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Gry Hoffmann Barfod

New Lu–Hf and Pb–Pb age constraints on the earliest animal fossils

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

  • Gry Barfod
  • Francis Albarede, ENS de Lyon, Frankrig
  • Andrew Knoll, Harvard University, USA
  • Shuhai Xiao, Harvard Univerisity, USA
  • Philippe Telouk, ENS de Lyon, Frankrig
  • Robert Frei, Geology, University of Cph, Danmark
  • Joel Baker, DLC cph, Danmark
The Neoproterozoic Doushantuo Formation, South China, preserves a unique assemblage of early multicellular fossils and overlies rocks, which are thought to have formed during an ice age of global extent. The age of this formation is thus critical for understanding the important biological and climatic events that occurred towards the end of the Proterozoic Eon. Until now, direct dating of sedimentary formations such as the Doushantuo has been difficult and associated with large uncertainties. Here, we show that dating of Doushantuo phosphorites by a novel Lu–Hf dating method and conventional Pb–Pb geochronometry independently yield ages of 584±26 Ma and 599.3±4.2 Ma, respectively. These ages are in agreement with bio- and chemostratigraphical observations and show that the Doushantuo animal remains predate diverse Ediacaran fossil assemblages, making them the oldest unambiguous remains of metazoans currently known. Furthermore, the Pb–Pb age for the post-glacial Doushantuo rocks suggests that the Neoproterozoic glaciation in China might predate glacial rocks in Eastern North America commonly associated with the younger (Marinoan) of two major Neoproterozoic glaciations. The combination of Lu–Hf and Pb–Pb dating shows considerable potential for dating other phosphorite successions and future application of these methods could therefore provide further constraints on Proterozoic biological and environmental history.
TidsskriftEarth and Planetary Science Letters
Sider (fra-til)203-212
Antal sider9
StatusUdgivet - 2002
Eksternt udgivetJa

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