文章基本信息

标题：Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse
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作者：Thijs R. A. Vandenbroucke ; Howard A. Armstrong ; Mark Williams 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：34
页码：14983-14986
DOI：10.1073/pnas.1003220107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22x PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan ("mixed layer") marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55{degrees}-70{degrees} S to [~]40{degrees} S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of [~]8x PAL to [~]5x PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction.
关键词：chitinozoans ; Ordovician ; zooplankton biotopes ; Hirnantian glaciations ; climate belts