, Academy of Sciences of the USSR, Moscow and Robert L. Fisher, Scripps Institution of Oceanography, University of California, San Diego La Jolla, California Drilling at Site 231 encountered igneous rock, here acoustic basement, at a depth of 566.5 meters below the mudline. It was continued 17.5 meters into extrusive material, considered to be flows signifying the top of the basement, 7.7 meters of basaltic rock were recovered. Details of layering, fracturing, and structure are indicated on the visual core description columns. Megascopic Description The igneous rock recovered between 566.5 and 584 meters at Site 231 is predominantly dense, gray-black, slightly altered uniform basalt with small seams of glassy materials that generally coincide with steeply dipping fractures (Figure 6: 231-62-1, CC). The glassy zones, and brecciated glasses, are only 2-5 cm thick; but there are 14 Figure 6. Core catcher sample from 231­62­1, magnified 2Χ. Note dip of fracture andseam of brecciated glass. such seams within the 7.7 meters of core recovered. In the core catcher sample pictured, the fractured surface shows remains of glassy breccia and evidence of scratches made by movements during emplacement. The breccias commonly are cemented by fine-grained carbonate material, principally relics of foraminifers but also some Radiolaria, that has lodged in cracks in the basalt, forming veins up to 3-4 cm thick. Two inclusions of slightly metamorphosed sediment are present in the upper part (231-62-1) of the basalt section. These sediments display vestiges of layering and fossils. The upper of these inclusions is 10-15 cm thick; that of the lower is not known because it was partially destroyed during drilling. Altered or baked zones are clearly distinguishable in both inclusions; in each, the upper altered zone is 1-1.5 cm thick, and the lower is 3-4 cm. The contact between the uppermost glassy layer of basalt and the base of the overlying carbonate sediment was recovered in Section 231-62-1; the contact is marked by a zone of baking or alteration about 3 cm thick, containing fine grains of pyrite. The contact itself is almost horizontal, and the layered sediments above it dip less than 15°. 31 SITE 231 Preliminary Petrographic D escription At least fourteen thin sections prepared from Hole 231 "basement" were examined at sea. This inspection determined that the majority of these rocks are slightly altered variolitic basalts of tholeiitic composition, and contain variously olivine, Plagioclase, magnetite, and both clinopyroxene and orthopyroxene. Olivine occurs in small isolated skeletal crystals less than 0.1 mm long, colorless to pale yellow green (Figure 7,b). It is commonly replaced by serpentine or chlorite, and remains fresh only in the glass. Plagioclase, identified as labradorite Ang5 (1 010 40°), occurs as needle- like crystals, about 0.5 mm long, grouped in radial structures or fibrous aggregates (Figure 8). Skeletal forms predominate. Pyroxene, both clinopyroxene and orthopyroxene, interstitial among Plagioclase crystals, is found only in the granular basalts. It forms xenomorphs of colorless grains that display characteristic cleavage. H ypersthene is distinguishable by parallel extinction and augite by c λ Z 50°. Magnetite is disseminated in the glass as finely dispersed dusty grains. At Site 231, the basalt section consists principally of dense massive fragments, with typical variolitic texture, that contain 40- 50 percent palagonitized or fresh glass (Figure 9). G ranular basalts are rare; in the lower part of the drill hole, such rocks are present and contain pyroxene and 5- 10 percent glass (Figure 10). The porosity of the basalts is constant at about 2 percent but is about half that in the granular basalts. Vesicles generally have a regular sphenoidal shape and average 0.3 mm in diameter; there is one zone with oval vesicles and tachylitic structure in the same section (231- 64- 2- 3). Chilled zones, averaging 3- 4 cm thick, are similar to those in typical pillow lavas of submarine origin. The external surfaces are typically brown unaltered glass, with isolated crystals of olivine (Figure lla ) . Further toward the interior small dark brown spots appear, as the first stages of devitrification (Figure lib ) . Further inside, these spots or nuclei give way to common variolitic basalt. 0 . 1 mm 0 . 5 mm 0 . 5 mm Figure 7.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Skeletal crystals of olivine in fresh glass; Figure 8. Skeletal crystals of Plagioclase in variolitic basalt; 231- 64- 1- 1; unpolarized light. 231- 64- 2- 4; unpolarized light. 32 SITE 231 Ii n •4 <" ^# . , X , r mm • ­ k •: i * ; ~j Jx% • • v <;, • **r Α *Χ\i t f m m 1 , M*0zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Φ If f * , ?1 •» < *!*^ 1 • ** «• , * 1 mm Figure 9.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Radial structure of Plagioclase needles in variolitic basalt; 231- 64- 2- 2; unpolarized light. i» w . j . • ^? f ! • 6 β% I L. '" • - - - * *- M l "– t ' Λ I, i ( • 4 1 •" 1 • •* • *- * • zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA t ' \ * * * E j i• 1 mm Figure 10. Microdoleritic texture in basalt; 231- 64- 2- 4; unpolarized light. Figure 11. Glassy margin on a pillow surface; 231- 64- 1- 1: (a) external zone, fresh glass with palagonitization around fracture: (I)fracture filled by carbonatechlorite- zeolite material, (2) palagonite, (3) fresh glass; (b) initiation of devitrification. 33 SITE 231 The majority of this basalt pile is only slightly altered; such alteration includes palagonization of glass, serpentinization or chloritization of olivine, and chloritization of pyroxenes. 1) Glassy rind is everywhere fresh. Palagonization, in zones thinner than 1.5-2.0 mm, spreads from thin fractures filled by the chlorite-zeolite-carbonate material cementing glassy breccias. 