Timing of the Last Glacial Maximum from observed sea-level minima

During the Last Glacial Maximum, ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today. But few direct estimates exist of the volume of the ice sheets, or the timing and rates of change during their advance and retreat. Here we analyse four distinct sediment facies in the shallow, tectonically stable Bonaparte Gulf, Australia—each of which is characteristic of a distinct range in sea level—to estimate the maximum volume of land-based ice during the last glaciation and the timing of the initial melting phase. We use faunal assemblages and preservation status of the sediments to distinguish open marine, shallow marine, marginal marine and brackish conditions, and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio-hydro-isostatic modelling. Our results indicate that from at least 22,000 to 19,000 (calendar) years before present, land-based ice volume was at its maximum, exceeding today's grounded ice sheets by 52.5 × 106 km3. A rapid decrease in ice volume by about 10% within a few hundred years terminated the Last Glacial Maximum at 19,000 ± 250 years.

[1]  H. Moriwaki,et al.  Notes on the Holocene Sea-level Study in Japan , 1982 .

[2]  K. Suslick,et al.  Shape-Selective Discrimination of Small Organic Molecules , 2000 .

[3]  D. Scott.  FORAMINIFERIDA AND OSTRACODA FROM ESTUARINE AND SHELF ENVIRONMENTS ON THE SOUTHEASTERN COAST OF AUSTRALIA , 1996 .

[4]  E. Bard,et al.  Ice Age Temperatures and Geochemistry , 1999, Science.

[5]  G. Camoin,et al.  Sea-Level Changes and δ18O Record for the Past 34,000 yr from Mayotte Reef, Indian Ocean , 1996, Quaternary Research.

[6]  J. Andrews.  A case of missing water , 1992, Nature.

[7]  K. Lambeck,et al.  Automatic inference of ice models from postglacial sea-level observations: Theory and application to the British Isles , 2000 .

[8]  K. Lambeck,et al.  Refining the eustatic sea-level curve since the Last Glacial Maximum using far- and intermediate-field sites , 1998 .

[9]  Paul Johnston,et al.  Sea‐level change, glacial rebound and mantle viscosity fornorthern Europe , 1998 .

[10]  D. Macayeal,et al.  Deglaciation of a Soft-Bedded Laurentide Ice Sheet , 1998 .

[11]  K. Lambeck,et al.  Late Pleistocene and Holocene sea-level change along the Australian coast , 1990 .

[12]  M. Stuiver,et al.  Modeling Atmospheric 14C Influences and 14C Ages of Marine Samples to 10,000 BC , 1993, Radiocarbon: An International Journal of Cosmogenic Isotope Research.

[13]  P. Reimer,et al.  Extended 14C Data Base and Revised CALIB 3.0 14C Age Calibration Program , 1993, Radiocarbon: An International Journal of Cosmogenic Isotope Research.

[14]  P. Deckker.  An account of the techniques using ostracodes in palaeolimnology in Australia , 1988 .

[15]  P. Quilty.  The Antarctic Region: Geological Evolution and Processes , 1998 .

[16]  E. Bard,et al.  U-Th ages obtained by mass spectrometry in corals from Barbados: sea level during the past 130,000 years , 1990, Nature.

[17]  D. Henderson,et al.  Cursoriality in bipedal archosaurs , 2000, Nature.

[18]  R. Fairbanks.  A 17,000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation , 1989, Nature.

[19]  T. H. Andel,et al.  Late Quaternary history, climate, and oceanography of the Timor sea, northwestern Australia , 1967 .

[20]  E. Bard,et al.  Radiocarbon Calibration by Means of Mass Spectrometric 230Th/234U and 14C Ages of Corals: An Updated Database Including Samples from Barbados, Mururoa and Tahiti , 1998, Radiocarbon.

[21]  J. Beck,et al.  A Large Drop in Atmospheric 14C/12C and Reduced Melting in the Younger Dryas, Documented with 230Th Ages of Corals , 1993, Science.

[22]  J. Kleman,et al.  Frozen-bed Fennoscandian and Laurentide ice sheets during the Last Glacial Maximum , 1999, Nature.

[23]  K. Lambeck,et al.  Glacial rebound and relative sea-level variations: a new appraisal , 1987 .

[24]  W. Peltier,et al.  Ice Age Paleotopography , 1994, Science.

[25]  A. Mcintyre,et al.  Seasonal reconstructions of the earth's surface at the last glacial maximum , 1981 .

[26]  K. Lambeck,et al.  The melting history of the late Pleistocene Antarctic ice sheet , 1988, Nature.

[27]  K. Lambeck.  Limits on the areal extent of the Barents Sea ice sheet in Late Weichselian time , 1996 .

[28]  W. Peltier,et al.  ICE-3G: A new global model of late Pleistocene deglaciation based upon geophysical predictions of po , 1991 .

[29]  Richard B. Alley,et al.  Northern Hemisphere Ice-Sheet Influences on Global Climate Change , 1999 .

[30]  C. Murray-Wallace,et al.  Glacial Lowstand Deposits on the Outer Continental Shelf of Southeastern Australia , 1995, Quaternary Research.