Papers by Dale Schneeberger
Journal of Geophysical Research, 1993
The northern lowland plains comprise approximately one third Mars' surface area. Most outflow cha... more The northern lowland plains comprise approximately one third Mars' surface area. Most outflow channels and many valley networks debouch into the lowlands, yet there is little or no morphologic evidence to suggest that channel cutting continued far into the plains, despite a continued basinward regional topographic gradient. The immediate fate of the water discharged from these channels was dependent on the prevailing paleoclimate at the time of its emplacement. Though current models of the martian paleoclimate suggest that mean annual temperatures were likely below freezing throughout most of martian history, geomorphic evidence suggests that coastal erosion on a scale comparable to that of well-known terrestrial paleolakes occurred. These landforms can be traced to nearly complete closure of the northern plains and appear to require at least two, and perhaps several, highstands of a sea or ocean with temperatures above freezing at least for geologically brief periods of time. The latest highstand may have been as recent as Early Amazonian time. The elevations and areal extent of these landforms provide independent estimates of the martian water budget that can be compared to prevailing models of martian volatile evolution. Estimated volumes of water and sediment discharged by the major channel systems peripheral to the northern plains can be compared to the volume of the basin based on the available topography. Values for the circum-Chryse outflow channels alone are sufficient to have produced large bodies of standing water within the basin. These estimates may be comparable to the basin volume contained within the younger, least extensive highstand identified. The earlier, more extensive highstand delineates a basin with a much larger implied volume that may require the presence of a semi-permanent, possibly ice-covered ocean in the northern plains prior to major channeling events. The northern plains today probably consist of water-lain sediments interbedded to considerable depths with flood lavas from the major volcanic centers, with sediment comprising most of the present surface.
NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986, May 1, 1987
Very high resolution (lOm/pixel or better) Viking Orbiter images of the martian surface, though r... more Very high resolution (lOm/pixel or better) Viking Orbiter images of the martian surface, though rare, make it possible to examine specific areas at image scales approaching those of high altitude terrestrial aerial photographs.
NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986, May 1, 1987
Lunar and Planetary Science Conference, Mar 1, 1988
NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986, May 1, 1987
LPICo, 1988
Alba Patera presents styles of volcanism that are unique to Mars. Its very low profile, large are... more Alba Patera presents styles of volcanism that are unique to Mars. Its very low profile, large areal extent, unusually long and voluminous lava flows, and circumferential graben make it among Mars' most interesting volcanic features. Clues to Alba's volcanic history are preserved in its morphology and stratigraphy. Understanding the relationship of lava flow morphology to emplacement processes should enable estimates
Journal of Geophysical Research, 1991
ABSTRACT
Journal of Geophysical Research, 1991
Geomorphic and stratigraphic analysis of Alba Patera suggests a volcanic construct built by lavas... more Geomorphic and stratigraphic analysis of Alba Patera suggests a volcanic construct built by lavas with rheologic properties similar to basalts. A series of evolving eruptive styles is suggested by changes in morphology and inferred progressive reductions in flow volume with higher stratigraphic position. Alba Patera's volcanic history has been summarized into four main phases. The first is characterized by extensive flood like flows presumably erupted from fissures associated with the initial intrusion of magma into the region. The second phase is associated with the emplacement of pyroclastic rock, a more speculative interpretation. The third phase produced the voluminous tabular, crested, and undifferentiated flows, probably from a more centralized vent source. The fourth and last phase is marked the effusion of levee like flows and the collapse of the summit calderas and final graben formation.
Journal of Geophysical Research, 1993
The northern lowland plains comprise approximately one third Mars' surface area. Most outflow cha... more The northern lowland plains comprise approximately one third Mars' surface area. Most outflow channels and many valley networks debouch into the lowlands, yet there is little or no morphologic evidence to suggest that channel cutting continued far into the plains, despite a continued basinward regional topographic gradient. The immediate fate of the water discharged from these channels was dependent on the prevailing paleoclimate at the time of its emplacement. Though current models of the martian paleoclimate suggest that mean annual temperatures were likely below freezing throughout most of martian history, geomorphic evidence suggests that coastal erosion on a scale comparable to that of well-known terrestrial paleolakes occurred. These landforms can be traced to nearly complete closure of the northern plains and appear to require at least two, and perhaps several, highstands of a sea or ocean with temperatures above freezing at least for geologically brief periods of time. The latest highstand may have been as recent as Early Amazonian time. The elevations and areal extent of these landforms provide independent estimates of the martian water budget that can be compared to prevailing models of martian volatile evolution. Estimated volumes of water and sediment discharged by the major channel systems peripheral to the northern plains can be compared to the volume of the basin based on the available topography. Values for the circum-Chryse outflow channels alone are sufficient to have produced large bodies of standing water within the basin. These estimates may be comparable to the basin volume contained within the younger, least extensive highstand identified. The earlier, more extensive highstand delineates a basin with a much larger implied volume that may require the presence of a semi-permanent, possibly ice-covered ocean in the northern plains prior to major channeling events. The northern plains today probably consist of water-lain sediments interbedded to considerable depths with flood lavas from the major volcanic centers, with sediment comprising most of the present surface.
