本文選題：成礦流體 + 成礦物質(zhì)來源　； 參考：《中國地質(zhì)大學(北京)》2015年碩士論文

【摘要】：中秦嶺弧前盆地系內(nèi)的山陽-柞水礦集區(qū)內(nèi)經(jīng)歷了古生代俯沖-增生造山作用和中生代碰撞造山作用,構(gòu)造復雜,巖漿活動強烈,成礦地質(zhì)條件優(yōu)越。在該礦集區(qū)內(nèi)存在一系列大中型金礦床,其中龍頭溝金礦是區(qū)內(nèi)規(guī)模最大的金礦床。本文選取龍頭溝金礦作為研究對象,結(jié)合野外地質(zhì)觀察和室內(nèi)研究工作,通過顯微鏡下觀察,劃分出不同成礦期次,并利用電子探針對不同階段、不同種類的金屬礦物進行成分分析,同時對流體包裹體進行測溫并估算成礦流體的物理化學條件,并對石英和方解石進行C-H-O同位素及不同成礦階段硫化物S同位素分析,并結(jié)合區(qū)域內(nèi)構(gòu)造演化特征,對該礦床的成因及其與該區(qū)地球動力學背景之間的聯(lián)系進行了研究,取得如下主要認識:(1)礦床賦存在區(qū)內(nèi)大楓溝組砂巖中,控礦構(gòu)造為近東西向逆斷層,礦體主要沿破碎蝕變帶分布,礦化類型主要為破碎蝕變巖型,少量是石英脈型;主要載金礦物為黃鐵礦,其次為黝銅礦;其成礦階段可分為三個礦化階段:石英-黃鐵礦階段、石英-金-多金屬硫化物階段、石英-方解石階段;(2)通過對不同礦化階段流體包裹體的顯微測溫工作,可知石英-黃鐵礦階段形成于160-200℃,成礦鹽度為0.18-1wt%Na Cl;石英-金-多金屬硫化物階段形成于200-260℃,成礦鹽度為1.5-4wt%Na Cl;石英-方解石階段形成于120-180℃,成礦鹽度為0.5-2wt%Na Cl。通過上述對比可以發(fā)現(xiàn),從礦化的早階段到晚階段,成礦流體的溫度逐漸降低,鹽度逐漸降低。同時通過流體的顯微測溫,估算出礦床的成礦壓力為140-200MPa,形成深度6.3-15.5km。(3)S同位素特征表明,龍頭溝金礦床中硫來源為深部巖漿,成礦與幔源巖漿熱液關(guān)系密切;C-O同位素特征則表明該礦床碳同位素來源屬于地幔且受到海相碳酸鹽巖地層的混染,說明成礦流體來自地幔且受到地層的混染;H-O同位素的特征則說明本區(qū)水的來源主要為大氣降水,并有微弱的向巖漿水靠近的趨勢;(4)綜合區(qū)域資料并結(jié)合龍頭溝金礦地質(zhì)特征,在287.8±2.6Ma形成了山陽-鳳鎮(zhèn)大斷裂及礦區(qū)褶皺,在此應力條件下,200.9±1.9Ma在褶皺的基礎上形成切割其軸部的逆沖斷層及其反沖斷層(容礦構(gòu)造),并在幔源巖漿的活動形成了龍頭溝金礦床;(5)通過與世界典型造山型金礦各項特征的對比,可知其成礦特征在構(gòu)造背景、賦礦地質(zhì)體、控礦構(gòu)造性質(zhì)、蝕變礦物組合、礦石類型、主成礦溫度、壓力、鹽度等方面有許多相似之處,屬于造山型金礦。
[Abstract]:The Shanyang-tussah Ore concentration area in the Middle Qinling forearc basin has undergone the Paleozoic subduction-accretive orogeny and Mesozoic collision orogeny with complex structure strong magmatic activity and superior metallogenic geological conditions. There are a series of large and medium gold deposits in this area, among which the Longtougou gold deposit is the largest gold deposit in the area. In this paper, the authors select the Longtougou Gold Mine as the research object, combine the field geological observation and the laboratory research work, through the observation under the microscope, divide the different metallogenic times, and use the electronic exploration to aim at the different stages. The composition of different kinds of metallic minerals is analyzed, and the temperature of fluid inclusions is measured and the physicochemical conditions of ore-forming fluids are estimated. The C-H-O isotopes of quartz and calcite and S isotopes of sulphide in different metallogenic stages are also analyzed. Combined with the characteristics of tectonic evolution in the region, the origin of the deposit and its relationship with the geodynamic background of the area are studied. The main results are as follows: 1) the deposit occurs in the sandstone of the Dafenggou formation in the region. The ore-controlling structure is near east-west reverse fault, the orebody mainly distributes along the broken alteration zone, the mineralization type is mainly broken altered rock type, a few is quartz vein type, the main gold bearing material is pyrite, the next is tetrahedrite. The ore-forming stage can be divided into three stages: quartz-pyrite stage, quartz-gold-polymetallic sulfide stage, quartz-calcite stage, etc. It can be seen that the quartz-pyrite stage was formed at 160-200 鈩，

本文編號：1860179