金沙江造山带的大地构造环境及演化模式

金沙江造山带一直被当作古板块缝合带，但其物质组成和结构并不反映当时典型的洋盆环境，主要证据有：（１）沉积地层表明，金沙江海盆在规模和水体深度两方面都是有限的；（２）所产的火山岩与标准洋中脊不同，其岩石化学特点与弧后盆地相吻合；（３）澜沧江洋盆与金沙江海盆隔着昌都长条形地块相向俯冲，而且金沙江海盆的俯冲始于澜沧江洋的闭合。据此提出金沙江造山带的弧后盆地演化模式，认为自西而东的澜沧江带、昌都地块、金沙江带、扬子板块分别代表洋盆和海沟、岛弧、弧后盆地、大陆板块等构造单元，构成一个完整的大陆边缘。

TECTONIC SETTING AND EVOLUTIONARY PATTERN OF THE JINSHAJIANG OROGENIC BELT

inshajiang orogenic belt used to be regarded as a plate suture, but its composition and structure do not reflect the background of typical ocean basin during that time. The following is the main foundations: (1) The strata indicate that Jinshajiang sea basin was finite both in its dimensions and depth. (2) The volcanic rocks in the belt are different from these of typical mid oceanic ridge, and similar to those of back arc basin in lithogeochemical feature. (3) The directions of subduction of Lancangjiang basin and Jinshajiang basin which are seperated by Changdu massif are opposite, and the subduction of Jinshajiang basin began at the time of closure of Lancangjiang basin. According to these foundations, we put forward an evolutionary pattern of back arc basin for Jinshajiang orogenic belt. Lancangjiang belt, Changdu massif, Jinshajiang belt and Yangtze plate are regarded respectively as the tectonic units of ocean basin and trench, island arc, back arc basin and continental plate which constituted a complete continental margin.