Application of Strontium Isotopic Stratigraphy to Dating Marine Sedimentary Units:A Case Study from the Permian Stratotype Section in Southern China  

作　　者：QU Hongjun CHEN Shuo HAN Xing WANG Li GUAN Liqun FAN Yuhai 

机构地区：[1]Department of Geology,Northwest University,Xi'an 710069,China [2]State Key Laboratory of Continental Dynamics,Northwest University,Xi'an 710069,China [3]Remote Sensing Application Institute of ARSC,Xi'an 710054,China

出　　处：《Acta Geologica Sinica(English Edition)》2021年第2期355-369,共15页地质学报（英文版）

基　　金：financially supported by the National Key Research and Development Program(Grant No.2016YFC0601003);the scientific team foundation of Department of Geology,China Northwest University;the National Natural Science Foundation of China(Grant No.41172101)。

摘　　要：The calibration of sedimentary rock absolute dates is one of the difficulties in sedimentological and stratigraphic research.Since strontium(Sr)resides in seawater much longer(≈10^(6) a)than the seawater intermixing time(≈10^(3) a),the Sr isotopic composition of global seawater is uniform at any time and results in a stable system throughout geological history,based on which a global Sr isotope composition dating database has been established for age-calibration of marine strata.The Permian stratigraphic sections in the northern part of the Upper Yangtze block,southern China,record continuous marine sediments with clear stratigraphic boundaries and is suitable for stratigraphic dating of Sr isotopes.Based on sampling and Sr isotopic compositions of Permian carbonate strata in the northern part of the Upper Yangtze,a Permian Sr isotope evolution curve was established.According to the basic principles of Sr isotope stratigraphy,the global Strontium isotope age database can be used to calibrate the Permian stratigraphic dates in the northern Upper Yangtze.The results show that the Sr isotope evolution curves for the marine carbonate rocks in the Permian stratigraphic section of the Upper Yangtze present a decreasing trend from the mid-Qixia stage(P_(2))to the mid-Wujiaping stage(P_(3)),and then rise from the middle Wujiaping stage to the end of Changxing stage(P_(3)).When the Permian Sr-isotope evolution curve is compared with the global Sr isotope evolution curve in the northern Upper Yangtze,the two are consistent in their long-term evolutionary trend,indicating that Permian global geological events are important controlling factors for the composition and evolution of Sr isotopes.The 87 Sr/86 Sr value decreased gradually in the background of large-scale regressions at the turn of middle to late Permian period,revealing that the Emeishan basalt eruption occurred near the Maokou/Wujiaping boundary(GLB).Srisotope stratigraphy dating was performed on the boundaries of the Qixia Formation/Maokou Formation,Maokou F

关 键 词：geochronology STRATIGRAPHY strontium isotopes marine sediments global correlation Guadalupian-Lopingian Upper Yangtze region 

分 类 号：P534.46[天文地球—古生物学与地层学] P597.3[天文地球—地质学]