本文選題：羅山金銀礦床 + 侵入巖　； 參考：《中國地質大學(北京)》2015年碩士論文

【摘要】：浙中東陽地區(qū)羅山金銀礦床位于江紹斷裂帶和麗水-余姚斷裂帶之間、陳蔡-遂昌隆起帶北東側,次級構造芙蓉山破火山口的南東側。論文在總結前人工作基礎上,對羅山金銀礦床的礦床地質特征、成礦流體、巖石地球化學、成礦年代學等方面進行了研究,并探討了羅山金銀礦床的成因類型,建立了成礦模式。礦床賦存在新元古界基底陳蔡群變質巖及混合巖中,主要受NE-NEE向構造裂隙控制;礦體主要呈脈狀產出,傾向呈SE、SSE,傾角在60-80°;主要礦石類型為石英脈型,發(fā)育低溫蝕變類型,如硅化、絹云母化和碳酸鹽化等。礦區(qū)脈巖廣布,與礦床空間和成因皆有緊密聯(lián)系,礦區(qū)中酸性侵入巖為過鋁質高鉀鈣堿質系列巖石,稀土配分曲線上,輕稀土富集,負Eu異常較明顯,微量元素蛛網(wǎng)圖顯示“TNT”異常,表現(xiàn)為俯沖帶形成的島弧型火山巖特征,侵入巖為熱液成礦提供了成礦物質和熱源。根據(jù)野外觀察可以將主成礦期劃分三個成礦階段:黃鐵礦-石英階段;石英-多金屬硫化物階段;石英-碳酸鹽階段。石英-多金屬硫化物階段為礦床主成礦階段。礦石石英流體包裹體類型以富液相包裹體為主,缺乏含CO2和含子晶包裹體,均一溫度集中在140~220℃,流體鹽度為0.70~5.26%(Na Cleq),密度為0.738~0.955g/cm3,成礦壓力為62.58~110.05 bar,成礦深度為0.23~0.53km,流體性質跟淺成低溫熱液型相似,為低溫低鹽度低密度流體,成礦流體以古大氣降水為主;礦石鉛同位素在208Pb/204Pb-206Pb/204Pb圖上主要表現(xiàn)為造山帶(島弧)殼幔混合鉛,并結合前人資料,可以得出成礦物質主要來自基底變質巖及混合巖的結論;硫同位素特征顯示成礦物質為深源(下地殼或上地幔)。對礦區(qū)侵入巖做了系統(tǒng)的LA-ICP-MS U-Pb同位素年齡測定:輝綠玢巖的成巖年齡為129~130Ma,花崗斑巖的成巖年齡為154.9±2.9Ma,石英斑巖的成巖年齡為131.2±3.3Ma,混合巖年齡為230.1±2.4Ma,根據(jù)脈巖與礦體的空間關系和成因聯(lián)系,推測礦床成礦時代為:129~230Ma。礦床總體表現(xiàn)為淺成低溫熱液金銀礦床。
[Abstract]:The Luoshan gold and silver deposit in Dongyang area of central Zhejiang is located between Jiangshao fault zone and Lishui-Yuyao fault zone east of Chen Cai-Suichang uplift belt and south of the crater of secondary structure Furongshan crater. On the basis of summarizing the previous work, this paper studies the geological characteristics, ore-forming fluid, petrogeochemistry, metallogenic chronology of the Luoshan gold and silver deposit, and discusses the genetic types of the Luoshan gold and silver deposit. A metallogenic model was established. The deposit occurs in the metamorphic rocks and migmatites of the Chencai Group in the Neoproterozoic basement, which is mainly controlled by the NE-NEE trending structural fissures, the orebody is mainly vein-like, tends to be SESSE with a dip angle of 60-80 擄, and the main ore type is quartz vein type, which develops low temperature alteration type. For example, silicification, sericite and carbonization. Dikes are widely distributed in the ore area and are closely related to the space and genesis of the deposit. The intermediate-acid intrusive rocks in the ore area are peraluminous, high-potassium, calc-alkali series rocks. On the rare earth distribution curve, the REE is enriched with LREE, and the negative EU anomaly is obvious. The trace element cobweb shows "TNT" anomaly, which is characterized by island arc volcanic rocks formed in subduction zone, and intrusive rocks provide ore-forming material and heat source for hydrothermal mineralization. According to field observation, the main metallogenic stage can be divided into three stages: pyrite-quartz stage, quartz-polymetallic sulfide stage, quartz-carbonate stage. The quartz-polymetallic sulfide stage is the main metallogenic stage of the deposit. The types of fluid inclusions in quartz ores are mainly rich liquid inclusions, lacking of CO2 and subcrystalline inclusions, and the homogenization temperature is concentrated at 140 ~ 220 鈩，

本文編號：1895249