滇西北金沙江带中基性火山岩的地球化学特征

Geochemical Characteristics of Basic-intermediate Volcanic Rocks from Jinshajiang Belt in Northwestern Yunnan, China

对滇西北金沙江带出露的东竹林火山岩、辉长岩和奔子栏、维西攀天阁、石鼓地区中基性火山岩进行了系统的主量元索、微量元素、Sr-Nd同位素的地球化学研究，并对东竹林辉长岩进行了Sm-Nd等时线年龄的测定，以探讨金沙江地区的大地构造背景及其演化。研究表明，金沙江带出露的从泥盆纪到三叠纪的火山岩形成于弧后盆地、初始裂谷和岛弧等各种不同的构造环境。研究为金沙江带构造演化的多次裂开，多次俯冲消减的多岛洋模式提供了新的证据。

In order to discuss the tectonic setting and evolution of J inshajiang area, systematic geochemical studies of major elements, trace elements and Sr-Nd isotopes are performed for basic-intermediate volcanic rocks from Dongzulin,Benzilan,Pantiange and Shigu, and gabbros from Dongzhuiin in Jinshajiang belt, northwestern Yunnan. Age of gabbroic rocks from the Dongzhulin area was determined by Sm-Nd isochronal method. It indicated that the Devonian to Triassic volcanic rocks outcropped in Jinshajiang belt were formed in different tectonic environments, such as back-arc basin,initial rift,island arc, and so on. Our studies provide new evidences for the archipelagic evolutionary model with multi-rift and multi-subduction of Jinshajiang belt.