天山地区下石炭统与下伏地层角度不整合接触的地质意义

新疆天山地区下石炭统出露广泛且与下伏地层多呈角度不整合接触,如西部北天山的大哈拉军山组,中部中天山的马鞍桥组及东部南天山的甘草湖组均与下伏地层呈角度不整合接触。显然,这是一个区域性角度不整合。两套地层间的角度不整合是鉴别造山运动的直接标志之一,此不整合可能暗示了古天山洋在早石炭世前已经闭合碰撞造山并进入陆内伸展演化阶段。

Geological meaning of unconformility of dip between the Lower Carboniferous strata and its underlying strata

The Lower Carboniferous strata outcropped in the most of Tianshan mountains in China , and most of them are in contact with underlying strata by unconformability of dip, such as Dahalaljunshan Formation in west ,which belongs to north Tianshan tectonics , Maanqiao Formation in middle, which belongs to middle Tianshan tectonics, Gancaohu Formation in east,which belongs to south Tianshan tectonics and so on . They are all in this way distinctly , it is a kind of zonal unconformility of dip, and always regarded as a directly sign to appraise orogeny , so it probably imply us that the Paleozoic ocean had closed and collided before Early Carboniferous. From that time , Tianshan has come into continental activity .