2) Vesicles are lined with carbonates, chlorite, and zeolites. When the filling is zoned, the exterior layer is chlorite and the center of the vesicle contains carbonate or zeolites. 3) Oxidation along thin fractures represents the most recent alteration; it results in formation of dark brown iron hydroxides which are adsorbed on Plagioclase grains and the inside of vesicles. The oxidized zone or aureole extends 1.0-1.5 cm outside the fracture. or fragments resting on the lava surface, have their primary character preserved; some of this material may have trickled into cracks and been little affected. Figure 12 portrays a schematic cross-section through such a sediment-lava pile. 4. The minor alteration of the basalts from Site 231 may indicate absence here of conditions causing greenstone metamorphism, or of hydrothermal activity. Discussion and Implications 1. The structure and composition of this basalt within the present Gulf of Aden is characteristic of oceanic tholeiite, and the glassy zones mantling the outer surfaces, variolitic texture, and skeletal form of crystals suggest it was formed by eruption under water. 2. The uniformity in composition and structure throughout the section recovered suggests that this hole was drilled through only one group of lava flows, which was the product of just one eruption. 3. The abundant interlayering of brecciated glass and dense basalt suggests that these components are part of a lava flow which moved down a steep slope and cooled rapidly. The numerous glassy zones suggest a very fluid magma. Internal fragmentation in the flow would result from incorporation or over-riding of the solidified crust to mix with the fluid lava. In this way, some fragments of sediments could be introduced into the moving mass, be metamorphosed, and their constituents cement fracture zones containing the brecciated glasses. Sediments, as chips 34 Leg 24, Site 231 Figure 12. Schematic cross­section through lava flow on a steep slope: (1) glass, (2) variolitic basalt, (3) inclusions of sediments, (4) later sediments, (5) drill hole. SITE 231 LITHOLOGY LITHOLOGIC DESCRIPTION NANNOFOSSILS FORAMINIFERA RADIOLARIA SERIES AGE (my ) DEPTH (in) <- > \ εc \ > Nanno ooze. 25- E._huxleyi2 Nanno ooze with intercalated sandy horizons consisting mainly of marly, shelly, silty, and G. oaeaniaa clayey sands. N23 N22 50 - 75 - G Nanno ooze uniform light olive gray, containing some shallow water fossils. . laribbeanioa P. laβunosa 100 - N21 1.8 102 C. 125- maaintyrei 150 - D. pentaradiatus 175 - Nanno ooze with intercalated sandy horizons. Volcanic glass and ash layers present. D. tamalis - 3.0 178 5.0 254 200 R. pseudo- N20- N19 umbilica 225 - C. acutuε 250 - N18 C. tvvoorniaulatus 275 300 - N17 Uniform, grayish olive nanno ooze becoming light gray toward" base. H 2 S present in freshly cut sections. primus 325 - N16- N15 350 35 SITE 231 S " I = LITHOLOGY LITHOLOGIC DESCRIPTION NANNOFOSSILS FORAMINIFERA RADIOLARIA SERIES AGE (m.y.) DEPTH (m) 350 C. primus 375 N16-N15 400 D. berggvenii LATE 425 •D. neohamatus 450 N14-N13 D. bellus 475 — 11.0 500 -. 482 D. hamatus 525 - MID. D. kugleri N14-N13 550 NI 3 D. exilis • 567 Basalt and volcanic glass with intercalated lithified nanno chalk. 600 36 S. heter­ omorphus Site 231 Hole Corel Cored I n t e r v a l : 0.0-0.5 m Site 231 Hole Core 3 LITHOLOGIC LITHOLOGIC DESCRIPTION MICARB BEARING NANNO OOZE Light o l i v e gray (5Y5/2) becoming grayer towards the base Smear 1-1-115 Micarb 5-10% Sand 5% Nannos 60% Quartz 1 - 2% S i l t 40% Forams 5XFG Feldspar <1% Clay 55% Diatoms 1JFP Rads Heavy Min. <1% 12FP Sponge Spic. <l>S Dolo. Rhombs < U <U Silicoflag. Smear 3-2-80 Sand 10% Nannos 70% S i l t 30% Plank. Forams 5%FG Clay 60% Benth. Forams 1% Rads 1%FP Cored Interval: 0.5-7.0 m LITHOLOGIC DESCRIPTION FORAM BEARING NANNO OOZE Light olive gray (5Y5/2) Smear 2-2-72 Sand 5% Nannos 70% Silt 30% Forams 5%FG Clay 65% Diatoms 2%FP Rads 2%FP Sponge Spic. <1% Fish Debris <1% NANNO OOZE Light olive gray (5Y5/2) Smear CC Sand 5% Nannos 60% Silt 45% Forams 5%FG Clay 50% Rads Pteropods 2% Diatoms 1% Sponge Spic. 1% Grain Size Sand 3% Silt 45% Clay 52% Explanatory notes in chapter 1 DESCRIPTION NANNO OOZE Light o l i v e gray (5Y5/2) A/G R/V C/G A/M A/G Cored Interval:7-16.5 m FOSSIL CHARACTER FOSSIL CHARACTER Quartz Micarb Glauconite Pyrite Dolo. Rhombs Bands s l i g h t l y more o l i v e and gray. Thickness of bands 30-40 cm. C/G A/M R/M Quartz Micarb Feldspar Mica Dolo. 2% 1-2% 1% 1% Rhombs 1% Core Catchei Quartz Feldspar Heavy Min. Dolo. Rhombs Vole. Glass Pyri te 51% Explanatory notes in chapter 1 NANNO RICH QUARTZ SAND Smear 3-4-120 Sand 50% Nannos 20% Plank. Forams 10% S i l t 25% Clay 25% 5% Pteropods Benth. Forams 1% Rads 1% Sponge S p i c 1% Echinoid Debris 1% Fish Debris 1% Quartz 50% 5% Micarb Pyrite 2% Feldspar 1% 1% Mica Dolo. Rhombs 1% Smear 3-4-146 Sand 30% Nannos !50%FG 5%FG S i l t 35% Forams 2%FP Clay 35% Rads Sponge Spic. 1% Pteropods 1% 2 0% Micarb 5% Quartz 1% Feldspar Heavy Min. Pyrite Site 231 Hole Core 4 Cored Interval:16.5-26.0 m S i t e 231 LITHOLOGIC NANNO RICH FORAM SAND LAYERS (4-2-30 to 35 and 4-2-44 to 54) Smear 4-2-54 Plank. Forams 40%FG Nannos 20%FG Pteropods 10%FM B e n t h . Forams 5% Rads 5%FM Sponge Spic. 1% Smear 4-2-120 Sand 5% Nannos 80XFG S i l t 40% Forams 5SSFG Clay 55% Rads 1%FP Grain Sand Silt Clay Size 38% 40% 23% Core 5 Cored I n t e r v a l : 26.0-35.5 m LITHOLOGIC DESCRIPTION Quartz Micarb Mica Heavy M i n . Pyrite Dolo. Rhombs DESCRIPTION MICARB RICH NANNO OOZE Light olive gray (5Y5/2) Smear 5-1-95 Sand 5% Nannos 50% Silt 40% Forams 5% Clay 55% NANNO OOZE Light olive gray (5Y5/2), H2S odor. Sand 40% S i l t 30% Clay 30% Hole 10% 10% 1% 1% 1% 1% Quartz 5% Heavy Min. 1-2% Mica 1% Smear 5-2-120 Sand 5% Nannos Silt 45% Forams Clay 50% Rads Diatoms Sponge Spic. Micarb Quartz Mica Vole. Glass Pyrite Dolo. Rhombs Heavy Min. 60% 5%FG 2%FP 1% 1% QUARTZ RICH SHELL SAND Grayish olive (10Y4/2) Smear 5-2-145 Sand 70% Nannos 20% Silt 15% Indet. Shell Clay 15% Detrit. 