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黄金科学技术 ›› 2018, Vol. 26 ›› Issue (5): 559-569.doi: 10.11872/j.issn.1005-2518.2018.05.559

• •    下一篇

水/岩相互作用对焦家金矿金成色的影响

胡换龙1,2(),范宏瑞1,2()   

  1. 1 中国科学院地质与地球物理研究所矿产资源研究院重点实验室,北京 100029
    2 中国科学院大学地球科学学院,北京 100049
  • 收稿日期:2018-08-16 修回日期:2018-09-28 出版日期:2018-10-20 发布日期:2018-10-31
  • 作者简介:胡换龙(1992-),男,广西桂林人,博士研究生,从事成矿过程水/岩相互作用研究工作。|范宏瑞(1963-),男,安徽巢湖人,研究员,从事成矿流体研究工作。
  • 基金资助:
    国家自然科学基金项目“胶西北巨量金堆积成矿系统时空结构与演化”(41672094)

The Effect of Water/Rock Interaction for the Gold Fineness of Jiaojia Gold Deposit

Huanlong HU1,2(),Hongrui FAN1,2()   

  1. 1 Key Laboratory of Mineral Resources, Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029, China
    2 College of Earth Science,University of Chinese Academy of Sciences,Beijing 100049, China
  • Received:2018-08-16 Revised:2018-09-28 Online:2018-10-20 Published:2018-10-31

摘要:

金成色对于金矿研究是一个重要的参数,其受到成矿流体的pH值和Na/(Na+K)等因素的影响。成矿过程的水/岩相互作用过程往往控制着这些物理化学参数。焦家金矿以强烈的水/岩相互作用为特征,并且由于其Ⅰ号矿体和Ⅲ号矿体的围岩不同,导致水/岩相互作用存在差异。本文研究聚焦于焦家金矿Ⅰ号矿体和Ⅲ号矿体不同的水/岩相互作用对金成色的影响。通过镜下矿石矿物组合显微观察确定出产于Ⅰ号矿体和Ⅲ号矿体中多金属硫化物阶段(第Ⅲ成矿阶段)的银金矿,并利用电子探针分析第Ⅲ成矿阶段银金矿以及进行围岩蚀变矿物对平衡热力学计算,对影响金成色的pH和Na/(Na+K)进行探究后认为:(1)焦家金矿Ⅰ号矿体和Ⅲ号矿体中第Ⅲ成矿阶段银金矿金成色相近;(2)水/岩相互作用过程中,成矿流体受黄铁绢英岩和钾长石化花岗岩缓冲后导致pH和Na/(Na+K)发生一定的变化,但这2种变化对金成色的影响不大。

关键词: 金成色, 水/岩相互作用, pH值, Na/(Na+K), 平衡相图

Abstract:

The gold fineness is a very important parameter for the gold deposit research and it is affected by many factors such as pH value and Na/(Na+K) of the ore-forming fluid.The water/rock interaction between ore-forming fluid and wall rock usually controls those important physico-chemical parameters.Jiaojia gold deposit is characterized by the intense water/rock interaction.No.Ⅰand No.Ⅲ orebodies in the Jiaojia gold deposit have different water/rock interaction due to different wall rocks.The study in this paper mainly focuses on the gold fineness comparison of the stage Ⅲ mineralization(quartz-polymetallic sulfide stage) between No.Ⅰand No.Ⅲ orebodies.The stage Ⅲ gold in two orebodies has been distinguished under the microscope.They were analyzed by the EPMA and the gold fineness was calculated according to analysis results.The mineral equilibrium phase image was calculated to estimate the variation tendency of pH value and Na/(Na+K) of the ore-forming fluid. Two points could been known according to this study:(1)The gold fineness in the stage III mineralization between No.Ⅰ and No.Ⅲ is similar;(2)pH value and Na/(Na+K) could be different when the ore-forming fluid was buffered by the pyrite-sericite-quartz alterated rock and K-feldsparation rock,but this difference has a little effect on the gold fineness.

Key words: gold fineness, water/rock interaction, pH value, Na/(Na+K), equilibrium phase diagram

中图分类号: 

  • P614

图1

胶东金矿区域地质图(据范宏瑞等 [ 25 ] 修改) 1.第四系;2.早白垩世花岗闪长岩;3.早白垩世花岗岩;4.早白垩世火山岩;5.晚三叠世花岗岩类;6.晚侏罗世花岗岩类;7.元古宙岩石;8.太古代岩石;9.超高压变质岩;10.主要断裂;11.焦家式金矿(图例中3种符号由大到小依次代表特大型金矿、大型金矿、中小型金矿或者金矿化点);12.玲珑式金矿(图例中3种符号由大到小依次代表大型金矿、中型金矿、小型金矿或者金矿化点) "

图2

焦家金矿矿区地质图 [ 26 ] 1.第四系;2.太古宙变辉长岩;3.晚侏罗世玲珑花岗岩;4.早白垩世郭家岭花岗闪长岩;5.蚀变带;6.断裂;7.矿床浅部位置;8.矿床深部位置 "

