虹螺山-五指山一带成矿岩体地球化学特征及成矿意义
Geochemistry Characteristics and Ore-Forming Significance of Mineralization Rock in Hongluoshan-Wuzhishan Region
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摘要: 虹螺山-五指山地区是辽西钼、铅、锌、金多金属重要的成矿带,前人研究成果表明,其成矿作用与该区广泛分布的花岗质岩石成因关系密切。笔者通过对野外成矿岩体的考察、采样和分析,对其岩石地球化学特征及成因进行分析,并探讨其成矿地质意义。测试分析结果表明,区内成矿岩体的岩石类型主要为钾长花岗岩和二长花岗岩;岩体的SiO2含量为72.86%~76.56%,A/CNK为1.39~1.73,Alk为7.07~9.09,属强过铝质钙碱性岩石;岩石微量元素Rb/Sr值为0.63~2.31,平均值为1.17,反映岩体结晶分异程度较高;据Rb-Hf-Ta、Rb-Y+Nb、Rb-Yb+Ta 等投影图解结果,属火山弧花岗岩,岩石成因类型主要为Ⅰ(同熔)型,熔融温度较高;成岩过程与幔源岩浆的底侵作用有关,热的幔源不仅为地壳的部分熔融提供了热量,且与熔融的壳源岩浆发生了混合等地质作用,随着岩浆分异演化到一定的阶段,形成一定的矿种和矿床(矿化)类型组合,相应形成一个Pb-Zn-Ag、Pb-Zn-Mo、Mo-Pb-Zn-Cu成矿系列。Abstract: The Hongluoshan-Wuzhishan region is important molybdenum, lead and zinc polymetallic metallogenic belt in west Liaoning. Results of previous studies show that the mineralization in this area has a close genetic relationship with widespread granitic rocks. Based on field investigation and indoor testing analysis methods, the origin, geochemical characteristics and its geological significance of these granites have been studied in this paper. The result show that these granites belong to K-feldspar granite andmonzonitic granite. Their w (SiO2) content are 72.86%~76.56%, A/CNK ratios are 1.39~1.73, Alk values are 7.07~9.09, and the rock chemical parameters indicate that these granites are strongly peraluminous calc-alkaline rocks. Their Rb/Sr ratios are 0.63~2.31, with an average of 1.17, reflecting a higher degree of rock crystal fractionation. According to the results of Rb-Hf-Ta, Rb-Y+Nb and Rb-Yb+Ta diagrams, it's thought that these granites belongs to volcanic arc type, with genetic type of I (syntexis) type, having higher melting temperature. The diagenetic processes of these granites are related to the underplating of mantle-derived magma. The hot mantle-derived magma not only provides the thermal mass for the partial melting of crust, but also occurs the mixing with the molten crustal magma. With the evolution of magmatic differentiation, some minerals and ore deposit(mineralization) combination have been formed, and then developing Pb-Zn-Ag, Pb-Zn-Mo and Mo-Pb-Zn-Cu metallogenic series.