20% Forams 15% Pteropods 15% Rads 1% Sponge Spic. 1% Smear 5-3-90 Sand 50% Forams 30%FG S i l t 25% Indet. Shell Clay 25% Detrit. 30% Nannos 10-15% Pteropods Rads Sponge Spic. 5%FG 5%FP 20% 5% 2% 2% 2% 2% 1% Micarb 20% Quartz 2% Pyrite 2% Dolo. Rhombs 2% Quartz 20% Feldspar 5% Heavy Min. 5% Mica 2% Quartz Heavy Min. Feldspar Dolo. Rhombs 10% 5% 2% 2% 2% NANNO OOZE Light olive gray (5Y5/2) Smear 5-5-80 Sand 5% Nannos 80% Quartz 5% Silt 20% Forams 5%FG Dolo. Rhombs 1% Clay 75% Rads 2%FP Heavy Min. <H Alternate bands (10-30 cm thick) of predominantly greenish and olive gray respectively (Section 5 and 6) SHELL SAND 5-6-60 to 75 Olive black (5Y2/1) Grain Size Sand 1% Silt 56% Clay 43% Site 231 Hole Core 6 Cored Interval:35.5- 45.0 π Site 231 LITHOLOGIC Hole Core 7 Cored Interval:45.0- 54.5 m LITHOLOGIC DESCRIPTION FORAM RICH NANNO OOZE Light olive gray (5Y5/2) Smear 6- 1- 105 Sand 30% Nannos 50% Silt 30% Forams 20% Clay 40% Indet. Shell Detrit. 10% Rads 2%FP Sponge Spic. 1% SHELL SAND Grayish o l i v e (10Y4/ 2) Smear 6- 2- 100 Sand 60% Nannos S i l t 20% P l a n k . Foram s C l a y 20% In d e t . Shell Detrit. Benth. Forams Pteropods Lam e l l i b r . Sponge Sp ic . 30% 20%FG 20% 10%FG 5% 5% 2% Quartz 10% Pyrite 2% Mica 1% Heavy Min. 1% zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Smear 7- 3- 80 Sand 5% Nannos Silt 40% Forams Clay 55% Rads Sponge Spic. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA λ% 1% NANNO OOZE Light olive gray (5Y5/2) Smear 6- 4- 100 Sand 2% Nannos 80% Silt 40% Forams 5% Clay 58% Rads 1% Sponge Spic. 1% NANNO OOZE Light olive gray (5Y5/2) 5% Quartz Fe l d s p ar 1% Heavy M in. 2% Dolo. Rhombs 1% FORAM NANNO OOZE Lig h t o l i v e gray (5Y5/ 2) ( d is t u r b e d l a y e r dark r ed d ish brown [ 10R3/ 4] ) Smear 6- 2- 144 Sand 10% Nannos 40% Quartz 10% S i l t 40% P l a n k . Forams 20%FG Heavy M i n . 2% C l a y 50% B e n t h . Fo r am s 10%FG Pyrite 2% Pt er op od s 5% D o l o . Rhombs 1% Rads 2%FP Sponge Spic. Fish Debris DESCRIPTION Mica 2% quartz 1% Pyrite 1% Dolo. Rhombs 1% SHELL Smear Sand Silt Clay 80%FG 5%FG 1%FP U SAND 7- 3- 142 60% Nannos 30X 20% Forams 30% 20% Indet. Shell Detrit. 20% Pteropods 5% Lamellibr. 5% NANNO OOZE Light olive gray (5Y5/2) Quartz 2% Mica 1% Heavy Min. U Pyrite 1% Dolo. Rhombs 1% Quartz 5% Pyrite 5% Site 231 Cored Interval: 54.5-64.0 m Core 9 Cored Interval:64.0-73.5 m FOSSIL CHARACTER FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2), burrow mottling between 1 m and 3 m Smear 8-1-80 Sand 10% S i l t 40% Clay 50% A/M F/M Nannos 70% Forams 5% Sponge Spic. 1% Smear 8-2-80 Sand 5% Nannos 80% S i l t 40% Forams 1% Clay 50% C/P C/G Quartz Feldspar Pyrite Dolo. Rhombs Mica Heavy Min. 5% 2% 2% 2% 1% 1% Micarb 10% Quartz 1% Pyrite 1% Dolo. Rhombs 1% A/P NANNO OOZE Light olive gray (5Y5/2) with ooze filled burrows throughout. C/M Smear 9-2-90 Sand 5% Nannos Silt 40% Forams Clay 55% Sponge Spic. Rads A/M 8-3-0 to 30 some burrow mottling Smear Sand 5% S i l t 45% Clay 50% Nannos Pteropods Rads Silicoflag. Fish Frags. 70% 2% 1%FP 1% 1% Quartz Feldspar Mica Heavy Min. Pyrite 2% 1% 1% 1% 1% DESCRIPTION 80% 5% 5% 1%FP Quartz 5% Pyrite 2% Feldspar 1% Dolo. Rhombs 1% A/M 8-4-75 to 95 sand filled burrows Smear 8-4-91 Sand 40% Silt 30% Clay 30% (from burrow) Plank. Forams 40% Nannos 30% Indet. Shell Detrit. 5% Benth. Forams 2- 5% Pteropods 2% Quartz Pyrite Feldspar Dolo. Rhombs Heavy Min. 5% 5% 2% 2% 1% Some sand filled burrows 9-4-5 to 30. A/M 8-5-0 to 90 sand filled burrows, 8-5-90 to 8 cc ooze filled burrows QUARTZ RICH SHELL SAND 8-5-27 to 36 Smear 8-5-35 Sand 40% Nannos 30% S i l t 30% Forams 20% Clay 30% Rads 5% Echinoid Debris5% Fish Debris 1% Quartz 20% Feldspar 5% Pyrite 5% Heavy Min. 1% A/M Occasional coarse shell d e t r i t u s throughout. A/P Smear 9-5-90 Sand 3% Nannos Forams S i l t 45% Clay 52% Sponge Spic. Rads A/P C/M C/G A/M Core Catcher Explanatory notes in chapter 1 C/M Core Catche Explanatory notes in chapter 1 MH 5% 2% • Quartz Feldspar Mica 5=, 2% _ Pyrite Dolo. Rhombs 1% Core 10 Cored Interval: 73.5-83.0 m Site 231 FOSSIL CHARACTER LITHOLOGIC 10-2-5 10-2-55 10-2-95 10-2-112 Core 11 Quartz 2% Dolo. Rhombs 2% C/G Foram limestone fragment Sandstone fragment Large Scaphopod Large ' C e r i t h i d ' Smear 11-3-80 Sand 5% Nannos Silt 45% Forams Clay 50% Rads Sponge Spic. Diatoms Pteropods A/P Core Catcher A/M Smear 10-4-80 Nannos Sand 3% Silt 35% Sponge Spic. Clay 62% Forams Rads Fish Debris Cor Catcher Explanatory notes in chapter 1 DESCRIPTION NANNO OOZE Light o l i v e gray (5Y5/2); some m o t t l i n g in 11-2 and 11-3 10-3-145 Sandstone fragment 10­4­10 Foram limestone fragment Some mottling in 10-4 and 10-5 A/M Cored Interval: 83.0-92.5 m LITHOLOGIC DESCRIPTION FORAM RICH NANNO OOZE Light olive gray (5Y5/2) Large Gastropod at 10-1-110 Smear 10-1-100 Nannos 80% Sand 3% Plank. Forams 10% Silt 40% Clay 57% Benth. Forams 2% Rads 2%FP Sponge Spic. 2% Pteropods 1% A/P Hole FOSSIL CHARACTER Explanatory notes i n chapter 1 80% 3% 1%FG HFP 1% Quartz Feldspar Pyrite Dolo. Rhombs 5% 1% 1% 1% 70% 5%FG 2«FP 2% 1%FP 1% Quartz Mica Pyri te Dolo. Rhombs Feldspar 10% 2% 2% 2% 1% Site 231 Hole Core 12 Cored Interval:92.5-102.0 m Site 231 LITHOLOGIC DESCRIPTION Hole Core 13 Cored I n t e r v a l : 1 0 2 . 0 - 1 1 1 . 