ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    北-中祁连过渡带龙王山花岗岩体与花石峡钨钼矿关系讨论

    Discussion on the Relationship Between the Longwangshan Granite Mass and the Huashixia W-Mo Deposit in the Transitional Belt of Northdern-Central Qilian

    • 摘要: 花石峡钨钼矿位于青海省东部的互助县,大地构造位置处于北祁连造山带南缘,为典型的矽卡岩型钨钼矿,其与岩浆侵入活动有关。利用LA-ICP-MS锆石U-Pb定年方法对花石峡钨钼矿区外围二长花岗岩体进行了年代学定年,获得(418.2±1.1) Ma U-Pb年龄。岩石地球化学特征显示为高钾钙碱性系列,轻稀土元素富集,重稀土元素较亏损,δEu为0.50~0.88,具弱负Eu异常。微量元素富集大离子亲石元素,而明显亏损高场元素和重稀土元素。地球化学特征表明,龙王山花岗岩是板块碰撞期阶段的产物,属I型花岗岩,岩浆来源于下地壳。龙王山花岗岩同位素的获取,表明花石峡钨钼矿的成矿时代与岩浆侵入时间相近,为晚志留世。龙王山二长花岗岩为该矿提供了热源和物源。

       

      Abstract: The Huashixia tungsten-molybdenum deposit is located in Huzhu County, Eastern Qinghai Province, which is tectonically ocurred in the southern margin of North Qilian orogenic belt. This deposit belongs to a typical skarn-type W-Mo deposit, which is related to the magma intrusion. In this paper, the LA-ICP-MS zircon U-Pb dating method has been used to study the chronology of monzonite granites from the peripheral area of the Huashixia W-Mo deposit, obtained an U-Pb age of (418.2±1.1)Ma. The geochemical results show that these monzonite granites belong to high potassium cal-alkaline series, with LREE enrichment and HREE loss. Their δEu values vary from 0.50 to 0.88, with weak negative Eu anomaly. The trace element results suggest that these granites are enriched in large ion lithotropic elements, but depleted in high field elements and heavy rave earth elements. Geochemical characteristics indicate that the Longwangshan granite was the product of plate collision and sourced from lower crust, belonging to I-type granite. The isotopic results of the Longwangshan granite indicate that the ore-forming period of the Huashixia W-Mo deposit is similar to the ones of magmatic intrusion, and both of them were formed in Late Silurian Epoch. The Longwangshan monzonite granite had provided the heat and material sources for the formation of the Huashixia deposit.

       

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