本文選題：礦床成因　切入點：區(qū)域找礦標志　出處：《中國地質(zhì)大學(北京)》2017年博士論文　論文類型：學位論文

【摘要】：云南保山西邑鉛鋅礦床位于西藏-三江造山系保山地塊內(nèi),鉛鋅儲量達1.2Mt,為一大型鉛鋅礦床。近年來,前人主要對該礦床的地質(zhì)特征進行了初步研究,在礦床地球化學特征、成礦流體性質(zhì)和來源、成礦物質(zhì)來源和成礦規(guī)律等方面的研究薄弱,礦床成因存在爭議,在一定程度上制約了礦區(qū)和外圍的進一步找礦。本文系統(tǒng)研究了西邑鉛鋅礦床的地質(zhì)特征、賦礦巖石地球化學、成礦流體地球化學、同位素地球化學等,厘定了礦床成因類型,提出了成礦模式。并和區(qū)域上典型鉛鋅礦床進行了對比研究,總結(jié)了區(qū)域礦床的控礦因素,指明了區(qū)域找礦標志。礦床分為董家寨、趙寨和魯圖3個礦段,礦體賦存在泥盆系向陽寺組、何元寨組和下石炭統(tǒng)香山組灰?guī)r中,受北東向構(gòu)造控制,呈似層狀、脈狀和透鏡狀產(chǎn)出。礦石中金屬礦物主要為方鉛礦和閃鋅礦,含少量黃鐵礦,偶見白鐵礦、黃銅礦和毒砂,非金屬礦物主要為方解石,含少量重晶石,偶見石英。成礦過程分為I閃鋅礦+方鉛礦+方解石、II方鉛礦+毒砂+方解石±閃鋅礦以及III方解石+黃鐵礦±重晶石±石英3個熱液成礦階段。流體包裹體和同位素研究表明,成礦流體為低溫(100~200℃)、中等鹽度(8~20wt%NaCleq)、中等密度(1.0~1.1g/cm3)的H2O-NaCl體系,含有少量CH4,流體來源于盆地鹵水。成礦階段方解石δ13CPDB值變化較小(5.2‰~3.2‰),而δ18OSMOW值變化范圍較大(12.5‰~20.0‰),表明成礦流體中碳主要來源于海相碳酸巖的溶解。成礦階段硫化物的δ34S值集中(0~3‰),重晶石的δ34S值為5~14‰,礦床中硫主要來自地層中的硫酸鹽,沉積成巖時期細菌還原作用導致了硫同位素的分餾。鉛同位素研究表明,成礦階段中硫化物與圍巖泥盆系何元寨組灰?guī)r中黃鐵礦的鉛同位素特征相似,具有上地殼來源,表明鉛來源于區(qū)域上的地層。綜合研究認為,西邑鉛鋅礦床是產(chǎn)在碳酸鹽巖地層中受構(gòu)造控制的盆地熱鹵水成因的后生熱液礦床,在大地構(gòu)造背景、礦床地質(zhì)特征、礦床地球化學特征、成礦流體、成礦物質(zhì)來源等方面類似于MVT鉛鋅礦床,應為MVT鉛鋅礦床。在此基礎上,建立了礦床的成因模型,并與區(qū)域典型礦床對比研究,總結(jié)了區(qū)域礦床的控礦因素,指明了區(qū)域找礦標志。
[Abstract]:The Xiyi Pb-Zn deposit in Baoshan, Yunnan Province, is located in the Baoshan block of Xizang-Sanjiang orogenic system, with a Pb-Zn reserves of 1.2 Mt. It is a large Pb-Zn deposit. In recent years, the geological characteristics of the deposit have been preliminarily studied, and the geochemical characteristics of the deposit have been studied. The study on the nature and source of ore-forming fluid, the source of ore-forming material and metallogenic regularity is weak, and the origin of ore deposit is controversial. In this paper, the geological characteristics, ore-hosting rock geochemistry, ore-forming fluid geochemistry, isotopic geochemistry of the Xiyi lead-zinc deposit are systematically studied, and the genetic types of the deposits are determined. A metallogenic model is put forward, and a comparative study is made with typical regional lead-zinc deposits. The ore-controlling factors of regional deposits are summarized, and the regional prospecting indicators are pointed out. The deposits are divided into three sections: Dongjiazhai, Zhaozhai and Lutu. The orebodies occur in the limestone of Xiangyangsi formation, Heyuanzhai formation and Xiangshan formation of Lower Carboniferous in Devonian system, controlled by the structure of NNE, and are stratiform, vein-like and lenticular. The main metallic minerals in the ore are galena and sphalerite, containing a small amount of pyrite. Occasionally, there are bauxite, chalcopyrite and arsenopyrite. The non-metallic minerals are mainly calcite and contain a small amount of barite. The metallogenic process is divided into three hydrothermal metallogenic stages: I sphalerite galena calcite II galena arsenopyrite + sphalerite and III calcite pyrite 鹵barite 鹵quartz. Isotopic studies show that. The ore-forming fluid is a H2O-NaCl system with a low temperature of 100 ~ 100 鈩，

本文編號：1645585