5 m LITHOLOGIC DESCRIPTION QUARTZ RICH NANNO OOZE Light olive gray (5Y5/2) QUARTZ RICH NANNO OOZE Light o l i v e gray (5Y5/2) Smear 12-2-80 Sand 5% Nannos 60% S i l t 4058 Forams 5% Clay 55X Sponge Spic. 2% Rads IX Pteropods 1% Fish Debris IX Quartz 10-20% Heavy Min. 2% Dolo. Rhombs 2% Feldspar 1% Vole. Glass 1% Pyrite 1% Grayish o l i v e (10Y4/2) Zone 12-3-0 to 45 Sand f i l l e d burrows a t 13-3-100 and 13-3-145 Smear 13-3-80 Nannos 60-7OX Sand 5% S i l t 25X Forams 2% Clay 70X Rads 2% Sponge Spic. 2% Smear 12-4-40 Sand 5X Nannos 50% S i l t 20% Forams 5% Clay 75% Rads 1% Sponge Spic. 1% Quartz 10-20% Heavy Min. 2- 5% Vole. Glass 2% Pyrite 2% Dolo. Rhombs 1% Quartz 10-20X Feldspar 2% Dolo. Rhombs 1% Some burrow mottling in 13-4 Yellowish gray from 12-4-143 (5Y7/2) Occasional sand f i l l e d burrows at 13-5-100 Hole Core 14 Cored Interval:111.5-121.0 m Site 231 Hole Core 15 Cored Interval:121.0-130.5 m FOSSIL CHARACTER FOSSIL CHARACTER LITHOLOGIC DESCRIPTION LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2); structureless A/P Smear 14-2-8 Sand 2% Nannos 80% Silt 28% Forams 2% Clay 70% Rads 1% Sponge Spic. 1% Quartz Heavy Min. Pyrite Dolo. Rhombs QUARTZ RICH NANNO OOZE Grayish olive (10Y4/2), slowly grading to light olive gray (5Y5/2) Smear 15-1-90 Sand 5% 'tO-50% Quartz Nannos Silt 25% Rads 3% Micarb Clay 70% 2% Feldspar Sponge Spic. Forams 1% Vole. Glass Heavy Min. Pyrite Dolo. Rhombs C/G 52 U 1* 1% C/P R/M QUARTZ RICH NANNO OOZE (15-2-120 to 15-3-30) Grayish o l i v e (1OY4/2) Smear 15-3-20 Sand 40% Nannos 50% Quartz 1 Silt 30% lOOT> Feldspar Rads Clay 30% Plank. Forams 5% Heavy Min. Benth. Forams 5% 1% Sponge Spic. Echinoid Debrisl% t, £ A/M Smear 14-4-8 0 Sand 5% Nannos 803! S i l t ::: Sponge Spic. 2% Clay Forams 1% Rads 1% C/G Micarb Quartz Pyrite Dolo. Rhombs 2 cm thick sand layer at 14-5-112 Grayish olive (10Y4/2) Zone 14-5-125 to 135 Explanatory notes in chapter 1 Core Catcher Explanatory notes in chapter 1 Light olive gray (5Y5/2) Zone (15-3-35 to 85) with sand filled burrows at 15-3-60 Grain Size Grain Size Sand 1% Sand 41% Silt 56% Silt 38% Clay 43% Clay 21% Site 231 Hole Core 16 Cored Interval:130.5-140.0 m Site 231 LITHOLOGIC DESCRIPTION Hole Core 17 Cored Interval:140.0­149.5 m LITHOLOGIC DESCRIPTION QUARTZ RICH NANNO OOZE Grayish o l i v e (10Y4/2) Smear 17-1-100 Sand 3% Nannos 50% S i l t 27% Forams 5% C l a y 70% Rads 2% Sponge S p i c . 1% NANNO OOZE Light olive gray (5Y5/2) NANNO DOLOMITIC CLAYEY S I L T L i g h t o l i v e gray (5Y5/2) Smear 17-2-100 Sand 25% Nannos 20-30% S i l t 40% Forams 5% Clay 35% Rads 5% Sponge S p i c . 2% Occasional sand filled burrows Quartz 10­20% Feldspar 5% Pyrite 5% D o l o . Rhombs 5% Heavy Min. 2% Dolo. Rhombs 20-30% Quartz 10% Heavy M i n . 1% Grayish o l i v e (10Y4/2) Large c l a y b a l l a t 17-2-125 Smear 16-4-80 Sand 3% Nannos 80% Silt 27% Rads 1% Clay 70% Sponge Spic. 1% Quartz Pyrite Vole. Glass Mica Dolo. Rhombs 5% 5% 2% 1% 1% Mottled burrows QUARTZ RICH NANNO OOZE Color grading to l i g h t o l i v e gray (5Y4/2) Site 231 Hole FOSSIL CHARACTER Core 18 Cored Interval .- 149.5- 159.0 m Core 19 Cored Interval .- 159.0- 168.5 m FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) NANNO OOZE Light olive gray (5Y5/2) Smear 18- 2- 80 Sand 5% Nannos 70- 80% Silt 352! Rads 3% Clay 60* Forams Z% DESCRIPTION FORAM RICH NANNO OOZE Smear 19- 2- 44 30% Nannos 30- 40% Pl an k . Forams 10% 35% B en t h . Forams Clay 35% Rads Sponge S p i c . C/H F/M Sand zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Quartz 5% Silt Pyrite 2% Heavy Min. U Dolo. Rhombs U R/M Qu ar t z Fe l d s p ar Heavy M i n . Do l o . Rhombs NANNO OOZE Occasional burrow mottling C/P Smear 19- 3- 90 Nannos Sand 5% 80S S i l t 35% 2% Forams 1%FP Clay 60% Rads Sponge S p i c . 1% zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO Quartz Color change to grayish olive (10Y4/2) Mica Heavy Min. Pyr it e λ% Dolo. Rhombs 1% Core Catcher Explanatory notes in chapter 1 C/P Core Catcher Explanatory notes in chapter 1 Core 20 Cored Interval .-178.0-187.5 m Cored Interval:168.5-178.0 m FOSSIL CHARACTER H W FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Light o l i v e gray (5Y5/2) NANNO OOZE Light olive gray (5Y5/2) C/G A/M VOLCANIC ASH Medium dark gray (N4) Smear 21-2-22 VOLCANIC ASH Dark gray (N3) Smear 20-2-31 Sand 5058 Rads 1% S i l t 25* Clay 252! DESCRIPTION Sand 50% S i l t 3056 Clay 20% Vole. Glass 90% Feldspar 5% Quartz 1% Vole. Glass 95% Quartz 2% Feldspar 2% Heavy Min. U Color grading into grayish o l i v e (10Y4/2) a t 20-2-115 and l i g h t o l i v e gray (5Y5/2) at 20-3-5 Smear 20-3-80 Sand 5% Nannos Forams Silt 35% Clay 60% Rads Quartz 2% Feldspar 2% D o l o . Rhombs 2% Heavy M i n . 1% Pyrite 1% NANNO AND FORAM RICH SILTY QUARTZ SAND Olive gray (5Y3/2) Smear 21-2-108 Sand 40% Nannos 20% 50% Quartz S i l t 30% Feldspar 10% Forams 10-20% 1 - 5% Pyrite 5% Rads Clay 30% Heavy M i n . 2% Micarb 2% D o l o . Rhombs 2% A/M Color grading into grayish o l i v e (10Y4/2) a t 20-3-140 Smear 21-4-100 Sand 5% Nannos 80% Silt 35% Forams 2% Clay 60% Rads 1%FP NANNO OOZE Light olive gray (5Y5/2); occasional thin sandy layers Color grading to grayish olive (10Y4/2) at 20-5-40 Color grading to light olive gray (5Y5/2) at 20-5-90 C/M Core Catchei Explanatory notes in chapter 1 C/M Colorless Glass 60% Palagonitized and Recryst. Glass " 30% Zeolites 1% Feldspathoids 1% Core Catche Explanatory notes in chapter 1 Quartz 5% Feldspar 2% Dolo. Rhombs 2% Mi ca 1% Vole. Glass 1% Pyrite 1% Site 231 Hole Core 22 Cored I n t e r v a l : 1 8 7 . 5 - 1 9 7 . 0 m Site 231 LITHOLOGIC DESCRIPTION NANNO OOZE Light o l i v e gray (5Y5/2) VOLCANIC ASH in l i g h t o l i v e gray (5Y5/2) sandy s i l t y zone Smear 22-1-88 Sand 60% Vole. Glass S i l t 25% (Colorless) 90-95% Clay 15% Quartz 1 - 3% Feldspar 2% Heavy Min. 1% NANNO OOZE Smear 22-5-40 Sand 2- 5% Nannos 90% Silt 25% Rads Z% Clay 70% Sponge Spic. 1% Quartz 2% Feldspar 2% Vole. Glass 2% Dolo. Rhombs 1% Hole Core 23 Cored I n t e r v a l .-197.0-206.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) with sandy zones at 23-3-20 Site 231 Hole Core 24 Cored Interval:206.5- 216.0 m Site 231 LITHOLOGIC Hole DETRITAL SILTY SAND 24- 2- 10 30% Nannos 402! 40% Forams 10- 20% 30% Rads 5% Sp o n g e S p i c . λ% Smear 24- 4- 100 Sand 1 - 5% Nannos S i l t 30- 40% Forams C l a y 50- 60% Quartz Feldspar Heavy M i n . D o l o . Rhombs Py r i t e Cored Interval:216.0- 225.