The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
James R. Zimbelman - One of the best experts on this subject based on the ideXlab platform.
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white rock an eroded martian Lacustrine Deposit
Geology, 1994Co-Authors: Steven H. Williams, James R. ZimbelmanAbstract:The existence and location of ancient lake sites and sediments have important implications for Martian paleoclimate and exobiology. White Rock, an enigmatic crater interior Deposit, may be the eroded remnant of such a Lacustrine Deposit. Stereogrammetric analysis of newly processed Viking images allows better determination of the dimensions of White Rock (12.5 x 15 km, thickness 180 to 540 m, volume ∼40 km 3 ), reveals differences in erosion patterns that may reflect differences in Depositional environment, and allows the identification in or on the crater wall of a possible source region of the high-albedo White Rock material. If White Rock is the remnant of a once-larger Deposit, then open- system circulation may have been required to deliver the required quantity of evaporites.
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"White Rock": an eroded Martian Lacustrine Deposit(?)
Geology, 1994Co-Authors: Steven H. Williams, James R. ZimbelmanAbstract:The existence and location of ancient lake sites and sediments have important implications for Martian paleoclimate and exobiology. White Rock, an enigmatic crater interior Deposit, may be the eroded remnant of such a Lacustrine Deposit. Stereogrammetric analysis of newly processed Viking images allows better determination of the dimensions of White Rock (12.5 x 15 km, thickness 180 to 540 m, volume ∼40 km 3 ), reveals differences in erosion patterns that may reflect differences in Depositional environment, and allows the identification in or on the crater wall of a possible source region of the high-albedo White Rock material. If White Rock is the remnant of a once-larger Deposit, then open- system circulation may have been required to deliver the required quantity of evaporites.
Steven H. Williams - One of the best experts on this subject based on the ideXlab platform.
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white rock an eroded martian Lacustrine Deposit
Geology, 1994Co-Authors: Steven H. Williams, James R. ZimbelmanAbstract:The existence and location of ancient lake sites and sediments have important implications for Martian paleoclimate and exobiology. White Rock, an enigmatic crater interior Deposit, may be the eroded remnant of such a Lacustrine Deposit. Stereogrammetric analysis of newly processed Viking images allows better determination of the dimensions of White Rock (12.5 x 15 km, thickness 180 to 540 m, volume ∼40 km 3 ), reveals differences in erosion patterns that may reflect differences in Depositional environment, and allows the identification in or on the crater wall of a possible source region of the high-albedo White Rock material. If White Rock is the remnant of a once-larger Deposit, then open- system circulation may have been required to deliver the required quantity of evaporites.
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"White Rock": an eroded Martian Lacustrine Deposit(?)
Geology, 1994Co-Authors: Steven H. Williams, James R. ZimbelmanAbstract:The existence and location of ancient lake sites and sediments have important implications for Martian paleoclimate and exobiology. White Rock, an enigmatic crater interior Deposit, may be the eroded remnant of such a Lacustrine Deposit. Stereogrammetric analysis of newly processed Viking images allows better determination of the dimensions of White Rock (12.5 x 15 km, thickness 180 to 540 m, volume ∼40 km 3 ), reveals differences in erosion patterns that may reflect differences in Depositional environment, and allows the identification in or on the crater wall of a possible source region of the high-albedo White Rock material. If White Rock is the remnant of a once-larger Deposit, then open- system circulation may have been required to deliver the required quantity of evaporites.
Barbara Wohlfarth - One of the best experts on this subject based on the ideXlab platform.
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The First Dated Eemian Lacustrine Deposit in Romania
Quaternary Research, 2001Co-Authors: Bogdan P. Onac, Leif Björkman, Svante Björck, Octavian Clichici, T. Tamas, David W. Peate, Barbara WohlfarthAbstract:Abstract A complex interglacial sequence of Lacustrine sediments has been found near the village of Turbuta in NW Romania. Mollusk, plant macrofossil, and pollen analyses reflect climatic and environmental changes around the last interglacial climatic optimum. U-Th TIMS dating of snails strongly indicates an Eemian age of the organic sediments.
G Eglinton - One of the best experts on this subject based on the ideXlab platform.
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biogeochemistry of the miocene Lacustrine Deposit at clarkia northern idaho u s a
Organic Geochemistry, 1994Co-Authors: Graham A Logan, G EglintonAbstract:Abstract The lipid preservation observed in the sediments from Clarkia reflects an extremely immature thermal history. Many biomarkers have still retained functionality even after 17–20 million years. The soluble components are predominantly higher plant and algal derived lipids, and the original sources for these compounds are still preserved in the sediment. Thus biogeochemical data are in agreement with the associated palaeontological evidence. Chemical changes noted in the lipids preserved in these sediments are similar to those observed in modern fresh water mesotropic or eutrophic Lacustrine sediments. Therefore it can be inferred that the processes that operate in modern Lacustrine sediments are similar to those that took place within the sediments at Clarkia 17–20 million years ago.
Neal S Gupta - One of the best experts on this subject based on the ideXlab platform.
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molecular preservation of plant and insect cuticles from the oligocene enspel formation germany evidence against derivation of aliphatic polymer from sediment
Organic Geochemistry, 2007Co-Authors: Neal S Gupta, Derek E G Briggs, Margaret E Collinson, Richard P Evershed, Raymond Michels, Richard D PancostAbstract:The 25 Ma Lacustrine Deposit of Enspel, Germany, is important for molecular taphonomy as weevils from this site have yielded the oldest preserved traces of chitin. These weevil cuticles show excellent morphological and ultrastructural preservation. Plant cuticle is also preserved but it is obscured or distorted by diatom impressions. Molecular analysis of dicotyledonous angiosperm leaf from the Enspel Deposit revealed the presence of polysaccharide, guaiacyl and syringyl related lignin, and possibly degraded protein moieties in the insoluble macromolecular component. Analysis of fossil conifer leaf showed the same moieties, but syringyl related lignin units were absent. Py-GC/MS revealed C 9-33 n-alkyl components from both types of leaf, with C 13,14.29 homologues being the most abundant n-alkanes. TMAH pyrolysis yielded a fatty acid distribution ranging in carbon number from C 6-30, with the C 16,18,14 components being the most abundant. Analysis of fossil weevil cuticle also revealed the presence of an aliphatic polymer as evidenced by C 9-33 n-alkyl components in the pyrolysate and C 6-26 FAMEs (predominantly even-numbered C 14-18 components) in the TMAH pyrolysate. Pyrolysates of the sediments contain alkanes with distributions similar to those observed in the fossils; however, TMAH pyrolysates of sediments were distinct from those of the fossils with C 20-22 components being the most abundant in the conifer-bearing sediment and the even-numbered C 22-26 components dominating in the weevil-bearing sediment. Thus, the aliphatic polymers in the fossils and sediment are different, apparently comprised of moieties of different chain length. This suggests that the aliphatic polymer in the plant and insect fossils is not derived from migration from the organic-rich host sediment.
