新疆西天山伊犁地区石炭纪火山—沉积序列及盆地性质  

Carboniferous Volcanic-Sedimentary Succession and Basin Properties in Ili Area,Western Tianshan,Xinjiang

作　　者：白建科[1,2] 李智佩[1,2] 徐学义[1,2] 孙吉明[1,2] 牛亚卓[1,2] 

机构地区：[1]中国地质调查局西安地质调查中心,西安710054 [2]国土资源部岩浆作用成矿与找矿重点实验室,西安地质调查中心,西安710054

出　　处：《地质论评》2015年第1期195-206,共12页Geological Review

基　　金：国家自然科学青年基金项目(编号:41202077);中国地质调查局项目(编号:12120113041000;1212011085475;12120113042200;1212011220649)联合资助成果

摘　　要：新疆西天山伊犁地区作为中天山微板块的一部分,呈"倒三角形"被缝合带或断裂带所围限。其上广泛出露的石炭纪火山—沉积岩系,是研究西天山石炭纪盆地性质和天山古生代造山作用演化过程最为直接的载体。本文通过对石炭纪火山—沉积剖面的岩石组合、地层序列、构造环境及盆地演化过程研究表明:伊犁地区石炭纪火山—沉积岩与下伏地层(前寒武纪结晶基底或前石炭纪褶皱基底)之间呈广泛的区域性角度不整合接触;火山—沉积岩系由下到上可以划分为2个序列,分别对应于盆地伸展—裂陷演化的两个旋回:序列Ⅰ:大哈拉军山组底部扇三角洲相、向上出现2次爆发相—喷溢相的火山喷发旋回,阿克沙克组底部扇三角洲相,向上过渡为滨浅海相—开阔台地相;序列Ⅱ:伊什基里克组由下到上由3次爆发相—喷溢相的火山喷发旋回构成,东图津河组为浅海陆棚相。西天山伊犁地区石炭纪火山—沉积序列反映了后碰撞伸展环境下的裂谷盆地充填演化过程。The Ili area, as a part of the Central Tianshan micro-continent, is a inverse-triangular area bordered by sutures and zones in the Tianshan belt. Carboniferous volcanic--sedimentary rocks widely outcropping in Ili area is the most direct carrier in the study of Carboniferous basin properties of western Tianshan and Paleozoic orogenic evolution of Tianshan. According to the rock assemblage, stratigraphic sequence, tectonic setting and basin evolution of the Carboniferous volcanic--sedimentary section, we can draw the following conclusions ： there is a wide regional angular crystalline basemen or unconformity between the Lower Carboniferous and its underlying strata （the Precambrian pre-Carboniferous folded basement ）. From bottom to top, Carboniferous volcanic-- sedimentary rocks can be divided into two sequences respectively corresponding to two cycles of extensional--rift evolution in the basin. Sequence I consists of Dahalajunshan Formation with fan delta facies in the bottom, upward transition as two cycles from volcano explosive facies to effusive facies and Akeshake Formation with fan delta facies in the bottom, upward transition Yishijilike Formation with three as from shore--shallow sea laeles to open platform facies. Sequence Ⅱ consists ofYishijilike Formation with three cycles by volcano explosive facies to effusive facies and Dongtujinhe Formation with neritic shelf facies. It is believed that the fill sequences in Carboniferous volcanic--sedimentary basin reflected the process of rift basin filling and evolution in post-collision extensional setting.

关 键 词：火山—沉积序列 后碰撞伸展环境 石炭纪 伊犁地区 西天山 

分 类 号：P534.45[天文地球—古生物学与地层学]