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Li g h t o l i v e g ray (5Y5/ 2), a t 24- 1- 132 1 cm sand l aye r NANNO Smear Sand Silt Clay Core 25 DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) 20? 10% 2% 2% 1% zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 80% 2% Quartz Fe l d s p a r Heavy M i n . Pyrite Dolo. Rhombs 5% 2% 2% 2% 2% Smear 25- 4- 100 Sand 1 - 5% Nannos Silt 30% Forams Clay 65% Rads 90% 2% 1% Quartz 2% Py r i t e 1- 2% Feldspar 1% Do lo . Rhombs 1% Site 231 Hole Core 26 Site 231 Cored Interval:225.5-235.0 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2); 1 cm sandy layer at 26-1-140 Hole Core 27 Cored Interval: 235.0-244.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) Site 231 Hole Cere 28 Site 231 Cored Interval: 244.5-254.0 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) Hole Core 29 Cored Interval:254.0-263.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) Site 231 Hole Core 30 Cored Interval:263.5­273.0 m Site 231 LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) Hole Core 31 Cored Interval: 273.0-281.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) Site 231 Hole Core 32 Cored Interval:282.5-292.0 m Site 231 Hole Core 33 Cored Interval: 292.0-301.5 m Site 231 Hole Core 34 Cored Interval:301.5-311.0 m Site 231 Hole Core 35 Cored Interval:311.0-320.5 m Core 36 Cored Interval .-320.5-330.0 m Site 231 FOSSIL CHARACTER Hole Core 37 Cored I n t e r v a l : 3 3 0 . 0 - 3 3 9 . 5 m FOSSIL CHARACTER LITHOLOGIC DESCRIPTION LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) NANNO OOZE Light o l i v e gray (5Y5/2); s l i g h t color changes t o very l i g h t o l i v e gray a t 2-80 and back to l i g h t o l i v e gray a t 2-140 Smear 36-2-110 Sand 1 - 3% Nannos 90% S i l t 20-30% Forams 1* Clay 70% Rads 1% Heavy M i n . 1% D o l o . Rhombs 158 Smear 37-3-73 Sand 1 - 2% Nannos Silt 25% Rads Clay 70% Forams C/M 90% 2% 1% Pyrite Quartz Feidspar Heavy Min. Vole. Glass 2% 1% 1% 1% 1% Dolo. Rhombs 1% Zeolite U C/G Core Catcher Explanatory notes in chapter 1 Core Catchei Explanatory notes in chapter 1 Site 231 Hole Core 38 Cored Interval .­339.5­349.0 m Site 231 Hole Core 39 Cored Interval:349.0­358.5 m Core 40 Cored Interval .-358.5-368.0 m Site 231 Hole Core 41 Cored Interval:368.0-377.5 m FOSSIL CHARACTER FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION DESCRIPTION NANNO OOZE L i g h t o l i v e gray ( 5 Y 5 / 2 ) ; small s c a l e burrow mottling C/P NANNO OOZE Light o l i v e gray (5Y5/2) w i t h very l i g h t o l i v e gray zone from 40-2-60 to 140 and 40-3-40 t o 90 Smear 40-3-80 Sand 1 - 5% Nannos 90* S i l t 20-30JS Forams IX Clay 65% Rads 1XFP C/M Dolo. Rhombs 2% Quartz 1 - 2% Feldspar IX Heavy Min. IX Pyrite IX Smear 41-3-100 Sand 1 - 3X Nannos 80-9056 S i l t 20-303; Forams IX Clay 70% Rads TX C/M Burrows a t 41-4-110 t o 120 C/P C/G A/M Explanatory C/P Core Catcher notes i n chapter 1 Explanatory Core Catcher notes i n chapter 1 Quartz 2% Pyri te 2X Dolo. Rhombs 1 - 2X Feldspar IX Heavy M i n . 1% Site 231 Hole Core 42 Cored Interval:377.5-387.0 m Site 231 LITHOLOGIC DESCRIPTION Hole Core 43 Cored Interval: 387.0-396.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2); burrowed throughout NANNO OOZE Light olive gray (5Y5/2) Many small burrows in 42-2, 42-3 and 42-4. 00 Core 44 Cored Interval:396.5- 406.0 m Site 231 FOSSIL CHARACTER LITHOLOGIC Hole FOSSIL CHARACTER Core 45 Cored Interval:406.0- 415.5 m LITHOLOGIC DESCRIPTION DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) with some small burrows. QUARTZ AND FORAM BEARING NANNO OOZE Grayish o l i ve (10Y4/ 2), s l i g h t l y c ons o l i d a t e d . Bitumen st reaks 44- 1- 80 t o 95 Smear 44- 1- 90 Sand 5% Nannos 30- 50$ Opaque m atter S i l t 30? 5X Forams ( o i l e d or Clay 653; Sponge Sp ic . bitumenous?) 5- 10$ Quartz 5% Pyr it e? 5X Feldspar 1% Heavy M in. Dolo. Rhombs C/P π R/P n u Color change to pale olive (10Y6/2) at 44- 2- 80 and back to grayish olive (10Y4/2) at 44- 2- 105 Core Catcher Smear 45- 3- 120 Sand 1 - 2% Nannos 902 Silt 20% Forams IX Clay 753S Rads IX Sponge Sp ic . IX Explanatory notes in chapter 1 C/P C/P C/P Core Catcher Explanatory notes i n chapter 1 Feldspar U Heavy M in. 1 * Site 231 Hole Core 46 Site 231 Cored Interval: 415.5-425.0 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) with burrows throughout. Hole Core 47 Cored Interval:425.0-434.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2), burrowed throughout Cored Interval .-434.5-444.0 m ON o Hole Core 50 LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Olive gray (5Y3/2) and color changes to l i g h t o l i v e gray (5Y5/2) a t 48-1-70 to grayish o l i v e (10Y4/2) a t 48-2-20 to l i g h t o l i v e gray (5Y5/2) a t 48-2-80 to grayish o l i v e (10Y4/2) a t 48-2-110 to o l i v e gray (5Y3/2) a t 48-3-0 to l i g h t o l i v e gray (5Y5/2) a t 48-3-25 to o l i v e gray (5Y3/2) a t 48-3-50 grading to l i g h t o l i v e gray (5Y5/2) to grayish o l i v e (10Y4/2) a t 48-3-130 Smear 48-3-80 Sand 1- 2% Nannos 80-903; S i l t 20-25% Forams 1% Clay 75% Rads UP Color change to pale o l i v e (10Y6/2) at 50-2-50 and to grayish o l i v e (10Y4/2) at 50-2-100 C/P A/M Smear 50-3-100 Sand 1- 3% Nannos 90% S i l t 15-20% Forams 1% Clay 80% Quartz 1% Mica 1% Pyrite 1* Core Catcher R/P PLE METERS LITHOLOGY RADS NANN< FORAt AGE ZONE 5ECTIOI FOSSIL CHARACTER ION Cored In terval:444.0-453.5 m ORMAT : Core 49 ^. o LITHOLOGIC DESCRIPTION LITI Hole C/P 0.5— VOID neoha matu 1 1.0- D. z•L.~j~-1- , -L z NANNO OOZE Olive gray (5Y3/2) grading to grayish olive (10Y4/2) with some burrows. C/P B C/P 2 1 1 1 1 1 LATE M:IOCENE Discoast er belli N 14-N13 C/G C/G x •ji" L "i~ L J— -l_ -L J^ -1— -L C/P J- I 3 R/M c t ore Catcher Explanatory notes in chapter 1 DESCRIPTION NANNO OOZE Grayish o l i v e (10Y4/2) with burrows. Burrows i n part f i l l e d with coarser m a t e r i a l : Smear 50-1-97 (from burrow) Quartz 10-15% Sand 10-30% Nannos 30-50% S i l t 30-40% Forams 5% Feldspar 2 - 5% Clay 30% Rads 3 - 5J!FP Heavy M i n . 