ISSN 00167029, Geochemistry International, 2012, Vol. 50, No. 9, pp. 791–797. © Pleiades Publishing, Ltd., 2012. Original Russian Text © A.E. Budyak, N.N. Bryukhanova, 2012, published in Geokhimiya, 2012, Vol. 50, No. 9, pp. 881–888.
SHORT COMMUNICATIONS
Selenium, Bismuth, and Mercury in Black ShaleHosted Gold Deposits of Different Genetic Types A. E. Budyak and N. N. Bryukhanova Vinogradov Institute of Geochemistry, ul. Favorskogo 1a, Irkutsk, 664033 Russia email:
[email protected] Received May 12, 2010; accepted June 21, 2011
Keywords: selenium, bismuth, mercury, thiophiles, ore genesis, gold, black shales DOI: 10.1134/S0016702912070038
INTRODUCTION From a geochemical point of view, black shales in metamorphic and sedimentary complexes often show anomalous enrichment in ore and associated elements. Black shale units in different regions of the world host numerous gold, uranium, PGE, base metal, and other mineral deposits of different genetic types and signifi cance. Gold deposits hosted by carbonaceous sedimen tary–metamorphogenic complexes, which are consid ered by many geologists to represent the black shale sequence [1, 2], have different metal sources and min eralization models. This study aimed at understanding the behavior of the thiophile elements Hg, Bi, As, Se, and Te in the for mation of black shalehosted gold deposits of different genesis. The focus of our study was metamorphogenic hydrothermal gold deposits (Sukhoi Log and Golets Vysochaishy of the Bodaibo region, East Siberia) [3] and plutonrelated hydrothermal gold deposits (Prira zlomnoye of the Muya structural zone and Pogromnoye of the Shilka district, Chita oblast) [4]. The element concentrations in rocks were analyzed using fluorimetry with 2,3diaminonaphthalene for Se (with a detection limit (DL) of 0.04 ppm and a preci sion (sr) of 50%); atomic absorption spectrometry (AAS) for Bi (DL 0.1 ppm, sr 60%), Au (DL 0.005 ppm, sr 25%), and Ag (DL 0.001 ppm, sr 25%); hydride gen eration AAS for As; and coldvapor AAS for Hg (DL 0.002 ppm, sr 20%). GEOLOGIC FRAMEWORK OF THE DEPOSITS The Sukhoi Log and Golets Vysochaishy gold deposits are located in the central part of the Lena gold field within the Baikal–Patom Upland (BPU). From a geotectonic point of view, the BPU is considered as a rift
basin formed at the passive margin of Siberia during the Neoproterozoic [5]. The region is composed mainly of terrigenous and carbonate–terrigenous sedimentary rocks of Riphean and Vendian age. The rift basin is bounded to the south by a large Paleozoic granitoid massif of the Konkuder– Mamakan complex. A smaller granite massif known as the Konstantinovka stockwork occurs 6 km southwest of the Sukhoi Log deposit and is also assigned to the Konkuder–Mamakan complex. The Riphean carbonrich complexes of the BPU exhibit a distinct metamorphic zonation from amphib olite and epidoteamphibolite facies in the periphery of the synclinorium to lowgrade greenschist facies in its central part, which hosts most of the gold mineraliza tion of the Bodaibo region [6]. The Sukhoi Log and Golets Vysochaishy gold deposits are hosted by the Khomolkho Formation, which represents the upper member of the Dalnyaya Taiga horizon and consists of interbedded black and grey carbonaceous pelitic shales, aleuropelites, and subordinate sandstones. The content of carbonaceous material in the shales ranges from 0.5 to 5.0 wt %. Ele vated concentrations of Fe, Mg, Mn, P, as well as Au, Ni, Co, Cu, Zn, and Ag define the metallogenic trend of the formation [7]. Both deposits are confined to thirdorder structures. The mineralization of Golets Vysochaishy and Sukhoi Log occurs, respectively, in the hanging wall of the Kamenka anticline and the core of the Sukhoi Log southoverturned anticline. The commercial mineral ization is dominated by veinlet–disseminated quartz– sulfide occurrences. The principal ore minerals are native gold, pyrite, and pyrrhotite, whereas chalcopy rite, sphalerite, and marcasite are rare. The Vetvistoye deposit is confined to the syncolli sional Syulban fault of Late Riphean age. The deposit is located in the Muya structural zone of the Baikal
