Open-file Geologic Map 140 This draft geologic map is preliminary and will undergo revision. It w... more Open-file Geologic Map 140 This draft geologic map is preliminary and will undergo revision. It was produced from either scans of hand-drafted originals or from digitally drafted original maps and figures using a wide variety of software, and is currently in cartographic production. It is being distributed in this draft form as part of the bureau's Open-file map series (OFGM), due to high demand for current geologic map data in these areas where STATEMAP quadrangles are located, and it is the bureau's policy to disseminate geologic data to the public as soon as possible. After this map has undergone scientific peer review, editing, and final cartographic production adhering to bureau map standards, it will be released in our Geologic Map (GM) series. This final version will receive a new GM number and will supercede this preliminary open-file geologic map.
Recent interest in the availability of deep groundwater resources along the structurally complica... more Recent interest in the availability of deep groundwater resources along the structurally complicated transition between the Colorado Plateau and the Rio Grande rift in north-central New Mexico, resulted in the development of groundwater-flow models that suggested an impact on the Middle Rio Grande Basin (MRGB, also known as the Albuquerque Basin) from long-term pumping of wells that would exploit pre-Cenozoic aquifer units (Melis, 2009). Refinement of the regional conceptual geologic framework of the Colorado Plateau-MRGB transition was done in order to aid in the development of a revised groundwater-flow model of this region by Melis et al. (2011). The refined geologic framework was based on a compilation of previous stratigraphic work, an examination of data from 72 deep wells, and modifications to structure-contour maps of the base of the Upper Cretaceous Dakota Formation (Thaden and Zech, 1984) and the top of Proterozoic basement (Broadhead et al., 2009). The internal structure of the MRGB is dominated by subbasins and buried structural culminations that likely influence flows of deep groundwater. Structural control on the distribution of springs along the western flank of the MRGB is suggested by variations in basin-margin structure and stratal dips. Few springs are found along the highly faulted Laguna bench, whereas springs are common along the faulted eastern front of the Lucero uplift, where strata dip away from the MRGB boundary. Groundwater-flow across faults was examined by projecting juxtaposition seals and conduits across three fault zones that locally define the northwestern structural margin of the MRGB. A preliminary result of the fault juxtaposition analyses suggest discontinuous and discrete windows of groundwater flow along portions of basin-margin faults.
The primary goals of this investigation are to provide information on (1) large, geologically rec... more The primary goals of this investigation are to provide information on (1) large, geologically recent earthquakes along the southern Sangre de Cristo fault, and (2) document fault characteristics in the shallow subsurface to help evaluate influences of the fault on vadose zone groundwater flow. The 240km-long Sangre de Cristo fault shows prominent geomorphic evidence of geologically recent surface rupture, and is recognized as a significant potential source of large earthquakes. The data obtained from this effort will be applicable to other similar faults throughout northern and central New Mexico. Defining the earthquake history of the Sangre de Cristo fault helps reduce the uncertainty in characterizing earthquake sources throughout the Rio Grande rift, including possible fault ruptures close to Santa Fe, Albuquerque, and other areas in New Mexico. Also, this work documents the near-surface characteristics WLA Project 1605 January 16, iii
The Ancha Formation contains granite-bearing gravel, sand, and subordinate mud derived from the s... more The Ancha Formation contains granite-bearing gravel, sand, and subordinate mud derived from the southwestern flank of the Sangre de Cristo Mountains and deposited on a streamflow-dominated piedmont. These strata compose a locally important, albeit thin (less than 45 m [148 ft] of saturated thickness), aquifer for domestic water wells south of Santa Fe, New Mexico. Spiegel and Baldwin (1963) originally defined a partial type section for the Ancha Formation using a 49-m-thick (16-ft-thick) exposed interval of weakly consolidated, subhorizontal, arkosic strata on the southwest slope of Cañada Ancha. However, new geologic mapping, sedimentologic field studies, and