俄罗斯堪察加中部Baranevskoy金-银矿床矿物学与流体包裹体研究

doi:10.13745/j.esf.sf.2020.5.58

摘要/Abstract

摘要：

Baranevskoy金-银矿床产于巴尔喀什火山的火山口,该火山坐落在堪察加中部矿区东南部。本文基于矿物学原理和流体包裹体数据分析探讨了Baranevskoy金-银矿床的成矿环境及其物理化学条件。Baranevskoy金-银矿床的围岩为中新世—上新世的安山岩和玄武岩。热液蚀变活动随深度逐渐变化,从而可以进一步划分出最深部的石英带、中部的石英-绢云母(明矾石)-黄铁矿-铁钛氧化物带及其伴生的石英-绢云母-伊利石-黄铁矿矿物组合和浅部的石英-冰长石-水云母-黏土矿物-碳酸盐岩带。成矿早期存在密集浸染的铜矿化,主要矿石矿物有黄铜矿、斑铜矿、砷黝铜矿-黝铜矿,并在Rhzavaya矿脉中存在少量的自然金。其中砷黝铜矿-黝铜矿系列以砷黝铜矿和黝铜矿两个端员作为代表,且以黝铜矿为主。成矿后期产出代表晚期金-银矿化的自然金、黄铁矿、黄铜矿、闪锌矿、方铅矿、碲化物和硫酸盐等标志性矿物。早期铜矿化(第一期)被认为是中硫阶段,紧随其后的为低硫型金-银矿化(第二期和第三期)。金从第一期到第三期都有沉淀。经研究发现,自然金也赋存于变质围岩的岩石裂隙内。早期的自然金相对富银,其中金的摩尔分数为59%~65%,低于后期(第二、第三期)自然金中金的摩尔分数(64%~72%)。流体包裹体显微测温结果显示,位于中部(Central)矿脉的包裹体均一温度为190~280 ℃,Rzhavaya矿脉的包裹体为190~240 ℃,产出自然金的蚀变围岩中石英的包裹体温度为230~310 ℃。包裹体总体表现出低盐度(0.9%~2.4% NaCl_eq)特征,推测存在大气水的混入。

关键词: 金, 矿床, 火山弧, 斑铜矿, 气液包裹体, 堪察加

Abstract:

The Baranevskoye gold-silver deposit occurs within the caldera of the Balkhach volcano in the south-east part of the Central Kamchatka mining district. The host rocks are andesite, basalt of Miocene-Pliocene age. The hydrothermal alteration varies as a function of depth and is subdivided into deepest quartize zone, intermediate zones of quartz-sericite(alunite)-pyrite-Fe-Ti-oxides and quartz-sericite-illite-pyrite associations, and shallow quartz-adularia-hydromica-clay-carbonate zone. Mineralogical study reveals three major stages of mineralization. The early stage is present by a highly disseminated copper-rich mineralization with main ore minerals of chalcopyrite, bornite, tennantite-tetrahedrite, and rare gold occurring in the Rzhavaya vein. Tennantite-tetrahedrite series is represented by two end-members of tennantite and tetrahedrite with tetrahedrite preponderating. Later stages are characterized by advanced Au-Ag mineralization containing gold, pyrite, chalcopyrite, sphalerite, galena, tellurides, and sulfosalts. The early Cu-rich mineralization (stage I) is designated as an intermediated state, followed by later low-sulfidation Au-Ag mineralization (stages II and III). Gold was constantly deposited through from Stage I to Stage III. Crystalline gold was also found in void-space in the altered host rocks. Early gold is relatively Ag-rich with Au content of about 59-65% compared to later gold of Stage II and III (Au 64-72%). Fluid inclusion microthermometry shows homogenization temperatures between 190-280 ℃ for the Central vein, 190-240 ℃ for the Rzhavaya vein and 230-310 ℃ for the quartz of the altered host rocks associated with crystalline gold. Low salinity of the fluid inclusions (0.9-2.4 wt.% NaCl eq.) suggests an influx of the meteoric waters. Based on mineralogical and fluid inclusions data the physicochemical conditions of the ore formation are discussed.

