Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

Alan D. Rooney; Francis A. Macdonald; Justin V. StraussFrancis ?. DudásChristian HallmannDavid Selby

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Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

机译：Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

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After nearly a billion years with no evidence for glaciation, ice advanced to equatorial latitudes at least twice between 717 and 635 Mya. Although the initiation mechanism of these Neoproterozoic Snowball Earth events has remained a mystery, the broad synchronicity of rifting of the supercontinent Rodinia, the emplacement of large igneous provinces at low latitude, and the onset of the Sturtian glaciation has suggested a tectonic forcing. We present unique Re-Os geochronology and high-resolution Os and Sr isotope profiles bracketing Sturtian-age glacial deposits of the Rapitan Group in northwest Canada. Coupled with existing U-Pb dates, the postglacial Re-Os date of 662.4 ± 3.9 Mya represents direct geochronological constraints for both the onset and demise of a Cryogenian glaciation from the same continental margin and suggests a 55-My duration of the Sturtian glacial epoch. The Os and Sr isotope data allow us to assess the relative weathering input of old radiogenic crust and more juvenile, mantle-derived substrate. The preglacial isotopic signals are consistent with an enhanced contribution of juvenile material to the oceans and glacial initiation through enhanced global weatherability. In contrast, postglacial strata feature radiogenic Os and Sr isotope compositions indicative of extensive glacial scouring of the continents and intense silicate weathering in a post–Snowball Earth hothouse.

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《Proceedings of the National Academy of Sciences of the United States of America》 |2014年第1期|51-56|共6页
作者
Alan D. Rooney; Francis A. Macdonald; Justin V. StraussFrancis ?. DudásChristian HallmannDavid Selby;
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作者单位

Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138;

Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139;

Department of Earth Sciences, Durham University, Durham DH1 3LE, United Kingdom;

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收录信息美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
原文格式 PDF
正文语种英语
中图分类自然科学总论;
关键词
rhenium-osmium geochronology; strontium isotopes; osmium isotopes; Windermere Supergroup; Neoproterozoic glaciation;

Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth

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