西天山阿吾拉勒一带石炭系阿克沙克组风暴岩及其意义

Tempestite of Akeshake Formation in Awulale Area,Western Tianshan and its significance

西天山阿吾拉勒阔尔库一带早石炭世阿克沙克组以海相碳酸盐岩夹碎屑岩为主,发育典型风暴成因的竹叶状砾屑灰岩。风暴沉积构造主要有风暴侵蚀构造、风暴撕裂构造、风暴浪构造、风暴涡流构造及风暴期后快速沉积构造等。已识别出的风暴沉积类型有具块状层理的竹叶状砾屑灰岩,具递变层理的砾屑灰岩和砾屑砂岩,具丘状、洼状交错层理和平行层理的砂屑灰岩及生物碎屑砾屑粉砂质灰岩,具平行层理的砂屑灰岩、长石岩屑砂岩,具波痕交错层理的砂屑灰岩和砾屑粉砂质灰岩,具水平层理的粉屑灰岩和具块状或水平层理的生物碎屑砾屑粉砂质灰岩。新发现的风暴沉积,说明早石炭世该地区处于低纬度带陆棚浅水沉积环境,因而对于分析西天山石炭纪的古地理、古气候、古构造及板块的运动规律具有重要意义。

The Early Carboniferous Akeshake Formation in the Awulale Kuoerku Area, Western Tianshan, is mainly marked by carbonate rocks and clastic rock. In this set of strata, the bamboo-leaf-like calcrudite belonging to storm deposit developed. The storm sedimentary structures include erosional structures, tear-pull structures, storm-surge structures, storm eddy structures and quickly deposited structures after storm. These types of storm deposits that have been recognized include the hamboo-leaf-like calcirudite with massive bedding, the bamboo-leaf-like calcirudite and sandstone with graded bedding, the calearenite with hummocky and hollow cross bedding and parallel bedding, the calearenite and feldspathic litharenite with parallel bedding, the calcarenite and bioclastic silty caleirudite with wavy cross bedding, the ealcisiltite and silty ealcirudite with horizontal bedding, and the bioclastie silty calcirudite with homogeneous or horizontal bedding. These storm deposits may indicate the sedimentary environment being the shelf of low latitude zone in the Early Carboniferous. The discovery of the storm deposits is of significance in the interpretation of the Carboniferous palaeogeography, palaeoclimate, palaeotectonics and plate motion of Western Tianshan.