Shelf, coastal and subglacial polar carbonates, East Antarctica
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Modern and Pleistocene polar carbonates occur in East Antarctica in shelf, coast, lakes and marginal to underneath glaciers, associated mainly with glacigene muds, boulder tills and diamictites. Shelf carbonates (in Prydz Bay) are calcitic and unlithified, and consist mainly of sponges, bryozoans, echinoderms, bivalves and diatoms. Coastal carbonates (in the Vestfold Hills) are calcitic and contain faunal assemblages similar to those on the shelf, with calcareous algae, microbial mats, minor peloids and cements. Lake carbonates are aragonitic micrites and peloids. Carbonates close to glaciers (the Løken Moraines) are aragonitic and contain abundant ooids with intragranular fibrous cements. Subglacial carbonates are aragonitic micrites and peloids. Carbonate mineralogy changes from mainly low-Mg calcite in marine shelf to aragonite in brackish to freshwater dominated inland regions.
Antarctic carbonate δ18O values (4.5 to −47‰ PDB) vary markedly due to frigid temperatures (0 to −2°C) and salinity (0 to 35‰) changes, as a result of meltwater dilution from adjacent glaciers. Their δ13C values (−9 to 8‰ PDB) also vary markedly due to exposure to atmospheric CO2, the circulation of water masses and reaction of carbonate with CO2 trapped in glacial ice.
The regional distribution of carbonate sediments and their sedimentology, mineralogy, and δ18O and δ13C compositions indicate three types of glacial environments of formation. The first corresponds to a glacial stage and the formation of subglacial and bank carbonates, when the Antarctic ice sheet expanded onto the inner shelves. The second corresponds to interglacial stages and the formation of ice-marginal carbonates, during the retreat of the ice sheet from the inner shelf grounding line and accompanying the discharge of appreciable meltwater. The third corresponds to an interglacial oasis and the formation of coastal carbonates, proximal to distal lacustrine carbonates, and distal subglacial carbonates.
KeywordsCalcite Foraminifera Aragonite Ooids Benthic Foraminifera
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- ANDERSON, T.F. and ARTHUR, M.A., 1983, Stable isotopes of oxygen and carbon and their application to sedimentologic and environmental problems, in Stable Isotopes in Sedimentary Geology, edited by M.A. Arthur and T.F. Anderson, Society of Economic Paleontologists and Mineralogist, Tulsa, Oklahoma, p. 1–151.Google Scholar
- ANDERSON, J.B. and ASHLEY, G.M., 1991, Glacial Marine Sedimentation; Paleoclimatic significance. Geological Society of America, Inc., 232 p.Google Scholar
- BARDIN, V.I., PISKUN, A.A., and SHMIDBERG, N.A., 1990, Hydrological and hydrochemical characteristics of deep water basins in Prince Charles Mountains: Antarktika, doklady komissii, No. 29, p. 97–112Google Scholar
- BJAERKE, T. and DYPVIK, H., 1977, Quaternary “stromatolitic” limestone of subglacial origin from Scandinavia:Journal of Sedimentary Petrology, v. 47, p. 1321–1327.Google Scholar
- CRAIG, H., 1965, The measurement of oxygen isotope paleotemperatures,in Stable isotopes in Oceanographic Studies and Paleotemperatures: Spoleto, July 26–27, 1965, Consiglio Nazionale delle Richerche, Laboratorio di Geologia Nucleare, Pisa, p. 1–124.Google Scholar
- FRANKLIN, D.C., 1993, Recent diatom and foraminiferal assemblages in surficial sediments of Prydz Bay, Antarctica: Australian National Antarctic Research Expedition Research Notes, v. 90, 27 p.Google Scholar
- HAMBREY, M., 1995, Glacial Environments, UCL press, London, 296 p.Google Scholar
- HARRIS, P.T., O’BRIEN, P.E., SEDWICK, P. and TRUSWELL, E.M., 1996, Late Quaternary history of sedimentation on the Mac. Robertson Shelf, East Antarctica: problems with14C-dating of marine sediment core:Papers and Proceedings Royal Society of Tasmnia, v. 130, p. 47–53.Google Scholar
- JACOBS, S.S., FAIRBANKS, R.G., and HUBBERTEN, H.W., 1995, Origin and evolution of water masses near the Antarctic continental margin: Evidence from H2 18O/H2 16O ratios in seawater:Antarctic Research Series, v. 43, p. 59–86.Google Scholar
- LEMMENS, M., LORRAIN, R., and HAREN, J., 1982, Isotopic composition of ice and subglacially precipitated calcite in an alpine area:Zeischrift fur Gletscherkunde und Glazialgeologie, v. 18, p. 151–159.Google Scholar
- MORGAN, V.I., 1982, Antarctic ice sheet surface oxygen isotope values:Journal of Glaciology, v. 28, p. 315–323.Google Scholar
- MORSE, J.W. and MacKENZIE, F.T., 1990, Geochemistry of Sedimentary Carbonates. Developments in Sedimentology 48, Elsevier, 707 p.Google Scholar
- PETERSON, J.A. and MORESBY, J.F., 1979, Subglacial travertine and associated deposits in the Carstensz area, Irian Jaya, Republic of Indonesia:Zeitschrift fur Glescherkunde and Glazialgeologie, v. 15, p. 23–29.Google Scholar
- PICKARD, J., ADAMSON, D., HARWOOD, D.M., MILLER, G.H., QUILTY, P.G., and DELL, R.K., 1984, Early Pliocene marine sediments in the Vestfold Hills, East Antarctica: Implication for coastline, ice sheet, and climate:South African Journal of Science, v. 82, p. 520–521.Google Scholar
- RAO, C.P., 1981, Criteria for recognition of cold-water carbonate sedimentation: Berriedale Limestone (Lower Permian), Tasmania, Australia:Journal of Sedimentary Petrology, v. 51, p. 491–506.Google Scholar
- RAO, C.P., 1983, Cold-water spherical grains from a fresh-water drainage pipe, Gordon Dam, Tasmania, Australia:Journal of Sedimentary Petrology, v. 53, p. 1169–1173.Google Scholar
- RAO, C.P., 1996, Modern Carbonates: tropical, temperate and polar_ — introduction to sedimentology and geochemistry, Carbonates, Hobart, 206 p.Google Scholar
- RAO, C.P. and GREEN, D.C., 1982, Oxygen and carbon isotopes of Early Permian cold-water carbonates, Tasmania, Australia:Journal of Sedimentary Petrology, v. 52, p. 1111–1125.Google Scholar
- RAO, C.P., AMINI, Z.Z., and FRANKLIN, D., 1995, Grain-size, biota, sedimentology and oxygen and carbon isotopes of sediments, Davies Station and Prydz Bay, Antarctica: evidence for occurrence and recession of shelf ice:ANARE Res. News, v. 94, p. 33–34.Google Scholar
- RAO, C.P., AMINI, Z.Z., and FRANKLIN, D., 1996, Comparison between modern polar and temperate skeletal carbonate mineralogy and oxygen and carbon isotopes, Antarctica and Tasmania shelves.In Banks, M.R. and Brown, M.J, eds., Climatic succession and glacial history of the southern hemisphere over the last five million years:Papers and Proceedings of Royal Society of Tasmania, v. 130, p. 87–93.Google Scholar
- TAVIANI, M., REID, D.E., and ANDERSON, J.B., 1993, Skeleltal and isotopic composition and paleoclimatic significance of late Pleistocene carbonates, Ross Sea, Antarctica:Journal Sedimentary Petrology, v. 63, p. 84–90.Google Scholar