湖南大义山、塔山岩体锆石U-Pb年龄及其构造意义  

Zircon U-Pb Dating of Dayishan and Tashan Plutons in Hunan Province and Its Tectonic Implications

作　　者：李勇[1,2] 张岳桥[2] 苏金宝[3] 李建华[2] 董树文[4] 

机构地区：[1]北京大学,北京100871 [2]中国地质科学院地质力学研究所,北京100081 [3]河海大学,江苏南京210098 [4]中国地质科学院,北京100037

出　　处：《地球学报》2015年第3期303-312,共10页Acta Geoscientica Sinica

基　　金：财政部"深部探测技术与实验研究"专项之子课题(编号:Sinoprobe-08-01)资助

摘　　要：华南中部地区大义山、塔山等早中生代花岗岩的展布和侵入特征与这一时期褶皱构造之间存在着非常密切的关系,对这些岩体进行精确年代学研究,可以为构造变形时代提供年代学约束。大义山岩体南部地区锆石U-Pb LA-ICP-MS年龄为东缘(171.8±1.9)Ma、西缘(169.9±1.8)Ma、中部(164.2±2.6)Ma,塔山岩体东段为(247±5.9)Ma。大义山岩体在164.2—171.8 Ma之间经历两个期次的侵入,形成了一个复式岩体,岩体形成后至125 Ma经历了快速隆升,之后以接近1°C/Ma的冷却速率抬升到地表。大义山和塔山岩体记录了华南早中生代印支和燕山两期重要的岩浆活动。阳明山、塔山岩体等E—W向展布岩体受印支期构造带控制;大义山、骑田岭等岩体年龄限定了燕山期构造地层的变形下限时代,华南地区NNE向褶皱构造形成时代应早于(171.8±1.9)Ma。The distribution and intrusion of Early Mesozoic granites in central South China such as Dayishan pluton and Tashan pluton are closely related to folded structure in this region. Precise chronologic studies can constrain the age of the tectonic deformation. This paper report zircon U-Pb LA-ICP-MS ages of the southern part of Dayishan pluton based on dating of 3 samples：the age of the eastern margin is （171.8±1.9） Ma, that of the western margin is （169.9±1.8） Ma and that of the central part is （164.2±2.6） Ma. The zircon U-Pb LA-ICP-MS age of the eastern part of Tashan pluton is （247±5.9） Ma. Dayishan pluton experienced two phases of intrusion between 164.2 and 171.8 Ma and formed a composite pluton;after that, it experienced rapid uplift prior to 125 Ma, and then it was rapidly raised to the surface at the cooling rate of 1＆#176;C/Ma. Dayishan pluton and Tashan pluton recorded Indosinian and Yanshanian magmatic activities. The EW-trending structural zone controlled Indosinian granites, such as Yangmingshan and Tashan; the ages of Dayishan and Qitianling plutons constrain the Yanshanian tectonic deformation, and the formation of the NNE-trending folds in South China should be earlier than （171.8±1.9） Ma.

关 键 词：华南地区 大义山岩体 塔山岩体 锆石U-PB年龄 

分 类 号：P588.121[天文地球—岩石学] P597.1[天文地球—地质学]