The Genesis of Neoarchean TTG in the Shangyi Area of the Northern Margin of North China Craton：Melt From Basalt of Oceanic Crust at Varying Depth

详细信息   

• 责任者：Li Mengjiang (Key Laboratory of Mineralogy and Metallogeny ; Guangzhou Institute of Geochemistry ; Chinese Academy of Sciences ; Guangzhou 510640 ; China) ; Wang Renmin
• 刊名：Geological Bulletin of China
• 出版年：2012
• 卷期：31(5)
• 关键词：玄武岩 ; basalts ; 华北板块 ; North China Plate
• 页码：p.686-695
• 图表：4 illus., 2 tables, 3 refs.
• 分类号：0801
• issnNo：ISSN1671-2552
• isbnNo：CN11-4648/P

摘要

Shangyi basalt is a component part of Neoarchean oceanic crust in Shangyi-Chicheng fault zone, and its geochemical characteristics suggest an enriched mantle source. The basalt can be divided into two types： TH1（Flat-REE） and TH2（Fractionated-REE）.Shangyi TTG is mainly of the medium-potassium,metaluminous and calc-alkaline type, and similar to low-Al₂O₃ TTG owing to its low Al₂O₃ content. In addition, Shangyi TTG shows features of adakite by slab melting according to trace elements Rb, Sr, Y and REE. Based on features of major and trace elements（SiO₂, K₂O, Na₂O, Al₂O₃, Rb, Sr, Y, REE） and trace element equilibrium melting calculation, the authors have reached the conclusion that Shangyi TTG was formed throughout the low-high pressure range and was probably produced from partial melting of oceanic crust basalts（TH1 type） at varying depth, with the low-Al₂O₃type formed under low pressure.