Key words: gold, ore deposit, volcanic arc, bornite, fluid inclusion, Kamchatka

中图分类号:

Victor M. Okrugin, Elena D. Skilskaia. 俄罗斯堪察加中部Baranevskoy金-银矿床矿物学与流体包裹体研究[J]. 地学前缘, 2020, 27(5): 136-150.

Victor M. Okrugin, Elena D. Skilskaia. Mineralogy and fluid inclusions study of the Baranevskoye gold-silver deposit, central Kamchatka, Russia[J]. Earth Science Frontiers, 2020, 27(5): 136-150.

图/表 14

Fig.1 A simplified map showing location of the Baranevskoye deposit in the Central Kamchatka Mining District in the south of the Central Kamchatka Volcanic Belt.

Fig.2 A geological map of the Baranevskoye deposit.

Fig.3 Representative ore specimens of the Baranevskoye deposit from the Rhzavaya vein (a), the Central vein (b), the Stockwork (c), and the Yuznaya vein (d).

Table 1 Representative electron microprobe analyses of sulfide minerals from the Central and Rhzavaya veins.

Elements	Mass fraction (%)
	Galena				Pyrite							Sphalerite					Chalcopyrite					Bornite
	1	2		3			4		5^*		6			7		8			9^*		10			11
S	12.34		12.21			51.73		53.36		51.8			34.32		31.81			33.6		34.29			25.13		25.44
As	-		-			3.19		-		-			-		-			-		-			-		-
Pb	86.95		88.38			-		-		-			-		-			-		-			-		-
Fe	-		-			45.09		46.72		46.81			2.64		0.24			30.72		31.01			11.76		11.37
Cd	-		-			-		-		-			0.35		0.12			-		-			-		-
Cu	-		-			-		-		-			-		-			34.52		34.76			63.69		62.97
Zn	-		-			-		-		-			62.53		64.88			-		-			-		-
Sum	99.29		100.59			100.01		100.08		98.61			99.84		97.05			98.84		100.06			100.58		99.78
Elements	Mole fraction (%)
	Galena				Pyrite							Sphalerite					Chalcopyrite					Bornite
	1	2		3			4		5^*		6			7		8			9^*		10			11
S	47.31		46.89			65.50		66.45		65.74			51.46		49.82			48.94		49.24			39.26		39.92
As	-		-			1.72		-		34.26			-		-			-		-			-		-
Pb	52.69		53.11			-		-		-			-		-			-		-			-		-
Fe	-		-			32.78		33.55		-			2.40		0.22			25.69		25.52			10.54		10.24
Cd	-		-			-		-		-			0.15		0.12			-		-			-		-
Cu	-		-			-		-		-			-		-			25.37		25.24			50.2		49.84
Zn	-		-			-		-		-			45.99		49.82			-		-			-		-

Table 2 Representative electron microprobe analyses and calculated formulas of tetrahedrite-tennantite group minerals.

Elements	Mass fraction (%)
Cu	43.19	44.20	41.81	42.14	45.3	43.19	42.02	42.52	44.49	41.17
Ag	0.12	0.04	0.14	0.08	0.04	0.12	0.14	0.19	0.06	0.12
Fe	2.88	3.41	2.35	2.35	4.38	3.20	2.82	2.81	3.33	3.92
Zn	3.32	2.77	3.80	3.92	1.93	2.98	2.73	3.10	2.82	3.74
Sb	17.53	9.69	19.93	19.03	3.31	18.21	22.59	17.47	5.05	18.25
As	8.35	13.78	6.77	7.18	18.84	9.17	5.39	8.73	17.57	7.29
S	25.61	27.10	26.04	25.66	27.94	25.63	25.26	25.80	26.97	25.84
Sum	101.00	100.99	100.84	100.36	101.74	102.5	100.95	100.62	100.29	100.33
Elements	Number of atoms
Cu	10.727	10.571	10.449	10.571	10.484	10.626	10.652	10.582	10.571	10.266
Ag	0.017	0.006	0.020	0.023	0.006	0.017	0.020	0.026	0.009	0.020
Fe	0.815	0.928	0.670	0.670	1.151	0.896	0.812	0.798	0.896	1.114
Zn	0.800	0.644	0.925	0.954	0.432	0.711	0.673	0.748	0.650	0.748
Sb	2.274	1.212	2.598	2.491	0.403	2.337	2.990	2.271	0.638	2.375
As	1.760	2.799	1.436	1.528	3.698	1.911	1.16	1.844	3.541	1.543
S	12.606	12.841	12.902	12.763	12.821	12.502	12.693	12.731	12.696	12.775

