栾川矿集区花岗岩地质地球化学特征及其找矿指示意义

发布时间：2018-07-07 07:08

本文选题：地球化学 + 岩石成因　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：栾川矿集区位于东秦岭Mo多金属成矿带的中部,区内晚中生代形成了众多的Mo-W-Pb-Zn矿床与花岗岩体。在岩体地质学、地球化学、年代学研究的基础上,结合不同Mo矿床,评价栾川矿集区花岗岩体的含矿性特征及其找矿标志。对岩体地质地球化学的研究取得如下成果:(1)区内花岗岩体以二长花岗岩和花岗斑岩为主,具有南部岩体粒度粗,北部岩体粒度细;深部二长花岗岩、浅部花岗斑岩的特征;(2)花岗岩黑云母成分特征表现出高Si,富Mg,低Al以及贫Fe的特征,大部分属镁质黑云母。南泥湖和上房岩体黑云母受到更多后期流体影响;(3)花岗岩体为I型准铝质-弱过铝质高钾钙碱性-钾玄岩系列花岗岩。含矿岩体更加富集轻稀土元素和大离子亲石元素,亏损Ba、P、Ti等高场强元素。南泥湖与上房岩体具有更高的分异程度;(4)鱼库岩体的锆石U-Pb年龄为149.6±2.4 Ma。Hf同位素TDM2为1998-2156Ma,εHf(t)在-16.9~-19.7之间;(5)矿集区晚侏罗世-早白垩世阶段岩浆活动可以分为160-154Ma、150-141Ma和136-130Ma三个阶段。成岩和Mo-W成矿高峰在150-139Ma。老君山岩体形成于早白垩世晚期,无大规模成矿活动。含矿性指的是岩浆岩体所表现的成矿潜力与能力,就是评价是否含矿、含哪种矿以及含矿的规模。对花岗岩体以及相关Mo矿床的研究表明,其含矿性特征及制约因素如下:(1)花岗岩体成矿与否受到源区特征和岩石成因的制约。两类岩体岩浆来源均是以古老地壳的部分熔融为主,并混入地幔物质。但源区组分存在差异,老君山岩体源区地幔组分更多,更加年轻。两类岩体的构造环境和成因也不相同;(2)成矿的规模受岩浆的物理化学状态、岩石的成分特征和岩体的形态的影响。具有更大成矿规模的南泥湖矿田的岩体的氧逸度更高、温度更高、侵位压力更低。其次经历更高程度的演化,更高含量的K、Si、成矿元素和产热元素,有利于形成大规模的矿床。出露面积小,剥蚀程度低的岩体含矿规模更大;(3)伴生的矿种受到围岩的制约。具有钙质矽卡岩化围岩的南泥湖岩体有利于形成W矿床,而具有镁质矽卡岩化围岩的上房沟矿床则不利于W矿化,利于产生磁铁矿体。对比黄背岭岩体与含矿岩体的特征后,认为黄背岭岩体成矿潜力巨大,是栾川矿集区Mo-W成矿远景区。
[Abstract]:Luanchuan ore concentration area is located in the middle of the East Qinling Mo polymetallic metallogenic belt, and many Mo-W-Pb-Zn deposits and granite bodies were formed in the late Mesozoic. Based on the study of geology, geochemistry and geochronology of rock mass, combined with different Mo deposits, the ore-bearing characteristics and prospecting criteria of granites in Luanchuan ore concentration area are evaluated. The results of geological and geochemical study of the rock mass are as follows: (1) the granite body in the area is mainly composed of monzogranite and granitic porphyry, with coarse granularity in the south and fine granularity in the north, and the deep monzomorphic granite, (2) the composition of granite biotite is characterized by high Si, rich mg, low Al and poor Fe, most of which belong to magnesia biotite. The biotite of Nannihu and Shangfang pluton is affected by more late fluid. (3) the granitic body is I type quasi-aluminous-weak peraluminous high potassium calc-alkaline-potakite series granites. The ore-bearing rock bodies are more enriched in light rare earth elements and large ion lithophile elements, and are depleted of high field strength elements such as Baqipi Ti. (4) the zircon U-Pb age of Yuku is 149.6 卤2.4Ma.Hf isotopic TDM2 is 1998-2156Maand 蔚 HF (t) is -16.9 ~ 19.7; (5) magmatic activity of late Jurassic-early Cretaceous stage in the ore-gathering area can be divided into three stages: 160-154Ma-150-141Ma and 136-130Ma. The peak of diagenesis and Mo-W mineralization is 150-139 Ma. The Laojunshan rock body was formed in the late early Cretaceous and there was no large-scale metallogenic activity. Ore-bearing refers to the ore-forming potential and ability of magmatic rock body, which is to evaluate whether ore is contained, what kind of ore is contained and the scale of ore-bearing. The study on granites and related Mo deposits shows that the ore-bearing characteristics and constraints are as follows: (1) the ore-forming of granites is restricted by source characteristics and petrogenesis. The magma of the two types of rock bodies is mainly derived from the partial melting of the ancient crust and mixed with mantle material. However, there are differences in the source regions, and the mantle components of Laojunshan rock body are more and younger. The tectonic environment and genesis of the two types of rock bodies are also different. (2) the scale of mineralization is affected by the physical and chemical state of the magma, the composition characteristics of the rocks and the shape of the rock mass. The ore-forming scale of Nannihu ore field has higher oxygen fugacity, higher temperature and lower emplacement pressure. Secondly, it is advantageous to form large scale deposits by going through a higher degree of evolution, higher content of K ~ (2 +) Si, ore-forming elements and heat-producing elements. The ore-bearing scale of rock mass with small exposed area and low denudation is larger; (3) the associated ore type is restricted by surrounding rock. The Nannihu rock body with calcareous skarn rocks is favorable to the formation of W deposit, while the Shangfanggou deposit with magnesite skarn rock surrounding rock is not conducive to W mineralization and to the generation of magnetite bodies. After comparing the characteristics of Huangbei Ling rock body with ore-bearing rock mass, it is considered that the Huangbei Ling rock body has great metallogenic potential and is the Mo-W metallogenic prospect in Luanchuan ore concentration area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P612;P588.121

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