TY - JOUR

T1 - New Lu-Hf and Pb-Pb age constraints on the earliest animal fossils

AU - Barfod, Gry H.

AU - Albarède, Francis

AU - Knoll, Andrew H.

AU - Xiao, Shuhai

AU - Télouk, Philippe

AU - Frei, Robert

AU - Baker, Joel

PY - 2002/8/13

Y1 - 2002/8/13

N2 - 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.

AB - 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.

KW - Absolute age

KW - Biologic evolution

KW - Doushantuo Formation

KW - Geochronology

KW - Guizhou China

KW - Lu Hf system

KW - Neoproterozoic

KW - Pb/Pb

KW - Phosphate rocks

KW - Sinian

UR - http://www.scopus.com/inward/record.url?scp=0036328836&partnerID=8YFLogxK

U2 - 10.1016/S0012-821X(02)00687-8

DO - 10.1016/S0012-821X(02)00687-8

M3 - Journal article

AN - SCOPUS:0036328836

VL - 201

SP - 203

EP - 212

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

IS - 1

ER -