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Oxygen isotope values from Permian high latitudes: clues for palaeolatitudinal sea-surface temperature gradients and Late Palaeozoic deglaciation.

Korte, C.1, Jones, P.J.2, Brand, U.3, Mertmann, D.4 & Veizer, J.1,5

1 Institut für Geologie, Mineralogie und Geophysik, Ruhr Universität 44801 Bochum, Germany
2 Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
3 Department of Earth Sciences, Brock University, St Catharines, Ontario, Canada L2S 3A1
4 Institut für Geowissenschaften, FU Berlin, Malteserstrasse 74-100, 12249 Berlin, Germany
5 Ottawa-Carleton Geoscience Centre, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5

Abstract.  The Permian was a period of waning large-scale continental glaciations in the southern Hemisphere. The waning of these ice sheets during the Early Permian led to discharge of 18O-depleted ice-melt water into the oceans. This, coupled with rising seawater temperatures, resulted in a concomitant decline of about 2.5 ‰in the δ18O of seawater, as recorded by brachiopod shells from low-latitude (< 30°) habitats. The transition from ice- to greenhouse conditions is reflected also in the oxygen isotope data of unaltered brachiopods and bivalves from high latitudes. Moreover, the high-latitude specimens have consistently more positive δ18O, by about 2.5‰, than their coeval low-latitude counterparts, suggesting a Permian sea- surface temperature (SST) gradient of about 9 to 12°C between tropical-subtropical (<30°) and high southern (55 ±10°) latitude localities, apparently irrespective of whether in a greenhouse or an icehouse mode. This Permian SST gradient is comparable to the SST gradient of about 14°C. The δ18O seawater records suggest that the global warming that resulted in the waning of the Permo-Carboniferous ice sheets during the Sakmarian was followed by another cooling during the late Kungurian and by renewed warming during the Mid- and Late Permian.

Institut für Geologie, Mineralogie Korte, C., Jones, P.J., Brand, U., Mertmann, D. & Veizer, J. (2008) Oxygen isotope values from Permian high latitudes: clues for palaeolatitudinal sea-surface temperature gradients and Late Palaeozoic deglaciation. Palaeogeography, Palaeoclimatatology, Palaeoecology 269, 1-16.