东昆仑西段噶顺达乌地区中泥盆世中酸性侵入岩地球化学特征及构造环境分析

东昆仑西段噶顺达乌地区分布有大量的中酸性侵入岩,岩性组合由中粒黑云母二长花岗岩和斑状黑云母二长花岗岩两类组成,综合其岩石学、岩石地球化学、同位素测年及接触关系资料,岩石属典型的高钾钙碱性—弱过铝质花岗岩;岩石具轻稀土富集型;Eu负异常中等,稀土总量较低,显示幔源分异特点;在黑云母二长花岗岩获得LA-ICP-MS锆石U-Pb同位素年龄为(393.1±1.6)Ma,表明侵入体的侵位时代为中泥盆世。通过综合分析,认为噶顺达乌地区中泥盆世中酸性侵入岩为大陆碰撞结束后的造山后花岗岩,而与板内后造山花岗岩不同。

Geochemical characteristics and tectonic setting analysis of middle Devonian intermediate-acid intrusive rock in the Gashundawu area, eastern Kunlun belt

Intensive intermediate-acid intrusive rocks, which include medium-fine grain biotite monzontic granite and prophyritic biotite monzontic granite, are widely outcropped in the Geshundawu area, eastern Kunlun mountain blet. Through comprehensive analysis of petrology, petrochemistry, isotopic dating and the contact relationship information, the result indicates that the intrusive rocks belong to highpotassic calc-alkali peraluminous granite with enriched light REE,medium negative Eu anomalies and lower total REE, which shows the characteristics of derived mantle. The U-Pb isotopic dating measurement of zircon mineral collected from the biotite monzontic granite by LA-ICP-MS method is (393.1±1.6) Ma, which suggests that the intrusion emplacement age is middle Devonian period. Based on the integrated analysis, the acid intrusive rocks of the middle Devonian in Gashundawu area is post-tectonic granite emplaced after continental collision, which is different from intraplate post-orogenic granite.