Yamatuo intrusive rocks, distributing in the northern margin of Qaidam basin, compose the east part of Tataleng River batholith. The lithology of these rocks is the combination of porphyritic-like syenogranite and porphyritic monzogranite. The phenocryst content in the rocks is 6~25% and its grain size is 1~5 cm, revealing rapakivi texture. The geochemical characteristics show that Eu is with obvious depleted characteristics reflecting the strong fractional crystallization of rocks which is very similar to crustal-derived granite ( S) . All the facts indicate the intrusive rocks are the partial melting of the crust, belonging to the mixture of crust-derived magmatite in post-collisional tectonic setting. The result analysis of LA-ICP-MS zircon U-Pb dating indicates that the rock mass was formed in early Silurian 429. 9 ± 1. 4 Ma, being the signature of the end or near the end of the orogenic process in early Paleozoic This finding provides important chronological constraints for further study of the tectonic evolution of the northern margin of Qaidam orogenic belt.%亚马托侵入岩位于柴达木盆地东北缘,为塔塔楞河大岩基的东段部分.岩性为似斑状正长花岗岩+斑状二长花岗岩组合,岩石中斑晶含量6%~25%,颗粒达1~5 cm,构成环斑结构.该侵入岩地球化学特征显示,Eu具明显的亏损特征,反映岩石经历了强烈的分离结晶作用,与壳源花岗岩(S型)很相似,表明这些花岗岩为地壳部分熔融的产物,属后碰撞环境的壳源岩浆岩组合.LA-ICP-MS锆石U-Pb测年结果表明岩体形成于429.9±1.4 Ma,时代为早志留世,佐证了其是早古生代造山过程结束或近于结束的标志,这一成果为进一步研究柴北缘造山带的构造演化提供了重要的年代学约束.
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