云南德钦鲁春—红坡牛场上叠裂谷盆地演化

鲁春－红坡牛场上叠裂谷盆地是在金沙江弧－陆碰撞之后的地壳伸展环境下形成,时间上发育于中三叠世晚期至晚三叠世,空间上叠置于江达－德钦－维西陆缘火山弧上。盆地中发育由浅水→深水→浅水的沉积组合序列和由玄武岩－－流纹岩组合成的“双峰式”火山岩系,岩石地球化学特征和Nd,Sr同位素结果表明玄武岩与流纹岩为同一岩浆源,从早期的基性岩浆演化为晚期的酸性岩浆。鲁春－红坡牛场上叠裂谷盆地的拉裂速度为0．43cm/a,扩宽距离为140km。中三叠世晚期至晚三叠世的上叠裂谷盆地已成为金沙江带中生代重要的赋矿盆地。

THE EVOLUTION OF THE LUCHUN-HONGPONIUCHANG SUPERIMPOSED RIFTING BASIN,DEQIN COUNTY, YUNNAN PROVINCE

The Luchun Hongponiuchang superimposed rifting basin formed in the crustal extension environment after Jinshajiang arc continent collision. It appeared during the Late Middle Triassic and Late Triassic and overlay the Jiangda Deqin Weixi continental marginal volcanic arc. In the superimposed rifting basin the sedimentary sequence varied from shallow water,deep water to shallow water and the "bimodal"volcanic rocks consisted of the basalt and rhyolites. The geochemical feature and analytical result of Nd and Sr isotopes show that the basalt and rhyolites were originated from the identical magma which changed from the early basicity to the late sourness. The Luchun Hongponiuchang superimposed rifting basin spread at a rate of 0.43cm/a and a distance of 140 km. The superimposed rifting basin during the Late Middle Triassic and Late Triassic was the important ore bearing basin.