geochronologic data indicate that the Ancha Formation should be restricted to the upper 12 m (39 ft) of Spiegel and Baldwin's type section, with the underlying strata being correlative to the upper Tesuque Formation. Because this 12-m (39-ft) interval is not well exposed at the type section, we designate four new reference sections that illustrate the textural variability of the Ancha Formation and its stratigraphic relationship with other rock units. New 40 Ar/ 39 Ar data help constrain the age of the Ancha Formation. A bed of rhyolite lapilli (1.48 ± 0.02 Ma) that is temporally correlative to one of the Cerro Toledo events is recognized near the top of the section south of Santa Fe, New Mexico. A fluvial deposit interpreted to be inset against the Ancha Formation contains lapilli dated at 1.25 ± 0.06 Ma. These dates indicate that deposition of the Ancha Formation generally ended during early Pleistocene time. However, there is evidence suggesting that aggradation continued into the middle or late Pleistocene in mountain-front canyons east of the Santa Fe embayment. The age of the basal Ancha Formation is diachronous and ranges from 2.7-3.5(?) Ma in the western Santa Fe embayment to ~1.6 Ma in the eastern embayment near the Sangre de Cristo Mountains. The Pliocene-early Pleistocene aggradation that formed the Ancha Formation in the Santa Fe embayment occurred elsewhere in the Española and Albuquerque Basins, suggesting a regional climatic influence on deposition in the uppermost Santa Fe Group. A rise in base level due to late Pliocene volcanism and tectonism may be responsible for the significant differences of accommodation space, as reflected in deposit thickness, of the Santa Fe embayment compared with the piedmont regions to the south and the generally degraded upland regions to the north. Regional geology and previous work The southern Española Basin contains several lithostratigraphic units relevant to the Ancha Formation. The Tesuque Formation underlies most of the Ancha Formation and is a pinkish-tan, arkosic, silty sandstone with minor conglomerate and siltstone that is commonly exposed in the central and eastern parts of the Española Basin north of Santa Fe. Galusha and Blick (1971) proposed the Chamita Formation for Santa Fe Group strata of Miocene age that unconformably lie above the Tesuque Formation north of the Santa Fe embayment. The Chamita Formation is generally brown or gray sand with subordinate gravel of mixed provenance; the gravel contains significant quartzite and other metamorphic clasts mixed together with granite, sedimentary, and volcanic clasts (Galusha and Blick, 1971; Tedford and Barghoorn, 1993). The Puye Formation is a coarse-grained, volcaniclastic, alluvial sequence on the western margin of the Española Basin that was shed primarily from the Tschicoma volcanic center during the Pliocene-early Pleistocene (Manley, 1976b; Waresback,
This draft geologic map was produced from scans of hand-drafted originals from the author(s). It ... more This draft geologic map was produced from scans of hand-drafted originals from the author(s). It is being distributed in this form because of the demand for current geologic mapping in this important area. The final release of this map will be made following peer review and redrafting in color using NMBGMR cartographic standards. The final product will be made available on the internet as a PDF file and in a GIS format.
Colluvium and landslide deposits Qca Colluvium and alluvium, undivided (upper to middle Pleistoce... more Colluvium and landslide deposits Qca Colluvium and alluvium, undivided (upper to middle Pleistocene)-Poorly consolidated, poorly sorted and stratified, fine-to coarse-grained, clast-and matrix-supported deposits derived from a variety of mass-movement hillslope processes, including debris flow, shallow slump and creep. Discontinuously preserved along margins of valleys capped by the Tuerto Formation. Locally differentiated where areally extensive or thick. Variable thickness, ranging 0-3 m. Qls Landslide debris (middle Pleistocene)-Blocks of well cemented conglomerate from the basal Tuerto Formation. Locally found as discontinuous boulders just below basal Tuerto Formation contact about 15-25 m above local base level. This high elevation relative to base level suggests deposits formed prior to late Pleistocene time. Variable thickness and grades into thin hillslope colluvium with an estimated thickness ranging from 0-6 m. Alluvium Qae Eolian sand, stream alluvium, and colluvium, undivided (Holocene to upper Pleistocene)-Very poorly consolidated, moderately to well sorted, light brown to yellow brown (7.5 5/4 to 2.5YR 7/6), fine-to medium-grained