揚子克拉通北緣 ～630Ma 裂解事件

——來自A型花崗巖年代學和地球化學的制約

打開文本圖片集

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

超大陸周期性聚合和裂解驅動了地球水圈、大氣圈和生物圈的演變，對宜居地球的形成起著舉足輕重的作用（趙國春等，2022；Nance，2022）。（剩余32250字）