金沙江缝合带弯岛湖蛇绿混杂岩带的岩石地球化学特征及其构造背景要点解析.pdf

1000-0569 / 2012 /028 (04)-1291-04 Acta Petrologica Sinica 岩石学报 金沙江缝合带弯岛湖蛇绿混杂岩带的岩石地球化学 * 特征及其构造背景 1，2 1 1 1 张能 李剑波 杨云松 那福超 ZHANG Neng1，2 ，LI JianBo1 ，YANG YunSong1 and NA FuChao1 1. ， 100083 中国地质大学地球科学与资源学院 北京 2. ， 54 1003 广西壮族自治区地质调查研究院 桂林 1. School of Earth Science and Resources ，China University of Geosciences ，Beij ing 100083 ，China 2. Geological Survey of Guangxi Zhuang Autonomous Region ，Guilin 54 1003 ，China 20 11-09-13 收稿，20 12-02-28 改回. Zhang N ，Li JB ，Yang YS and Na FC. 2012. Petrogeochemical characteristics and tectonic setting of the Wandaohu ophiolite mélange ，Jinshajiang suture ，Tibet. Acta Petrologica Sinica ，28 (4):1291 － 1304 Abstract The Wandaohu ophiolitic mélange is an essential component of the western part of Jinshajiang suture zone. The ophiolites are mixed in the Upper Triassic metaclastic rocks which interlayered by metavolcanic rocks. The main components of ophiolites are mafic-ultramafic complexes ，in which metaperidotites ，metacrystal-stacking gabbros and concomitant island-arc granites are included. Geochemical data indicate that most of the ophiolitic mélange are tholeiites of low-Ti (island arc-back arc)type and enriched middle- ridge type (E-MORB). The basic extrusive rocks ，diabase veins accompanied with above mentioned ophiolites could be classified as interplate rift-type alkaline basalts and other transitional series. Metagabbro ，dated at 232 ± 11Ma with Sm-Nd isochron ，represents the formation age of the mafic-ultramafic complexes and initial metamorphic age of the subduction of oceanic crust. The radiolarites were found in the sillcalites which overlained ophiolite. The age of the radiolarites is between Late Latin stage of Middle Triassic and Early Kaning stage of Late Triassic ，indicating that the Wand