英吉苏凹陷碎屑锆石测年及其对沉积物源的指示

DETRITAL ZIRCON U-PB AGES AND ITS SIGNIFICANCE FROM YINGJISU SAG IN TARIM BASIN

首次应用碎屑锆石LA-ICP-MSU-Pb定年方法，研究塔里木盆地英吉苏凹陷中生界物源．单颗粒碎屑锆石测年结果表明，侏罗系物源年龄值有3组：350-500Ma、760-970Ma、1400—1600Ma；白垩系物源年龄值有2组：320-380Ma、1400-1800Ma．碎屑锆石测年数据分析表明，阿尔金山是本区侏罗系的主要物源区，奥陶纪末—志留纪的火成岩是侏罗系的主要物源；侏罗系上下层位测年数据有反序特征，是经历再搬运沉积的产物；白垩纪英吉苏凹陷物源区发生南北反转，物源来自北部库鲁克塔格山；中生界最古老的物源来自中元古代．碎屑锆石年龄的变化反映了本区中生界盆山耦合关系．

According to the appliance of the new U-Pb isotopic age analysis of zircon by LA-ICP-MS from clastic rocks of Yingjisu sag,there are three groups sedimentary source ages of Jurassic：350-500Ma,760-970Ma, 1400-1600Ma,and there are two groups sedimentary source ages of Cretaceous：320-354Ma,1400-1800Ma.The date of zircon ages from the clastic rocks indicated that Altun Tagh is the Jurassic sedimentary province of Yingjisu sag, and the igneous rocks of late Ordovician - early Silurian were the main source. It is demonstrated that Altun Tagh Mountain had intense uplift in Jurassic and its rehandling sedimentary sources of the area. On the contrary, the sediments comes from the northern Kuruktag Mountain in Cretaceous. It is also showed that the oldest source rocks originated from Mesoproterozoic. The alternation of detrital zircon ages reflected the basin-mountain coupling of the area.