Magma Origin and Evolution of Maanshan Volcano, Dayingshan Volcano and Heikongshan Volcano in Tengchong Area
详细信息
- 责任者：Zhao Yongwei (Institute of Geology ; China Earthquake Administration ; Beijing 100029 ; China) ; Fan Qicheng
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(4)
- 关键词：火山岩 ; volcanic rocks ; 云南 ; Yunnan Province
- 页码：p.1133-1140
- 图表：illus., 3 tables, 21 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
On the basis of studies of major elements, trace elements and strontium, neodymium and lead isotopic compositions of Maanshan, Dayingshan and Heikongshan volcanic rocks, it is thought that the magma source of Tengchong volcanoes is the mixture of mid-ocean ridge basalts (MORB) and enriched mantle. It is deduced that the Neotethys subducted ocean crust refused; hence volcanoes were activated with high potassium calc-alkaline magma. This explains why volcanic rocks with geochemical characteristics which suggest tectonic settings of island arcs or active continental margins appeared in the intra-plate background. The magma of Maanshan, Dayingshan and Heikongshan endure crystal fractionation of pyroxene and ilmenite at the chamber stage and plagioclase fractionation at the ascending stage, which induced the magma evolving, from intermediate-basic magma to intermediate-acidic magma, and lava evolving by the course of basaltic trachyandesite-trachyandesite-trachydacite.