山东中基性脉岩特征及其与金矿化的关系
发布时间：2019-02-16 14:37
【摘要】：山东省位于华北克拉通的东南缘,是非常重要的金矿集中区。在该区大多数金矿床中伴生有大量的中基性脉岩,包括煌斑岩、辉长岩、辉绿岩、闪长岩等。长期以来,关于该区中基性脉岩的成因及其与金成矿的关系没有定论。本文基于岩石学、岩石地球化学和成因矿物学的方法,试图总结中基性脉岩的时空分布特点,讨论其成因、物质来源及其与金矿化的关系,为深刻研究该区金的成矿模式,进一步探索金成矿规律提供依据。研究表明,山东地区中基性脉岩主要为高钾钙碱性和钾玄岩系列,表现为大离子亲石元素和轻稀土元素富集、高场强元素和重稀土元素亏损的特征。大多数脉岩属于弧火成岩形成环境,其成因与太平洋板块向华北板块俯冲有关,成岩模式可以理解为:由于富集不相容元素的岩石圈地幔发生部分熔融,进而熔体上升侵位并与地壳发生了混染作用后定位于地壳浅部。进一步研究结果还显示,该区不同区域中基性脉岩的岩石特征存在差异,岩石指数特征和稀土元素特征显示:中基性脉岩在栖霞、沂水地区岩浆分异程度较弱,碱度偏低,其他地区则分异程度略强、碱度略偏高;Sr-Nd同位素特征还揭示:鲁西地区之济南、邹平的辉长岩及莱芜的闪长岩源自EMⅠ型富集地幔,应为古老岩石圈地幔熔融的产物;而鲁西地区之上峪、沂南的闪长岩及胶东的大多数中基性脉岩源自EMⅠ+EMⅡ型复合型富集地幔,此类地幔来源可能受扬子板块俯冲作用影响。通过对中基性脉岩中主要暗色矿物辉石、角闪石等测试计算,其温压条件为:(1)辉绿岩中的辉石温度和压力从鲁西地区(1139.50~1201.08℃,0.08~5.77kbar)至栖霞地区(1178.85~1272.69℃,3.71~12.36 kbar)呈上升趋势;(2)煌斑岩中辉石的温度和压力从胶西北地区(1197.02~1284.38℃,5.38~13.44kbar)至牟乳地区(1100.81~1278.53℃,0.27~12.90 kbar)呈现明显降低趋势;(3)几种脉岩之角闪石的结晶压力计算结果显示:鲁西的铜石矿区结晶压力(6.02~9.41 kbar)最大;胶西北的玲珑矿区(2.73~5.91kbar)、栖霞的笏山矿区(3.45~6.13kbar)、牟乳成矿带的郭城矿区(4.24~7.47kbar)和王格庄区域(0.35~5.95kbar)次之;鲁西铜井矿区(1.15~6.91kbar)和栖霞部分区域(1.55~5.03kbar)角闪石结晶压力较低;青岛区域结晶压力最低(0.07~0.56kbar)。总之,山东地区中基性脉岩与金矿脉存在明显的时空一致性,且中基性脉岩金元素的地球化学背景值往往较高,因此认为其在金成矿过程中具有重要作用,对金成矿具有一定指示意义。
[Abstract]:Shandong Province is located in the southeastern margin of North China Craton, which is a very important gold concentration area. In most gold deposits in this area, there are a large number of intermediate basic dikes, including lamprophyre, gabbro, diabase, diorite and so on. For a long time, there has been no conclusion on the origin of middle-basic dikes and its relationship with gold mineralization. Based on the methods of petrology, petrogeochemistry and genetic mineralogy, this paper attempts to summarize the space-time distribution characteristics of middle basic dike rocks, and to discuss their origin, material source and their relationship with gold mineralization, in order to study the metallogenic model of gold in this area. To further explore the rules of gold mineralization to provide the basis. The results show that the medium-basic dikes in Shandong area are mainly composed of high-potassium calc-alkaline and kaliumite series, which are characterized by the enrichment of large ion lithophile elements and light rare earth elements, and the depletion of high field strength elements and heavy rare earth elements. Most of the dikes belong to the arc igneous environment, which is related to the subduction of the Pacific plate to the North China plate. The diagenetic model can be understood as the partial melting of the lithospheric mantle enriched with incompatible elements. Then the melt rises and emplacement, and after mixed with the crust, it is located in the shallow part of the crust. The results of further study also show that there are differences in rock characteristics among different regions of the region, and the rock index and REE characteristics show that the differentiation degree of magma in Qixia, Yishui area is weak, and the alkalinity is low, the characteristics of rock index and rare earth elements show that the middle basic dike rocks have weak differentiation degree and low basicity in Qixia, Yishui area. In other areas, the degree of differentiation is slightly stronger and the alkalinity is slightly higher. The Sr-Nd isotopic characteristics also reveal that the pyroxene of Zouping and the diorite of Laiwu originated from the EM 鈪，
本文编号：2424545
[Abstract]:Shandong Province is located in the southeastern margin of North China Craton, which is a very important gold concentration area. In most gold deposits in this area, there are a large number of intermediate basic dikes, including lamprophyre, gabbro, diabase, diorite and so on. For a long time, there has been no conclusion on the origin of middle-basic dikes and its relationship with gold mineralization. Based on the methods of petrology, petrogeochemistry and genetic mineralogy, this paper attempts to summarize the space-time distribution characteristics of middle basic dike rocks, and to discuss their origin, material source and their relationship with gold mineralization, in order to study the metallogenic model of gold in this area. To further explore the rules of gold mineralization to provide the basis. The results show that the medium-basic dikes in Shandong area are mainly composed of high-potassium calc-alkaline and kaliumite series, which are characterized by the enrichment of large ion lithophile elements and light rare earth elements, and the depletion of high field strength elements and heavy rare earth elements. Most of the dikes belong to the arc igneous environment, which is related to the subduction of the Pacific plate to the North China plate. The diagenetic model can be understood as the partial melting of the lithospheric mantle enriched with incompatible elements. Then the melt rises and emplacement, and after mixed with the crust, it is located in the shallow part of the crust. The results of further study also show that there are differences in rock characteristics among different regions of the region, and the rock index and REE characteristics show that the differentiation degree of magma in Qixia, Yishui area is weak, and the alkalinity is low, the characteristics of rock index and rare earth elements show that the middle basic dike rocks have weak differentiation degree and low basicity in Qixia, Yishui area. In other areas, the degree of differentiation is slightly stronger and the alkalinity is slightly higher. The Sr-Nd isotopic characteristics also reveal that the pyroxene of Zouping and the diorite of Laiwu originated from the EM 鈪，
本文编号：2424545
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