扬子克拉通北缘 ～630Ma 裂解事件

——来自A型花岗岩年代学和地球化学的制约

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The ～630 Ma rifting event in the northern margin of the Yangtze Craton： Constraints from geochronology and geochemistry of A-type granite

JIN Wei1²，LIUJianhui1*，TIAN Yang²，XU Yang²，DENG Xin²，LIU Shude³ 1.InstituteofGeology，ChineseAcademy ofGeologicalSciences，Beijing ooo37，China; 2.Wuhan Center，China Geological Survey，Wuhan 430205，China; 3.HubeiInstituteofGeosciences，Wuhan 43o034，China

Abstract： The late Neoproterozoic tectonic evolution of the northern margin of the Yangtze Craton remains controversial，hindering our understandingof itsposition withinthe Rodinia supercontinent.Determining the formation ageand natureoflate Neoproterozoic magmatic rocks is crucial for constraining the tectonic seting of the northern margin of the Yangtze Craton. This paper reports for the first time the resultsof zircon U-Pb-Hf isotope， whole-rock geochemistry，and Sr-Nd isotope analyses conducted on newly discovered late Neoproterozoic syenogranite inthe Dabie area.The zircon LA-ICP-MS chronologyreveals that the formation age ofthesyenogranite is 630±4Ma ，belonging to a late Neoproterozoic magmatic event. The rocks have high contents of total alkali （K2O+Na2O ，ranging from 7.49% to 8.27% and FeOT/（FeOT+MgO） ， ranging from 0.97 to 0.99）， as well as high Zr content （ranging from 289×10-6 to 431×10-6 ，with 104×Ga/Al values ranging from 2.98 to 5.02 and values ranging from 626×10-6 to 690×10-6 ）.The zircon saturation temperature is as high as 847～891°C ， indicating it is typical A-type granite. Its zircon εHf（t） values range from -0.5 to +1.3 ， corresponding to a TDM2 of 1475～1374Ma ， and the whole-rock εNd（t） values range from -4.5 to -4.4 ，corresponding to a TDM2 of 1709～1701Ms a; these indicate that the zircon was derived from partial melting ofthe Mesoproterozoic crust.Combined with the regional geological setting，the northern margin of the Yangtze Craton was ina continental riftenvironment during thelate Neoproterozoic （ ～630Ma） ）

Key words：late Neoproterozoic；A-type granite； continental rifting；Dabie area；northern margin of the Yangtze Craton

超大陆周期性聚合和裂解驱动了地球水圈、大气圈和生物圈的演变，对宜居地球的形成起着举足轻重的作用（赵国春等，2022；Nance，2022）。（剩余32250字）