sand and silty sand with scattered pebbles that commonly forms a relatively thin, discontinuous mantle over broad upland areas, most notably on interfluves of streams cut into the Tuerto Formation and on ridges underlain by Mesozoic strata. Soil development is generally weak with Bw and Bwk horizons, and Stage I and II carbonate morphology. Surface is commonly stabilized by vegetation where not disturbed by human activity. May locally contain hydrocollapsible soils. Mapped only where areally extensive or thick. Variable thickness, ranging from 0-2 m. Qa Modern and historic stream alluvium (Historic to Holocene)-Unconsolidated deposits of sand and pebbly to cobbly gravel with minor, thin silty to clayey sand lenses. Inset against young stream alluvium of unit Qvy and underlies modern arroyos. Alluvium derived from Triassic rocks is reddishbrown, whereas, alluvium derived from Cretaceous rocks are pale-brown to yellow. Differentiated only in deep or wide valleys. Soils are development is minimal and deposit surface exhibit well-developed bouldery and cobbly gravel-bar topography. May locally contain hydrocollapsible soils. Base not exposed, but thickness is estimated to be less than 4-9 m. Qvy Young stream alluvium (Holocene to uppermost Pleistocene)-Poorly consolidated deposits of light-brown to yellow (2.5-10YR) sand and gravel inset against upper and middle Pleistocene deposits of units Qpm1 and Qpm2. Slightly dissected surface contains weakly developed soils exhibiting Stage
may in places be age-correlative to Qaro or Qarm All ages are 40 Ar/ 39 Ar ages, recalculated to ... more may in places be age-correlative to Qaro or Qarm All ages are 40 Ar/ 39 Ar ages, recalculated to the Fish Canyon sanidine standard age of Renne et al. (1998). 1-Age of Lava Creek B (from Lanphere et al., 2002), to which an ash in Qaro was geochemically correlated by Izett and Wilcox (1982). 2-Plagioclase single-crystal laser fusion age from Connell et al. (in press). 3-Groundmass resistance furnace incremental heating age from Maldonado et al. (2006). * Sur cial sand and clayey-silty sand sheet over units Qaro and Qam accumulated in the mid-late Pleistocene and Holocene.
New Mexico Geological Society Annual Spring Meeting, Apr 27, 2012
We summarize Miocene clastic deposition in the Española Basin (EB) and examine how drainage syste... more We summarize Miocene clastic deposition in the Española Basin (EB) and examine how drainage systems may respond to tectonic and paleoclimatic controls. The EB is a half-graben tilted west towards the Embudo-Santa Clara-Pajarito fault system (ESPFS). An arm of the EB, called the Cañada Ancha graben (CAG), extends SE away from the ESPFS. A faulted structural platform lies NW of the ESPFS. Syn-rift deposits of the Santa Fe Group are particularly well exposed in the EB, and we could readily map western alluvial slope, central basin floor, and eastern alluvial slope lithofacies assemblages. Abundant tephra and fossils provide exceptional age control. Previous studies documented an increase in ESPFS throw rates at 15-11 Ma and decreased subsidence rates in the CAG after 13.5-13.0 Ma. Paleodrainage changes included: 1) coarsening ca. 13.2 Ma; 2) progressive westward progradation of the eastern alluvial slope during 18-10 Ma and a narrowing of the basin floor, with a particularly rapid advance at 13.5-11 Ma; 3) development of a gravel-bearing ancestral Rio Chama by 12 Ma; and 4) shifting of the axial river onto the northwest structural platform after 11 Ma, at least episodically. The progradation of the eastern alluvial slope is interpreted to be controlled by increased activity along the basin master fault (ESPFS) and slower subsidence in the CAG. Poorly constrained middle Miocene progradation also occurred for eastern alluvial slope deposits in the San Luis Basin to the north, and streams of the western alluvial slope carried coarser bedload at ~14 Ma. These observations imply a paleoclimatic influence for the rapid 13.5-11 Ma progradation, driven by increased discharge and stream competence. Increased precipitation, higher subsidence rates along the ESPFS, and emergence of the nearby Jemez volcanic field perhaps facilitated integration and headward elaboration of streams draining the Colorado Plateau, forming a single river roughly coincident with the location of the modern Rio Chama. High throw rates on a fault west of the ESPFS at 11-8 Ma facilitated the shift of the San Luis Basin-draining, axial river onto the northwest structural platform. But another driver for this westward shift may be larger sediment delivery from streams draining the eastern alluvial slope compared to the western alluvial slope and axial river.
