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东昆仑造山带在三叠纪不仅是一个重要的构造-岩浆带,也是一个对于国民经济非常重要的多金属成矿带.该区在三叠纪形成了大量与成矿有关的花岗岩,它们之间的联系、与区域构造运动的关系目前尚未明确.在莫河下拉银多金属矿花岗斑岩岩相学、地球化学和锆石年代学的研究基础上,总结了东昆仑地区三叠纪与成矿有关花岗岩的基本特征,并探讨了它们的演化规律.结果表明:(1)东昆仑与成矿有关的三叠纪花岗岩年龄为250~200Ma,具有一个由低K系列-中K钙碱性系列向高K系列-钾玄岩系列过渡的明显趋势,240~200Ma,A/NK比值由2.00降到1.00;(2)(~(87)Sr/~(86)Sr)i为0.710~0.715,ε_(Nd)(t)值为-0.6~0.0,ε_(Hf)(t)主要集中在-5~1,峰值为-2~-1,表明东昆仑与成矿有关三叠纪花岗岩物质主要来源于古老的地壳物质,同时有少量的幔源物质加入;(3)东昆仑地区在240Ma进入后造山阶段,出现大规模的钙碱性花岗岩,220Ma之后花岗岩大量减少,210~204Ma出现的花岗岩以碱性A型花岗岩为主,标志着碰撞造山结束进入到板内裂解阶段.
The East Kunlun orogenic belt was not only an important tectonic-magmatic belt in the Triassic, but also a polymetallic metallogenic belt important to the national economy. This area formed a large number of granitoids associated with metallogenesis in the Triassic. The relationship between them and regional tectonic movement is not yet clear.On the basis of the study of lithofacies, geochemistry and zircon chronology of the Xiayin silver polymetallic granite porphyry in the Mohe river, The basic characteristics of the granites related to metallogenesis and the evolution of them are discussed.The results show that: (1) the Triassic granites related to mineralization in the East Kunlun are aged 250 ~ 200Ma, Alkaline series to the high-K series - Karst series transition obvious trend, 240 ~ 200Ma, A / NK ratio decreased from 2.00 to 1.00; (2) (87) Sr / ~ (86) Sr) i was 0.710 ~ 0.715, ε_ (Nd) (t) is -0.6 ~ 0.0, ε_ (Hf) (t) is mainly concentrated in -5 ~ 1 and -2 ~ -1 peak, indicating that the East Kunlun Mountains is related to the Triassic The granite is mainly derived from ancient crustal materials with a small amount of mantle-derived materials added into it. (3) After the East Kunlun area entered the post-orogenic phase with 240Ma, large-scale calc-alkali Granite, granite significant reduction after 220Ma, 210 ~ 204Ma granite appearing mainly granite alkaline type A, marking the end of the collisional plate into the cracking stage.