甘肃夏河-合作地区中生代岩浆岩特征及对金成矿的指示意义

发布时间：2018-02-26 08:30

本文关键词： 地球化学全岩分析埃达克岩枣子沟金矿　出处：《矿物岩石》2017年02期 　论文类型：期刊论文

【摘要】：针对西秦岭夏河-合作金集矿区出露的岩浆岩矿物学及地球化学研究,结果表明金集矿区岩浆岩可分为两类:第一类以德乌鲁花岗闪长岩、三索玛似斑状黑云母花岗闪长岩和马久勒中细粒黑云母花岗闪长岩为代表,属于高钾钙碱性准铝质至过铝质中酸性岩,均富集大离子亲石元素w(Rb)平均134.4×10~(-6),w(Ba)平均775.8×10~(-6),w(Th)平均15.8×10~(-6),w(U)平均3.08×10~(-6)等和轻稀土元素,相对亏损w(Nb)平均10.95×10~(-6),w(Ta)平均0.97×10~(-6)等高场强元素,显示"I"型花岗岩地球化学特征,A/CNK值在0.95~1.07之间,Mg#值为41.87~61.92,δEu值为0.64~0.89,岩石既具埃达克质岩特征,又显示火山弧花岗岩特征。第二类以唐晒日村、扎油乡北的花岗斑岩为代表,属于钙碱性过铝质酸性岩,均富集大离子亲石元素w(Rb)平均92.4×10~(-6),w(Ba)平均561.7×10~(-6),w(Th)平均7.8×10~(-6),w(U)平均2.36×10~(-6)等和轻稀土元素,相对亏损w(Nb)平均9.96×10~(-6),w(Ta)平均0.76×10~(-6)等高场强元素,A/CNK值在1.07~1.66之间,显示出具"S"型花岗岩地球化学特征,具有喜马拉雅型岩浆岩特征,Mg#值为49.76~73.37,δEu为0.83~1.03,岩浆存在幔源物质的参与。研究表明,第一类岩浆岩形成于板块消减的陆缘环境,由玄武质岩浆部分熔融形成,并有部分幔源物质加入;第二类岩浆岩可能形成于沉积岩部分熔融,且有幔源物质参与的环境。第一类岩浆岩与枣子沟金矿存在紧密的时空关系,表现出明显的成矿专属性,是指导夏河-合作金集矿区金矿勘探开发的重要依据之一;第二类岩浆岩与金矿无关。
[Abstract]:In view of the mineralogical and geochemical study of magmatic rocks exposed from Xiahe-Hehe-Hehe-Xiujinji deposit in the western Qinling, the results show that the magmatic rocks in the Jinji mine can be divided into two types: the first type is the Deulu granodiorite. Sansomar porphyry biotite granodiorite and medium and fine biotite granodiorite are represented by high potassium calc-alkaline pseudo-aluminite to peraluminous intermediate-acid rock. High field strength elements, such as Rb) and light rare earth element (WNB) and light rare earth elements (WNB), and the relative depletion of WNb (10.95 脳 10 ~ (10)) ~ (6) and (0.97 脳 10 ~ (10)) ~ (-6)), have an average value of 775.8 脳 10 ~ (8) ~ (-6) ~ (~ (-1)) ~ (15.8 脳 10 ~ (10) ~ (-6)) and 3.08 脳 10 ~ (10) ~ (-6), respectively, and the relative depletion of such elements is 10.95 脳 10 ~ (10) ~ (~ (10)) ~ (~ (6)). The results show that the geochemical characteristics of "I" type granites are as follows: a / C _ (K) values range from 0.95g ~ (1.07) to 41.87 ~ 61.92, 未 EU = 0.64 ~ 0.89. The rocks have the characteristics of adakitic rocks and volcanic arc granites. The second type is represented by the granitic porphyry in Tangsunicun and the northern part of Zhayou Township. Belong to calc-alkaline peraluminous acid rocks, the average value of high field and strong elements (such as (92.4 脳 10 ~ (10) ~ (-6) ~ (-6)) ~ (92.4) 脳 10 ~ (10) ~ (-6) ~ (-6)) ~ (7. 8 脳 10 ~ (10)) ~ (6) ~ (~ (6)) = 2.36 脳 10 ~ (-6)) and light rare earth elements (= 9.96 脳 10 ~ (10) ~ (-6) ~ 0.76 脳 10 ~ (-1) ~ (-6)), etc., and light rare earth elements, the relative depletion of which is 9.96 脳 10 ~ (10) ~ (-6) ~ (-6) ~ (-1)), and the average value of ACNK is between 1.07 and 1.66, and the average value of ACNK is 0.76 脳 10 ~ (-6). It shows that the geochemical characteristics of "S" type granites, with the characteristics of Himalayan magmatic rocks, such as Mg# value 49.7673.37, 未 EU = 0.83U 1.03and magma with the participation of mantle-derived materials, show that the first type magmatic rocks were formed in the continental margin environment of plate subduction, and the results show that the magmatic rocks of the first type are formed in the continental margin environment of plate subduction. The magma was formed by partial melting of Black Tortoise magma, and some mantle source materials were added. The second type magmatic rocks may be formed in environments where sedimentary rocks are partially melted and have the participation of mantle-derived materials. The first type magmatic rocks have a close temporal and spatial relationship with the Zaozigou gold deposit. It shows obvious metallogenic specificity and is one of the important bases to guide the exploration and development of gold deposits in Xiahe-Cojinji mining area, while the second type magmatic rock has nothing to do with gold deposits.
【作者单位】：东华理工大学地球科学学院;中国地质科学院地质力学研究所;甘肃省地矿局第三地质矿产勘查院;中国地质大学(北京);
【基金】：国家科技支撑计划项目(2015BAB05B04-01、2015BAB05B04-02) 国家自然科学基金项目(U1403292,41472196) 江西省研究生创新专项资金项目(YC2016-S280)
【分类号】：P588.1;P618.51

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