西准噶尔玛依勒山枕状熔岩地质特征及大地构造意义  

THE MAYILESHANG PILLOW LAVAS (WESTERN JUNGGAR,XINJIANG) AND THEIR TECTONIC IMPLICATIONS:CONSTRAINTS FROM THE GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS AND RB-SR ISOCHRON AGES

作　　者：魏荣珠[1] 

机构地区：[1]山西省地质调查院,山西太原030006

出　　处：《新疆地质》2010年第3期229-235,共7页Xinjiang Geology

基　　金：新疆维吾尔自治区1:5万区域地质矿产调查(XJQDZ2007-03)项目资助

摘　　要：玛依勒蛇绿混杂岩带位于西准噶尔增生造山带西南缘.本文重点研究分布于玛依勒山一带枕状熔岩的地质地球化学特征和形成时代,为讨论西准噶尔造山带的形成演化提供依据.玛依勒山蛇绿混杂岩剖面中枕状熔岩、放射虫硅质岩和岩墙等出露较齐全,枕状熔岩为一套碱性玄武岩,源区为富集地幔,构造环境可能为洋盆中海山或洋岛.枕状熔岩Rb-Sr同位素等时线年龄为(435.3±6.5)Ma和(432.5±7.4)Ma,说明其形成时代为志留纪.奥陶—志留纪时,沿玛依勒一线可能出现较开阔的洋盆,现存的玛依勒枕状熔岩和超镁铁质岩代表了志留纪海山或洋岛残片.The Mayile ophiolitic malange is exposed along the southwestern margin of the Western Junggar accretionary orogenic belt.The geological and geochemical characteristic and formation time of the paillow lavas exposed along the Mayileshan are presented in this paper to provide some constraints on the evolution of the the Western Junggar orogenic belt.Pillow lavas,radiolara-bearing cherts and dikes are exposed along the Mayile ophioltic mélange section.The pillow lava is a suit of alkaline basalts derived form the enriched mantle.It may be formed in a seamount or oceanic island setting.The Rb-Sr isochron ages are（435.3±6.5） Ma and（432.5±7.4） Ma,indicating that the pillow lava were formed in the Silurian time.A relatively wide ocean may exist along the Mayileshan from Ordovician to Silurian.The Mayileshan pillow lavas and ultra-mafic rocks probably represent the relict slices of a Silurian seamount or an oceanic island.

关 键 词：西准噶尔 玛依勒山 枕状熔岩 RB-SR等时线年龄 蛇绿混杂岩 

分 类 号：P597.3[天文地球—地球化学] P541[天文地球—地质学]