塔中地区志留系碎屑锆石测年及其地质意义

Detrital zircon U-Pb ages and its significance of Silurian from Tazhong area in Tarim Basin

志留系是塔里木盆地第一套砂岩储层广泛分布的沉积盖层,其沉积来源与成因对志留纪构造演化及周边造山带的研究具有重要意义。塔中地区3个志留系样品的碎屑锆石LA-ICP-MS U-Pb定年研究表明,志留系具有比较集中的二期物源年龄:南华纪中期、古元古代中期。碎屑锆石测定的年龄表明塔中志留系物源均来自前寒武纪,塔中东部源区方向的塔南隆起基底在奥陶纪已隆升成为蚀源区。大量的新元古代中期锆石年龄表明塔里木板块在新元古代时期可能与Rodinia超大陆具有相似的聚合与裂解演化史。

The analysis of sedimentary provenances of Silurian plays an important role in the evolution of Silurian in Tarim Basin and the surrounding orogenic belts in that it is the first widespread sandstone cap rock in Tarim Basin. The U-Pb isotopic age of zircons from 3 clastic rocks in Tazhong area was performed in situ by LA-ICP-MS,it indicated that there were two groups sedimentary source ages of Silurian ： 740 - 820 Ma, 2000 - 2200 Ma. It is showed that all of the Silurian clastic rocks came from Precambrian basement. The Tanan uplift in the eastern of Tazhong area have been uplift to be provenance area in Silurian. It also demonstrated that the Tarim plate had the same assembly and breakup history as Rodinia supercontinent in Neoproterozoic.