کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4468609 1622334 2008 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Constraining the amplitude of Late Oligocene bathymetric changes in western Ross Sea during orbitally-induced oscillations in the East Antarctic Ice Sheet: (2) Implications for global sea-level changes
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Constraining the amplitude of Late Oligocene bathymetric changes in western Ross Sea during orbitally-induced oscillations in the East Antarctic Ice Sheet: (2) Implications for global sea-level changes
چکیده انگلیسی

Calibrations of deep-sea δ18O ice volume records imply glacial–interglacial (G–I), eustatic sea-level fluctuations of 10–30 m during the Late Oligocene. But it has hitherto not been possible to evaluate these inferred changes from direct evidence for coeval oscillations of sea-level and changes in the volume of the Antarctic ice sheets. Here we utilise a grainsize-derived paleobathymetry curve [Dunbar, G.B., Naish, T.R., Powell, R.P., Barrett, P.J., this volume. Constraining the amplitude of late Oligocene bathymetric changes in western Ross Sea during orbitally-induced oscillations in the East Antarctic Ice Sheet: (1) Implications for cycle stratigraphic models. Palaeogeography, Palaeoclimatology, Palaeoecology], to determine the amplitude of eustatic sea-level fluctuations, from three well-dated, Late Oligocene, shallow glacimarine sedimentary cycles cored by the Cape Roberts project in western Ross Sea. Our approach estimates the eustatic sea-level contribution to the paleobathymetry curve by placing constraints on total subsidence, decompacted sediment accumulation and glacio-isostasy. These sedimentary cycles link the extent of the East Antarctic Ice Sheet, and local paleobathymetry changes directly to orbital cycles, by using a new chronostratigraphy that enables the three sedimentary cycles to be correlated with individual cycles on the new astronomically-tuned δ18O timescale. Our new eustatic estimates are consistent with the Late Oligocene δ18O-to-sea-level calibrations of Pekar et al. [Pekar, S.F., DeConto, R.M., Harwood, D.M., 2006. Resolving a late Oligocene conundrum: Deep-sea warming and Antarctic glaciation. Palaeogeography, Palaeoclimatology and Palaeoecology 231, 29–40], and show that eustatic sea-level fluctuated between 10 m and 40 m, and represented ice volume fluctuations involving 15% to 60% of the present day Antarctic Ice Sheet. Moreover, our eustatic estimates imply a δ18O calibration for the Mi-1 excursion that supports a significant expansion of ice on Antarctica, perhaps equivalent to 120% of the present day EAIS (assuming no northern hemisphere ice), with an attendant fall in global sea-level of ~ 50 m.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Palaeogeography, Palaeoclimatology, Palaeoecology - Volume 260, Issues 1–2, 7 April 2008, Pages 66–76
نویسندگان
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