Fig.4 Reflected-light photomicrographs (a-i) and back-scattering images (j,k) of ore minerals showing the textural relations and the internal structure. (a) Later chalcopyrite (cp) filling up the factures in early pyrite (py), the Rhzavaya vein. (b) Later gold (au) occurring in fractures of pyrite, the Rhzavaya vein. (c) Gold enclosed in chalcopyrite, the Rhzavaya vein. (d) Micrographic texture of exsolution chalcopyrite from bornite, the Rhzavaya vein. Chalcocite forms rims around bornite. (e) Assemblage of chalcopyrite, bornite (bor) and tennantite-tetrahedrite (ten-tet), the Rhzavaya vein. Chalcocite (light blue) replaces bornite along fractures and margins. Chalcocite (light blue) is partly replaced by covelline (dark blue). (f) Sphalerite (sp) intergrown with chalcopyrite, pyrite and galena (ga), the Central vein. (g) A gold inclusion in euhedral pyrite, the Central vein. (h) Euhedral pyrite in contact with gold, the Stockwork ore body. (i) Gold crystals in interstices between carbonate grains, the Yuzhnaya vein. (j,k) Internal zonal structure of tennantite-tetrahedrite solid-solution.

Fig.5 Chemical variations of tennantite-tetrahedrite series from the Baranevskoye deposit as a function of Fe/(Fe+Zn) and Sb/(Sb+As).

Table 3 Representative electron microprobe analyses of gold from the Baranevskoye deposit.

Vein	Mass fraction (%)			Mole fraction (%)
Vein	Au	Ag	∑	Au	Ag
The Central vein	80.55	19.10	99.65	69.79	30.21
	80.60	19.40	100.00	69.47	30.53
	81.69	18.30	99.99	70.97	29.03
	82.00	18.68	100.68	70.63	29.37
	82.51	17.96	100.47	71.55	28.45
The stockwork	79.15	18.74	97.89	69.81	30.19
	80.35	18.79	99.14	79.08	29.93
	78.57	18.86	97.43	69.52	30.48
	79.48	18.72	98.20	69.92	30,08
	79.17	18.65	97.82	69.93	30.07
The Yuzhnaya vein	78.87	20.00	98.87	68.76	31.24
	79.76	20.43	100.19	68.85	31.25
	79.33	20.67	100.00	68.44	31.56
	80.89	19.40	100.29	69.84	30.16
	80.73	19.71	100.45	69.42	30.58
Gold crystals in voids of the altered host rocks	78.75	18.67	97.42	69.79	30.21
	79.95	20.05	100.00	68.59	31.41
	80.90	18.17	99.07	70.92	29.08
	81.95	18.08	100.03	71.28	28.72
	94.15	6.18	100.33	89.29	10.71
The Rhzavaya vein	76.84	23.16	100.00	65.50	34.50
	42.90	57.10	100.00	59.21	40.79
	84.24	15.86	100.08	72.24	27.76

Fig.6 Variety of gold crystals developing in void space of the altered host rocks. (a) Remarkable single octahedron gold crystal with the growth steps on a surface. (b) Dentritic branch of gold crystals. The growth steps are recognized at the surface of individual crystal. (d) The deformed dendritic branch of gold crystals.

Fig.7 Diagrams of gold composition. (a) The Yuznaya vein. (b) The Stockwork ore body. (c) The Central vein. (d) Gold from the host rocks and placer deposit.

