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491.
矿床产于火山岩系中,围岩蚀变发育,其硅化、绢云母化、菱锰矿化、冰长石化与矿化有关。成矿流体组分为Na+、K+、Ca2+、F-、Cl-。流体包裹体氢氧同位素测定,成矿热液以岩浆水为主.有大气降水加入形成混合流体,并以低盐度为特征。成矿温度205~236℃,为中低温矿床,成矿压力3.80×105~5.00×107Pa。矿床成因类型可确定为浅成中低温火山热液贵金属矿床。 相似文献
492.
ZHANG Yaoyao CHU Fengyou LI Zhenggang DONG Yanhui LONG Jiangping WANG Hao ZHU Jihao LIU Jiqiang 《《地质学报》英文版》2020,94(1):126-140
The Okinawa Trough is characterized by enrichment of Ag in hydrothermal precipitates; however, the distribution of this enrichment remains poorly constrained. This study presents the results of a field-emission scanning electron microscopy and electron-microprobe analysis based mineralogical and geochemical investigation of the spatial distribution of Ag within Ag-rich sulfide samples from the Okinawa Trough. The tetrahedrite, covellite, and galena in these samples contain high concentrations of Ag(average values of 1.60, 0.78, and 0.23 wt%, respectively) and also various Ag sulfosalts. Examination of the Ag budget of these samples indicates that most of the Ag is hosted by tetrahedrite followed by galena. The Ag within tetrahedrite is incorporated by substitution into the Cu site, whereas galena becomes Ag-enriched by the coupled incorporation of monovalent Ag, Tl, and Cu, and trivalent Sb and Bi into Pb lattice sites. Tetrahedrite and galena containing higher concentrations of Sb favor increased Ag substitution. Four sets of Ag host minerals are identified with distinct ore formation temperatures. Tetrahedrite and galena concentrate the majority of Ag at medium temperatures(150–300°C). Other Ag host minerals concentrate only minor or trace amounts of Ag, including massive sphalerite, chalcopyrite, and pyrite at high temperatures(300°C), colloform pyrite and sphalerite at low temperatures(150°C), and Ag-sulfosalts at even lower temperatures(100°C). 相似文献
493.
银洞沟银多金属矿是一个典型的碰撞造山带型脉状矿床,产出于北秦岭褶皱带二郎坪地体早古生界二郎坪群(Pz1 er)内,是在二郎坪地体内所取得的重大找矿突破,具大型乃至超大型规模.金属矿物以独立矿物(银金、辉银矿)、硫化物形式赋存,银、铅、锌共生关系密切.通过对矿床地质、铅同位素、碳氢氧同位素、稀土元素和流体包裹体地球化学特... 相似文献
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富营养化湖泊中的鲢、鳙控藻问题:争议与共识 总被引:3,自引:0,他引:3
我国湖泊富营养化的治理方向正在从污染控制走向湖泊的生态修复与管理,因此以鲢、鳙为主导的非经典生物操纵技术受到了关注和重视.然而,鲢、鳙控藻的研究有成败两方面的案例,导致人们对能否利用鲢、鳙控制富营养化湖泊中藻类的过度增长的看法仍有分歧.本文通过对国内大量相关研究案例进行剖析,指出了导致鲢、鳙控藻试验产生不同结果的可能原因,提出了对鲢、鳙控藻研究可以得到的共识,以便为我国湖泊环境的管理和保护提供借鉴. 相似文献
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辽西地区金银矿成矿模式探讨 总被引:1,自引:0,他引:1
通过对金矿的成矿时代,温度及物质来源的分析研究,认为辽西地区金矿床均属广义的岩浆热液矿床。论述金矿成矿作用及基 化过程,研究和建立金矿床区域成矿模式。 相似文献
500.
The Haenam–Jindo area, located on the southwestern margin of the Korean Peninsula, was the site of vigorous volcanic activity during the Late Cretaceous and Early Tertiary periods. Large parts of the area record strong hydrothermal alteration, and there exist many clay–alunite and gold–silver deposits. We undertook potassium–argon (K–Ar) age dating of five mineral samples (including adularia, sericite and alunite) from the Eunsan, Moisan and Gasado epithermal gold–silver deposits in this area. The purities of the samples were confirmed by X‐ray diffraction analysis. The K–Ar ages of adularia from the Eunsan deposit and adularia and sericite from the Moisan deposit (related to gold–silver mineralization) are 75.0 ± 1.6, 74.7 ± 1.6 and 75.1 ± 1.6 Ma, respectively. The similarity of these ages, combined with the close proximity and similar geochemical characteristics of the deposits, indicates that the mineralization occurred as part of a single hydrothermal system. The K–Ar ages of alunite at the surface and adularia at depth within the Gasado deposit are 82.2 ± 1.9 and 70.7 ± 1.9 Ma, respectively, revealing that the clay–alunite and gold–silver mineralization formed at different ages. K–Ar age data indicate that the gold–silver mineralization in this area occurred mainly at 75–70 Ma, resulting from hydrothermal activity in the Haenam–Jindo area (82–70 Ma). This is the first time that the mineralization of precious metals in Korea has been identified during this period. 相似文献