粤北地区“南华系”沉积时代的重新厘定:来自碎屑锆石年代学的证据  

Recalibrating the“Nanhuan”in Northern Guangdong Province:Evidence from Detrital Zircon U-Pb Dating

作　　者：何垚砚 杨文强 林小明 廖小华 宋芳 HE Yao-Yan;YANG Wen-Qiang;LIN Xiao-Ming;LIAO Xiao-Hua;SONG Fang(Hubei Key Laboratory of Paleontology and Geological Environment Evolution,Wuhan 430205,Hubei,China;Wuhan Center,China Geological Survey(Central South China Innovation Center for Geosciences),Wuhan 430205,Hubei,China;Guangdong Geological Survey,Guangzhou 510060,Guangdong,China;3rdGeological Exploration Brigade of Guangdong Geological Bureau,Shaoguan 512029,Guangdong,China)

机构地区：[1]古生物与地质环境演化湖北省重点实验室,湖北武汉430205 [2]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [3]广东省地质调查院,广东广州510060 [4]广东省地质局第三地质大队,广东韶关512029

出　　处：《华南地质》2024年第2期307-322,共16页South China Geology

基　　金：古生物与地质环境演化湖北省重点实验室开放基金课题(PEL-202106);中国地质调查局地质调查项目(DD20243455、DD20240038、DD20230226);国家自然科学基金项目(U2244212、41772019)。

摘　　要：粤北地区横跨湘桂赣和武夷两个地层分区,大地构造上位于华夏地块西部,介于武夷、云开两个微陆块之间。粤北南华纪地层是研究华夏地块新元古代晚期构造演化等问题的重要载体,但该地区南华系的确定和划分较大程度上依赖与周边省份相应岩石地层的岩性组合和层序的对比,而周边省份的相应岩石地层单位的认识近年来发生较大的变化,因此,粤北地区“南华系”的重新厘定显得极为必要。本文对粤北地区原定为“南华系”大绀山组和活道组开展碎屑锆石U-Pb年代学研究,获得最年轻一组锆石加权平均年龄分别为422±4 Ma和430±4 Ma。结合岩性组合、区域地质调查研究成果及文献数据,暂将该地区原定的南华系厘定为下泥盆统。碎屑锆石年龄谱显示,其与周边地区泥盆系均具有450~420 Ma、1000~900 Ma以及~2450 Ma为主的锆石年龄显示,且在800~550 Ma之间形成复杂的次级峰值,可能指示了相似的物源。综上,建议在开展华夏地块新元古代构造演化等研究中,需首先对南武夷-云开地区南华系的沉积层位做细致的认定。Northern Guangdong was located in West Cathaysia,between Wuyi and Yunkai areas,and it stretched across two stratigraphic subdivision of Xiang(Hunan)-Gui(Guangxi)-Gan(Jiangxi) and Wuyi.Its tectonic and stratigraphic location makes it essential to research the“Nanhuan”in the area when exploring the issue of tectonic evolution of the Cathaysia during late Neoproterozoic.However,the calibration of the“Nanhuan”in Northern Guangdong has been uncredible because of lacking evidence except lithological and sequence correlation with adjacent provinces and areas.In addition,recent research makes the correlation not robust.This paper focuses on the“Nanhuan”in Northern Guangdong to achieve U-Pb dating of detrital zircons.The youngest zircon weighted ages data in this research(422±4 Ma and 430±4 Ma) with the data from geological survey and previous researching documents in the same area proves that the initial defined“Nanhuan”in Northern Guangdong should be Lower Devonian and its provenance has been similar to the Devonian sedimentation of adjacent areas with peaks of 450~420 Ma,1000~900 Ma and ~2450 Ma as well as complex secondary peak of 800~550 Ma.In further tectonic evolution research of southern Cathaysia to Yunkai areas during late Neoproterozoic,the“Nanhuan”in this area should be reconsidered.

关 键 词：华夏地块 粤北 大绀山组 活道组 锆石U-PB定年 南华系 下泥盆统 

分 类 号：P535[天文地球—古生物学与地层学] P534.3[天文地球—地质学]