中天山造山作用的同位素年代分期  

DIVISION OF THE CENTRAL-TIANSHAN OROGENY BASED ON ISOTOPIC AGES

作　　者：车自成[1] 刘良[1] 刘洪福[1] 罗金海[1] 

机构地区：[1]西北大学地质系

出　　处：《地质论评》1995年第3期261-271,共11页Geological Review

基　　金：国家自然科学基金 (编号49070131)

摘　　要：我们把近年来所获得的一些年龄数据以及前人已有的年龄数据与区域地层接触关系作了对比,发现二者有意想不到的一致性,据此将中天山造山作用划分为5期,年龄分别大约为452—439Ma,412—402Ma,355—345Ma,334—327Ma和315—289Ma。中生代还可能有3期构造热事件,年龄大约为226—200Ma,165—160Ma和83Ma,代表了中天山的后期演化。上述年龄数据主要是从中天山南缘断裂带构造岩中获得的,它与区域年龄一致,这说明沿中天山两条边界断裂的逆冲推覆可能是导致中天山造山带变形的基本方式和原因。The Tianshan Mountains are a huge intracratonic orogienic belt, lying in Central Asia. It underwent polygenetic metamorphism and deformation in the Paleozoic. Therefore the Tianshan orogeny is regarded as a representative of the Hercynian orogeny in China.The Central Tianshan Mountains were formed in the Early Palaeozoic and later experienced intense reconstruction. Recently the authors have obtained several 40Ar/39Ar cooling ages and other isotopic ages of this area. On the basis of these ages combined with previous age data and in comparison with the regional stratigraphic contact relationships, the Central Tianshan orogeny is divided into five stages, whose isotopic ages are about 315 - 289 Ma, 327 - 334 Ma, 345 - 355 Ma, 402 - 412 Ma, and 439 - 452 Ma respectively. The Mesozoic Era might have witnessed three tectonothermal events with isotopic ages of about 226 - 200 Ma, 165 -160 Ma and 83 Ma, representing the later evolution of the Central Tianshan Mountains.Most of the above-mentioned ages were obtained by dating the tectonites from the fault zone at the southern margin of the Central Tianshan Moutnains. Their coincidence with regional ages indicates that the overthrusting along two boundary faults of the Central Tianshan Mountains might be the fundamental mode and cause of the deformation of the Central Tianshan erogenic belt.

关 键 词：中天山 造山带 氩同位素 构造运动 同位素年代 

分 类 号：P542.2[天文地球—构造地质学] P597[天文地球—地质学]