The Silurian-Devonian boundary in East Yunnan(South China)and the minimum constraint for the lungfish-tetrapod split  

作　　者：Wenjin ZHAO Xiaolin ZHANG Guodong JIA Yan’an SHEN Min ZHU 

机构地区：[1]Key CAS Laboratory of Vertebrate Evolution and Human Origins,Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]CAS Center for Excellence in Life and Paleoenvironment,Beijing 100044,China [4]School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China [5]State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China

出　　处：《Science China Earth Sciences》2021年第10期1784-1797,共14页中国科学（地球科学英文版）

基　　金：supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(Grant Nos.XDB26000000,XDA19050102);the National Natural Science Foundation of China(Grant Nos.42072026,41972006&41530102);the Key Research Program of Frontier Sciences of CAS(Grant No.QYZDJ-SSWDQC002).

摘　　要：The Silurian-Devonian interval is an essential period in Earth history for witnessing the rise of sarcopterygian fishes and terrestrial vascular plants.In addition to its implication in global stratigraphic correlation,the precise location of the Silurian-Devonian boundary(SDB)in East Yunnan closely relates to the minimal and maximal estimated dates for the lungfish-tetrapod split.Several geochemical indicators including the values and curves ofδ^(13)C_(org),δ^(13)Ccarb and TOC are obtained from the continuous SDB sequence in Dahe,Yiliang County,East Yunnan.The results reveal the significant positiveδ^(13)C_(org) shifts in the upper part of the Yulungssu Formation and the lower part of the Xishancun Formation,and the peak value(−20.0‰)in the sample YD-25 from the lowermost of the Xishancun Formation,replicating theδ^(13)C_(org) variation trend from the uppermost Silurian to the lowermost Devonian worldwide.Theδ^(13)C_(org) variation across the SDB at the Dahe Section resembles the SDB curve from the borehole Klonk-1 drilled at the top of the Klonk GSSP in the Prague Basin,Czech Republic.As such,we place the SDB in the Dahe Area between the samples of YD-17 and YD-18 from the lowermost part of the Xishancun Formation.This SDB assignment is corroborated by new findings of Early Devonian thelodont Parathelodus from the lower part of the Xishancun Formation in Qujing Area.The resolution of the SDB in Dahe,coupled with available paleontological data and the biostratigraphic zonation in East Yunnan,has provided vital data for the geological ages of the fish-bearing strata in East Yunnan.The earliest rhipidistian Youngolepis from the Xishancun Formation(Lochkovian,Devonian)and earliest stem-sarcopterygian Psarolepis from the Kuanti Formation(Ludfordian,Silurian)in East Yunnan indicate that the split between lungfish and tetrapods occurred between 426.5 and 416.0 Ma.

关 键 词：Carbon isotope stratigraphy Silurian-Devonian boundary East Yunnan South China Lungfish-tetrapod split Calibration date 

分 类 号：Q915[天文地球—古生物学与地层学]