1 - 3 % Pyrite 1 - 2% Mica 1% Burrowed throughout. Site 231 Cored Interval: 453.5-463.0 m FOSSIL CHARACTER FOSSIL CHARACTER Core Catcher -1- -JExplanatory notes in chapter 1 Quartz 2% D o l o . Rhombs 1 - 2% Feldspar 1% Vole. Glass 1% Zeolite 1% Site 231 Hole FOSSIL CHARACTER Core 51 Cored Interval .-463.0-472.5 m Site 231 Hole FOSSIL CHARACTER Core 52 LITHOLOGIC DESCRIPTION Cored Interval:472.5-482.0 m LITHOLOGIC DESCRIPTION NANNO OOZE Grayish olive (10Y4/2) with burrows throughout. NANNO OOZE Olive gray (5Y3/2) grading to grayish olive (10Y4/2) at 52-1-60. Burrows throughout. C/P C/P Color change to light olive gray (5Y5/2) at 51-3-50 and to grayish olive (10Y4/2) at 51-3-110 Smear 52-3-80 Sand 1- 3% Nannos 30% Forams Silt Clay 70% Thin sandy layer at 51-4-38 to 45 R/P Thin sandy layer at 51-6-48 to 52 Smear 51-6-50 Sand 30% S i l t 35% Clay 35% C/G A/P Core Catcher Explanatory notes in chapter 1 Nannos 30-40% 3- 5% Forams Rads 2- 3%FP 1% Sponge Spic. Quartz 15-;10% 1 - 5% Feldspar 1 - 5% Pyrite Heavy Min. 1 - 3% Vole. Glass 1 - 3% Dolo. Rhombs 2% 1% Mica Zeoli te R/P Core Catcher Explanatory notes in chapter 1 902 IS Quartz 1- 2% Heavy Min. 11 Vole. Glass 1J Pyrite Dolo. Rhombs 1% Zeolite Core 53 Cored Interval: 482.0- 491.5 m Core 54 Site 231 FOSSIL CHARACTER Cored Interval:491.5- 501.0 m FOSSIL CHARACTER LITHOLOGIC DESCRIPTION LITHOLOGIC NANNO OOZE Burrows t hr o ug ho ut . Grayish o l i v e (10Y4/ 2) g r ad ing to o l i ve gray (5Y3/ 2) a t 53- 1- 100 to g r ayish o l i v e (10Y4/ 2) a t 53- 2- 20 to o l i ve gray (5Y3/ 2) a t 53- 2- 60 to l i g h t o l i v e gray (5Y5/ 2) at 53- 2- 120 t o g r ayish o l i v e (10Y4/ 2) a t 53- 3- 0 DESCRIPTION NANNO OOZE Grayish olive (10Y4/2) grading to light olive gray (5Y5/2) at 54to grayish olive (10Y4/2) at 54- 1to light olive gray (5Y5/2) at 54to grayish olive (10Y4/2) at 54- 2- 1- 90 135 2- 0 30 C/G Burrows t hr oug hout . Smear Sand 1 - 2% Nannos 80- 90% Silt 30% Sponge Sp ic . 1% 70% Clay C/P Smear 53- 3- 80 90* Sand 1 - 2% Nannos Silt 25% Sponge Sp ic . U Clay 75% Quartz Heavy M in. Vo le. Glass Py r i t e Dolo. Rhombs Zeo li t e U π i% 1% 1% 1% 1% 1% 1* Core Catcher C/P Hole FOSSIL CHARACTER C/P Quartz Heavy M in. Dolo. Rhombs Py r i t e Core 55 Cored Interval: 501.0- 509.5 m LITHOLOGIC DESCRIPTION NANNO OOZE Grayish o l i v e (10Y4/ 2) w i t h b urrows. R/P C/G Smear 55- 2- 8 Sand 1 - 5% Nannos 80- 90% Silt 40% Rads U Clay 60% Quartz zyxwvutsrqponmlkjihgfedcbaZYXWV Heavy M in. C/P Core Catchei R/P Explanatory notes in chapter 1 Core Catcher Explanatory notes i n c hapter 1 Vo le. Glass Do lo . Rhombs Site 231 Core 56 Cored Interval:509.5- 519.0 m Site 231 FOSSIL CHARACTER LITHOLOGIC Hole FOSSIL CHARACTER Core 57 DESCRIPTION LITHOLOGIC Smear 56- 3- 90 Sand 1 - 3% Nannos Silt 50% Forams Clay 50% Rads (5Y5/ 2) at 56- 3- 75 110 4- 10 40 4- 80 85 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA >90% Quartz IX IX UFP Mica Heavy M in. Pyrite D o l o . Rhombs 1% 1% λ% 1% Core Catchei Explanatory notes in chapter 1 C/P Core Catcher Explanatory notes in chapter 1 DESCRIPTION NANNO OOZE Grayish olive (10Y4/2) with burrows throughout. NANNO OOZE Grayish o l i v e (10Y4/ 2) w i t h b ur r ows. Color g r ad ing t o l i g h t o l i v e gray to g r ayish o l i v e (10Y4/ 2) at 56- 3t o l i g h t o l i v e gray (5Y5/ 2) a t 56to g r ayish o l i v e (10Y4/ 2) a t 56- 4to l i g h t o l i v e gray (5Y5/ 2) at 56to g r ayish o l i v e (10Y4/ 2) a t 56- 5- Cored Interval:519.0- 528.5 m Core 58 Cored Interval:528.5-538.0 Core 59 FOSSIL CHARACTER Cored Interval:538.0-547.5 FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Light olive gray (5Y5/2) grading to grayish olive (10Y4/2) at 58-1-75 to light olive gray (5Y5/2) at 58-2-40 to grayish olive (10Y4/2) at 58-2-120 to light olive gray (5Y5/2) at 58-4-0 to grayish olive (10Y4/2) at 58-4-15 to light olive gray (5Y5/2) at 58-4-50 to grayish olive (10Y4/2) at 58-4-70 DESCRIPTION NANNO OOZE Grayish olive (10Y4/2) to pale olive (10Y6/2) with burrows throughout. Semi lithified. Burrows throughout. to light olive gray (5Y5/2) at 58-4-110 to grayish olive (10Y4/2) at 58-5-0 Smear 58-3-80 Sand 1 - 3% Nannos 90S S i l t 30-403! Forams 1%FP Clay 60-703! Rads 13SFP Sponge Spic. U Smear 59-3-120 Sand 5* Nannos 80-903! Silt 303! Rads 1- 2%FP Clay 65% Forams U Quartz Feldspar Pyrite Dolo. Rhombs A/M C/G C/P A/M Core Catcher Explanatory notes in chapter 1 A/M Core Catcher Explanatory notes in chapter 1 Quartz U Vole. Glass U Pyrite 1% Site 231 Hole Core 60 Site 231 Cored Interval: 547.5-557.0 m Hole Core 61 Cored Interval:557.0-566.5 m FOSSIL CHARACTER FOSSIL CHARACTER LITHOLOGIC LITHOLOGIC DESCRIPTION NANNO OOZE Grayish o l i v e (10Y4/2) to pale o l i v e (10Y6/2) DESCRIPTION NANNO OOZE Grayish o l i v e (10Y4/2) with burrows throughout. C/M Core Catcher Smear 61 -4-80 Sand 1 - 3% Nannos 70-80% S i l t 20-30% Rads 1% Clay 70% Explanatory notes i n chapter 1 Pyrite 5% Quartz 2% Feldspar 2% D o l o . Rhombs 1% Color grading to l i g h t olive gray (5Y5/2) at 61-4-90 and back to grayish olive (10Y4/2) at 61-4-140 Grain Sand Silt Clay C/G C/P A/M Core Catche Explanatory notes in chapter 1 Size Z% 23% 75% Cored Interval .