Numerical model of circumpolar Antarctic ice shelves
Extensive floating ice shelves in the Antarctic have been proposed to explain the discrepancies between Pleistocene high sea levels shown by dated coral reefs and coeval low sea levels inferred from glacial ice volumes calculated from oxygen isotope ratios in deep sea cores. A numerical model using the floating shelf creep analysis of Weertman (1957) has provided a plausible basis for the acceptance of such shelves. Shelf outer limits were set at 55/sup 0/S in East Antarctica and 58/sup 0/S in West Antarctica, based in part on diatom-deficient deep sea sediments deposited prior to the Holocene. Precipitation varied from 10 gm cm/sup -2/yr/sup -1/ at 75/sup 0/S to 80 gm cm/sup -2/yr/sup -1/ at 55/sup 0/S. Mean air temperatures varied from -35/sup 0/C at the 75/sup 0/S coast to -17/sup 0/C at the outer limits. Isotope ratios were those of present Antarctic precipitation at corresponding model shelf temperatures. In the calculation, a steady state is assumed. Integration begins at the coast with summation over successive years as creep and continental ice discharge move the integration element to the outer limits. The oceanic oxygen isotope ratio change required by the discrepancies in the record is 0.40 to 0.50 ppmil. Using the flow law constant of 4.2 and a creep activation energy of 134 kjoules mol/sup -1/, the resulting change is 0.44 ppmil. Difference results reflect the uncertainties associated with the critical creep constants used in the modeling. Nevertheless, the results suggest that a quantity of Antarctic shelf ice comparable to ice volumes in major Northern glacial areas existed at times during the Pleistocene.
- Research Organization:
- Honeywell Physical Sciences Center, Bloomington, MN (USA)
- OSTI ID:
- 6463795
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTARCTIC REGIONS
ICE CAPS
PALEOCLIMATOLOGY
SEA LEVEL
CREEP
VARIATIONS
ACTIVATION ENERGY
ANTARCTICA
ATMOSPHERIC PRECIPITATIONS
CONTINENTAL SHELF
FORAMINIFERA
ICEBERGS
ISOTOPE RATIO
MATHEMATICAL MODELS
NUMERICAL ANALYSIS
OXYGEN ISOTOPES
PLEISTOCENE EPOCH
REEFS
SEDIMENTS
STRESS RELAXATION
TEMPERATURE MEASUREMENT
ANIMALS
CENOZOIC ERA
CONTINENTAL MARGIN
ENERGY
GEOLOGIC AGES
GEOLOGIC STRUCTURES
ICE
INVERTEBRATES
ISOTOPES
LEVELS
MATHEMATICS
MECHANICAL PROPERTIES
MICROORGANISMS
PALEONTOLOGY
POLAR REGIONS
PROTOZOA
QUATERNARY PERIOD
RELAXATION
SARCODINA
580100* - Geology & Hydrology- (-1989)