甘南玛曲大水金矿原生晕特征研究及深部成矿预测

发布时间：2018-05-27 02:37

  本文选题：大水金矿 + 原生晕　； 参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：大水金矿是西秦岭地区一个典型的富赤铁矿的超大型金矿床,该矿床产于三叠系一套碳酸盐岩中,严格受断裂带控制。矿化蚀变主要为硅化、赤(褐)铁矿化和碳酸盐化,硅化和赤铁矿化蚀变越强,矿体越发育。大水金矿与矿区发育的中酸性脉岩具有密切的时-空关系,部分脉岩可直接蚀变矿化为矿体。原生晕法是国内外公认的寻找盲(或隐伏)矿体最有效的方法。为探讨大水金矿深部找矿潜力,本文基于对大水金矿矿床地质特征认识的基础上,从矿区的地球化学背景、矿床元素含量特征和Au2矿体原生晕轴向分带特征等几方面有针对性地对Au2矿体开展了原生晕研究。矿区内Au、Sb、Ag、As、Hg、U等元素背景含量较高,总体来看格尔括合岩体中元素平均含量较灰岩地层元素含量高。地球化学数据为成分数据,为满足数据统计分析要求,需要消除成分数据的“闭合效应(closure effect)”。本文则使用对数比(log-ratio)变换法对地化成分数据进行处理,并对比地化数据变换前后基于主成分法(PCA)分析地化数据的差异,表明成矿元素组合为Au、Ag、As、Sb、Hg、W、Te(Mo、Se)等元素。Au2矿体原生晕浓度分带总体上呈现出前缘晕元素异常发育明显,而尾晕元素浓度异常相对较弱的特点;Au、Ag、Hg、As、Sb、Te、W等元素的内、中、外带异常发育较完整,且具有多浓集中心,表明大水金矿原生晕具有叠加特征。在标高3800m附近前缘晕元素As、Sb异常与W、Ni、Co、V等尾晕指示元素形成前、尾晕叠加或共存,指示上部有矿体剥蚀;而在矿体下部(尾部)又发育Hg、Te、As、Sb等前缘晕元素的内、中带强异常,是深部盲矿体前缘晕叠加的结果。矿体中Au元素的浓集中心有向下浓集的趋势,尤其在标高3500m-3600m间显著。Au2矿体原生晕轴向分带序列呈现“反分带”现象,前缘晕/尾晕比值在3490中段附近仍继续升高,表明深部仍有矿体延伸或盲矿体存在。最后,基于大水金矿的矿床地质和原生晕特征,建立了大水金矿的原生叠加晕模式,并总结了大水金矿的原生晕找矿标志。
[Abstract]:Dashui gold deposit is a typical super-large hematite rich gold deposit in the West Qinling area. It occurs in a set of carbonate rocks of the Triassic and is strictly controlled by the fault zone. The mineralization alteration is mainly silicification, red (brown) iron ore and carbonization. The stronger the silicification and hematite alteration, the more developed the orebody. The Dashui gold deposit has a close time-space system with the intermediate-acid dikes developed in the ore area, and some of the dikes can be directly altered and mineralized into orebodies. Primary halo method is the most effective method to find blind (or concealed) orebodies at home and abroad. In order to discuss the deep prospecting potential of Dashui gold deposit, this paper based on the understanding of the geological characteristics of the Dashui gold deposit, from the geochemical background of the ore area. The primary halo of Au2 orebody was studied in several aspects, such as the element content characteristics of the deposit and the primary halo axial zonation of the Au2 orebody. In the mining area, the background content of elements such as Au-SbSbAg-Ag-As-HgGU is relatively high, and the average content of elements in the Gehuahe rock mass is higher than that in limestone strata as a whole. Geochemical data are component data. In order to meet the requirement of statistical analysis, it is necessary to eliminate the closure effect of composition data. In this paper, the log-ratio transformation method is used to process geochemical composition data, and the differences of geochemistry data before and after geochemistry data transformation based on principal component method (PCA) are compared. The results show that the ore-forming element assemblage is composed of elements such as Au-Ag-As-SbSbSg-HgSG-HgSG-SbTeMo-See). The primary halo concentration zonation of the Au2 orebody shows that the anomaly of the leading halo elements is obvious, while the anomaly of the tail halo element is relatively weak. The anomalies in the middle and outer zones are relatively intact in the inner, middle and outer zones of the elements such as Au-Ag-HgSG-SgSG-SbTeW, and so on. The multiple concentration centers indicate that the primary halo of Dashui gold deposit is superimposed. Before the formation of the leading halo element As-Sb anomaly near 3800m and the tail halo indicator element WNI-CoCoV, the caudal halo superposes or coexists, indicating the denudation of the ore body in the upper part, while in the lower part of the orebody (tail), there is a strong anomaly in the middle zone of the front halo elements, such as Hgn TeAsSb, etc., which are found in the lower part of the orebody (tail). It is the result of the superposition of the front halo of the deep blind orebody. The concentration center of au in the orebody tends to be concentrated downwards, especially in the striped 3500m-3600m. Au2 orebody presents a "reverse zoning" phenomenon in the primary halo axial zonation sequence, and the ratio of front halo to tail halo continues to increase near the middle section of 3490. The results indicate that there are still extended orebodies or blind orebodies in the deep part. Finally, based on the geological and primary halo characteristics of Dashui gold deposit, the primary superimposed halo model of Dashui gold deposit is established, and the primary halo prospecting criteria of Dashui gold deposit are summarized.
【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】：P618.51
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本文编号：1940081