江南造山带东段赣东北蛇绿岩的形成时代:来自辉长岩LA-ICP-MS锆石U-Pb年龄的证据  

Formation Time of the Northeastern Jiangxi Ophiolite in the Eastern Jiangnan Orogenic Belt: Evidence from LA-ICP-MS Zircon U-Pb Dating of the Gabbro

作　　者：蒋幸福[1,2] 彭松柏[2,3] KUSKY Timothy 王璐[3,4] 邓浩[2] 王军鹏[2] 

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]中国地质大学(武汉)地球科学学院,湖北武汉430074 [3]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,湖北武汉430074 [4]中国地质大学(武汉)教育部长江三峡库区地质灾害研究中心,湖北武汉430074

出　　处：《现代地质》2017年第4期697-704,745,共9页Geoscience

基　　金：国家自然科学基金项目(41272242);江西省教育厅科技项目(GJJ150562);东华理工大学博士启动基金项目(DHBK2015321)

摘　　要：赣东北元古宙蛇绿岩位于江南造山带东段,主要由蛇纹石化超基性岩、堆晶岩、辉长岩、辉绿岩、低温高压蓝片岩以及斜长花岗岩组成。对赣东北蛇绿岩中辉长岩进行了LA-ICP-MS锆石U-Pb定年,获得^(207)Pb/^(206)Pb加权平均年龄值为(992±25)Ma(MSWD=1.19),以此代表该辉长岩的结晶年龄。这一年代学结果表明扬子陆块东南缘古洋盆在新元古代早期就已存在,但晚于扬子北缘中元古代晚期古洋盆(~1 120 Ma),暗示扬子克拉通中—新元古代结晶基底的形成具有从西北往东南逐步拼贴的特征。Proterozoic Ophiolite of the eastern Jiangnan orogenic belt in Northeastern Jiangxi was mainly com-posed of serpentinized ultramafic rock, cumulated rock, isotropic gabbro and diabase, low-temperature and high-pressure blueschist and plagiogranite. LA-ICP-MS zircon U-Pb dating for one gabbro sample from the Northeastern Jiangxi Ophiolite yielded a 2〇 7P b / 2〇6P b age of （992 ± 2 5 ） Ma （MSWD =1. 19） , which represented the intrusion time of the gabbro. The geochronological result suggests the existence of Early Proterozoic palaeo- oceanic basin in the southeastern Yangtze block, which is younger than the late Meso-Proterozoic oceanic basin in the northern margin of the Yangtze block. Therefore, it is proposed that the Meso-Neoproterozoic crystalliza-tion basement rocks in the Yangtze craton were formed in a gradually aggregated process with characteristics of trending from northwest to southeast direction.

关 键 词：江南造山带 赣东北蛇绿岩 辉长岩 锆石U-PB定年 新元古代早期 

分 类 号：P588.12[天文地球—岩石学]