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Geoscience ›› 2022, Vol. 36 ›› Issue (01): 347-361.DOI: 10.19657/j.geoscience.1000-8527.2022.01.31

• Geochemistry • Previous Articles     Next Articles

LA-MC-ICP-MS Zircon U-Pb Dating and Provenance Characteristic from Baoshuping Formation of Erlangping Group of the North Qinling

OU Weicheng1,2(), LI Chengdong3(), ZHANG Yongqing3, ZHAO Ligang3, XU Teng3, XU Yawen3, SUN Xuanye4   

  1. 1. Chinese Academy of Geological Sciences,Beijing 100037,China
    2. China University of Geosciences, Beijing 100083,China
    3. Tianjin Center of Geological Survey,China Geological Survey,Tianjin 300170,China
    4. Sinosteel Tianjin Geology Co.,Ltd.,Tianjin 300061,China
  • Received:2021-03-09 Revised:2021-07-07 Online:2022-02-10 Published:2022-03-08
  • Contact: LI Chengdong

Abstract:

The tectonic attributes and age of Erlangping Group in the North Qinling orogenic belt have been controversial,and Baoshuping Formation lacks chronological data.In order to further determine the age and tectonic setting of Baoshuping Formation,detrital zircon dating and provenance studies by LA-MC-ICP-MS were carried out. The results show that the plagioclase biotite quartzite (18P3TW2) and the diopside-bearing biotite actinolite plagioclase granulite (18P3TW3) from Baoshuping Formation have completely different zircon age spectrum characteristics,indicate that they belong to the strata of different ages. The detrital zircons age spectrum of 18P3TW2,which originates from the North Qinling micro-continental block and North China block,is multi-peaked but short of the data about Early Paleozoic magmatic arc. The youngest group of zircons range from 493 Ma to 972 Ma. The detrital zircons age spectrum of the 18P3TW3 is unimodal,and the main source of zircons is the Erlangping arc magmatic rocks,of while the youngest group of zircons is 420-440 Ma. With comprehensive analysis of field characteristics,age spectrum of zircons and provenance characteristics,the strata represented by 18P3TW2 was formed in the early stage of the basin without large-scale volcanic action,so it should not be attributed to Baoshuping Formation. Baoshuping Formation, represented by the 18P3TW3,was formed in the late period of the basin,the main sedimentary age is Ordovician-Silurian,and the latest strata may extend to Early Devonian. Combined with the regional geological background,Baoshuping Formation was formed in the tectonic environment of the back-arc extensional basin caused by the northward subduction of Shangdan Ocean in Early Paleozoic.

Key words: the North Qinling, Erlangping Group, Baoshuping Formation, detrital zircon, LA-MC-ICP-MS zircon U-Pb dating

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