Mineralogy of Spinel from Mafic-Ultramafic Rocks in Dongdegou, Southwestern Tianshan and Its Geological Significance
详细信息
- 责任者：Kong Fanmei (Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Minerals ; Institute of Geological Science and Engineering ; Shandong University of Science and Technology ; Qingdao 266510 ; China) ; Li Xuping
- 刊名：Acta Petrologica et Mineralogica
- 出版年：2011
- 卷期：30(5)
- 关键词：镁铁质岩 ; mafic rocks ; 超镁铁质岩 ; ultramafics ; 尖晶石 ; spinel ; 天山 ; Tianshan Mountains
- 页码：p.951-960
- 图表：4 illus., 2 tables, 43 refs.
- 分类号：0801
- 出版序号：183
- issnNo：ISSN1000-6524
- isbnNo：CN11-1966/P
摘要
The mafic-ultramafic rocks of Dongdougou are located in the orogenic belt between the Tarim plate and the Yili-central Tianshan plate,southwestern Tianshan.Harzburgite is the main type of peridotite,generally metasomatized by hydrous melt or fluid.It includes different types of spinels,being red-brown,brown,dark green,and light green in color.Cr2O3 and FeO decrease gradually whereas Al2O3 and MgO increase with the metasomatism.Studies indicate that red-brown and brown picotiles constitute the primary type,while green magnesium spinels possess the second place.The compositions of the primary picotiles are variable with Cr# and Mg# in the range of 0.41~0.87 and 0.21~0.61 respectively,which may indicate polyphase origin of melting.Secondary spinels have different shapes,and their compositions vary tremendously,exhibiting two stages of metasomatism or metamorphism.The primary picotiles have characteristics of peridotite in a subducting upper plate mantle wedge zone,which implies the host rocks might have been the fragments of peridotite from a SSZ volcanic arc environment.
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