南岭地区白垩纪至古近纪陆相盆地及其对气候变化与构造域转换的制约  

Constraint of Cretaceous to Paleogene Terrestrial Basins in the Nanling Area on Climate Changes and Tectonic Transition

作　　者：徐先兵[1] XU Xian-Bing(School of Earth Sciences,China University of Geosciences,Wuhan 430074,Hubei,China)

机构地区：[1]中国地质大学(武汉)地球科学学院,湖北武汉430074

出　　处：《华南地质》2022年第4期569-582,共14页South China Geology

基　　金：中国地质调查局地质调查项目(DD20190811)。

摘　　要：南岭地区白垩纪至古近纪陆相盆地对华南晚中生代-新生代早期气候与构造具有重要制约意义。通过综述盆地的分布规律、沉积时代、沉积厚度、物质来源和构造特征,本文讨论了华南晚白垩世-古近纪气候变化和构造域转换。以3条近E-W向花岗岩带为界,南岭地区白垩纪至古近纪陆相盆地可以划分为北部、中部和南部三个亚带。中部亚带以晚白垩世至古近纪盆地为主,盆地规模与沉积厚度变化大。以NNE向郴州-临武断裂为界,南岭地区北部亚带和南部亚带均可以划分为东西两段,其西段以规模较大的白垩纪至古近纪盆地为主,而东段主要发育晚白垩世至古近纪盆地。巨厚的红层说明白垩纪至古近纪以湿热环境为主。但晚白垩世中期风成沉积和蒸发岩却指示短期的干旱性沙漠气候,是东南沿海NE-SW向山脉和南岭地区E-W向山脉隔绝水汽运移的结果。基于碎屑锆石U-Pb年代学的物源分析指示南岭地区中部南雄盆地上白垩统底部和古新统物源以盆地周缘基岩为主,而南部和北部盆地白垩系物源以南岭地区中部和盆地周缘基岩为主。这种物源差别指示南岭地区经历了早白垩世、晚白垩世和古新世三期伸展作用。早、晚白垩世盆地的迁移和两期NW-SE伸展作用指示古太平洋板块在白垩纪发生由西向东的后撤、断离和角度变陡。而白垩纪与古近纪伸展应力场由NW-SE向转变为NE-SW向,指示华南内陆由古太平洋域向新特提斯域的构造转换发生在白垩纪与古近纪之交。Cretaceous to Paleogene terrestrial basins in the Nanling area have important constraint on early climate changes and tectonic transition for the South China Block from late Mesozoic to Cenozoic.On the basis of overviews of distribution rules,depositional ages and thickness,provenances and structural features of terrestrial basins,Cretaceous to Paleogene climate changes and tectonic transition were discussed for the South China Block.The Nanling area can be divided into northern,middle and southern parts according to the three E-W Late Jurassic granitic belts.The middle part is mainly characterized by Late Cretaceous to Paleogene basins with varied exposed areas and depositional thickness.Both northern and southern parts can be divided into eastern and western segments by the NNE-striking Chenzhou-Linwu fault.The western segment is featured by bigger Cretaceous to Paleogene basins whereas the eastern segment by Late Cretaceous to Paleogene basins.Thick red beds indicate wet and hot climate conditions in the Nanling area during Cretaceous to Paleogene.During the middle Upper Cretaceous,aridity desert climate documented by aeolian deposits and evaporites occurred as a result of steam isolation by NE-SE striking mountains in the Southeast Coast and E-W striking mountains in the Nanling area.Provenance analysis through detrital zircon U-Pb ages imply that the lowest Upper Cretaceous and Paleocene in the Nanxiong Basin were derived mainly from peripheral bedrocks whereas Cretaceous to Paleogene basins in both the southern and northern parts from the middle part and its peripheral bedrocks.The disparity indicates that the Nanling area underwent three stages of extension throughout Early Cretaceous,Late Cretaceous and Paleocene.Migration of the Early and Late Cretaceous basins and two stages of NW-SE extension indicate the retreat,foundering and steepening of the Paleo-Pacific Plate during Cretaceous from west to east.The extension shift of Cretaceous and Paleogene from NW-SE to NE-SW imply that tectonic transition from

关 键 词：白垩纪-古近纪盆地 气候变化 构造转换 南岭地区 华南板块 

分 类 号：P548[天文地球—构造地质学]