Geochemistry and Tectonic Significance of Eclogites in Central Qiangtang , Tibetan Plateau
详细信息
- 责任者：Zhang Xiuzheng (Research Center for Tibetan Plateau ; Jilin University ; Changchun 130061 ; China) ; Dong Yongsheng
- 刊名：Geological Bulletin of China
- 出版年：2010
- 卷期：29(12)
- 关键词：榴辉岩 ; eclogite ; 岩石地球化学 ; lithogeochemistry ; 羌塘盆地 ; Qiangtang Basin
- 页码：p.1804-1814
- 图表：6 illus., 1 table, 74 refs.
- 分类号：0802
- issnNo：ISSN1671-2552
- isbnNo：CN11-4648/P
摘要
Based on equilibrium texture and mineral chemistry, thermobarometric estimates indicate that the central Qiangtang eclogites formed in low temperature condition. The geochemical characteristics show that their protolith are tholeiitic basalt and alkaline basalt with 45.83wt%~48.94wt% SiO2, 10.34wt%~15.02wt% Al2O3 and 1.88wt%~3.91wt% total alkalis（Na2O+K2O）. Most samples which protolith are tholeiitic basalt are characterized by moderate TiO2 content（1.62wt%~1.87wt%）, slight enrichment LREE distribution patterns,suggesting a typical E-MORB source. Immo-bile elements covariance diagrams show that most of them formed in an E-MORB and MORB setting and their REE distribution patterns and primitive mantle normalized trace elements patterns are similar to that of the typical E-MORB. All the eclogite samples with the feature of both E-MORB and OIB indicate a plume-ridge interac-tion or hotspot-ridge interaction during the evolution process of Paleo-Tethys.
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