Open-file Geologic Map 140 This draft geologic map is preliminary and will undergo revision. It w... more Open-file Geologic Map 140 This draft geologic map is preliminary and will undergo revision. It was produced from either scans of hand-drafted originals or from digitally drafted original maps and figures using a wide variety of software, and is currently in cartographic production. It is being distributed in this draft form as part of the bureau's Open-file map series (OFGM), due to high demand for current geologic map data in these areas where STATEMAP quadrangles are located, and it is the bureau's policy to disseminate geologic data to the public as soon as possible. After this map has undergone scientific peer review, editing, and final cartographic production adhering to bureau map standards, it will be released in our Geologic Map (GM) series. This final version will receive a new GM number and will supercede this preliminary open-file geologic map.
Recent interest in the availability of deep groundwater resources along the structurally complica... more Recent interest in the availability of deep groundwater resources along the structurally complicated transition between the Colorado Plateau and the Rio Grande rift in north-central New Mexico, resulted in the development of groundwater-flow models that suggested an impact on the Middle Rio Grande Basin (MRGB, also known as the Albuquerque Basin) from long-term pumping of wells that would exploit pre-Cenozoic aquifer units (Melis, 2009). Refinement of the regional conceptual geologic framework of the Colorado Plateau-MRGB transition was done in order to aid in the development of a revised groundwater-flow model of this region by Melis et al. (2011). The refined geologic framework was based on a compilation of previous stratigraphic work, an examination of data from 72 deep wells, and modifications to structure-contour maps of the base of the Upper Cretaceous Dakota Formation (Thaden and Zech, 1984) and the top of Proterozoic basement (Broadhead et al., 2009). The internal structure of the MRGB is dominated by subbasins and buried structural culminations that likely influence flows of deep groundwater. Structural control on the distribution of springs along the western flank of the MRGB is suggested by variations in basin-margin structure and stratal dips. Few springs are found along the highly faulted Laguna bench, whereas springs are common along the faulted eastern front of the Lucero uplift, where strata dip away from the MRGB boundary. Groundwater-flow across faults was examined by projecting juxtaposition seals and conduits across three fault zones that locally define the northwestern structural margin of the MRGB. A preliminary result of the fault juxtaposition analyses suggest discontinuous and discrete windows of groundwater flow along portions of basin-margin faults.
The primary goals of this investigation are to provide information on (1) large, geologically rec... more The primary goals of this investigation are to provide information on (1) large, geologically recent earthquakes along the southern Sangre de Cristo fault, and (2) document fault characteristics in the shallow subsurface to help evaluate influences of the fault on vadose zone groundwater flow. The 240km-long Sangre de Cristo fault shows prominent geomorphic evidence of geologically recent surface rupture, and is recognized as a significant potential source of large earthquakes. The data obtained from this effort will be applicable to other similar faults throughout northern and central New Mexico. Defining the earthquake history of the Sangre de Cristo fault helps reduce the uncertainty in characterizing earthquake sources throughout the Rio Grande rift, including possible fault ruptures close to Santa Fe, Albuquerque, and other areas in New Mexico. Also, this work documents the near-surface characteristics WLA Project 1605 January 16, iii
The Ancha Formation contains granite-bearing gravel, sand, and subordinate mud derived from the s... more The Ancha Formation contains granite-bearing gravel, sand, and subordinate mud derived from the southwestern flank of the Sangre de Cristo Mountains and deposited on a streamflow-dominated piedmont. These strata compose a locally important, albeit thin (less than 45 m [148 ft] of saturated thickness), aquifer for domestic water wells south of Santa Fe, New Mexico. Spiegel and Baldwin (1963) originally defined a partial type section for the Ancha Formation using a 49-m-thick (16-ft-thick) exposed interval of weakly consolidated, subhorizontal, arkosic strata on the southwest slope of Cañada Ancha. However, new geologic mapping, sedimentologic field studies, and geochronologic