Fig.9 Homogenization temperatures obtained from fluid inclusions in quartz from the Central vein (a), the Rhzavaya vein (b), and altered host rocks (c).

Fig.8 Microphotographs of the fluid inclusions from the Central vein. (a) Individual gaseous inclusion in quartz. (b) Group of two phase fluid inclusions.

Fig.10 Mineralization stages at the Barenevskoye deposit. Ten-tet*-tennantite-tetrahedrite series.

Fig.11 Plot of homogenization temperature versus salinity for fluid inclusions of the Central vein, Rhzavaya vein, and quartz druses in the altered host rocks.

参考文献 32

[1]	ANDREEVA E D, 2006. Textural features of epithermal mineralization of the Zolotoye ore body, Central Kamchatka[J]. Bulletin of Kamchatka Regional Association “Educational-Scientific Center”. Earth Sciences, 8:195-200.
[2]	AVDEIKO G P, VOLYNETS O N, ANTONOV A Y, et al., 1991. Kurile Island arc volcanism: structural and petrological aspects[J]. Tectonophysics, 199:271-287.
[3]	BINDEMAN I N, LEONOV V L, IZBEKOV P E, et al., 2010. Large-volume silicic volcanism in Kamchatka: Ar-Ar and U-Pb ages, isotopic, and geochemical characteristics of major pre-Holocene caldera-forming eruptions[J]. Journal of Volcanology and Geothermal Research, 189:57-80. DOI URL
[4]	BRETT R, YUND R A, 1964. Sulfur-rich bornite[J]. American Mineralogist, 49:1084-1089.
[5]	BOLSHAKOV V M, FLOROV A I, MINEEV S D, et al., 2010. Geological structure of the Baranevskoe gold ore deposits (Central Kamchatka)[J]. Otechestvenaya Geologiya, 4:15-22 (in Russian).
[6]	EINAUDI M T, HEDENQUIST J W, INAN E E, 2003. Sulfidation state of fluids in active and extinct hydrothermal systems: transitions from porphyry to epithermal environments[J]. Economic Geology Special Publication, 10:1-50.
[7]	FADDA S, FIORI M, GRILLO S M, 2005. Chemical variations in tetrahedrite-tennantite minerals from the Furtei epithermal Au deposit, Sardinia, Italy: mineral zoning and ore fluid evolution[J]. Geochemistry, Mineralogy and Petrology: 79-84.
[8]	FEISS P G, 1974. Reconnaissance of the tetrahedrite-tennantite/enargite-famatinite phase relations as a possible geothermometer[J]. Economic Geology, 69:383-390. DOI URL
[9]	FILIMONOV S V, 2009. Tetrahedrite-tennantite group minerals as indicators of ore genesis on the hydrothermal deposits[D]. Moscow: MSU: 26.
[10]	HEALD P, FOLEY N K, HAYBA D O, 1987. Comparative anatomy of volcanic-hosted epithermal deposits: acid-sulfate and adularia-sericite types[J]. Economic Geology, 82:1-26. DOI URL
[11]	HEDENQUIST J W, HENLEY R W, 1985. The importance of CO₂ on freezing point measurements of fluid inclusion: evidence from active geothermal systems and implications for epithermal ore deposition[J]. Economic Geology, 80:1379-1406. DOI URL
[12]	HERNANDEZ A N G, AKASAKA M, 2010. Ag-rich tetrahedrite in the El Zancudo deposit, Colombia: occurrence, chemical compositions and genetic temperatures[J]. Resource Geology, 60:218-234.
[13]	IMAI A, SATOSHI O, 2005. Primary ore mineral assemblage and fluid inclusion study of the BatuHijau Porphyry Cu-Au deposit, Sumbawa, Indonesia[J]. Resource Geology, 55:239-248. DOI URL
