东昆仑西段库德尔特金多金属矿床成因探讨

Ore genesis of Kudeerte gold-polymetallic deposit in western part of East Kunlun

库德尔特金多金属矿床位于东昆仑西段卡尔却卡矿田内,具有独特的金矿成矿特点。基于矿床特征分析、成矿阶段划分、金矿主成矿期的流体包裹体及氢、氧、硫同位素研究,探讨矿床形成机制和矿床成因,这不仅对区域金矿成矿规律研究具有科学价值,而且对于促进东昆仑区域金矿勘查具有重要的实际意义。通过工作,取得以下认识和成果:①金矿石中流体包裹体主要是富液相两相水溶液包裹体(Ⅰ型),少量为含CO_(2)三相水溶液包裹体(Ⅱ型)。②金矿成矿流体具有中低温(160.7~259.9℃)、中低盐度(3.5%~12.9%NaCl_(eqv))的特点。③成分测定显示,成矿流体主要是NaCl-H_(2)O体系,其次为NaCl-CO_(2)-H_(2)O体系。④氢、氧同位素组成分别为δD=-37‰~-72‰,平均为-56‰,δ^(18)O_(Water)=-3.3‰~-0.3‰,平均为-2.08‰,说明金矿成矿流体主要为岩浆建造水和大气降水的混合;硫同位素组成为δ^(34)S=10.5‰~10.8‰,反映矿石中的硫来源单一,硫主要来自岩浆热液。⑤综合分析认为,库德尔特金多金属矿床属于接触交代-中低温热液型矿床,成矿与花岗闪长岩密切相关,多金属矿形成于接触交代作用;金矿形成于石英硫化物晚期,是花岗闪长岩岩浆期后热液活动的结果;金矿石具有细脉浸染型特点(广义斑岩型),该类型金矿在东昆仑西段具有优越的成矿背景,找矿前景巨大。

Kuderte gold-polymetallic deposit located in the Kaerqueka ore-field in the western part of East Kunlun,which has unique characteristics of gold mineralization.Based on the analysis of deposit characteristics,the classification of metallogenic stages,and the study on the fluid inclusion in the main gold metallogenic period and the H-O-S isotopes,metallogenic mechanism and origin of ore deposit have been discussed.The study is not only scientific valuable for regional gold metallogenic regularity,but also it is important practical significance for promoting gold ore exploration in East Kunlun.The following knowledge and achievements were achieved:①Fluid inclusions in the gold-ore is mainly rich liquid two-phase aqueous inclusions(I-type),small amount of aqueous solution containing CO_(2) three-phase inclusions(Ⅱ);②The ore-forming fluids has the characteristics of middle-low temperature(160.7-259.9℃)and middle-low salinity(3.5%-12.9%NaCl_(eqv));③Fluid inclusion composition testing shows that the ore-forming fluid is mainly NaCl-H_(2)O system,followed is NaCl-CO_(2)-H2O system;④The δD_(V-SMOW) ratios are -37‰--72‰,with an average of-56‰ and the δ^(18)O_(warter(V-SMOW))ratios are-3.3‰--0.3‰,with an average of -2.08‰.The results of hydrogen and oxygen isotopes indicate that the gold ore-forming fluid is mainly mixture of magmatic water and atmospheric precipitation.The δ^(34)S ratios are 10.5‰ -10.8‰,reflecting the sulfur in the ore is single source,mainly from magmatic hydrothermal;⑤According to the comprehensive analysis,the genesis of Kudeerte gold-polymetallic deposit belongs to the contact metasomatism-medium and low temperature hydrothermal type.Metallogenesis is closely related to granodiorite.The polymetallic ore was formed by contact metasomatism and the gold ore was formed in the late quartz sulfide period,which was the result of hydrothermal activity after the magmatic period of granodiorite.The gold ore has the characteristic of veins-disseminated type(Generalized porphyry type).This type gold deposit has the superior metallogenic background and huge prospecting foreground in western part of East Kunlun.