广西凭祥地区早二叠世的岩浆弧及其构造意义  

EARLY PERMIAN MAGMATIC ARC IN PINGXIANG,GUANGXI AND ITS TECTONIC IMPLICATIONS

作　　者：吴根耀[1] 季建清[2] 何顺东[1] 钟大赉[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]北京大学地质系

出　　处：《矿物岩石》2002年第3期61-65,共5页Mineralogy and Petrology

基　　金：国家自然科学基金资助项目 (编号 :495 72 15 4)

摘　　要：广西凭祥地区有 3种不同建造背景的二叠三叠系。深水相的下二叠统呈一飞来峰推覆在台地型的石炭纪早三叠世沉积和早中三叠世浊积岩上 ,与前者共生的基性 -超基性岩是古特提斯岩浆弧的记录 ,当时的被动大陆边缘在百色阳圩田林八渡 ,说明洋壳向南西消减 ,早二叠世弧的原形成位置可能在越南境内 ,早 -中三叠世的弧则已向北东迁移 ,在中越交界区形成图尔基式造山带。There are three lithostratigraphic units of Permian-Triassic strata in Pingxiang area with varied formational settings:1)plateform-type sediments aging from Carboniferous to Early Triassic,which may comprehend an accreted submarine plateau in the Paleotethyan ocean;2)the Luolou Group,the Baifeng and Hekou Formations aging of Early-Middle Triassic consisting of volcaniclastic trubidites sandwiched with intermediate-acidic lavas,standing for an active continental margin;and 3)the Lower Permian strata of deep-marine facies,associated with intermediate-basaltic lava and ultramafic rocks,being survived in a nappe-outlier thrust onto the former two units.The petro-chemical features indicate that the volcanic lava was low-potassium tholeiite,erupted in a tectonic setting of island-arc which might be situated in north Vietnam originally.The basalts along Yangxü-Badu represented a passive continental margin in Early Permian.Both the island-arc and passive continental margin might have migrated towards the northeast during Early-Middle Triassic.Namely,the Indosinides bordering China and Vietnam should be a Turkic-type orogen.

关 键 词：广西 凭祥地区 早二叠世 岩浆弧 古特提斯 中越交界区 

分 类 号：P588.1[天文地球—岩石学]