-566.5-568.5 Core 64 LITHOLOGIC DESCRIPTION LITHOLOGIC A/M C/M I - BLACK VOLCANIC GLASS 62-1-65 to 85 NANNO CHALK 62-1-85 to 102 Greenish gray (5G6/1) Smear 62-1-89 Sand 1% Nannos 95% Quartz 1% Silt 30% Feldspar 1% Clay 70% Core Catchei VOLCANIC GLASS AND BASALT 62-1-102 to 125 with intrusional contacts NANNO CHALK 62-1-125 to 135 Greenish gray (5G6/1) Smear 62-1-130 90-95% Sand 1% Nannos Silt 30% Heavy Min. 1% Clay 70% Vole. Glass 1% VESICULAR BASALT 62-1-135 to 150 C/P DEFORMATION METERS 0.5- 1 LITHO.SAMPLE RADS NANNOS FORAMS ZONE AGE MIDDLE MIOCENE D. exilis-S. heteromorphus SECTION Cored Interval: 568.5-574.5 m LITHOLOGY Core Catcher LITHOLOGIC DESCRIPTION Explanatory notes in chapter 1 VOID BLACK VESICULAR BASALT 1.0- 2 ~~~~~- BLACK VOLCANIC GLASS BLACK VESICULAR BASALT with brownish gray (5YR4/1) vein. ^ BLACK VOLCANIC GLASS - ^ BLACK VESICULAR BASALT with brownish gray vein (5YR4/1) consisting of muscovite> talc and serpentine aggregates. core Ca tcher Explanatory notes in chapter 1 DESCRIPTION BLACK BASALT with glass breccias and veins. See detailed descriptions on 'Visual Core Descriptions'. NANNO CHALK Greenish gray (5G6/1) 62-1-60 to 65 Smear 62-1-60 (ea. 5 cm over Basalt!) Sand 1% Nannos >95% Quartz M Silt 252! Feldspar 1% Clay 75% FOSSIL CHARACTER Cored Interval:574.5-584 FOSSIL CHARACTER FOSSIL CHARACTER SITE 231 DETAILED CORE DESCRIPTIONS raph Lon Site 231 Core 62 Site 231zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Core 62 Section CC Section 1 o 4) CO o o — o 4- » H o o 4- > o xz U cd H +J ex c o •s. s o α> CO fµ o 00 cd µ o 4-H J +J D escription ft. § in H α> H +J xx c A α> V) µ αµ > Description 4- > U 0 —1 α> CO Mylonitized zone. Black massive vesicular basalt. 2 5 —1 25— 5 0 —I 5 0 ^ Layered sediments. Baked zone in sediments, with pyrite: Contact. en Fractured zone in glass Brecciated glass. 7 5 —^ <c al CD Tempered upper margin in sediments. o Slightly metamorphosed sediment inclusions without layering. '/$?.- - _s 100- Glassy breccia cemented by tempered metamorphosed sediments lodged in cracks. Fractured glass. L25 15 Slightly metamorphosed sediment inclusion. Tempered zone in sediments. Glassy rind overlying black massive basalt. 125— 150- J 67 SITE 231 DETAILED CORE DESCRIPTIONS Site 231 Core 63 Section 2 Site 231 Core 63 Section 1 uzyxwvutsrqponmlkjihgfedcbaZYXWVUT Λ Description Description Massive black basalt: slightly fractured with narrow zones of oxidation around tiny veins and fractures. 25— 25— Fragmented glass. Variolitic vesicular basalt. 50— 50— fi. l_ L L?lil.  L L L L. ,»«V | ^ | L L |» 75— 75— Black massive vesicular doleritic basalt, slightly altered, with minor fracturing and oxidation along fractures. ESSSS 100— 100— Chlorite- sericite- talcaragonite veins (thickness from 1 mm to 1.5 cm) in variolitic, vesicular basalt. Thin vertical vein incrusted with finegrained aggregates of talc, sericite, chlorite, and an oxidized zone bordering vein. L25— L25— Glassy breccia. SITE 231 DETAILED CORE DESCRIPTIONS Site 231 Core 64 Section 1 Site 231 Core 63 Section CC uzyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA o u 4 o (/> U 4 α> uzyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA α> o rt O α> co Description ί o H o 4J Pi. c o α> zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA f α> & & u 0— O—i f Description (4- 1 Black vesicular basalt, with vein of talc ser ic it e- c hlor it e, and narrow zone of oxidation around vein. Def α> M- i Black massive basalt. 25— 25— SO- 50— Fragmented volcanic glass with thin veins of aragonite (?). Massive basalt; slightly fractured. <c 75— Vein of aragonite, chlorite, sericite. CD O Massive basalt. 100— 100— Fractured zone of glass and glassy breccia impregnated with aragonite, sericite, chloritic material in irregular veins. L25— L25— Massive vesicular basalt. Massive basalt. 150- J 69 SITE 231 DETAILED CORE DESCRIPTIONS Site 231 Core 64 Section 3 Site 231 Core 64 Section 2 Description Description 0—i Fragments of vein of talc-chlori te-sericite. Massive basalt, slightly fractured and altered. Fragmented glass along fracture zone. Chlorite, sericite, quartz (?) veins along small fractures. Vein of chloritesericite-talc mixture. 25— 25— Massive vesicular basalt. so­ L L L L L L L L 1/ L Massive variolitic basalt, only slightly fractured, and altered. Vein of chloritesericite-talc material. 50— Basalt. ' . L L L L 1/ L L L L l/L EL : ' L L L L,7L L Brecciated glass; veins. Fracture zone with basalt fragments bonded by chlorite-sericitetalc vein material. 75— Variolitic basalt. Fractured zone: upper part fragmented glass; lower part talc, calcite, sericite vein as fine-grained aggregates. 100­ L L L>f T L Vesicular basalt. 100— Fracture zone in basalt: upper part, brecciated more than lower, contains thin veins of chlorite-sericite-talc. L V I L#LM. L L L L L L L L Doleritic basalt. L25— Brecciated volcanic glass impregnated with chlorite-sericite-talc aggregates, cemented to vein of such material. Vesicular basalt. SITE 231 DETAILED CORE DESCRIPTIONS graph m u o IΛ 4- > Pk c4) H o U Λ a. co •H O 4) CO raphi ;sent mete of S o et 4) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 4> o Description >TIS U * ion from :ion Site 231 Core 64 Section CC >V4 cβ D, 4> CC 1 o a Massive vesicular basalt, slig ht ly alt er ed and fractured. Some brecciated glass, impregnated with t alc c hlor it e- ser ic it e vein material, occurs in the fractures. — &££ 25— < 50— IM LA LU 1 CD - 75— Q_ α: CD o o Q- - o 100— 125— 150- 71 SITE 231 Ocm — 25 — 50 231-1-1 72 231-2-1 231-2-2 SITE 231 73 SITE 231 231- 4 DENSITY G RATE = •• SYRINGE = / 2 ' 1 > 1 1 SONIC 'VERTICAL = HORIZONTAL = WATER CONTENT/ POROSITY Δ 1 1 1 —s^^^ GRM D SYRINGE W. C. = SYRINGE POROSITY = 2.00 40 SECTION CM - 0 3 II II k i l l J 0.00 m Δ D 1 1 1 1 1 l M 100 A 0 - o a \ α i o '. D? \ A 1 - } α α α D CD O π 4 i r 1 r - 25 1- D| \ 2- A - 50 al A A 3- A | A A A A I 4 - I - 75 - - 5- - 6- - 100 - 7- - 125 - 8- - 9— - 150 74 SITE 231 DENSITY GRAPE = SYRINGE « Δ 231- 5 CM JTTTTJ SONIC VERTICAL = Δ HORIZONTAL = D 40 2.00 SECTION ro WATER CONTENT/ POROSITY GRAPE =• SYRINGE W. C. = ∆ SYRINGE POROSITY = D i j'  i - 25 I- 2- - 5o 4- - 75 CD GJ 5- α o - 100 6- CD CD 7- CD - 125 CD CD .CD CD α cα A G 9- J L- 150 75 SITE 231 231- 6 DENSITY SRAPË = SYRINGE = Δ 1 SONIC VERTICAL HORIZONTAL 40 f f 3 CM ro  WATER CONTENT/POROSITY Wm. rt^- D SYRINGE W. C. = Δ SYRINGE POROSITY « D 2.00 I SECTION 11 II 1 1 1 1 1 1 1 1 1 0.00 