库鲁克塔格地区新元古代沉积物源分析:来自碎屑锆石年代学的证据

Provenance of Neoproterozoic rocks in Quruqtagh area,Xinjiang: Evidence from detrital zircon geochronology

库鲁克塔格位于南天山和塔里木盆地接合部,保留相对较完整的地层记录。新元古代贝义西组主要为一套火山-沉积组合序列,育肯沟组为浊流成因的砂岩和粉砂岩组合。对取自两个地层的沉积岩样品,分别进行了碎屑锆石LA-ICP-MSU-Pb测年,并分别获得了93组和71组U-Pb有效年龄。其中贝义西组锆石U-Pb年龄主峰值为821Ma、次峰值为861Ma的碎屑锆石(761～847Ma)具有显著优势,育肯沟组年龄值为768Ma(次峰值为800Ma和741Ma)的碎屑锆石比较集中,说明库鲁克塔格地区在741Ma、768Ma、800Ma、821Ma和861Ma有大规模的岩浆活动。10个太古代碎屑锆石年龄以及综合已有的研究成果,确认库鲁克塔格存在中-新太古代基底。贝义西组砂岩主要源自761～847Ma、851～972Ma和1808～2498Ma岩石。育肯沟组主要来自734～845Ma、858～963Ma和1708～2486Ma的岩石。

The Quruqtagh area is situated in the linkage of South Tianshan and Tarim basin where well preserved sedimentary records.The Beiyixi Formation in the Quruqtagh area is a volcanic-sedimentary succession which consists of igneous rocks and sandstones.The Yukengou Formation is characterized by sandstones and siltstones formed by turbidity current.Detrital zircon U-Pb ages of two samples from the sandstones were measured by the LA-ICP-MS method.The sample 09DPL25 and 09DPL41 respectively records 93 and 71 age data.Detrital zircons of sample 09DPL25 from Beiyixi Formation whose peak age is 821Ma and subordinate peak age is 861Ma are prevalent.And the majority of detrital zircons of sample 09DPL41 from Yukengou Formation is weighted-age 768Ma （subordinate 800Ma and 741Ma）.Based on CL images,there occurred a few magmatic events about 741Ma,768Ma,821Ma and 861Ma.Together with the literature data,it strongly suggests that the basement rocks in the Quruqtagh region were formed in the Meso- to Neo-Archean period.Detrital zircons indicate that the provenances of Beiyixi Formation are 761~847Ma,851~972Ma and 1808~2498Ma rocks and main provenance ages of Yukengou Formation are 734~845Ma,858~963Ma and 1708~2486Ma.