The Westward Extension of Comei Fragmented Large Igneous Province in oft-com:office:smarttags" />
详细信息
- 责任者：Qiu Bibo (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Science and Mineral Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Zhu Dicheng
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(7)
- 关键词：大火成岩省 ; large igneous provinces ; 西藏 ; Tibet
- 页码：p.2207-2216
- 图表：7 illus., 2 tables, 53 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The spatial extent of the newly identified Early Cretaceous Comei-Bunbury large igneous province(LIP)in the southeastern Tibet and the southwestern Australia is not well constrained yet.To probe into the issue,here the authors report the petrological and geochemical data of the extensive E-W-trending mafic dykes and minor occurrence of basalt distributed in Gyangze,Kangma,and western Nagarze-Lhozhag area in the southern Tibet.These mafic rocks,consisting mainly of diabase and gabbro,are alkali to sub-alkali,and can be divided into two groups according to their geochemical characteristics,i.e.,high-Ti type that is similar to OIB,and low-Ti type that resembles MORB,with εNd(t)values of +0.9~+2.0 and +4.6~+5.8, respectively,both of which are geochemically comparable to the corresponding groups in the Comei fragmented LIP to the east,and are inferred to be formed within an extensional setting caused by mantle plume-lithosphere interaction.It follows that the mafic rocks reported here could be the westward extension of the province.The authors’ results indicate that the areal extent of the fragmented Comei-Bunbury LIP preserved in the present-day Tethyan Himalaya is close to 50 000 km2.The extensive magmatism of the Comei-Bunbury LIP is likely to be responsible for the Early Cretaceous oceanic anoxic event in the area or even in a global context.