data indicate that the Ancha Formation should be restricted to the upper 12 m (39 ft) of Spiegel and Baldwin's type section, with the underlying strata being correlative to the upper Tesuque Formation. Because this 12-m (39-ft) interval is not well exposed at the type section, we designate four new reference sections that illustrate the textural variability of the Ancha Formation and its stratigraphic relationship with other rock units. New 40 Ar/ 39 Ar data help constrain the age of the Ancha Formation. A bed of rhyolite lapilli (1.48 ± 0.02 Ma) that is temporally correlative to one of the Cerro Toledo events is recognized near the top of the section south of Santa Fe, New Mexico. A fluvial deposit interpreted to be inset against the Ancha Formation contains lapilli dated at 1.25 ± 0.06 Ma. These dates indicate that deposition of the Ancha Formation generally ended during early Pleistocene time. However, there is evidence suggesting that aggradation continued into the middle or late Pleistocene in mountain-front canyons east of the Santa Fe embayment. The age of the basal Ancha Formation is diachronous and ranges from 2.7-3.5(?) Ma in the western Santa Fe embayment to ~1.6 Ma in the eastern embayment near the Sangre de Cristo Mountains. The Pliocene-early Pleistocene aggradation that formed the Ancha Formation in the Santa Fe embayment occurred elsewhere in the Española and Albuquerque Basins, suggesting a regional climatic influence on deposition in the uppermost Santa Fe Group. A rise in base level due to late Pliocene volcanism and tectonism may be responsible for the significant differences of accommodation space, as reflected in deposit thickness, of the Santa Fe embayment compared with the piedmont regions to the south and the generally degraded upland regions to the north. Regional geology and previous work The southern Española Basin contains several lithostratigraphic units relevant to the Ancha Formation. The Tesuque Formation underlies most of the Ancha Formation and is a pinkish-tan, arkosic, silty sandstone with minor conglomerate and siltstone that is commonly exposed in the central and eastern parts of the Española Basin north of Santa Fe. Galusha and Blick (1971) proposed the Chamita Formation for Santa Fe Group strata of Miocene age that unconformably lie above the Tesuque Formation north of the Santa Fe embayment. The Chamita Formation is generally brown or gray sand with subordinate gravel of mixed provenance; the gravel contains significant quartzite and other metamorphic clasts mixed together with granite, sedimentary, and volcanic clasts (Galusha and Blick, 1971; Tedford and Barghoorn, 1993). The Puye Formation is a coarse-grained, volcaniclastic, alluvial sequence on the western margin of the Española Basin that was shed primarily from the Tschicoma volcanic center during the Pliocene-early Pleistocene (Manley, 1976b; Waresback,
This draft geologic map was produced from scans of hand-drafted originals from the author(s). It ... more This draft geologic map was produced from scans of hand-drafted originals from the author(s). It is being distributed in this form because of the demand for current geologic mapping in this important area. The final release of this map will be made following peer review and redrafting in color using NMBGMR cartographic standards. The final product will be made available on the internet as a PDF file and in a GIS format.
Colluvium and landslide deposits Qca Colluvium and alluvium, undivided (upper to middle Pleistoce... more Colluvium and landslide deposits Qca Colluvium and alluvium, undivided (upper to middle Pleistocene)-Poorly consolidated, poorly sorted and stratified, fine-to coarse-grained, clast-and matrix-supported deposits derived from a variety of mass-movement hillslope processes, including debris flow, shallow slump and creep. Discontinuously preserved along margins of valleys capped by the Tuerto Formation. Locally differentiated where areally extensive or thick. Variable thickness, ranging 0-3 m. Qls Landslide debris (middle Pleistocene)-Blocks of well cemented conglomerate from the basal Tuerto Formation. Locally found as discontinuous boulders just below basal Tuerto Formation contact about 15-25 m above local base level. This high elevation relative to base level suggests deposits formed prior to late Pleistocene time. Variable thickness and grades into thin hillslope colluvium with an estimated thickness ranging from 0-6 m. Alluvium Qae Eolian sand, stream alluvium, and colluvium, undivided (Holocene to upper Pleistocene)-Very poorly consolidated, moderately to well sorted, light brown to yellow brown (7.5 5/4 to 2.5YR 7/6), fine-to medium-grained sand and silty sand with scattered