东昆仑哈日扎含矿花岗闪长斑岩LA-ICP-MS锆石U-Pb定年及地质意义

摘要

哈日扎铜钼多金属矿床位于东昆仑成矿带东段,是大型斑岩型铜钼多金属矿床.笔者利用锆石LA-ICP-MS U-Pb法,获得花岗闪长斑岩的成岩年龄为(234.5±4.8) Ma(MSWD=0.24)；花岗闪长斑岩为其成矿母岩.对哈日扎花岗闪长斑岩的岩石学和地球化学研究表明,花岗闪长岩富SiO2(70.94％～76.08％)、K2O(4.91％ ～6.07％),贫CaO(0.16％ ～2.01％)、Na2O(0.24％ ～0.78％),属钾玄岩系列及高钾钙碱性系列.稀土元素总量变化较大(124.69×10-6～178.68×10-6),稀土元素配分曲线为平缓的右倾型,轻稀土元素相对富集,重稀土元素相对亏损.δEu变化范围0.26～0.30,具有弱负Eu异常.岩石微量元素相对富集大离子亲石元素(LILE),贫高场强元素(HFSE),即相对富集Rb、U、La和Nd,而亏损Ba、Sr、Nb和Y.花岗闪长斑岩形成于同碰撞构造环境.%The Harizha Cu-Mo poly-metallic deposit is one of the typical large-size porphyry deposits in the eastern Kunlun metallogenic belt, with the LA-ICP-MS U-Pb age of its mother rock granite diorite-porphyry being (234.5+ 4.8) Ma(MSWD= 0.24) . Detailed petrographic and geochemical studies show that the granite diorite-porphyry in Harizha belongs to high-K calc-alkaline series, rich in SiO2(70.94% ~76.08%) and K2O (4.91 % ~6.07%), and poor in CaO(0.16% -2.01 %) and Na2O(0.24% ~0.78% ) .The granite diorite-porphyry is characterized by total content of EREE varying greatly from 124.69X 10-6 to 178.68 X 10~6, rich in LREE and low HKEE, with SEu values from 0.26~0.30. Trace elements show enrichment of LILE such as Rb, U , La and Nd and depletion of HFSE like Ba, Sr, Nb and Y. Granite diorite-porphyry resulted from the syn-collisional tectonic setting.