發(fā)布時(shí)間：2018-07-22 13:57

【摘要】：甘肅陽(yáng)山金礦床是我國(guó)近幾年發(fā)現(xiàn)的超大型金礦床。本文基于野外觀測(cè)和前人總結(jié),對(duì)陽(yáng)山金礦床進(jìn)行系統(tǒng)研究,確定成礦階段以及成礦時(shí)代,并且進(jìn)行了流體包裹體顯微測(cè)溫、成分分析和H-O同位素研究,對(duì)成礦流體來(lái)源與演化和礦床成因進(jìn)行探討。1,根據(jù)野外工作成果,在總結(jié)前人工作的基礎(chǔ)上,提出陽(yáng)山金礦床存在多期次成礦的觀點(diǎn),并對(duì)成礦期次進(jìn)行了劃分。陽(yáng)山金礦床成礦作用可分為沉積成巖期、變質(zhì)熱液期、巖漿熱液期和表生氧化期,其中不同熱液期又可分為不同階段。變質(zhì)熱液期又可分為石英-絹云母-黃鐵礦階段、黃鐵礦-毒砂-石英階段、毒砂-黃鐵礦-石英階段以及石英-碳酸鹽階段;巖漿熱液期又可分為石英-黃鐵礦階段、自然金-輝銻礦-石英階段、石英-碳酸鹽階段。2,陽(yáng)山金礦床兩期成礦流體總體上表現(xiàn)為中低溫(110℃~380℃)、低鹽度(8wt.%NaCl eqv)、低密度。變質(zhì)熱液期成礦流體的均一溫度主要集中220℃~320℃,鹽度主要集中在2.0~6.6wt.%NaCl eqv,富含CO2。巖漿熱液期成礦流體均一溫度主要集中在120℃~220℃,鹽度主要集中在2.0~6.0wt.%NaCl eqv,富含有機(jī)氣體。3,成礦流體的H-O同位素結(jié)果顯示成礦流體來(lái)源特征。綜合以上流體包裹體特征,早期變質(zhì)熱液期成礦流體來(lái)自富礦下地殼地層的變質(zhì)流體,主要以變質(zhì)熱液為主。晚期巖漿熱期成礦流體可能為巖漿熱液和大氣降水的混合流體。4,綜合流體包裹體和H-O同位素研究,我們認(rèn)為在變質(zhì)熱液期,流體由于壓力降低,發(fā)生沸騰導(dǎo)致CO2等大量氣體逸出,其溫度降低,鹽度增高,導(dǎo)致Au以絡(luò)合物的形式被吸附到黃鐵礦表面,Au與黃鐵礦毒砂一起沉淀。巖漿熱液期有機(jī)氣體的加入和水巖反應(yīng),破壞了Au硫氫絡(luò)合物的平衡,導(dǎo)致大量Au硫氫絡(luò)合物形式沉淀。
[Abstract]:Yangshan gold deposit is a super-large gold deposit discovered in China in recent years. Based on the field observation and the previous summary, this paper makes a systematic study on the Yangshan gold deposit, determines the metallogenic stage and the metallogenic age, and carries out the fluid inclusion microthermometry, composition analysis and H-O isotopic study. The origin and evolution of ore-forming fluids and the genesis of ore deposits are discussed. Based on the results of field work and on the basis of summing up the previous work, the author puts forward the viewpoint that there are many times of mineralization in Yangshan gold deposit, and divides the times of mineralization. The mineralization of Yangshan gold deposit can be divided into sedimentary diagenesis metamorphic hydrothermal magmatic hydrothermal and supergene oxidation. The metamorphic hydrothermal period can be divided into quartz sericite pyrite stage pyrite arsenopyrite quartz stage and quartz carbonate stage and magmatic hydrothermal stage can be divided into quartz pyrite stage. The ore-forming fluids of the natural gold-stibnite-quartz stage, quartz-carbonate stage and Yangshan gold deposit generally show moderate and low temperature (110 鈩，

本文編號(hào)：2137682