图3

焦家金矿112线矿体剖面图 [ 27 ] 1.第四系;2.玲珑黑云母花岗岩;3.变辉长岩;4.辉绿玢岩;5.闪长玢岩;6.黄铁绢英岩化碎裂岩;7.黄铁绢英岩化花岗质碎裂岩;8.绢英岩化花岗质碎裂岩;9.绢英岩化变辉长质碎裂岩;10.绢英岩化变辉长岩;11.钾长石化花岗岩;12.矿体及编号;13.断裂 "

图4

焦家金矿~-600 m井下采矿巷道蚀变分带—矿化素描剖面图 1.玲珑花岗岩;2.断裂带;3.断层泥;4.黄铁绢英岩化带;5.绢英岩化带;6.钾长石化带;7.石英—黄铁矿网脉;8.蚀变带分界线"

图5

焦家金矿蚀变—矿化特征及样品 (a),(d)以断层泥作为标志的断层面及下盘黄铁绢英岩矿体;(b),(e)黄铁绢英岩和绢英岩的分界及绢英岩样品;(c),(f)钾长石化花岗岩及穿切其中的黄铁矿脉,钾长石发生弱绢云母化图中A,B,C对应图(a),(b),(c)"

图6

焦家金矿矿石矿物显微镜下特征 (a)~(d)穿切黄铁绢英岩的黄铁矿脉,黄铁矿被黄铜矿脉穿切;(e)~(f)为穿切钾长石化花岗岩黄铁矿脉,黄铁矿被黄铜矿脉穿切 Py-黄铁矿;Cpy-黄铜矿;Au-Ag-银金矿;Tet-硫锑铜矿"

表1

银金矿电子探针成分分析"

样品及编号 As Se Fe S Co Pb Ni Bi Cu Ag Zn Sb Te Au 总量 金成色
黄铁绢英岩 16JJ05-1 0 0 3.543 4.14 0 0 0.003 0.02 2.679 15.108 0.026 0 0.045 74.12 99.684 830
16JJ05-2 0 0.027 14.02 19.462 0 0.134 0.003 0.21 16.699 9.105 1.058 0 0.018 42.969 103.705 825
16JJ05-3 0.022 0 3.012 3.679 0 0 0 0 1.68 15.002 0.023 0 0.056 79.396 102.87 841
16JJ05-4 0 0 1.466 1.93 0 0 0.001 0 1.471 13.877 0.244 0 0 83.959 102.948 857
16JJ05-5 0.047 0.005 8.243 10.944 0 0.147 0 0.107 0 14.767 0.013 0 0.103 68.993 103.369 821
16JJ05-6 0.008 0 9.514 13.091 0 0 0 0 0 15.198 0.074 0 0.123 66.955 104.963 817
16JJ05-7 0.029 0 6.689 8.706 0 0 0 0.193 0.705 13.951 1.307 0 0 72.455 104.035 837
钾长石化花岗岩 16JJ15-1 0 0.007 6.778 9.972 0 0 0 0.352 0 16.019 0.03 0 0.074 69.65 102.882 813
16JJ15-2 0.058 0 6.422 8.726 0 0 0 0.001 0 16.313 0.02 0 0.045 74.302 105.887 831
16JJ11-1 0 0 3.749 5.369 0 0.615 0.008 0.059 0 15.182 0.005 0 0.016 78.747 103.75 838
16JJ11-2 0 0 2.91 3.921 0 3.346 0 0.311 0.008 16.121 0 0 0 75.995 102.612 825

表2

矿物对平衡热力学计算化学反应式及平衡常数"

编号 化学反应式 logK
(1) Na(AlSi 3 )O 8 +K + =K(AlSi 3 )O 8 +Na + 0.995
(2) 3Na(AlSi 3 )O 8 +2H + +K + =KAl 2 (AlSi 3 )O 10 (OH) 2 +6SiO 2 +3Na + 10.563
(3) 3K(AlSi 3 )O 8 +2H + =KAl 2 (AlSi 3 )O 10 (OH) 2 +6SiO 2 +2K + 7.578
(4) 2KAl 2 (AlSi 3 )O 10 (OH) 2 _+2H + +3H 2 O=3Al 2 Si 2 O 5 (OH) 4 +2K + 3.462
(5) Na + +KAl 2 (AlSi 3 )O 10 (OH) 2 =NaAl 2 (AlSi 3 )O 10 (OH) 2 +K + -1.604
(6) 3Na(AlSi 3 )O 8 +2H + =NaAl 2 (AlSi 3 )O 10 (OH) 2 +6SiO 2 +2Na + 8.959
(7) 2NaAl 2 (AlSi 3 )O 10 (OH) 2 +2H + +3H 2 O=3Al 2 Si 2 O 5 (OH) 4 +2Na + 6.670

图7

矿物对平衡相图"

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