Fluid Inclusions and Ore Genesis Analysis of the Uchkulach Lead-Zinc Ore Deposit in Nuratau Region, Uzbekistan

doi:10.19657/j.geoscience.1000-8527.2018.03.02

Abstract

Abstract:

The Uchkulach large lead-zinc deposit is located in the north margin of the South Tianshan orogenic belt, Uzbekistan. The orebodies are concordantly imbedded in the Middle-Upper Devonian carbonate successions. Because the lead-zinc ores are hosted over acid volcanic rocks, it still remains controversial if the formation of the Uchkulach lead-zinc deposit is correlated to magmatic activity. On the basis of the geological characteristics, we determined fluid inclusions in barite and sphalerite from the ores and chemical compositions of the major minerals by EPMA. Our results show that the homogenization temperatures of the liquid-rich inclusions range from 71 ℃ to 153 ℃, with the peak temperature of 93 ℃ to 133 ℃. The calculated salinities range from 11.0 to 20.2 NaCl wt% according to their determined ice temperatures of -7.4 to -16.9 ℃. Such low temperature and middle salinity fluids suggest that they were possibly derived mainly from the basin brine or evaporated seawater. The election microprobe analyses of sphalerite, galena and barite suggest that the sphalerites are characterized low Fe contents (<6%), which also indicates low-temperature fluids. Concludingly, the Uchkulach lead-zinc deposit belongs to Mississippi Valley-type, and cannot be classified into the one genetically related to underlying volcano-sedimentary rocks.

Key words: lead-zinc deposit, fluid inclusion, homogenization temperature, MVT, South Tianshan, Uzbekistan

CLC Number:

GAO Zhenzhen, ZHANG Zhaochong, CHENG Zhiguo, MIRZAEV A U, NURTAEV B S, KODIROV O. Fluid Inclusions and Ore Genesis Analysis of the Uchkulach Lead-Zinc Ore Deposit in Nuratau Region, Uzbekistan[J]. Geoscience, 2018, 32(03): 429-437.

Figures/Tables 10

References 25

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样号	S	Fe	Cu	Zn	Pb	总量	Zn/S	Pb/ S
UCH-3-4Gn	13.55	0.09	0.24	0.27	84.95	99.10	—	0.97
UCH-3-5Gn	13.63	—	—	—	86.19	99.82	—	0.98
UCH-3-6Gn	13.34	0.06	—	—	86.38	99.78	—	1.00
UCH-2-10Gn	13.20	0.03	—	0.28	86.07	99.58	—	1.01
UCH-2-11Gn	13.11	—	0.05	—	86.37	99.53	—	1.02
UCH-2-12Gn	13.24	—	—	—	86.18	99.42	—	1.01
UCH-2-13Gn	13.13	0.16	—	0.34	86.14	99.77	—	1.02
UCH-2-14Sp	33.06	0.39	0.10	64.61	1.40	99.56	0.96	—
UCH-2-15Sp	33.07	0.10	—	64.86	1.25	99.28	0.96	—
UCH-2-16Sp	32.97	0.22	—	64.99	1.41	99.59	0.97	—
UCH-2-17Sp	32.87	0.33	—	65.81	0.73	99.74	0.98	—
UCH-2-18Sp	33.13	0.11	—	65.39	0.48	99.11	0.97	—

样号	S	Fe	Cu	Zn	Pb	总量	Zn/S	Pb/ S
UCH-3-4Gn	13.55	0.09	0.24	0.27	84.95	99.10	—	0.97
UCH-3-5Gn	13.63	—	—	—	86.19	99.82	—	0.98
UCH-3-6Gn	13.34	0.06	—	—	86.38	99.78	—	1.00
UCH-2-10Gn	13.20	0.03	—	0.28	86.07	99.58	—	1.01
UCH-2-11Gn	13.11	—	0.05	—	86.37	99.53	—	1.02
UCH-2-12Gn	13.24	—	—	—	86.18	99.42	—	1.01
UCH-2-13Gn	13.13	0.16	—	0.34	86.14	99.77	—	1.02
UCH-2-14Sp	33.06	0.39	0.10	64.61	1.40	99.56	0.96	—
UCH-2-15Sp	33.07	0.10	—	64.86	1.25	99.28	0.96	—
UCH-2-16Sp	32.97	0.22	—	64.99	1.41	99.59	0.97	—
UCH-2-17Sp	32.87	0.33	—	65.81	0.73	99.74	0.98	—
UCH-2-18Sp	33.13	0.11	—	65.39	0.48	99.11	0.97	—

样号	MgO	SO₃	FeO	SrO	BaO	总量	Sr/Ba
UCH-3-1Brt	—	35.74	0.09	1.30	62.90	100.02	0.032
UCH-3-2Brt	0.06	35.89	0.13	0.97	63.25	100.30	0.024
UCH-3-3Brt	0.15	35.69	—	0.59	63.78	100.21	0.014
UCH-2-8Brt	0.05	36.36	—	1.07	63.48	100.96	0.026
UCH-2-9Brt	0.07	35.73	0.25	2.68	60.97	99.70	0.069

样号	MgO	SO₃	FeO	SrO	BaO	总量	Sr/Ba
UCH-3-1Brt	—	35.74	0.09	1.30	62.90	100.02	0.032
UCH-3-2Brt	0.06	35.89	0.13	0.97	63.25	100.30	0.024
UCH-3-3Brt	0.15	35.69	—	0.59	63.78	100.21	0.014
UCH-2-8Brt	0.05	36.36	—	1.07	63.48	100.96	0.026
UCH-2-9Brt	0.07	35.73	0.25	2.68	60.97	99.70	0.069

矿床类型	密西西比河谷型铅锌矿	Uchkulach铅锌矿
大地构造背景	最重要的是其产出于被动大陆边缘的碳酸盐岩台地白云岩和灰岩中,或位于盆地侧翼,造山前陆或前陆逆冲带	被动大陆边缘的碳酸盐岩台地
成矿方式	碳酸盐岩角砾间开放孔隙充填,对围岩和碎屑的交代作用,后生成矿特征	热液重晶石的出现,成矿围岩时代略早于成矿时代,金属矿物充填白云石孔隙,交代白云石,后生成矿特征
金属矿物	常见闪锌矿、方铅矿及铁硫化物,富银贫铜	闪锌矿、方铅矿、黄铁矿,Ag品位:2.4~42.19 g/t
脉石矿物	碳酸盐(白云石、菱铁矿、铁白云石、方解石),典型出现少量至大量重晶石	白云石、方解石、重晶石
含矿岩石	白云岩为主的碳酸盐岩,少量砂岩	白云岩、灰岩
流体包裹体	均一温度50~250 ℃,少部分达300 ℃,主要分布在90~150 ℃,盐度10%~30%,成矿流体来源主要是浓缩的海水	均一温度71~153 ℃,盐度11.0%~20.2%,成矿流体来源是盆地卤水
控矿因素	断层、破碎带、溶解坍塌角砾岩、基底隆起、岩性边界	背斜翼部、转折端的穹窿构造
矿体形态	层状、筒状、透镜状、不规则状等(层控、断层控制、喀斯特地形控制)	层状、条带状和透镜状
围岩蚀变	白云岩化、方解石化、硅化	白云石化、似碧玉化、硅化、赤铁矿化和泥化