云开地块西北缘三堡韧性剪切带变形特征及40^Ar-39^Ar年代学研究  

Deformation Characteristics and 40^Ar-39^Ar Age of the SanbaoDuctile Shear Zone on the Northwestern Margin ofYunkai Block,South China

作　　者：郭尚宇 黄锡强 农军年 何芝慧 孙明行 李伟[2] 谢植贵 GUO Shangyu;HUANG Xiqiang;NONG Junnian;HE Zhihui;SUN Minghang;LI Wei;XIE Zhigui(Geological Survey of Guangxi,Nanning 530023,Guangxi,China;No.4 Geological Party of Guangxi,Nanning 530023,Guangxi,China)

机构地区：[1]广西壮族自治区地质调查院,广西南宁530023 [2]广西壮族自治区第四地质队,广西南宁530023

出　　处：《大地构造与成矿学》2020年第3期357-366,共10页Geotectonica et Metallogenia

基　　金：桂东粤西成矿带云开抱板地区地质矿产调查项目资助。

摘　　要：博白‒岑溪断裂带位于云开地块西侧,本文通过野外地质调查、有限应变测量、运动学涡度分析及40^Ar-39^Ar年代学研究定量查明了其北东段岑溪市三堡镇一带的韧性变形特征。研究表明三堡韧性剪切带付林指数K为0.07~0.60,罗德参数ν为0.25~0.86,变形强度Es为0.34~0.73,属平面压扁型应变;运动学涡度值Wk为0.75~0.95,属以简单剪切为主的一般剪切;古差应力值σ为16.7~122.0 MPa;是在印支早期(231.9±2.2 Ma)造山环境,绿片岩相条件下形成的具右行走滑‒逆冲性质的剪切带。这一成果为研究云开地区构造演化过程提供了新证据。The Bobai-Cenxi shear zone is located on the west side of the Yunkai block.The ductile deformation around Sanbao town in Cenxi city,located at the northeast part of this shear zone,is investigated through geological survey,finite strain measurement,kinematic vorticity analysis,and 40^Ar-39^Ar dating.The Sanbao ductile shear zone is characterized by Flinn parameter(K)of 0.07–0.60,Lod parameter(ν)of 0.25–0.86,and strain intensities(Es)of 0.34–0.73,indicating a constriction to plane strain during the shearing.Moreover,it can be inferred that the shear zone is a simple shear-dominated general shear,as was manifested by the kinematic vorticity values(Wk=0.75–0.95),and characterized by a differential paleostress(σ)of 16.7–122.0 MPa.The Sanbao ductile shear zone is a dextral strike-slip thrusting shear zone formed under greenschist facies condition related to the early Indosinian orogeny(231.9±2.2 Ma).These results provide new information for the study of the regional tectonic evolution of the Yunkai area.

关 键 词：云开地块 韧性剪切带 有限应变 运动学涡度 40^Ar-39^Ar年代学 

分 类 号：P542[天文地球—构造地质学] P597[天文地球—地质学]