pebbles that commonly forms a relatively thin, discontinuous mantle over broad upland areas, most notably on interfluves of streams cut into the Tuerto Formation and on ridges underlain by Mesozoic strata. Soil development is generally weak with Bw and Bwk horizons, and Stage I and II carbonate morphology. Surface is commonly stabilized by vegetation where not disturbed by human activity. May locally contain hydrocollapsible soils. Mapped only where areally extensive or thick. Variable thickness, ranging from 0-2 m. Qa Modern and historic stream alluvium (Historic to Holocene)-Unconsolidated deposits of sand and pebbly to cobbly gravel with minor, thin silty to clayey sand lenses. Inset against young stream alluvium of unit Qvy and underlies modern arroyos. Alluvium derived from Triassic rocks is reddishbrown, whereas, alluvium derived from Cretaceous rocks are pale-brown to yellow. Differentiated only in deep or wide valleys. Soils are development is minimal and deposit surface exhibit well-developed bouldery and cobbly gravel-bar topography. May locally contain hydrocollapsible soils. Base not exposed, but thickness is estimated to be less than 4-9 m. Qvy Young stream alluvium (Holocene to uppermost Pleistocene)-Poorly consolidated deposits of light-brown to yellow (2.5-10YR) sand and gravel inset against upper and middle Pleistocene deposits of units Qpm1 and Qpm2. Slightly dissected surface contains weakly developed soils exhibiting Stage
may in places be age-correlative to Qaro or Qarm All ages are 40 Ar/ 39 Ar ages, recalculated to ... more may in places be age-correlative to Qaro or Qarm All ages are 40 Ar/ 39 Ar ages, recalculated to the Fish Canyon sanidine standard age of Renne et al. (1998). 1-Age of Lava Creek B (from Lanphere et al., 2002), to which an ash in Qaro was geochemically correlated by Izett and Wilcox (1982). 2-Plagioclase single-crystal laser fusion age from Connell et al. (in press). 3-Groundmass resistance furnace incremental heating age from Maldonado et al. (2006). * Sur cial sand and clayey-silty sand sheet over units Qaro and Qam accumulated in the mid-late Pleistocene and Holocene.
New Mexico Geological Society Annual Spring Meeting, Apr 27, 2012
We summarize Miocene clastic deposition in the Española Basin (EB) and examine how drainage syste... more We summarize Miocene clastic deposition in the Española Basin (EB) and examine how drainage systems may respond to tectonic and paleoclimatic controls. The EB is a half-graben tilted west towards the Embudo-Santa Clara-Pajarito fault system (ESPFS). An arm of the EB, called the Cañada Ancha graben (CAG), extends SE away from the ESPFS. A faulted structural platform lies NW of the ESPFS. Syn-rift deposits of the Santa Fe Group are particularly well exposed in the EB, and we could readily map western alluvial slope, central basin floor, and eastern alluvial slope lithofacies assemblages. Abundant tephra and fossils provide exceptional age control. Previous studies documented an increase in ESPFS throw rates at 15-11 Ma and decreased subsidence rates in the CAG after 13.5-13.0 Ma. Paleodrainage changes included: 1) coarsening ca. 13.2 Ma; 2) progressive westward progradation of the eastern alluvial slope during 18-10 Ma and a narrowing of the basin floor, with a particularly rapid advance at 13.5-11 Ma; 3) development of a gravel-bearing ancestral Rio Chama by 12 Ma; and 4) shifting of the axial river onto the northwest structural platform after 11 Ma, at least episodically. The progradation of the eastern alluvial slope is interpreted to be controlled by increased activity along the basin master fault (ESPFS) and slower subsidence in the CAG. Poorly constrained middle Miocene progradation also occurred for eastern alluvial slope deposits in the San Luis Basin to the north, and streams of the western alluvial slope carried coarser bedload at ~14 Ma. These observations imply a paleoclimatic influence for the rapid 13.5-11 Ma progradation, driven by increased discharge and stream competence. Increased precipitation, higher subsidence rates along the ESPFS, and emergence of the nearby Jemez volcanic field perhaps facilitated integration and headward elaboration of streams draining the Colorado Plateau, forming a single river roughly coincident with the location of the modern Rio Chama. High throw rates on a fault west of the ESPFS at 11-8 Ma facilitated the shift of the San Luis Basin-draining, axial river onto the northwest structural platform. But another driver for this westward shift may be larger sediment delivery from streams draining the eastern alluvial slope compared to the western alluvial slope and axial river.
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