Icarus, 1989
To the west, the boundary is gradational and to the east it is defined by fretted terrain. The tw... more To the west, the boundary is gradational and to the east it is defined by fretted terrain. The two types of boundaries do not merge with one another within the west Deuteronilns Mensae region, however. The gradational boundary materials appear to overlap the fretted terrain by about 500 km. Contacts between units associated with the gradational boundary and the fretted terrain boundary can both be recognized in the region of overlap. The fretted terrain can be identified as much as 300 km north of the gradational boundary in this region. Lowland units associated with the gradational boundary embay canyons of the fretted terrain in a topographically conformal fashion. Changes in the fretted terrain across the gradationai boundary (from uplands to lowlands) include a reduction of canyon wall slopes and depths, such that the fretted terrain north of the gradational boundary appears mantled but not obscured. There are at least two major classes of processes which might explain the lateral overlap: (1) erosion of stratified upland terrain and (2) deposition of plains materials onto the sloping upland margin and fretted terrain. Erosion of stratified upland terrain does not adequately explain the plainward decrease in crater densities across the gradationai boundary nor is it consistent with evidence that lowland plains material appears to onlap the sloping upland margin in several places. Of the possible plains emplacement mechanisms, eolian deposition would not produce the sharp, apparently topographically conformal gradational unit contacts. Volcanic plains emplacement would not preserve the complex geometry of the underlying fretted terrain. Sediment deposition in either a liquid or ice-covered sea could produce the draped appearance of the fretted terrain. Outflow channels along the lowland/ upland boundary, particularly those of the circum-Chryse and west Elysium regions, may have flooded the northern lowlands to depths of tens to hundreds of meters. The gradational unit contacts may represent the shorelines of such a sea. The scale of characteristic morphologies along these contacts may require an unfrozen condition of sufficient duration to allow lacustrine-style wave erosion and redistribution of material along the contacts. Our limited understanding of the Martian paleoclimate and H20 inventories allows the possibility of clement periods in the past, and other geological evidence (e.g., small valley networks and outflow channels) strongly suggests an extensive role of liquid water,
: The 412th Civil Engineer Group at Edwards AFB, California, proposes ongoing base-wide routine a... more : The 412th Civil Engineer Group at Edwards AFB, California, proposes ongoing base-wide routine and recurring realignment of units and personnel to facilities with suitable working space in support of the Air Force mission. These realignments allow Edwards AFB to make optimum use of facilities in a cost efficient manner that is consistent with installation priorities while preserving the ability to accomplish the mission. This environmental assessment (EA) documents the environmental analysis of relocation actions associated with the integrated approach to anticipated needs to continually relocate units and personnel on the base. This integrated approach will prevent duplication of effort (per Air Force Instruction 32-7062, Comprehensive Planning, and Title 40 Code of Federal Regulations (CFR] 1502.20), provide advance information for environmental planning and allow consideration of the environmental consequences of these actions consistent with the National Environmental Policy Ac...
Title: Comet Singer Brewster (1986d). Authors: Singer-Brewster, S.; Schneeberger, D.;Burr, E.; He... more Title: Comet Singer Brewster (1986d). Authors: Singer-Brewster, S.; Schneeberger, D.;Burr, E.; Helin, EF; Shoemaker, EM. Publication: IAU Circ., 4209, 1 (1986). Edited by Marsden, BG. Publication Date: 05/1986. Origin: CBAT. Objects: 1986d. ...
Lunar and Planetary Science Conference, Feb 27, 1989
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Papers by Dale Schneeberger