791
792
BUDYAK, BRYUKHANOVA
mountain region, within the area of occurrence of Riphean strata. The stratified complexes of the area comprise Late Riphean sedimentary and metamorphic sequences of the Syulban Group, which is divided into the Uryakh, UstUryakh, and Vodorazdelnaya blackshalebearing formations. Regional lineaments trending N–S and NE–SW [8] are traced by outcrops of the Riphean intrusive bodies of the Muya gabbro–granite subvolcanic series and volca nosedimentary rocks of the Kelyan Formation [9]. There are also outcrops of the Paleozoic intrusive bodies of the Konkuder–Mamakan complex, which is dominated by biotite and microcline–oligoclase granites hosting the main gold mineralization of the Muya zone [10]. The Syulban Group rocks are typically metamor phosed to greenschist facies (Uryakh, Ust–Uryakh, and Vodorazdelnaya formations). The host rocks and mineralized zones of the Vetvis toye deposit include metasomatically altered volca nosedimentary rocks of the Kelyan Formation at the contact with the carbonbearing sequences of the Vodorazdelnaya Formation. The rocks of the deposit area and the whole Tallai– Karolon zone show evidence for extensive metasomatic alteration (silicification, sericitization, etc.), which took place during Middle–Late Paleozoic time [11]. The Pogromnoye deposit is part of the Aprelkovo– Peshkovsky ore cluster (APOC) and located in the Shilka district of Chita oblast. The complex geologic structure of this area was formed as a result of the colli sion between the Mongolia–China and Siberian plates in the Jurassic and consists of a variety of sedimentary, metamorphic, and magmatic complexes of different ages. The majority of mesothermal gold occurrences in Transbaikalia are spatially and temporally associated with collisionrelated orogeny [12]. The stratified complexes of the area include Mid dle–Late Jurassic subcontinental volcanosedimentary sequences (Shadoron Group) and Quaternary sedi ments. The Shadoron Group (J2–3sd) is confined to isolated tectonic blocks and is represented by the Butorov For mation (J2–3bt) in the northwestern flank of the ore cluster. This formation is made up of sandstone, silt stone, and carbonaceous shale in its lower part and basaltic andesite, andesite, and dacite in its upper part. The Shadoron andesite–dacite complex (γδπ J2–3sd, ξ J23sd) forming a single association with the volcano plutonic rocks of the Shadoron Group consists of sub volcanic granodiorite porphyry, diorite porphyrite, and dacite. The Pogromnoye deposit is confined to one of the faults conjugated with the Mongolia–Okhotsk branch
