黑龙江省铁力鹿鸣钼矿床地质—地球化学特征及其成因

发布时间：2018-03-23 19:10

  本文选题：伊春-延寿成矿带　切入点：铁力鹿鸣　出处：《吉林大学》2015年硕士论文

【摘要】：鹿鸣钼矿床地处伊春-延寿成矿带中南部，该成矿带位于松嫩地块的东部，处于松嫩地块与佳木斯地块的拼合带上，本矿床作为成矿带内近年发现的特大型斑岩型钼矿床，备受关注。本文通过系统研究矿床地质 地球特征、成岩成矿年龄、成矿物理化学条件，探讨成矿物质来源和成矿动力学背景，揭示矿床成因。 矿体发育在花岗岩体内，赋矿岩体是蚀变二长花岗岩、花岗斑岩，金属矿物呈细脉浸染状、浸染状分布于其中，围岩蚀变具有典型斑岩矿床的分带特征。岩石地球化学特征表明，二长花岗岩和花岗斑岩属于高钾钙碱性I型花岗岩，岩浆源区发生了壳幔混染作用；岩体具有C型埃达克岩的地球化学属性，暗示岩浆来源于加厚的下地壳部分熔融。赋矿岩体的Sr同位素初始比值87Sr/86Sr为0.708946~0.711256，介于幔源岩浆和壳源岩浆之间，显示其岩浆源区具有壳幔混染的特点；金属矿物辉钼矿S同位素的δ34S值介于5.37‰~6.71‰之间，接近地幔岩浆值，表明金属矿物的来源可能是幔源岩浆。 与成矿有关的石英脉中流体包裹体多为气液两相包裹体，均一温度范围主要集中在280~320℃之间；计算出的盐度范围介于2.06~22.45wt%NaCl之间，压力在（123.34~418.52）×105Pa范围内，成矿深度大约在0.41~1.4km，说明鹿鸣钼矿床形成于浅部环境的中高温热液型钼矿床。采用LA-ICP-MS技术测得二长花岗岩的两组锆石206Pb/238U年龄分别为194.8±0.7Ma和176.2±2.1Ma，表明岩体形成于早侏罗世。结合区域地质背景，认为在燕山早期，由于受到蒙古-鄂霍茨克构造体系和环太平洋构造体系两者双向俯冲的影响，，佳木斯地块与松嫩地块发生拼合，深部幔源玄武质岩浆发生底侵，形成了区内新生的加厚下地壳。新生的加厚下地壳部分熔融形成了埃达克质岩浆，完成了成矿元素钼的初次富集。由于太平洋板块的持续俯冲，埃达克质岩浆沿着构造裂隙上侵，后期的热液活动最终形成了鹿鸣斑岩型钼矿床。
[Abstract]:The Luming molybdenum deposit is located in the central and southern part of the Yichun-Yanshou metallogenic belt, which is located in the eastern part of the Songnen block and the joint zone between the Songnen block and the Jiamusi block. The deposit is regarded as an extra large porphyry type molybdenum deposit discovered in the metallogenic belt in recent years. In this paper, the geological characteristics of ore deposits, the age of diagenetic mineralization, the physicochemical conditions of mineralization, the source of ore-forming materials and the background of metallogenic dynamics are studied systematically, and the genesis of the deposits is revealed. The orebody is developed in the granite body, the ore-bearing rock body is altered monzomorphic granite, granitic porphyry, and the metal minerals are vein-impregnated and disseminated in them. The rock alteration has the zonation characteristics of typical porphyry deposits. The petrogeochemical characteristics indicate that the monzonitic granite and granitic porphyry belong to high-potassium calc-alkaline I-type granite, and the crust and mantle are mixed in the magma source area. The geochemical properties of the C type adakite indicate that the magma originated from the thickening partial melting of the lower crust. The initial Sr isotope ratio 87Sr/86Sr of the ore-hosting body is 0.708946 / 0.711256, which is between mantle magma and crust-derived magma. The 未 34S value of S isotope of molybdenum is between 5.37 鈥

本文编号：1654790