西藏自治区堆龙德庆县马区典中组底砾岩特征及其地质构造意义

西藏自治区堆龙德庆县马区林子宗群典中组底砾岩在冈底斯火山岩浆弧中段广泛出露。由此形成的区域性角度不整合面及晚白垩世设兴组褶皱构造,标志着印度大陆与亚洲大陆碰撞作用的开始,时限在65Ma左右。而林子宗群典中组-年波组-帕那组之间的不整合事件,则是印度大陆与亚洲大陆碰撞作用的后继效应,伴有强烈的火山活动。笔者认为在大约45-40Ma,即始新世中晚期,印度大陆和亚洲大陆之间的陆-陆碰撞作用结束,随后转入强烈的陆内汇聚时期。

The tectonic significance and basal conglomerate characters of Dianzhong formation in Ma town,Doilungd(e)g(e)n county, Tibet

In the Linzizong group of Ma town of Doilungdegen County in Tibet, basal conglomerate rocks of Dianzhong formation widely occur in middle section of Gangdise vocanic magmatic arc. Regional angular unconformity surface and the fold tectonic in Shexing formation of upper Cretaceous were created after basal conglomerate rock time. They characterize the beginning of colliding effect between Indian Land and Asian Land,with time limited up to about 65Ma.While the uncomformity incident between Pana formation and Nianbo formation,and between Nianbo formation and Dianzhong formation in Linzizong group was the following-up effect of the collision between of Indian Land and Asian Land. Therefore the inter-land collision terminated in about45-40Ma, that is, mid-late Eocene, later turning into a strong intra-land convergence stage.