The Tuerkubantao ophiolite melange in Xinjiang,NW China:New evidence for the Erqis suture zone

作     者：Yuwang Wang Jingbin Wang Lijuan Wang Lingli Long Pingzhi Tang Zhen Liao Huiqiong Zhang Yu Shi 

作者机构：Beijing Institute of Geology for Mineral ResourcesBeijing 100012China KeyLaboratoryofMineralResourcesInstituteofGeoiog and GeophysicsCASBeijing 100029China SinoTechMetalsExplorationCo.Ltd.Beijing100012China ChinaUniversityofGeosciences(Beijing)Beijing100083China 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2012年第3卷第5期

页      面：587-602页

核心收录：

学科分类：083002[工学-环境工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 08[工学] 0713[理学-生态学] 

基　　金：supported by the Major State Basic Research Program of the People's Republic of China(Nos.2007CB411304 and 2001CB409806) 

主　　题：Ultramafic-mafic rocksGeochemistry U-Pb zircongeochronology Tectonics Subduction Collision 

摘      要：The extension of the suture zone between the Siberian and Kazakhstan continents in China has been a matter of debate because few outcrops of ophiolitic melange have been found so far. The recently found Tuerkubantao ophiolitic melange, which is located east of the Kekesentao Mt. in the Buer- jin County of the Chinese Altay, provides an important clue for this problem. This paper presents the results of field investigation, petrology, U-Pb isotope dating of zircons and bulk-rock geochemistry of the Tuerkubantao melange rocks. The melange consists of fault-contacted ultramafic rocks, gabbro, diabase, basalt, flysch and granitoids. The ultramafic-mafic rocks are Mg-rich （Mg#= 4.25-6.35） and w（SiO2） spans 38.8%--46.8%. Basalt and gabbro are geochemically similar and are characterized by low w（FeOt） （10.9%）, total alkali w（Na20 ＋ K20） = 2.58%） and w（TiO2） （1.17%） and affinity to the Mg-rich tholeiite series. The flat REE and trace-element patterns of the ultramafic-mafic rocks are indic- ative of their ophiolite origin, i.e., formation in a mid-oceanic ridge setting. The fragments of low-K gneissic granite formed in suprasubduction or syn-collisional setting. Zircons from gabbro and gneissic granite yielded U-Pb ages of 363 and 355 Ma, respectively, suggesting Late Devonian mid-oceanic spreading and oceanic subduction accompanied by suprasubduction magmatism. The Tuerkubantao ophiolite together with the Qiaoxiahala and Buergen ophiolites of the Kekesentao belt define an ophiolitic melange belt extending along the Erqis fault. This belt probably belongs to the Ural- Zaisan-South Mongolian suture-shear zone formed during the subduction of the Paleo-Asian Ocean and subsequent collision of the Siberian and Kazakhstan continents.