投稿时间：2021-04-14
修订日期：2021-08-11
网络发布日期：2021-10-22
中文摘要:德峨金矿位于桂西隆林孤立碳酸盐岩台地内部，赋矿地层为寒武系含砂泥质白云岩，近东西向断层或节理密集带是主要的控矿构造。矿化体包括断控型和层控型2种。热液矿物组合以黄铁矿-毒砂-辉锑矿-石英-方解石为主，蚀变以硅化、白云石化、绢云母化为特征。载金黄铁矿具显微环带结构，核部低As高S、Fe，环带反之，推测Au主要以离子形式赋存于黄铁矿环带和毒砂中。成矿流体具有中低温（182~296℃）、低盐度w （NaCleq）（0.53%~8.81%）的特点，石英包裹体中水的DV-SMOW值在-71.2‰~-62.9‰之间，石英矿物δ18OV-SMOW值在22.3‰~23.5‰之间，计算出与石英平衡的流体δ18OH2O为12.13‰~14.72‰，暗示成矿流体为多种流体混合。方解石δ13CV-PDB为-7.5‰~0.6‰，δ18OH2O为19.2‰~20.6‰，表明成矿热液中碳主要来源于海相碳酸盐岩的溶解。沉积成因黄铁矿δ34S为-21.81‰~14.15‰，离散度很大，具有沉积来源的特点；热液黄铁矿环带为-7.52‰~1.23‰，与毒砂类似（平均值为-3.83‰），且由核部向外环带逐渐向零值附近靠拢，结合金主要赋存在黄铁矿环带和毒砂的事实，暗示成矿热液可能以岩浆热液为主，环带的震荡变化可能跟岩浆硫上升过程中与大气降水、盆地建造水的不同程度混合有关。上述特征表明，德峨金矿具有卡林型金矿的一般特点，独特之处是其构造部位上处于孤立台地内部，赋矿地层为寒武系不纯白云岩。据此文章提出桂西孤立碳酸盐岩台地内部具有一定的找矿潜力，寒武系不纯白云岩是新的找矿层位和岩性，断裂构造和岩性是最主要的控矿因素。此认识对桂西地区卡林型金矿找矿工作向孤立台地内部探索具有重要的指导意义。
Abstract:The De'e gold deposit, located in the isolated carbonate platform of Longlin in western Guangxi, is the first deposit discovered that is hosted in Cambrian sandy and muddy dolostone, and controlled by E-W trending faults and/or zones with densely developed joints. The mineralized-bodies can be classified into two types:fault-controlled and stratabound. The hydrothermal mineral assemblage is mainly pyrite-arsenopyrite-stibnite-quartz-calcite, and the alterations are characterized by silicification, dolomitization and sericitization. The Au-bearing pyrites show core-rim texture with low As and high S、Fe in the core and vice versa, no visible Au indicating Au is likely hosted in the rims of pyrite and arsenopyrite in the form of Au+ ions. The ore-forming fluid is characterized by medium to low temperature (182~296℃) and low salinity w(NaCleq)(0.53%~8.81%). The value of DV-SMOW of fluid inclusions in quartz varies from -71.2‰ to -62.9‰ and the δ18OV-SMOW in quartz minerals varies from 22.3‰ to 23.5‰, the calculated δ18OH2O values with a range of 12.14‰ to 14.72‰. The results suggest that the oreforming fluid is a mixed source of multiple fluids. The δ13CV-PDB of calcite is -7.5‰~0.6‰ and δ18OH2O is 19.2‰~20.6‰, indicating that the carbon in ore-forming fluid mainly comes from the dissolution of marine carbonate rocks. The sedimentary pyrite with a large δ34S value range of-21.81‰ to 14.15‰ indicating a sedimentary source. The δ34S values of hydrothermal pyrite rims range from -7.52‰ to 1.23‰, is similar to arsenopyrite (average value is -3.83‰), and gradually approaches to zero from the core to the rim, suggesting that the oreforming fluid is likely derived from magma. The δ34S variation of hydrothermal pyrites may be related to the mixing of magmatic sulfur, meteoric water and basin formation water during ascending process. The above characteristics show that De'e gold deposit has the general characteristics of Carlin-type gold deposits, even though it is located in the interior of isolated carbonate platform, and the ore-hosting strata is Cambrian impure dolostone. Therefore, we propose that the isolated carbonate platform in western Guangxi has good Au prospecting potential, and the Cambrian impure dolostone is a new prospecting strata and ore-bearing lithology. Fault and lithology are the main ore-controlling factors. This result has important guiding significance for the exploration of Carlin-type gold deposits in the interior of isolated carbonate platform in western Guangxi.
keywords:geology isolated carbonate platform Cambrian impure dolostone fault De'e Carlin-type gold deposit
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基金项目:本文得到国家自然科学基金面上项目《桂西孤立台地内部寒武系中卡林型金矿成矿机理研究》（编号：42072110）和广西找矿突破战略行动地质矿产勘查项目《桂西隆林孤立台地卡林型金矿的"梯式"结构模型及找矿前景》（编号：桂国土资函[2018]377号）联合资助
引用文本：
陈懋弘,马克忠,陈港,王昱,乐兴文,李忠阳,陈忠斌.2021.桂西孤立台地寒武系白云岩中的卡林型金矿床——以隆林德峨金矿为例[J].矿床地质,40(5):891~914CHEN MaoHong,MAKeZhong,CHEN Gang,WANGYu,LE XingWen,LI ZhongYang,CHEN ZhongBin.2021.Carlin-type gold deposits hosted in Cambrian dolostone on isolated carbonate platform in western Guangxi, China: A case study from De'e gold deposit, Longlin[J].Mineral Deposits40(5):891~914
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