西天山特克斯县东南中元古代特克斯岩群变质砂岩构造背景探讨

TECTONIC SETTINGS OF METASANDSTONE OF MESO-PROTEROZOIC TEX TERRAIN IN THE SOUTHEAST TEX COUNTY OF WEST TIANSHAN

西天山特克斯县大地构造位于天山造山带西段—伊犁地块南缘,处于伊犁—伊赛克湖微板块的伊宁中央地块中。中元古界长城系特克斯岩群,由泊仑干布拉克岩组、莫合西萨依岩组和珠玛汗萨依岩组组成。岩石总体上以中等的SiO2含量、较高的(TFeO+MgO)值及低的CaO、Na2O和中等含量的TiO2为特征。稀土元素球粒陨石标准化曲线以轻稀土富集、重稀土平坦、铕负异常显著为特征。主量和微量元素分析物源具多源性。结合前人研究成果,认为本区特克斯岩群应属于被动大陆边缘盆地沉积,古构造环境为被动陆缘裂谷环境。

Tectonically,Tex County is situated in the margin of Yili block within Yining central block of Yili-Yisaikehu microplate which belongs to the west section of Tianshan Orogenic Belt.Meso-Proterozoic Chancheng System in Tex is composed of Bolunganbulake,Mohexisayi and Zhumahansayi Rock Group.The rock is characterized by middle content of SiO2 and TiO2,high of（TFeO＋MgO） and lower of CaO、Na2O.The chondrite-normalized patterns of REE show that HREE are concentrated,HREE flat,negative anomaly of Eu prominence.The source of main and trace elements is not single.On the basis of the fore-research,it is provided that Tex Rock Group was deposited in the basin at passive continental margin,and developed in rift environment of Atlantic continental margin.