东准噶尔原塔黑尔巴斯套组下部中基性火山岩建造归属

巴里坤煤矿北原划下泥盆统塔黑尔巴斯套组下部 ,发现一套中基性火山岩及火山碎屑岩建造。其岩石组合为 :下部中基性火山岩 ,向上是火山碎屑岩夹中基性熔岩 ,再向上碎屑岩增多 ,仅见海百合茎生物化石。它被中志留世色克森巴依超单元侵入 ,上部被上志留—下泥盆统含化石的红柳沟组不整合覆盖。根据东准噶尔构造演化历史 ,在奥陶纪末全面隆升 ,缺失下志留统。该火山岩建造应是奥陶纪的产物。东邻区哈密头道沟 ,周济元等在相当于火山岩建造的上部层位的火山碎屑岩夹中基性火山岩中发现早奥陶世腕足化石 :Orthambonites sp.,O.rotundiformis,Pragonambonites sp.,新建了恰干布拉克组。经研究对比 ,东准所发现的这套中基性火山岩建造与新建的恰干布拉克组为同时、同一岛弧拉斑玄武岩构造环境的产物。依据岩石地层单位命名优先原则 ,研究区采用“恰干布拉克组”这一组名 ,时代定为早奥陶世

DISCUSSION ON THE OWNERSHIP OF INTERMEDIATE BASIC VOLCANICS UNDER TAHEIERBASITAO FORMATION IN EAST JUNGGAR

A set of intermediate basic volcanics,pyroclastic rock and top part of clastic rock is found in north of Balikun coal mine.The only organic fossil is crinus stem.The volcanics intruded into Middle Silurian Sekeshenbayi super unit and uncomformably overlayed on Hongliugou Formation.Combined with tectonic evolution history of east Junggar,totally in Late Ordovician and lack of Early Silurian sediments,the volcanics should be the product of Ordovician.In east adjacent region,Toudaogou of Hami,Zhou Ji yuan found brachiopoda fossil of Early Ordovician in the same stratum of pyroclastic rock with intemediate basic volcanics :Orthambonites sp.,O.rotundiformis,pragonambonites sp.and mewly built Qiaganbulake Formation.The intermediate basic volcanic formation in East Junggar is produced in the same time and same structural environment as mewly built Qiaganbulake Formation.By study and contrast and occording to named priority principle of lithostratigraphic unit,we adopt the name of Qiaganbulake Formation,it belongs to Early Ordovician.