首页|Thermal History of Cambrian Burgess Shale-Type Deposits:New Insights from the Early Cambrian Chengjiang and Qingjiang Fossils of South China

Thermal History of Cambrian Burgess Shale-Type Deposits:New Insights from the Early Cambrian Chengjiang and Qingjiang Fossils of South China

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Burgess Shale-type deposits provide a wealth of information on the early evolution of ani-mals.Questions that are central to understanding the exceptional preservation of these biotas and the paleocnvironments they inhabited may be obscured by the post-depositional alteration due to metamor-phism at depth and weathering near the Earth's surface.Among over 50 Cambrian BST biotas,the Chengjiang and Qingjiang deposits are well known for their richness of soft-bodied taxa,fidelity of preservation,and Early Cambrian Age.While alteration via weathering has been well-investigated,the thermal maturity of the units bearing the two biotas has not yet been elucidated.Here we investigate peak metamorphic temperatures of the two deposits using two independent methods.Paleogeotempera-ture gradient analyses demonstrate that the most fossiliferous sections of the Chengjiang were buried at a maximum depth of～8 500 m in the Early Triassic,corresponding to～300 ℃,while the type area of the Qingjiang biota was buried at a maximum depth of～8 700 m in the Early Jurassic,corresponding to～240 ℃.Raman geothermometer analyses of fossil carbonaceous material demonstrate that peak temperatures varied across localities with different burial depth.The two productive sections of the Chengjiang biota were thermally altered at a peak temperature of approximately 300 ℃,and the main locality of the Qingjiang biota experienced a peak temperature of 238±22 ℃.These results from two independent methods are concordant.Among BST deposits for which thermal maturity has been docu-mented,the Qingjiang biota is the least thermally mature,and therefore holds promise for enriching our understanding of BST deposits.

the Chengjiang Biotathe Qingjiang Biotaburial historyRaman geothermometerthermal historyBurgess Shale-type Lagerstätte

Yuheng Qiao、Linhao Cui、Guangyuan Xing、Dongjing Fu、Chao Chang、Robert Gaines、Xingliang Zhang

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State Key Laboratory of Continental Dynamics,Shaanxi Key laboratory of Early Life and Environments,Department of Geology,Northwest University,Xi'an 710069,China

Department of Geology,Pomona College,Claremont CA 91711,USA

Natural Science Foundation of ChinaNatural Science Foundation of ChinaNatural Science Foundation of China111 ProjectNatural Science Basic Research Plan of Shaanxi Province

4193031941621003EAR-1554897D170132022JC-DW5-01

2024

10.1007/s12583-023-1921-2

地球科学学刊(英文版)
中国地质大学

地球科学学刊(英文版)

CSTPCD
影响因子：0.724
ISSN：1674-487X
年,卷(期)：2024.35(4)
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