Genesis of the Wandao Gold Deposit in Guangxi, China: Evidences from Fluid Inclusions and H-O-S-Pb Isotopes

Abstract

Abstract:

The Wandao gold deposit, located in Gupao ore field of Dayaoshan polymetallic metallogenic clusters area in the southeastern Guangxi, is a medium-sized ore deposit discovered in recent years. The source of ore-forming substance and ore genesis are still under debate. There is still a big difference between its material origin and genesis. Based on detailed observation in underground tunnel and petrographic study under microscope, the Wandao gold deposit can be divided into W-Mo-Cu-Au mineralization period and main gold dominated mine-ralization period. Furthermore, the main gold dominated mineralization period can be divided into main stage and late stage. Microscopic temperature measurements and Laser Raman Spectra analysis of fluid inclusions in quartz indicate that the ore-forming fluids of main gold dominated mineralization period in the Wandao gold deposit are fluids with high temperature, low salinity, low density and containing CO₂ and CH₄. Hydrogen and oxy-gen isotope analysis data of quartz indicate the ore-forming fluids of main gold dominated mineralization period mainly derived from metamorphic water, and the ore-forming fluids of W-Mo-Cu-Au mineralization period is the mixture of magmatic water and metamorphic water. The small positive value of sulfur isotope for W-Mo-Cu-Au mineralization period infers that sulfur come from magma reservoir in depth. Whereas, small average with large range of sulfur isotopic composition for gold dominated mineralization period suggests that the sulfur in ore proba-bly mainly derived from strata and partly from magmatic rocks. Based on the above analysis, it is considered that the Wandao gold deposit belongs to metamorphic and magmatic hydrothermal superimposed deposit type.

Key words: stable isotope, fluid inclusion, ore-forming fluid, Wandao gold deposit, Guangxi

CLC Number:

P618.51

LAI Xin, PANG Baocheng, LI Yuanqiang, ZHANG Qingwei, LÜ Jiawen, ZHOU Yequan, LI Peirong. Genesis of the Wandao Gold Deposit in Guangxi, China: Evidences from Fluid Inclusions and H-O-S-Pb Isotopes[J]. Geoscience, 2017, 31(05): 1006-1021.

Figures/Tables 17

References 26

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样品号	观测点	冰点温度/℃	均一温度/℃	笼合物/℃	盐度/ %NaCl	密度/ (g/cm³)	压力/MPa
14WD13-3 (金主成矿阶段包裹体片)	1	-1.1	326.4		1.91	0.67	21.4
	2	-0.9	384.0		1.57	0.53	25.2
	3	-1.7	374.8		2.90	0.58	24.9
	4	-1.8	377.4		3.06	0.57	25.0
	5	-1.0	364.3		1.74	0.58	23.9
14WD21-3 (金主成矿阶段包裹体片)	1	-1.7	376.3		2.90	0.57	25.0
	2	-1.9	328.8		3.23	0.68	21.8
	3	-0.9	362.7		1.57	0.59	23.8
	4	-0.9	330.1		1.57	0.66	21.7
	5	-0.9	334.6		1.57	0.65	21.9
	6	-1.0	336.7		1.74	0.65	22.3
	7	-1.1	323.5		1.91	0.68	21.3
金主成矿阶段		-1.9~-0.9	323.5~384.0		1.06~3.23	0.53~0.68	21.3~25.2
平均值		-1.2	351.6		2.06	0.62	23.18
14WD27-1 (金晚成矿阶段包裹体片)	1	-1	308.7		1.74	0.70	20.3
	2		272.3	9.1	1.81	0.77	17.9
	3	-1.4	237.7		2.41	0.83	15.7
	4	-2.3	259.2		3.87	0.81	17.3
14WD27-2 (金晚成矿阶段包裹体片)	1	-0.9	309.6		1.57	0.70	20.3
	2	-1.4	240.4		2.41	0.82	15.9
	3	-1.2	271.4		2.07	0.77	17.9
	4	-2.2	260.2		3.71	0.81	17.3
金晚成矿阶段		-2.3~-0.9	237.7~309.6		1.57~3.87	0.70~0.83	15.7~20.3
平均值	-1.5	269.9		2.45	0.78	17.8

