岩石矿物学杂志2017，Vol.36Issue(2)：163-174,12.
滇西双江县勐库地区湾河蛇绿混杂岩的形成时代、岩石地球化学特征及地质意义
The age of Wanhe ophiolitic mélange from Mengku area, Shuangjiang County, western Yunnnan Province, and its geological significance
摘要
Abstract
The Wanhe ophiolitic mélange is redefined along the Wanhe-Mengku-Dananmei line.It is located on the eastern side of the Tongchangjie ophiolitic mélange of Paleotethys in southwestern Yunnan Province.The rocks are composed of phengite-bearing quartz schist,green-schist and amphibolite schist,tonalite and plagioclasite,laminated amphibolite and gabbros,and retrograded eclogitem,respectively equivalent to pelagic sediments,sea-floor basalt,leucocrate,mafic cumulate rock and HP-UHP pyrolite in the ophiolite suite.The LAICP-MS U-Pb zircon age of 470.8 ± 5.3 Ma indicates that the Wanhe ophiolitic mélange was formed in Early Paleozoic.Based on cumulate plagioclasite in Mannahe section at northern Mengku Town in Shuangjiang County,the authors described the characteristics of major elements,REE and trace elements from igneous rocks in the Wanhe ophiolitic mélange.All igneous rocks could be divided into two types:① leucorate,with the data SiO2 =57.00％ ～69.68％,Na2O=1.36％ ～6.38％,K2O=0.26％ ～2.45％,and average Na2O/K2O=10.12,thus belonging to typical sodium granite with rich LREE and "L" distribution patterns.② basic rocks,with the data SiO2 =48.72 ％ ～ 53.72 ％,TiO2 =0.75 ％ ～ 1.96 ％,K2O =0.45 ％ ～ 1.29 ％,and depleted-slightly enriched LREE distribution patterns,similar to features of MORB or E-MORB;in the diagrams of Th-Hf-Nb and Nb-Zr-Y,the samples fall into MORB-CBA/arc-volcanic basalt.On the whole,the samples from Mangnahe section at northern Mengku Town in Shuangjiang County correspond to MORB or E-MORB and,what is more,there exist some arc-volcanic characteristics,which are similar to features of FAB (forearc basalt),or MORB-like basalt.H-Mg and Nb-rich basalt indicates that Proto-Tethys Ocean experienced its peak of development in late Early Ordovician,followed subsequently by ocean crust's subduction in Changning-Menglian tectonic belt.Afterwards,Paleotethys Ocean accomplished inheritance evolution from Proto-Tethys Ocean through the rapid spreading of Mid Ocean Ridge along Tongchangjie to Niujingshan area.关键词
湾河蛇绿混杂岩/类洋中脊玄武岩/原特提斯洋/古特提斯洋/继承性演化Key words
Wanhe ophiolitic mélange/MORB-like basalt/proto-Tethys Ocean/Paleotethys Ocean/inheritance evolution分类
天文与地球科学引用本文复制引用
刘桂春,孙载波,曾文涛,冯庆来,黄亮,张虎..滇西双江县勐库地区湾河蛇绿混杂岩的形成时代、岩石地球化学特征及地质意义[J].岩石矿物学杂志,2017,36(2):163-174,12.基金项目
云南区域地质调查片区总结与服务产品开发(DD20160345-02) （DD20160345-02）
云南省科技领军人才培养计划项目(2013HA001) （2013HA001）
中国地质调查局地质调查项目(12120114014601) （12120114014601）
国家自然科学基金项目(41672222)District Summary and Service Product Development of Yunnan Region Geologic Survey (DD20160345-02) （41672222）
Yunnan Science and Technology Leader Training Program(2013HA001) （2013HA001）
China Geological Survey Project(12120114014601) （12120114014601）
China Natural Science Foundation(41672222) （41672222）
