作　　者： ; ; ; ; ;

机构地区： 成都理工大学沉积地质研究所

出　　处： 《地质学报》 2005年第1期88-97,共10页

摘　　要： 应用单颗粒锆石 U - Pb法 ,对出露于羌塘地体中央隆起带唐古拉山北坡的花岗岩体进行侵位年代测定 ,结果表明它们是中生代末至新生代早期多次岩浆脉动、涌动上侵定位的产物。其中龙亚拉花岗岩体 (6 9.8± 2 .0Ma)、木乃花岗岩体 (6 7.1± 2 .0 Ma)是印 -亚板块早期碰撞的产物 ;赛多铺岗日花岗岩体 (40 .6± 3.1Ma)为印 -亚板块主碰撞期花岗岩。岩石类型主要包括辉石石英二长岩、二长花岗岩和钾长花岗岩 ,初始锶同位素比值 (87Sr/86 Sr)为 0 .70 6 0 39～ 0 .714 0 6 9。研究表明 ,中生代末至新生代花岗岩浆均起源于壳幔混熔 ,属同碰撞—晚造山期的壳幔型花岗岩。详细的单颗粒锆石 U - Pb同位素定年为研究青藏高原的形成演化与地球动力学过程提供了重要的依据。 By means of the single-grain zircon U-Pb technique, we have determined the emplacement age of the granite outcrops in the central uplift zone of the Qiangtang basin on the northern slope of the Tanggula range. The result suggests that they are products of repeated magmatic pulsations and upward emplacement from the late Mesozoic to the early Cenozoic. The Longyala granite body (69.8±2.0 Ma) and Munai granite body (67.1±2.0 Ma) are the products of the early-stage collision of the Indian and Asian plates and the Saiduopugangri intrusion (40.6±3.1 Ma) is the granite in the main collisional phase. The rock types mainly include pyroxene-adamellite, monzonite granite and moyite, and the initial strontium isotopic ratios( 87Sr/ 86Sr ) are in a range of 0.706039 to 0.714069. The research indicates that the granitic magma in the late Mesozoic originated in the crust-mantle mixture and is attributed to syncollisional and late orogenic crust-mantle type granite. Detailed single-grain zircon U-Pb isotope dating is the important basis for studying the evolution and geodynamical process of the Qinghai-Tibet Plateau.

关 键 词： 花岗岩体 锆石 年龄 大陆动力学 中新生代 青藏高原 地球化学特征 单颗粒 产物 研究

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]