新疆维宝多金属矿区辉绿岩脉SIMS年代学和地球化学

发布时间：2018-02-23 06:30

本文关键词： 辉绿岩 SIMS 矽卡岩矿床维宝祁漫塔格东昆仑　出处：《地质学报》2017年04期 　论文类型：期刊论文

【摘要】：东昆仑造山带海西期-印支期岩浆活动强烈,不仅出露大规模的中酸性侵入体,还发育数量较多的辉绿岩脉(墙)。相对于中酸性侵入体,目前对辉绿岩脉(墙)的研究还较薄弱。本文对新疆维宝多金属矿区辉绿岩脉进行了年代学和地球化学研究,确定了其形成时代,探讨了其形成的构造背景和岩石成因。SIMS锆石U-Pb测年结果显示:维宝多金属矿区辉绿岩形成于227.5±3.3Ma(1σ,MSWD=2.0),为晚三叠世。结合尚未发表的年代学资料,将维宝矽卡岩矿床成矿母岩侵位时间限定于232~227.5Ma之间,这一范围与祁漫塔格矽卡岩多金属矿床成矿母岩就位的峰期年龄一致。主量元素组成上,这些辉绿岩高SiO_2、K_2O,低MgO、Al_2O_3、CaO、FeO和Na_2O,大部分为钙碱性岩;轻重稀土元素分馏强,LaN/YbN5,大部分样品δEu介于0.73和0.77之间,因此在稀土元素配分曲线上表现为具有明显Eu负异常的右倾型配分模式;在微量元素蛛网图上,相对于原始地幔选择性富集大离子亲石元素(如LREE)、亏损高场强元素(如Ti、P元素等)。尽管维宝多金属矿区辉绿岩地球化学组成具有弧岩浆岩的特征,但根据区域构造演化历史,本文认为维宝矿区辉绿岩形成于后碰撞拉伸环境。其稀土和微量元素所显示的弧岩浆特征可能来源于早期俯冲物质对源区的混染。印支晚期东昆仑祁漫塔格地区幔源岩浆底侵作用导致下地壳部分熔融并分异出长英质岩浆,二者在上升过程中发生混合作用并最终在维宝矿区形成时代接近、稀土和微量元素组成相似的花岗闪长岩和辉绿岩脉。
[Abstract]:The Hercynian-Indosinian magmatic activity in the East Kunlun orogenic belt is strong, resulting in not only massive intermediate-acid intrusions, but also a large number of diabase veins (Dianhuo), as opposed to intermediate-acid intrusions. At present, the study of diabase veins (dikes) is still relatively weak. In this paper, chronological and geochemical studies of diabase veins in Weibao polymetallic ore area, Xinjiang, have been carried out, and their forming times have been determined. The zircon U-Pb dating results from the tectonic setting and the petrogenesis of SIMS show that the diabase of the Weibao polymetallic ore area was formed in 227.5 卤3.3 Mai 1 蟽 and MSWD 2. 0, which belongs to the late Triassic. Combined with the unpublished geochronological data, the zircon U-Pb dating shows that the diabase was formed in the Weibao polymetallic ore area. The emplacement time of ore-forming parent rock of Weibao skarn deposit is limited to 2322 ~ 227.5Ma, which is consistent with the peak age of metallogenic mother rock emplacement of Qimantage skarn polymetallic deposit. These diabase rocks have high SiO2K2Os, low MgOAl2O3CaO2OFeO and Na2Os, mostly calc-alkaline rocks, and heavy REE fractionation strong fractionation of LaN- / YbN5, most of which are between 0.73 and 0.77, so the REE distribution curve shows a right-dip pattern with obvious negative EU anomalies. In the trace element cobweb map, relative to the original mantle selective enrichment of large ion lithophile elements (such as LREEN), depleted high field strength elements (such as Tip elements, etc.), although the geochemical composition of diabase in the Weibao polymetallic ore area is characterized by arc magmatic rocks, But according to the history of regional tectonic evolution, In this paper, it is suggested that diabase was formed in the post-collisional extensional environment in Weibao mining area. The arc magma characteristics of rare earth elements and trace elements may be derived from the mixing of subduction materials to the source region. Qimantage area, East Kunlun, East Kunlun, Indosinian late Indosinian region. Mantle-derived magma underplating leads to partial melting of the lower crust and differentiation of felsic magma. They were mixed in the process of rising and finally formed in Weibao ore area. The granodiorite and diabase veins with similar composition of rare earth elements and trace elements were formed in Weibao mine area.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;
【基金】：国土资源部公益性行业科研专项经费项目(编号:201411025) 中国地质调查局地质调查项目(编号:1212011085528);中国地质调查局高层次地质人才培养计划(编号:201309) 青年地质英才计划(编号:201112)资助的成果
【分类号】：P597.3;P618.2

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