of the suture zone. Fault thrusting (J3) due to strong compression generated a large amount of cataclasites and mylonites within the deposit area; they served as highpermeability conduits for hydrothermal fluids and have undergone the most intense hydrothermal meta somatism. Thus, the main difference in geologic setting between the above deposits is the amagmatic character of the ore field comprising the Sukhoi Log and Golets Vysochaishy deposits, on the one hand, and a clear link of the Pogromnoye and Vetvistoye deposits to magmatic activity, on the other hand. GEOCHEMICAL FEATURES OF ROCKS AND ORES FROM THE STUDIED DEPOSITS Selenium is often a pathfinder element for precious metals in epithermal Au–Ag and massive sulfide depos its containing gold and silver selenides [13]. Of particu lar interest in this respect will be variations in the con centrations of Se and other thiophile elements and their relationships at different stages of ore formation. As can be seen in the table, the metamorphogenic hydrothermal deposits (Sukhoi Log and Golets Vysoch aishy) exhibit an increase in Se, Bi, Au, and Ag and a decrease in Hg contents from the unaltered rocks to mineralized and orebearing shales. This trend is char acterized by a more than 10fold increase in Se, whereas the black shales demonstrate a 10–20fold increase in Bi and a 2–5fold increase in As, which is usually accompanied by S enrichment [14]. Strong Hg deple tion in the ore zone is characteristic of the Sukhoi Log type deposits (from 0.n to 0.0n ppm). Correlation analysis was used to explore relation ships between elements. It revealed correlations between two groups of elements, (Se, Bi, An) and (As, Hg, Ag), in the host rock samples. In the wallrock min eralization zone, the correlation disappears between all of the above elements except for Se and Bi, for which the correlation coefficient (r) is high enough (+0.67). Gold was found to correlate strongly only with As (r = +0.58). In the ore zone, a strong positive corre lation (r = 0.60–0.86) was established among all the above elements except for Hg, whose concentra tions show significant negative correlations with the other elements (r is –0.7 for Se, –0.6 for Bi and Au, and –0.5 for As and Ag). The correlations between the above elements in the host rocks of the Golets Vysochaishy deposit are similar to those of the Sukhoi Log deposit. In the wallrock min eralization zone, the relationships among the elements are also identical except for Au and Hg (r = 0.52). However, in the ore zone, the correlations between the elements are almost the same as at Sukhoi Log. Mercury shows a similar negative correlation with either the major oreforming components of the
GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
2012
SELENIUM, BISMUTH, AND MERCURY IN BLACK SHALEHOSTED GOLD DEPOSITS
793
Mean element contents in the rocks of the Sukhoi Log, Golets Vysochaishy, Vetvistoye, and Pogromnoye deposits Trace element content, ppm/standard deviation Bi
As
Hg
Au
Ag
Black shale (barren) 8*
0.37 0.14
0.1 0.1
16.61 9.31
0.191 0.145
0.087 0.097
0.19 0.13
Black shale (mineralized) 8*
0.65 0.25
0.6 0.6
13.11 2.90
0.216 0.036
0.520 0.753
1.04 0.99
Black shale (mineralized) 7*
1.49 1.10
1.7 2.0
25.64 16.49
0.033 0.038
10.235 11.224
3.05 3.15
Black shale (orebearing) 8*
0.37 0.14
0.1 0.1
16.61 9.31
0.191 0.145
0.087 0.097
0.19 0.13
Black shale (mineralized) 9*
1.70 0.74
0.6 0.4
3.17 2.05
0.128 0.134
0.042 0.035
0.50 0.49
Black shale (barren) 9*
4.10 2.24
2.7 2.2
11.13 7.54
0.019 0.031
53.551 57.564
9.21 10.48
Metasomatic rock (propylite) 5*
0.17 0.02
0.1 0.05
6.75 2.84
0.021 0.009
0.039 0.048
0.18 0.22
Metasomatic rock (beresite) 5*
0.19 0.04
0.1 0.05
3.75 0.76
0.021 0.009
7.002 7.484
7.31 10.23
Metasomatic rock (propylite) 5*
0.24 0.04
0.2 0.07
18.93 24.41
0.023 0.015
0.212 0.126
0.08 0.05
Quartz albitophyre 7*
0.25 0.07
0.2 0.16
181.53 231.2
0.011 0.005
0.539 0.627
0.12 0.04
Secondary quartzite 6*
0.25 0.10
0.3 0.1
538.51 498.2
0.029 0.014
1.264 1.203
0.20 0.13
Sukhoi Log
Se
Golets Vysochaishy
Host lithology
Vetvistoye
Deposit
Pogromnoye
Metamorphogenicmagmatic (hydrothermal)
Metamorphogenic hydrothermal
Ore deposit type
* Number of samples.
