东昆仑东段坑德地区侵入岩岩石地球化学特征及其构造意义

Geochemical Characteristics and Tectonic Significance of Intrusive Rocks in Kengde Area in Eastern Kunlun Orogenic Belt

对东昆仑造山带东段坑德地区出露的侵入岩进行了详细的岩石地球化学研究。结果表明,东昆仑造山带东段坑德地区岩体为一套高钾钙碱性花岗闪长岩,岩石由准铝质向过铝质过渡。岩石稀土元素具LREE元素富集、HREE元素亏损,有弱的负Eu异常的特征,微量元素明显富集大离子亲石元素(Rb,Ba,K)和活泼的不相容元素Th,U等;相对亏损高场强元素Nb,Ti,P;Rb/Sr,Nb/Ta,Zr/Hf等特征显示岩石具壳幔混合特征。岩石具有板块俯冲碰撞前活动大陆边缘构造环境特征,应该为阿尼玛卿洋向北俯冲碰撞过程中壳幔岩浆混合作用形成。

Detailed geochemical study has been carried out on intrusive rocks outcropeed in Kengde area in easternKunlun orogenic belt. 1t is showed that intrusive rocks in Kengde area is high potassium alkaline granodiorite. Therocks are transferred from metaluminous to weak peraluminous. Rare earth elements have the characteristics of richLREE , low HREE and weak negative Eu anomaly. Trace elements are obviously enriched in large ion lithophile elements（R B, Ba, K ） and lively incompatible elements （Th, u ）; As showed by relatively depleted in high fieldstrength elements, such as Nb, T i, P , Rb / Sr and Nb / T a, Zr / HF, rocks have the characteristics of mixedcrust and mantle. Rocks have the characteristics of active continental margin tectonic environment before plate subductionand collision. 1t should be formed by crust mantle magma mixing during the period of Animaqing oceannorthward subduction and collision.