中国阿尔泰克孜勒花岗岩体LA-ICP-MS锆石U-Pb定年、岩石地球化学特征及其地质意义  

LA-ICP-MS Zircon U-Pb Age and Geochemistry of the Kezile Granitic Pluton in Altay of China and their Geological Implications

作　　者：赵玉梅[1] 彭戈[2] 赵得龙 尤悦程 

机构地区：[1]新疆地质矿产勘查开发局第七地质大队,新疆乌苏833000 [2]成都理工大学,四川成都610066 [3]甘肃省地质矿产勘查开发局第二地质矿产勘查院,甘肃兰州730020

出　　处：《地质与勘探》2016年第2期271-282,共12页Geology and Exploration

摘　　要：克孜勒花岗岩体位于新疆阿尔泰南缘西伯利亚和哈萨克斯坦-准噶尔板块的结合部位,岩体呈不规则圆形的岩基产出,主要岩石类型为石英闪长岩、花岗闪长岩、花岗岩、二长花岗岩、黑云母二长花岗岩。黑云母二长花岗岩的LA-ICP-MS锆石U-Pb年龄为289.5±4.3Ma,表明岩体形成于早二叠世。岩体具有高硅（SiO2=70.05%-75.78%）、高碱（K2O=3.32%-5.70%,Na2O=3.07%-4.48%）、富铝（Al2O3=12.49%-14.04%）和低MgO（0.01%-0.72%）、CaO（0.36%-1.60%）、TiO2（0.03%-0.45%）、P2O（0.07%-0.15%）特征,A/CNK=1.08-1.20,高FeOT/MgO比值（平均44.95）;富集Rb、Th、K、La、Ce,强烈亏损Ba、Sr、Nb、Ti,铕负异常明显（δEu=0.03-0.36）;具有I-A过渡特点的高分异钙碱性花岗岩体。克孜勒花岗岩体可能是区域上“双峰式”岩浆组合中的酸性端元,为典型的后碰撞岩体,是后碰撞拉张背景下幔源岩浆发生底侵作用导致大陆地壳生长过程的产物。The Altay orogenic zone in China is an important unit of the Central Asian Orogenic Belt （CAOB）, characterized by numerous young mantle source composition of intrusive rocks, especially a number of granitic plutons. These granitic plutons have the features such as multiple times, many types, and a variety of tectonic settings. The Kezile granitic pluton is an irregular round batholiths, occurring at the southern margin of Altay between the Siberia and Kazakhstan-Junggar plates. Its main rock types include biotite monzonitic granite, monzonitic granite, granite, granodiorite and quartz diorite. The LA-ICP-MS zircon U-Pb dating age of the biotite monzonitic granite is 289.5±4.3Ma, suggesting that the Kezile granitic pluton formed at early Permian. Petrological and geochemical data show that the pluton is characterized by high silicon （SiO2=70.05%-75.78%）, high alkali （K2O=3.32%-5.70%, Na2O=3.07%-4.48%）, abundant aluminum （Al2O3=12.49%-14.04%） and low MgO （0.01%-0.72%）, CaO （0.36%-1.60%）, TiO2 （0.03%-0.45%）, P2O5 （0.07%-0.15%）. It has a ratio of A/CNK=1.08-1.20 and high FeOT/MgO ratio （average 44.95）. Enrichment of Rb, Th, K, La, and Ce, strong depletion of Ba, Sr, Nb and Ti, and low δEu （0.03-0.36） characterize this rock. All of these data suggest that the Kezile granitic pluton has transition features from high-fractionated and high-K calc-alkaline I-type granites to A-type granites, and the pluton could be the acidic components of the ＂bimodal type＂ magma in the area, which is the product of growth of the continental crust triggered by the underplaying of the post-collision mantle-derived magma in Altay in an extensional tectonic setting.

关 键 词：阿尔泰南缘 I-A型花岗岩 后碰撞伸展 

分 类 号：P584[天文地球—岩石学]