deposit (r is –0.48 for Au and –0.44 for Ag) or the asso ciated elements (r from –0.63 to –0.71). The analysis of the behavior of the above elements in the plutonrelated hydrothermal deposits (Vetvistoye and Pogromnoye) showed that the contents of Se and Bi in the unaltered rocks of these deposits are within the background range. In the zones of metasomatic alter ation, despite an increase in the intensity of sulfide min eralization and elevated Au content, both Se and Bi remain within the local background (table). Neverthe less, the absence of fluidassisted input of these ele ments into the oreforming system is accompanied by strengthening of their correlation with the ore compo nents, suggesting their redistribution in the ore zone during the mineralization stage (Fig. 1). The correlation analysis of the thiophile elements from the plutonrelated hydrothermal deposits revealed a significant relationship between the oreforming pro GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
cess and fluid composition as a result of the emplace ment of granitoid intrusions. There is almost no corre lation between the thiophile elements in the propylitic zone of the Vetvistoye deposit, with the sole exception of a strong correlation between Se and Au (r = 0.9). The concentration of As in this deposit does not exceed its average abundance in sedimentary rocks (7.6 ppm [15]) and have a negative correlation with all thiophile ele ments. The zone of beresitetype metasomatic alteration contains two groups of mutually correlated elements, (Bi, As, Au, Ag) and (Se, Hg), and the two groups show a strong antagonism. The absence of an enrichment in Bi, As, Se, and Hg during ore formation may indicate element mobilization by the Konkuder–Mamakan granitoids from the host rocks of the Kelyan and Vodor azdelnaya formations, which show anomalous concen trations of siderophile and chalcophile elements [4] and no addition of these elements by endogenic fluids. It is 2012
794
BUDYAK, BRYUKHANOVA Pogromnoye
Vetvistoye
1
1
0
0
–1
–1 Se
Bi
As
Hg
Propylite
Bi
Propylite
Beresite
Sukhoi Log
1
Se
Ag
As
Hg
Ag
Quartz Albitophyre
Quartzite
Golets Vysochaishy
1
0
0
–1
–1 Bi Se Host rock
As Hg Mineralized
Se
Ag Ore
Bi Host rock
As
Hg Mineralized
Ag Ore
Fig. 1. Correlation between Au and thiophile elements. The y axis shows the correlation coefficient (r) for the elements indicated along the x axis.
most likely that gold was mobilized from the host rocks by endogenic fluids and redeposited in the mineraliza tion zone at the final stage of deposit evolution. Three stages of metasomatic alteration were revealed at the Pogromnoye deposit. The early propylitic alter ation stage is characterized by significant positive corre lations between Au–Bi (r = 0.72) and Au–As (r = 0.57) and negative correlations between Au–Ag and Au–Hg (r = –0.76 and –0.57, respectively). The premineraliza tion stage accompanied by the formation of quartz alb itophyres added Se (r = 0.45) to the ore elements corre lated with Au, whereas Hg still exhibits a negative cor relation with all the above elements except for Ag. The main ore stage accompanied by the formation of “sec ondary quartzites” is characterized by positive correla tions between the above elements. This fact and the ele vated concentrations of As and Hg clearly indicate an additional source of the ore component at the late stage of deposit evolution. DISCUSSION It is well known that black shales contain mainly aquagenic organic matter, which is a natural pool of nitrogen and sulfur ligands. Therefore, their character istic elements are those prone to form compounds with nitrogen and sulfur, for instance, Se and Bi. Selenium occurs in the black shales as Se2– (CuSe, Cu2Se, etc.), Seorg, or an isomorphic component replacing sulfur in
