The snowball Earth hypothesis: testing the limits of global change
- P. Hoffman, D. Schrag
- Environmental Science, Geography
- 1 June 2002
The gradual discovery that late Neoproterozoic ice sheets extended to sea level near the equator poses a palaeoenvironmental conundrum. Was the Earth's orbital obliquity > 60° (making the tropics…
The Salinity, Temperature, and δ18O of the Glacial Deep Ocean
- J. Adkins, K. McIntyre, D. Schrag
- Environmental Science, GeographyScience
- 29 November 2002
We use pore fluid measurements of the chloride concentration and the oxygen isotopic composition from Ocean Drilling Program cores to reconstruct salinity and temperature of the deep ocean during the…
The oxygen isotopic composition of seawater during the Last Glacial Maximum
- D. Schrag, J. Adkins, J. McManus
- Environmental Science, Geography
- 2002
Large Perturbations of the Carbon Cycle During Recovery from the End-Permian Extinction
- J. Payne, D. Lehrmann, Jiayong Wei, M. Orchard, D. Schrag, A. Knoll
- Environmental Science, GeographyScience
- 23 July 2004
High-resolution carbon isotope measurements of multiple stratigraphic sections in south China demonstrate that the pronounced carbon isotopic excursion at the Permian-Triassic boundary was not an…
Pore Fluid Constraints on the Temperature and Oxygen Isotopic Composition of the Glacial Ocean
- D. Schrag, Gretchen Hampt, D. Murray
- Environmental Science, GeographyScience
- 28 June 1996
Pore fluids from the upper 60 meters of sediment 3000 meters below the surface of the tropical Atlantic indicate that the oxygen isotopic composition (δ18O) of seawater at this site during the last…
Toward a Neoproterozoic composite carbon-isotope record
- G. Halverson, P. Hoffman, D. Schrag, A. Maloof, A. Rice
- Environmental Science, Geology
- 1 September 2005
Glacial deposits of Sturtian and Marinoan age occur in the well-studied Neoproterozoic successions of northern Namibia, South Australia, and northwestern Canada. In all three regions, the Marinoan…
Defining an absolute reference frame for 'clumped' isotope studies of CO 2
- K. Dennis, H. P. Affek, B. Passey, D. Schrag, J. Eiler
- Environmental Science
- 15 November 2011
Heterotrophic Archaea dominate sedimentary subsurface ecosystems off Peru.
- J. Biddle, J. Lipp, K. Hinrichs
- Environmental ScienceProceedings of the National Academy of Sciences…
- 7 March 2006
It is shown that extractable archaeal rRNA, selecting only for active community members in these ecosystems, is dominated by sequences of uncultivated Archaea affiliated with the Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group, whereas known methanotrophic Archaea are not detectable.
Calibrating the Cryogenian
- F. Macdonald, M. Schmitz, D. Schrag
- Geography, GeologyScience
- 5 March 2010
Four high-precision U-Pb ages for Neoproterozoic rocks in northwestern Canada are presented that constrain large perturbations in the carbon cycle, a major diversification and depletion in the microfossil record, and the onset of the Sturtian glaciation.
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