西昆仑陆内造山花岗岩特征及构造环境分析——以阿卡孜岩体为例  

Geochemical Characteristics of Akezi Pluton from Western Kunlun and Their Tectonic Implications

作　　者：谢朝永[1] 张红强 韩江伟[1] 巴燕[1] 

机构地区：[1]河南省地质调查院 [2]河南省地质调查四队,郑州450001

出　　处：《科学技术与工程》2013年第2期434-438,共5页Science Technology and Engineering

基　　金：国土资源大调查项目(200213000004)资助

摘　　要：阿卡孜岩体发育在西昆仑地区叶城县境内的阿卡孜大阪北侧。阿卡孜岩体不仅是西昆仑造山带构造演化的产物,也是大规模陆内造山作用开始的标志。通过对其地球化学特征的研究表明,其SiO2含量(63.68%～74.83%)较高,富钾(碱总量8.25%～9.02%)。里特曼指数2.14～3.25,属钙碱性岩系。铝指数在0.97～1.05之间,为铝饱和型花岗岩。其Rb、Th、Ce、Sm富集,Ba、Nb、Hf、Zr及Yb亏损。稀土元素丰度总体偏高(∑REE=(166.14～992.1)×10-6),斜率(La/Yb)N=10.85～30.45,为轻稀土富集型具微弱-强烈Eu负异常(δEu=0.16～0.77)。该岩体的化学成分在S型花岗岩区,微量元素比值K/Rb=206.5～278.1,Rb/Sr=0.72～3.83,Rb/Li=10.98～38.98,均属同熔型花岗岩。综合判定其形成环境为板内同碰撞期—造山晚期,岩体形成时代为古元古代。Akazi pluton on the northern side of Akezi Daban, Western Kunlun, is characterized by relatively high SiO2 （ （64.78%-74. 83% ）, alkali-rich（total alkali = 8.25%-9.02% ）. Rittmann index ranging from 2. 14 to 3.25 of Akazi plutonic rock suggests their affinity to calc-alkali series and ACNK from O. 97 to 1.05 indicates A1- saturated granite. The trace elements of the plutonic rock shows Rb-, Th-, Ce-, Sin- and LREE-enriched and Ba-, Nb-, Hf-, Zr-, Yb- depleted as well as Eu anomaly（δEu = 0. 16-O. 77）. Their chemical compositions plot into S- type granite field and their K/Rb （206.5-278.1）, Rb/Sr（ 0.72-3.83 ） and Rb/Li （ 10. 98-38.98 ） indicate that they are syntectic granite. All geochemical characteristics of above allow us to conclude that the tectonic envi- ronment of Akezi pluton belong to syn-eollision to post-orogenic period. The age of pluton emplacement occurred in Palaeoproterozoic. As the result of tectonic evolution of western Kunlun orogenic belt, Akezi pluton markes begin- ning of a large-scale intracontinental orogeny.

关 键 词：阿卡孜岩体 地球化学特征 西昆仑地区 

分 类 号：P617.945[天文地球—矿床学]