100 l- CD Φ to - 25 CO A A — 2- - 50 π A 3- 1 m - 4 —  A D A π - 75  m — Φ 0 Φ 5- a _ - IOC  6- 1 < i - a j; A - D r 7 — 3 - 125 ffl 8- - 9 — - 150 76 SITE 231 ­Ocm 25 — 50 — 75 100 — 125 150 231-7-1 231-7-2 231-7-3 77 SITE 231 DENSITY GRAPE = ~ SYRINGE = ∆ i* SONIC VERTICAL SECTION CM • • r WATER CONTENT/POROSITY GRATE = Δ HORIZONTAL ' D SYRINGE POROSITY = D 2.00 I = —–- SYRINGE W. C. = Δ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 40 I 231- 8 I I I I I I I I I I I I >I 0.00 100 i- D - 25 2- - 50 3- - 75 a 5- m - 100 6- CD CD CD 7 - CD - 125 8 - CD o — L- 150 78 SITE 231 DENSITY GRAPE - ~ SYRINGE = Δ 2 SONIC VERTICAL  Δ HORIZONTAL = D 40 2.00 I i r n 231- 9 SECTION CM - 0 WATER CONTENT/POROSITY ERAPl SYRINGE W. C. = Δ SYRINGE POROSITYzyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA * D i i i i i i i i 100 I — - 25 2— - 50 3 - α D 4 — - 75 π 5- D - 100 - CD CD 7- - 125 8- 1 9- 1 - 150 79 SITE 231 0 cm 50 75 —100 —125 150 231-10-1 80 231-10-2 231-10-3 231-10-4 231-10-5 231-11-1 SITE 231 •Ocm — 25 — 50 h­75 —100 —125 150 231-11-2 231-11-3 231-12-1 231-12-2 231-12-3 231-12-4 81 SITE 231 •0 cm — 25 — 50 — 75 —100 — 125 ISO 231-13-1 82 231-13-2 231-13-3 231-13-4 231-13-5 231-13-6 SITE 231 ­Ocm 25 — 50 —100 —125 150 231-14-1 231-14-2 231-14-3 231-14-4 231-14-5 231-15-1 83 SITE 231 •0 cm — 25 — 50 — 75 —100 125 150 231-15-2 84 231-15-3 231-16-1 231-16-2 231-16-3 231-16-4 SITE 231 Ocm —­25 — 50 h-75 —100 —125 150 231-16-5 231-16-6 231-17-1 231-17-2 231-17-3 231-17-4 85 SITE 231 •0 cm — 25 — 50 — 75 —100 — 125 1 150 231-17-5 86 231-18-1 231-18-2 231-18-3 231-19-1 231-19-2 SITE 231 0 cm — 25 — 50 — 75 —100 —125 150 231-19-3 231-19-4 231-20-1 234-20-2 234-20-3 234-20-4 87 SITE 231 •Ocm 25 — 50 — 75 100 —125 150 231-20-5 88 231-20-6 231-21-1 231-21-2 231-21-3 231-21-4 SITE 231 0 cm 25 50 — 75 —100 — 125 150 231-21-5 231-21-6 231-22-1 231-22-2 231-22-3 231-22-4 89 SITE 231 Ocm — 25 50 — 75 — 125 150 90 231-22-5 231-23-1 231-23-2 231-23-3 231-23-4 231-23-5 SITE 231 Ocm — 25 50 ­—75 —100 125 150 231-23-6 231-24-1 231-24-2 231-24-3 231-24-4 231-24-5 91 SITE 231 Ocm 50 1—75 100 I—125 150 231-24-6 92 231-25-1 231-25-2 231-25-3 231-25-4 231-25-5 SITE 231 0 cm — 25 50 — 75 100 — 125 150 231-25-6 231-26-1 231-26-2 231-26-3 231-26-4 231-26-5 93 SITE 231 •0 cm — 25 — 50 — 75 —100 — 125 150 231-26-6 94 231-27-1 231-27-2 231-27-3 231-27-4 231-27-5 SITE 231 •Ocm — 25 50 — 75 —100 —125 150 231-27-6 231-28-1 231-28-2 231-28-3 231-28-4 231-28-5 95 SITE 231 •0 cm 231-28-6 96 231-29-1 231-29-2 231-29-3 231-29-4 231-29-5 SITE 231 •0 cm — 25 — 50 75 —100 —125 150 231-29-6 231-30-1 231-30-2 231-30-3 231-30-4 231-30-5 97 SITE 231 231-30-6 98 231-31-1 231-31-2 231-31-3 231-31-4 231-31-5 SITE 231 •0 cm — 25 — 50 — 75 —100 — 125 150 231-32-1 231-32-2 231-32-3 231-32-4 231-32-5 231-32-6 99 SITE 231 •Ocm — 25 50 100 —125 ISO 231-33-1 100 231-33-2 231-33-3 231-33-4 231-33-5 231-34-1 SITE 231 Ocm — 25 — 50 — 75 100 — 125 150 231-34-2 231-34-3 231-34-4 231-34-5 231-34-6 231-35-1 101 SITE 231 Ocm µ ­25 I—50 1—75 I—100 150 231-35-2 102 231-35-3 231-36-1 231-36-2 231-36-3 231-36-4 SITE 231 i—Ocm — 25 50 — 75 —100 — 125 150 231-36-5 231-36-6 231-37-1 231-37-2 231-37-3 231-37-4 103 SITE 231 • Ocm1 7 — • PI á • 1 •- • i • • LJ r—i r 1 m ••1' I m ,:. *• i 1f 1 (1 ; II π < • • ..j ?| jj H T i ! ; j • —• j F : • 1 • ! 1 • 99 ji • 1 • —100 • |r l] - — 125 j • t . ' i fI 104 | [ } » Λ«I 150 1 i ] | _ i_ M M LJ 231- 37- 5 J 231- 38- 1 | fi : I "I :1 1 I1 j I9 - ; 1 I 1 * " i ; 1 1 j if ; j • ,. { • i % %\ ' 5» • rfL^^^B — 75 J ( • •• il J • 1 1 T *1 • 1 — SO f j f i I tl \ •i — 25 ; 1 U V1 • ''i A ) t > •) II j I • 231- 38- 2 0 L J l 231- 38- 3 1 v (j0 J I fi 1 ; i 1 i 1 1II 1 I • 1 231- 38- 4 231- 39- 1 SITE 231 •0 cm — 25 — 50 — 75 — 100 —125 150 231-39-2 231-39-3 231-39-4 231-40-1 231-40-2 231-40-3 105 SITE 231 Ocm — 25 50 — 75 100 — 125 150 231-40-4 106 231-40-5 231-41-1 231-41-2 231-41-3 231-41-4 SITE 231 •Ocm 25 50 — 75 100 — 125 150 231-41-5 231-42-1 231-42-2 231-42-3 231-42-4 231-42-5 107 SITE 231 Ocm — 25 50 — 75 —100 — 125 150 231-42-6 108 231-43-1 231-43-2 231-43-3 231-43-4 231-43-5 SITE 231 •Qcm — 25 50 — 75 —100 — 125 150 231-43-6 231-44-1 231-44-2 231-45-1 231-45-2 231-45-3 109 SITE 231 Ocm 25 — 50 — 75 —100 — 125 150 231-45-4 110 231-45-5 231-45-6 231-46-1 231-46-2 231-46-3 SITE 231 •0 cm — 25 — 50 CD < — 75 o o O —100 —125 150 231-46-4 231-46-5 231-46-6 231-47-1 231-47-2 231-47-3 ill SITE 231 231-47-4 112 231-47-5 231-47-6 SITE 231 231-48 DENSITY GRATΛ = •— SYRINGE = A SECTION CM SONIC VERTICAL » Δ HORIZONTAL = Q ro WATER CONTENT/POROSITY zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA = ,»- — GRAPE SYRINGE W. C. = Δ SYRINGE POROSITY = D π l- - 25  2- CD - 50 3- 4- - 75 if 5- i 6- - 100 7- - 125 8- 113 SITE 231 •Ocm — 25 — 50 — 75 —100 125 1 114 150 231-49-1 231-49-2 231-49-3 231-50-1 231-50-2 231-50-3 SITE 231 Ocm 231-50-4 231-50-5 231-50-6 115 SITE 231 WATER CONTENT/POROSITY SYRINGE W. C. SYRINGE POROSITY = D 116 SITE 231 •Ocm — 25 — 50 — 75 —100 —125 150 231-52-1 231-52-2 231-52-3 231-52-4 231-52-5 117 SITE 231 Ocm 25 — 50 — 75 —100 —125 150 231-53-1 118 231-53-2 231-53-3 231-53-4 231-53-5 231-53-6 SITE 231 •Ocm — 25 — 50 — 75 100 — 125 150 231-54-1 231-54-2 231-54-3 231-55-1 231-55-2 231-55-3 119 SITE 231 ­Ocm I—25 I—50 I—125 231-56-1 120 231-56-2 231-56-3 231-56-4 231-56-5 231-56-6 SITE 231 231-57-1 231-57-2 231-57-3 231-58-1 231-58-2 231-58-3 121 SITE 231 0 cm — 25 — 50 —100 — 125 231-58-4 122 231-58-5 231-58-6 231-59-1 231-59-2 231-59-3 SITE 231 0 cm — 2* — 50 ­—75 — 100 — 125 1 150 231-59-4 231-59-5 231-59-6 231-60-1 231-60-2 231-60-3 123 SITE 231 231-61 SECTION CM ­0 | WATER CONTENT/POROSITY GRAPE SYRINGE W. C SYRINGE POROSITY = D 1 M ­ ­25 1­ ­ 2­ ­ -50 j 3­ 4 — ­75 5­ ­100 o — ­ 7­ ­ ­125 I 8­ ­ 9­ ­150 124 | SITE 231 0 cm — 25 50 — 75 100 125 150 231-62-1 231-63-1 231-63-2 231-64-1 231-64-2 231-64-3 125