[14]	KEMKINA R A, 2007. Fahlores of the Prasolovka Au-Ag volcanogenic deposit, Kunashir island, Russian Far East[J]. Russian Journal of Pacific Geology, 1:130-143. DOI URL
[15]	KHASANOV S G, SIDORENKO V I, KRIKUN V I, et al., 2015. Explanatory notes to the map of the Khangar seria[J]. VSEGII: 143.
[16]	KUZHUGET R V, MONGUSH A A, MONGUSH A O, 2018. Evolution of chemical composition of fahlores of the Ak-Sug gold-molybdenum-copper-porphyry deposit (North-East Tuva)[J]. Bulletin of the Tomsk Polytechnic University, 329:81-91.
[17]	MASKE S, SKINNER B J, 1971. Studies of the sulfosalts of copper I. Phase and phase relations in the system, Cu-As-S[J]. Economic Geology, 66:901-918. DOI URL
[18]	MELEKESTSEV I V, 2009. The identification and diagnostics of active and potentially active volcanic features in the Kuril-Kamchatka island arc and the Commander islands link of the Aleutian arc[J]. Journal of Volcanology and Seismology, 4:221-245.
[19]	OKRUGIN V M, 2001. Age and genesis of epithermal deposits located along north-west coast of the Pacific Ocean[M]// Magmatism and metallogeny in continental margins along the Pacific Ocean. [S.l.]:[s.n.]: 39-41 (in Russian).
[20]	PETRENKO I D, 1999. Gold-silver mineralization in Kamchatka[J]. VSEGII: 115.
[21]	PEVZNER M M, VOLYNEC A O, 2006. Holocene volcanism in Sredinny Range, Kamchatka[C]// Proceeding of the International Symposium Explosive Volcanism Issues. [S.l.]:[s.n.]: 127-134.
[22]	PONOMAREVA V, MELEKESTSEV I, BRAITSEVA O, et al., 2007. Late Pleistocene-Holocene volcanism on the Kamchatka Peninsula, Northwest Pacific region. Volcanism and subduction: the Kamchatka Region[J]. Geophysical Monograph Series, 172:165-198.
[23]	ROEDDER E, 1984. Fluid inclusions[J]. Reviews in Mineralogy, 12:646.
[24]	SHADRIN A G, 1999. Epithermal precious metal mineralization in Kamchatka[J]. Geology and Mineral Resources of Kamchatka: 74-77 (in Russian).
[25]	SHEPOTEV Y M, VARTANYAN S S, ORESHIN V Y, et al., 1989. Gold deposits in the volcanic arcs of the Pacific Ocean[M]. Moscow: [s.n.]: 244.
[26]	SIMMONS S F, CHRISTENSON B W, 1994. Origins of calcite in a boiling geothermal system[J]. American Journal of Science, 294:361-400. DOI URL
[27]	SIMMONS S F, AREHART G, SIMPSON M P, et al., 2000. Origin of massive calcite veins in the Golden Cross low-sulfidation, epithermal Au-Ag deposit, New Zealand[J]. Economic Geology, 95:99-112. DOI URL
[28]	STEPANOV V A, KUNGUROVA V E, KOIDAN I A, 2019. Gold mineralization of the Median Massif, Kamchatka (Kamchatka Sredinnyi Massif)[J]. Proceedings of Higher Educational Establishments. Geology and Exploration, 2:44-53(in Russian).
[29]	SPIRIDONOV E, MALEEV M, KOVACHEV V, et al., 2005. Minerals of fahlore group: indictors of ore genesis[M]. Sofia: Bulgarian Geological Society: 79-82.
[30]	TATSUKA K, MORIMOTO N, 1973. Composition variation and polymorphism of tetrahedrite in the Cu-Sb-S system below 400 ℃[J]. American Mineralogist, 58:425-434.
[31]	VOLYNEC O, 1991. Geochemical types, petrology, and genesis of Late Cenozoic volcanic rocks from the Kurile-Kamchatka island-arc system[J]. International Geology Review, 36:373-405. DOI URL
[32]	WHITE N C, HEDENQUIST J, 1995. Epithermal gold deposits: styles, characteristics and exploration[J]. SEG Newsletter, 2:1-13.