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  本文關(guān)鍵詞： 西秦嶺 小溝里金礦床 花崗巖 地球化學 控礦因素 成礦模式　出處：《長安大學》2015年碩士論文　論文類型：學位論文

【摘要】：西秦嶺地區(qū)是我國重要的金礦產(chǎn)區(qū)之一,該區(qū)金礦床類型眾多,前人對多數(shù)礦床進行綜合研究,小溝里金礦床作為西秦嶺較獨特的石英脈型金礦,但對此研究較薄弱。本文以小溝里金礦床為研究對象,對該礦床地質(zhì)特征和成礦規(guī)律進行詳細研究,為西秦嶺地區(qū)金礦成礦規(guī)律的總結(jié)提供了原始資料和數(shù)據(jù),同時為本區(qū)找礦工作指明了方向。本文通過野外實地考察,對研究區(qū)礦床野外地質(zhì)特征進行了詳細的研究,厘清了礦體的產(chǎn)出特征以及與地層、構(gòu)造、巖漿巖的空間關(guān)系;通過室內(nèi)光薄片鑒定,成礦有關(guān)花崗巖主量、微量元素化學分析測試,成礦流體包裹體研究,穩(wěn)定同位素分析,花崗斑巖鋯石SHRIMP U-Pb定年測試,成礦年齡研究等工作,對區(qū)域礦床地質(zhì)特征及成礦規(guī)律進行了詳細研究,取得了以下幾點新的認識:1、花崗巖類巖石地球化學測試結(jié)果顯示:花崗斑巖為酸性、富堿富鈉,鈣堿性過鋁質(zhì)I型花崗;稀土元素配分型式為輕稀土富集型,重稀土虧損型,配分曲線右傾,為弱負銪異常,與I型花崗巖相似。閃長玢巖為中性巖石,偏酸性、富堿富鈉,高鉀鈣堿性弱過鋁質(zhì)I型花崗巖;稀土元素配分型式為輕稀土富集型,重稀土虧損型,配分曲線平緩右傾,弱負銪異常,與I型花崗巖相似。2、同位素年齡測試結(jié)果顯示,小溝里花崗斑巖成巖年齡為217.4Ma,閃長玢巖成巖年齡在201-212Ma之間,兩種巖體均形成與造山作用后期的構(gòu)造體制轉(zhuǎn)換階段。3、通過鋯石飽和溫度來估算巖漿結(jié)晶溫度,花崗斑巖的巖漿形成溫度比閃長玢巖的巖漿形成溫度低,可能是花崗斑巖巖漿源區(qū)比閃長玢巖巖漿源區(qū)淺。4、小溝里金礦床產(chǎn)于西秦嶺西成礦田中部,礦體產(chǎn)于花崗斑巖巖脈、閃長玢巖巖脈上、下盤處及其附近泥盆系地層中,受近東西向的韌性剪切帶及與之相配套的張、剪性裂隙的控制。小溝里金礦床單個礦體由脈狀、網(wǎng)脈狀、樹枝狀含金石英脈組成,礦體整體走向近東西,沿韌性剪切帶呈帶狀展布。5、小溝里金礦床礦石類型有石英脈型礦石和蝕變巖型礦石。金主要以獨立礦物存在,有少量銀金礦,主要載金礦物為石英、鈉長石、方解石、白云石等碳酸鹽礦物。金銀礦物主要嵌布與石英粒間、石英與黃鐵礦粒間、石英與鐵白云石粒間、石英細脈的邊部以及由細脈派生的微脈中及其交匯部位。6、礦床H、O、S、Pb穩(wěn)定同位素地球化學測試顯示:成礦流體具有巖漿水、變質(zhì)水、大氣降水多源混合流體的特點,以巖漿水為主;成礦物質(zhì)具有深源的特點。7、礦床成礦年齡為197.5Ma,略晚于閃長玢巖的成巖年齡;礦石的稀土、微量元素分析結(jié)果和元素球粒隕石(原始地幔)標準化配分模式圖與閃長玢巖具有相同的稀土、微量元素范圍和配分模式。結(jié)合礦床地質(zhì)及礦石結(jié)構(gòu)構(gòu)造特征,小溝里金礦床的形成與巖漿活動有關(guān),金礦化與閃長玢巖關(guān)系尤為密切,因而確定小溝里金礦床為與閃長玢巖巖漿熱液有關(guān)的巖漿熱液型金礦床。
[Abstract]:The West Qinling area is one of the most important gold-producing areas in China. There are many types of gold deposits in this area. Many of the gold deposits have been comprehensively studied. The Xiaogouli gold deposit is a relatively unique quartz vein type gold deposit in the West Qinling Mountains. In this paper, the geological characteristics and metallogenic regularity of the Xiaogouli gold deposit are studied in detail, which provides the original data and data for the summary of the metallogenic regularity of gold deposits in the West Qinling region. This paper makes a detailed study on the field geological characteristics of ore deposits in the study area, and clarifies the characteristics of ore bodies and strata and structures. Spatial relationship of magmatic rock; Through the laboratory light thin section identification, the ore-forming related granite main quantity, the trace element chemical analysis test, the ore-forming fluid inclusion research, the stable isotope analysis. Based on the SHRIMP U-Pb dating test and metallogenic age study of granitic porphyry, the geological characteristics and metallogenic regularity of regional deposits have been studied in detail, and some new understandings have been obtained as follows: 1. The geochemical tests of granitic rocks show that the granitic porphyry is acidic, alkali rich and sodium rich, and calc-alkaline peraluminous type I granitic; The REE distribution pattern is light rare earth enrichment