sulfides (Sesulf.). Bismuth may form solid solutions and intermetallic compounds, ((Ag, Pb)(TeBi), Pd, Ag)(TeBi), (Bi, Te), Bi3+–PbBi2S4, etc.; Hg also forms solid solutions and intermetallic compounds (Au, Ag, Cu, Hg, etc.) or Hgorg and Hgsulf; As occurs as arsenides (NiAs, Ni9As11, (Co, Ni)As3, NiAsS, FeAsS, etc.) or as Asorg, and Au and Ag may occur in their native forms, as solid solutions, intermetallic compounds, tellurides, etc. [16, 17]. A distinctive feature of the Sukhoi Logtype deposits is an enrichment in Se from the unaltered to mineral 0.65 ized and orebearing shales (0.37 1.7 4.1 ppm at 1.49 ppm at Sukhoi Log; 0.4 Golets Vysochaishy), which can be explained by sele nium bonding by organic matter at deep structural posi tions [17] and its subsequent deposition in structural traps under specific P–T conditions. Tagirov and Baranova [18] experimentally dem onstrated that the enrichment of fluids in hydrogen selenide (mH2Se ~ 10–4 mol kg–1 at 250°С and ~10–2 mol kg–1 at 450°С) can lead to precipitation of the ore component from the fluid. The equilibrium concentration of the metal is much less than that in the absence of Se. Therefore, according to [18], the pres ence of hydrogen selenide in the hydrothermal system is a key factor controlling ore component precipitation. Despite our limited knowledge of the geochemistry of Bi in black shales, the results of this study indicate
GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
2012
SELENIUM, BISMUTH, AND MERCURY IN BLACK SHALEHOSTED GOLD DEPOSITS Sukhoi Log
Golets Vysochaishy
Pogromnoye
Vetvistoye
6
1
5
2
4
3
Se (ppm)
Se (ppm)
795
3 2
1
1 R
O
R
0
O
R
O
R
O
R
O
R
O
5
3
Bi (ppm)
Bi (ppm)
4
2 1 R
O
R
1 0
O
R
O
4 Hg (ppm)
Hg (ppm)
5
3 2
2 1
1 R
O
R
O
R
O
Fig. 2. Contents of Se, Bi, and Hg in the host rocks and ores of the Sukhoi Logtype and Zunkholbatype deposits. R is host rock, and O is ore zone. (1) Unaltered rock, (2) premineralization zone, and (3) ore zone.
that the geochemical behavior of Bi during ore forma tion is similar to that of Se. The Sukhoi Logtype depos its show increasing Bi and Se contents during ore for mation (0.12 0.58 1.57 ppm at Sukhoi Log and 0.12 0.63 2.74 ppm at Golets Vysochaishy) (Fig. 2). In the plutonrelated hydrothermal deposits, both Bi and Se show an inert behavior in black shales. Their contents are close to their average abundances in the host rocks, with virtually no trend toward enrichment during ore formation (Fig. 2). As organophile elements, they exhibit no enrichment in the ore zone because of the minor role of organic matter in this type of ore forming process. Of critical importance here are gran GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
ites and hydrothermal solutions, and Se and Bi have no genetic link to them. The behavior of Hg clearly reflects the different gen esis of the deposits. A sharp decrease in Hg concentra tions in the ore zone of the Sukhoi Logtype deposits (Fig. 2) can be explained by Hg mobility at tempera tures much lower than those characteristic of the Sukhoi Logtype mineralization and by a remarkably high Hg sorption by micas (chlorite, sericite, and mus covite), which may cause Hg enrichment in the upper stratigraphic levels where strong silicification and seric itization occur. The absence of Hg input from deeper layers at the later (metamorphogenic) stage of ore for mation [3] indicates the formation of the ore deposit without involvement of an additional deep source. 2012
796
BUDYAK, BRYUKHANOVA
The behavior of Hg diverges most strikingly in plu tonrelated hydrothermal deposits. For example, the Vetvistoye deposit exhibits no Hg addition from the environment. Its ore zone has a much stronger negative correlation between Hg and Au than the metasomatic wall rocks (Fig. 1), which may indicate the different sources of these elements within the deposit area and, hence, the absence of a genetic link between the metal and the endogenic fluid generated by the emplacement of the Konkuder–Mamakan granitoids. However, the Hg content of “secondary quartzites” hosting mineralization at the Pogromnoye deposit is higher than that of premineralization quartz albito phyres, suggesting Hg input along major faults. Simul taneously, the correlation of Hg with Au increases. This supports the presence of a common endogenic source of Au and Hg at the late stage of deposit formation. In this study, several interesting results were obtained from As distribution in the deposits (table). It was shown that the As content increases from the unaltered to mineralized and orebearing shales at Sukhoi Log type deposits. As regards the formation of ore deposits related to granitoid magmatism controlled by thrust faults as a