| 王 伟.塔里木陆块西北缘滴水铜矿成矿流体特征与成矿作用[J].地质与勘探,2018,54(3):441-455 |
| 塔里木陆块西北缘滴水铜矿成矿流体特征与成矿作用 |
| Ore-forming fluid features and mineralization of Dishi copper deposit in northwestern of Tarim block |
| 投稿时间：2017-03-16 修订日期：2017-11-01 |
| DOI：10.12134/j.dzykt.2018.03.001 |
| 中文关键词: 塔里木陆块 滴水 砂岩型铜矿 成矿流体 成矿作用 |
| 英文关键词: Tarim block, Dishui, sandstone copper deposit, ore-forming fluid, mineralization |
| 基金项目:中国地质调查局地质调查项目（编号:DD20160009、12120113043700）联合资助 |
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| 中文摘要: |
| 滴水铜矿是库车盆地新生代砂岩型铜矿的典型代表，多位学者曾对其成因进行研究，但均缺乏详细地球化学证据。本次研究认为该矿床成矿期分为成岩成矿期与改造成矿期，以成岩成矿期为主。本文通过对该矿床两个成矿期流体包裹体显微测温、成分分析及氢、氧、碳、硫同位素的研究，探讨该矿床成矿流体形成演化与成矿作用关系。结果表明，该矿床成岩期成矿流体成分主要为CH4、H2S、H2O，代表还原性流体，具有中低温（82.4℃~181.6℃）、中高压（235.42MPa~454.44MPa）的特点；改造期成矿流体成分主要为H2O、CO2、CH4，代表弱氧化性流体，亦具有中低温（146.2℃~ 268.1℃）、中高压（267.83MPa ~457.64MPa）的特征；成岩成矿期石英的δD=-107.6‰~ -78.3‰、δ18OH2O=-4.50‰~4.06‰，改造成矿期石英的δD=-109.5‰~ -84.9‰、δ18OH2O=-4.26‰~5.14‰，指示该矿床两个成矿期成矿流体主要为大气降水与盆地卤水的混合。该铜矿矿石中辉铜矿δ34S=-31.6‰~ -21.3‰，表明硫主要源自硫酸盐细菌与有机质还原。成矿流体在新近系康村组矿源层中经水岩作用，演化形成含矿热卤水。该矿床碳同位素特征（δ13C值-25.3‰~ -22.4‰）、包裹体成分分析表明含矿热卤水中CH4等有机质应为油田卤水成分。油田卤水中有机质成分在成岩期、改造期均参与了该矿床成矿作用，在滴水铜矿成矿过程中起重要还原作用。本次研究表明，有机质与滴水铜矿成矿作用关系密切，该矿床是油田卤水参与成矿作用的沉积-改造型矿床。 |
| 英文摘要: |
| Dishui copper deposit is a typical representative of Cenozoic sandstone-type copper deposits in the Kuche basin. Many scholars have studied its genesis, but lack of detailed geochemical evidence. According to research findings of this paper the metallogenic period of the deposit is divided into diagenetic metallogenic period and reformation metallogenic period, and the former is the main stage. In this paper, the relationship between the ore-forming fluids evolution and mineralization is discussed by means of microthermometry, composition analysis, hydrogen, oxygen, carbon and sulfur isotopes of fluid inclusions in the two metallogenic stages of the deposit. The results show that the composition of ore-forming fluid in diagenetic period is mainly CH4, H2S and H2O, which represents reductive fluid, and has the characteristics of middle-low temperature (82.4℃~ 181.6℃) and pressure(235.42MPa~ 454.44MPa). While during the reformation period, the composition of ore-forming fluid is mainly H2O, CO2 and CH4, which is a weak oxidizing fluid, it also has the characteristics of middle-low temperature (146.2℃~ 268.1℃) and middle and high pressure (267.83MPa ~ 457.64MPa). In the diagenetic period, δD=-107.6‰ ~ -78.3‰, δ18OH2O=-4.50‰~4.06‰, and in the reformation period, δD=-109.5‰~ -84.9‰、δ18OH2O=-4.26‰~5.14‰, it indicating that the ore-forming fluids in the two metallogenic period are both mainly the mixture of atmospheric precipitation and basin halide. The δ34S of chalcocite varies from -31.6 ‰ to -21.3 ‰ and it indicates that sulfur is mainly derived from sulfate bacteria and organic matter reduction. The ore-forming fluids evolved into ore-bearing hot brine in the ore source-bed of the recent Kangcun Formation by means of water-rock interaction. The carbon isotopic characteristics of the deposit (δ13C=-25.3‰ ~ -22.4‰) and inclusion composition of the deposit indicate that the organic matter such as CH4 in the ore-bearing hot brine should be oilfield brine composition. The organic matter in the oilfield brine participated in the mineralization of Dishui deposit during the diagenesis and reformation period, and played an important role of reduction during the ore forming process. This study shows that organic matter is closely related to the mineralization of Dishui copper deposit, which is a sedimentation-reformation type deposit in which the oilfield brine takes part in the mineralization. |
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