type, heavy rare earth deficiency type, right deviation of partition curve, weak negative europium anomaly, similar to I-type granite. Diorite porphyrite is neutral rock, slightly acidic, rich in alkali and sodium. High potassium calcium alkaline weak peraluminous I type granite; The REE distribution pattern is light rare earth enrichment type, heavy rare earth deficiency type, the partition curve is gentle right dip, weak negative europium anomaly, similar to I-type granite. The isotopic age test results show. The diagenetic age of Xiaogouli granitic porphyry is 217.4 Ma.The diagenetic age of diorite-porphyrite is between 201-212Ma. The magmatic crystallization temperature is estimated by zircon saturation temperature. The magmatic formation temperature of granitic porphyry is lower than that of diorite porphyrite, which may be the shallow .4 of granitic porphyry magmatic source region than that of diorite-porphyrite magma source. The Xiaogouli gold deposit occurs in the central part of the Lingxi metallogenic field in the Western Qin Dynasty, and the orebody occurs in the granitic porphyry vein, diorite porphyrite vein, and Devonian strata at the lower part of the ore deposit and its adjacent Devonian strata. Controlled by near east-west ductile shear zone and associated tensioning and shearing fissures, the sheet orebody of Xiaogouli gold deposit is composed of vein, net vein, dendritic gold-bearing quartz vein, and the whole orebody is close to east and west. Along the ductile shear zone, the ore types of the Xiaogouli gold deposit are quartz vein type ore and altered rock type ore. Albite, calcite, dolomite and other carbonate minerals. Gold and silver minerals are mainly intercalated with quartz grains, quartz and pyrite grains, quartz and iron dolomite grains. At the edge of quartz vein and in the microvein derived from the vein and its intersection. 6, the stable isotopic geochemistry test of Hau Ou Szong Pb deposit shows that the ore-forming fluid has magmatic water and metamorphic water, and the ore-forming fluid is characterized by magmatic water and metamorphic water. The characteristics of multi-source mixed fluid of atmospheric precipitation are dominated by magmatic water; The ore-forming material has the characteristics of deep source. The ore-forming age of the deposit is 197.5Ma. it is a little later than the diagenetic age of diorite-porphyrite. The REE and trace element analysis results of ore and the standardized distribution pattern of elemental chondrites (primitive mantle) have the same REE as diorite-porphyrite. According to the geological and structural characteristics of the deposit, the formation of the Xiaogouli gold deposit is related to magmatic activity, especially to diorite porphyrite. Therefore, the Xiaogouli gold deposit is a magmatic hydrothermal gold deposit related to the magmatic hydrothermal solution of diorite porphyrite.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P618.51

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