Age and Geochemical Characteristics of Early Permian Diorite in the Baiyanghe Region, West Junggar: Petrogenesis and Tectonic Implication
详细信息
- 责任者：Yin Jiyuan (State Key Laboratory of Continental Tectonics and Dynamics ; Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Chen Wen
- 刊名：Geochimica
- 出版年：2013
- 卷期：42(4)
- 关键词：闪长岩 ; diorites ; 准噶尔盆地 ; Junggar Basin
- 页码：p.361-372
- 图表：illus., 3 tables, 39 refs.
- 分类号：0801
- issnNo：ISSN0379-1726
- isbnNo：CN44-1398/P
摘要
Ar-Ar dating on Mohetaixibei dioritic rock chips from Baiyanghe region,western Junggar,has yielded a plateau age of(283±3) Ma,i.e.,Early Permian.The diorite mainly contains plagioclase(65%-70%),pyroxene(10%-15%) and hornblende(10%-15%).The SiO2 contents vary between 55.1%-57.0% suggesting that they are diorite rather than gabbro or dolerite as marked in the geological map(1∶200000) of Baiyanghe,Xinjiang.The diorites are characterized by enrichments in large ion lithophile elements(LILE)(e.g.,Ba,K,Rb and U) and light rare earth elements(LREE) and depletions in high field strength elements(HFSE)(e.g.,Nb,Ta and Ti),which are consistent with geochemical characteristics of subduction-related magmas.The diorites can be generated by partial melting of the mantle wedge metasomatized by slab released fluid/sediment melts.High temperature magmatism in the West Junggar likely began at 321 Ma.Therefore,ridge subduction in the western Junggar likely occurred between 321-292 Ma.At 283 Ma,the western Junggar was in a normal subduction system or post-collisional setting.