西北地质2017，Vol.50Issue(3)：22-35,14.
西藏萨嘎二叠纪OIB型火山岩岩石地球化学特征及成因分析
Geochemical Characteristics and Genesis of Permian OIB-type Volcanic Rocks in Saga Region, Tibet
摘要
Abstract
The main types of Permian volcanic rocks are strongly altered basalt and altered stomatal-amygdaloid andesite.The study on petrology,lithochemistry,and geochemistryshows that these volcanic rocks have high Ti (basalt and andesite average in 3.16 and 2.15,respectively),FeOT (average in 12.21and 9.45,respectively) and low Mg (with the average values of 4.33 and 4.72,respectively) contents,which belong to alkaline series.The ∑REE,LREE/HREE and LaN/YbN of basalts are 210×10-6～444.7×10-6,1.77～12.18 and 1.14～29.66,while the ones of andesites are 94× 10-6 ～386.1 × 10-6,4.02～24.4 and 4.19～57.16,respectively.The REE distribution curve shows a dipped-right pattern,while the trace element spidergram shows "uplift" type,with thecharacteristics of alkaline basalt and OIB.The tectonic environment discriminant diagram also indicates that these rocks belong to the oceanic island basalt (OIB),which areserved as the products of mantle plume or hotspot material differentiation,without any crustal contamination.The volcanic rocks are derived from the same source of Permian Tethys rift as the other Permian volcanics in this belt,testifying that the Tethys Himalaya began to rift before Permian.关键词
OIB型火山岩/地幔柱热点/雅鲁藏布江缝合带/曲嘎组Key words
OIB type volcanic rocks/mantle plume hotspot/the Yarlungzangbo Suture Zone/Quga Formation分类
天文与地球科学引用本文复制引用
马涛,张健,王晓青,黄登鹏,李进喜,李斌,刘渭..西藏萨嘎二叠纪OIB型火山岩岩石地球化学特征及成因分析[J].西北地质,2017,50(3):22-35,14.基金项目
中国地质调查局“西藏1∶5万冷布岗日地区4幅区域地质矿产调查”(1212011221058) （1212011221058）