key source of heat and fluid, it can be assumed that As concentrations in oreforming processes are strongly dependent on the chemistry of the fluid which controls ore mobilization. The extremely irregular distribution of the high con centrations of As and associated components in rocks of similar composition from metamorphogenic/magmatic ore deposits confirms their epigenetic origin and con finement to fracture systems. CONCLUSIONS The results on thiophile element distribution (espe cially, Se, Bi, and Hg) clearly indicate the different gen esis of the Sukhoi Logtype deposits (Sukhoi Log and Golets Vysochaishy) and deposits formed by fault related granitoid magmatism, which served as the main heat and fluid source (Vetvistoye and Pogromnoye). The attempt to assign all the above gold deposits to the Sukhoi Log type [19] seems to be unjustified. It is most likely that Sukhoi Logtype deposits are confined exclusively to the Bodaibo synclinorium in terms of both a source for the ore components and the process of ore mineral formation. This was confirmed by Tauson et al. [20], who performed comprehensive structural investigations and suggested that carbonbearing phases, pyrite, and gold are cogenetic in the ores of the Sukhoi Log deposit, which indicates the presence of metalliferous naphthides in hydrothermal–metaso matic fluids during formation of veinlet–disseminated ore mineralization. Specific nanometersized struc tures on the surface of pyrite crystals (nanopits and nanoscratches) may be produced by sulfurreducing bacteria. Similar nanometersized structures are typo
morphic features of pyrites from the Sukhoi Log deposit but are not typical of endogenetic and synthetic pyrites. Our results suggest that the behavior of Se, Bi, and Hg can be useful indicators of the genetic type of black shalehosted Au deposits. Variations in element con centrations and correlations between elements in the rocks and ores of Au deposits at different stages of min eralization are indicators of the source of ore compo nents and their transport and deposition mechanisms up to commercial grade concentrations at different thermodynamic and geochemical barriers. ACKNOWLEDGMENTS This study was supported by the Russian Foundation for Basic Research, project no. 110500084a. REFERENCES 1. B. Ya. Vikhter, “Main Characteristics of the Host Ter rigenous Complexes of the Bakyrchik Gold Deposits,” Rudy Met., No. 5, 58–68 (2007). 2. Ch. Kh. Arifulov and I. V. Arsen’t’eva, “Conditions of Formation of Gold Deposits in Black Shale Sequences,” in Proceedings of Scientific Conference (2007), Vol. 1, pp. 151–155. 3. V. K. Nemerov, A. M. Spiridonov, E. A. Razvozzhaeva, N. L. Matel’, A. E. Budyak, and A. M. Stanevich, “Major Factors of the Ontogenesis of Sukhoi LogType NobleMetal Deposits,” Otechestvennaya Geol., No. 3, 17–24 (2005). 4. A. E. Budyak, Extended Abstract of Candidate’s Dis sertation in Geology and Mineralogy (Inst. Geochem., Sib. Branch, Russ. Acad. Sci., Irkutsk, 2009). 5. V. K. Nemerov and A. M. Stanevich, “Evolution of the Riphean–Vendian Biolithogenesis Setting in the Baikal Mountainous Area,” Russ. Geol. Geophys. 42 (3), 456–470 (2001). 6. V. A. Buryak and N. M. Khmelevskaya, Sukhoi Log— One of the World’s Largest Gold Deposits: Genesis, Distri bution of Mineralization, and Prediction Criteria (Dal’nauka, Vladivostok, 1997) [in Russian]. 7. V. K. Nemerov, Extended Abstracts of Candidate’s Dis sertation in Geology and Mineralogy (Irkutsk, 1989) [in Russian]. 8. A. V. Pertsov, B. C. Antipov, G. V. Gal’perov, and S. I. Gurchenko, “Lineament Network Controlling the Distribution of Superlarge Mineral Deposits in Rus sia,” Dokl. Earth Sci. 383 (2), 134–136 (2002). 9. A. M. Stanevich and V. A. Zheleznyakov, “Discovery of Acritarch Microbiota in the Kelyan Sequence of the Middle Vitim,” in Late Precambrian and Early Paleo zoic of Siberia. Problems of Regional Stratigraphy (IGiG SO RAN, Novosibirsk, 1990), pp. 135–146 [in Rus sian]. 10. A. E. Vladimirov, N. K. Korobeinikov, and I. V. Chet vertakov, “Report of the DelyunUranskaya Team Activity in 1995–2001 "Geological Additional Study on a 200 000 Scale and Preparation to the Publishing of a Set of Geological Map200, Sheet O5025 (Muya Series)” (2001) [in Russian].
GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
2012
SELENIUM, BISMUTH, AND MERCURY IN BLACK SHALEHOSTED GOLD DEPOSITS 11. Yu. Ya. Koshelev and V. S. Chechetkin, “Gold of the Chita North: Geology, State of Knowledge, and Pros pects,” in Problems of Ore Formation, Search, and Assessment of Mineral Resources: Proceedings of All Russian Conference Devoted to the 110th Anniversary of S.S. Smirnov (SO RAN, Novosibirsk, 1996), pp. 160– 165 [in Russian]. 12. A. M. Spiridonov, L. D. Zorina, and N. A. Kitaev, Gold Bearing OreMagmatic Systems of Transbaikalia (GEO, Novosibirsk, 2006) [in Russian]. 13. V. A. Kovalenker, “OreForming Systems of Epither mal Gold–Silver Deposits: Concepts, Reality, and Models,” in Problems of Ore Geology, Petrology, and Geochemistry (IGEM RAN, Moscow, 2004), pp. 160– 183 [in Russian]. 14. Ya. E. Yudovich and M. P. Ketris, “Selenium in the Pai Khoi Black Shales,” Geokhimiya, No. 11, 1767–1774 (1984). 15. N. A. Grigor’ev, “Clarke Content of Chemical Ele ments in the Upper Continental Crust,” Litosfera, No. 1, 61–71 (2002).
GEOCHEMISTRY INTERNATIONAL
Vol. 50
No. 9
797
16. V. V. Distler, G. L. Mitrofanov, and V. K. Nemerov, V. A. Kovalenker, A. V. Mokhov, L. K. Semeikina, and M. A. Yudovskaya, “Modes of Occurrence of the Plati num Group Elements and Their Origin in the Sukhoi Log Gold Deposit (Russia),” Geol. Ore Dep. 38 (6), 413–428 (1996). 17. Ya. E. Yudovich and M. P. Ketris, “Trace Elements in Black Shales” (Nauka, Yekaterinburg, 1994) [in Rus sian]. 18. B. R. Tagirov and N. N. Baranova, “Experimental Data on the Role of Selenium in Hydrothermal Silver Trans port,” Geochem. Int. 47 (6), 628–633 (2009). 19. V. A. Buryak and A. E. Perestronin, Malomyr—the First Sukhoi LogType Large Gold Deposits in the Amur Region (Blagoveshchensk–Khabarovsk, 2000) [in Rus sian]. 20. V. L. Tauson, V. K. Nemerov, E. A. Razvozzhaeva, A. M. Spiridonov, S. V. Lipko, A. E. Budyak, “Parage netic Relationships between Pyrite, Carbon, and Gold at the Sukhoi Log Deposit and Typomorphism of the Pyrite Surface,” Dokl. Earth Sci. 426 (4), 690–694 (2009).
2012