样品号	观测点	冰点温度/℃	均一温度/℃	笼合物/℃	盐度/ %NaCl	密度/ (g/cm³)	压力/MPa
14WD13-3 (金主成矿阶段包裹体片)	1	-1.1	326.4		1.91	0.67	21.4
	2	-0.9	384.0		1.57	0.53	25.2
	3	-1.7	374.8		2.90	0.58	24.9
	4	-1.8	377.4		3.06	0.57	25.0
	5	-1.0	364.3		1.74	0.58	23.9
14WD21-3 (金主成矿阶段包裹体片)	1	-1.7	376.3		2.90	0.57	25.0
	2	-1.9	328.8		3.23	0.68	21.8
	3	-0.9	362.7		1.57	0.59	23.8
	4	-0.9	330.1		1.57	0.66	21.7
	5	-0.9	334.6		1.57	0.65	21.9
	6	-1.0	336.7		1.74	0.65	22.3
	7	-1.1	323.5		1.91	0.68	21.3
金主成矿阶段		-1.9~-0.9	323.5~384.0		1.06~3.23	0.53~0.68	21.3~25.2
平均值		-1.2	351.6		2.06	0.62	23.18
14WD27-1 (金晚成矿阶段包裹体片)	1	-1	308.7		1.74	0.70	20.3
	2		272.3	9.1	1.81	0.77	17.9
	3	-1.4	237.7		2.41	0.83	15.7
	4	-2.3	259.2		3.87	0.81	17.3
14WD27-2 (金晚成矿阶段包裹体片)	1	-0.9	309.6		1.57	0.70	20.3
	2	-1.4	240.4		2.41	0.82	15.9
	3	-1.2	271.4		2.07	0.77	17.9
	4	-2.2	260.2		3.71	0.81	17.3
金晚成矿阶段		-2.3~-0.9	237.7~309.6		1.57~3.87	0.70~0.83	15.7~20.3
平均值	-1.5	269.9		2.45	0.78	17.8

样号	样品名称	δD/‰	δ¹⁸O_quartz/‰	δ¹⁸O_water/‰	均一温度/℃	成矿阶段
14WD13A	石英	-31	13.9	9.01	365.38	金主成矿期金主成矿阶段
14WD13B	石英	-40	13.7	8.81	365.38	金主成矿期金主成矿阶段
14WD17	石英	-39	14.3	9.41	365.38	金主成矿期金主成矿阶段
14WD21A	石英	-34	14.0	8.46	341.81	金主成矿期金主成矿阶段
14WD21B	石英	-42	13.5	7.96	341.81	金主成矿期金主成矿阶段
14WD26	石英	-68	12.7	6.14	309.60	金主成矿期金晚成矿阶段
14WD27	石英	-54	13.1	5.03	269.94	金主成矿期金晚成矿阶段
14WD36	石英	-48	15.0	9.46	341.81	金主成矿期金主成矿阶段
14WD51	石英	-48	13.9	8.36	341.81	金主成矿期金主成矿阶段
14WD52	石英	-46	12.6	7.06	341.81	金主成矿期金主成矿阶段
14WD53	石英	-38	13.4	5.33	269.94	金主成矿期金晚成矿阶段

样号	样品名称	δD/‰	δ¹⁸O_quartz/‰	δ¹⁸O_water/‰	均一温度/℃	成矿阶段
14WD13A	石英	-31	13.9	9.01	365.38	金主成矿期金主成矿阶段
14WD13B	石英	-40	13.7	8.81	365.38	金主成矿期金主成矿阶段
14WD17	石英	-39	14.3	9.41	365.38	金主成矿期金主成矿阶段
14WD21A	石英	-34	14.0	8.46	341.81	金主成矿期金主成矿阶段
14WD21B	石英	-42	13.5	7.96	341.81	金主成矿期金主成矿阶段
14WD26	石英	-68	12.7	6.14	309.60	金主成矿期金晚成矿阶段
14WD27	石英	-54	13.1	5.03	269.94	金主成矿期金晚成矿阶段
14WD36	石英	-48	15.0	9.46	341.81	金主成矿期金主成矿阶段
14WD51	石英	-48	13.9	8.36	341.81	金主成矿期金主成矿阶段
14WD52	石英	-46	12.6	7.06	341.81	金主成矿期金主成矿阶段
14WD53	石英	-38	13.4	5.33	269.94	金主成矿期金晚成矿阶段

样品编号	样品名称	δ³⁴S/‰	成矿期次
14WD01	黄铁矿	0.7	钨钼铜金成矿期
14WD02-1	黄铁矿	-3.5	金主成矿期
14WD02-3	黄铁矿	-2.8	金主成矿期
14WD02-3	黄铜矿	-2.9	金主成矿期
14WD03	黄铁矿	3.5	钨钼铜金成矿期
14WD04	黄铜矿	-3.2	金主成矿期
14WD08	黄铁矿	2.2	钨钼铜金成矿期
14WD10	花岗斑岩	1.2	-
14WD11	砂岩	2.6	-
14WD12	蚀变花岗斑岩	2.8	-
14WD16	黄铁矿	-3.0	金主成矿期
14WD25	黄铁矿	-4.8	金主成矿期
14WD28	花岗斑岩	-0.2	-
14WD36	黄铁矿	-16.2	金主成矿期
14WD41	黄铁矿	-0.2	钨钼铜金成矿期