塔里木盆地基底碎屑锆石定年的证据

应用碎屑LA-ICP-MS锆石U-Pb定年方法研究塔里木盆地志留系物源，测年结果表明志留系物源年龄有4期： 700~900Ma、400~500Ma、1450~1650Ma、 2000~2200Ma，志留系都具有新元古界物源，塔中具有古元古界物源，塔北、塔东具有奥陶纪与中元古界早期物源，不同地区物源时代具有明显差异。塔中与塔北、塔东地区志留系具有不同的物源区，塔东地区志留系物源主要来自阿尔金地区奥陶系火成岩，库车-温宿前寒武系基底是塔北志留系的主要源区，塔中志留系物源来自塔南隆起前寒武系基底。来自盆地内部碎屑锆石年代学数据表明塔里木板块早中元古代没有形成统一基底，南北塔里木块体演化各异，塔北微块体可能存在与Columbia超大陆裂解时间一致的构造事件。南北塔里木在新元古界早期才发生碰撞拼合形成统一的基底与演化进程，盆地内部碰撞拼合的时间可能始于前900Ma，大规模裂解期发生在前760Ma，并形成盆地碎屑岩最广泛的蚀源区，塔里木板块在新元古界与Rodinia超大陆具有相似的聚合与裂解演化史。

THE EVIDENCE OF DETRITAL ZIRCON AGE DETERMINATION OF TARIM BASIN BASEMENT

The analysis of sedimentary material source of Silurian plays an important role in petroleum exploration and the evolution of Precambrian basement,the UPb isotopic age of zircons from clastic rocks in Tarim basin is determined in situ by LA-ICP-MS，it is indicated there are four periods of sedimentary source ages in Silurian,i.e.,700～900Ma，400～500Ma，1450～1650Ma，2000～2200Ma.It is showed that in all of the Silurian clastic rocks,there is Neoproterozoic sedimentary source，and there is Paleoproterozoic source in central Tarim area，Ordovician and the early Mesoproterozoic sources are detected in northern and eastern area in the Tarim Basin.There are obvious difference source regions and source ages of Silurian in different areas.The igneous rocks of Ordovician in Altun Tagh are the main sources of Silurian in eastern area，and KuqaNorthern Precambrian basement uplift is the main material source of Silurian in northern area，and the sedimentary source of central area comes from the Southern uplift Precambrian basement.It is indicated that there was not uniform Tarim basement in Paleoproterozoic and Mesoproterozoic from the date of the zircon age，and in the North and South Tarim continents,there are the different evolution events,in the North Tarim continent,there is possibly the same tectonic event as the breakup of Columbia supercontinent.The North and South Tarim continental collision happened in the early Neoproterozoic,about 900Ma,and uniform Tarim basement formed，and the large scale breakup of the Tarim occurred about 760Ma which caused widespread denudation area for clastic rocks in the basin.It also demonstrates that there was the same assembly and breakup history as Rodinia supercontinent in Neoproterozoic.