Geology of the World’s Major Gold Deposits and Provinces最新文献

{"title":"Chapter 2: Metallogeny of the Neoarchean Malartic Gold Camp, Québec, Canada","authors":"Stéphane Souza De, S. Perrouty, B. Dubé, P. Mercier-Langevin, R. Linnen, G. Olivo","doi":"10.5382/sp.23.02","DOIUrl":"https://doi.org/10.5382/sp.23.02","url":null,"abstract":"The Malartic gold camp is located in the southern part of the Archean Superior Province and straddles the Larder Lake-Cadillac fault zone that is between the Abitibi and Pontiac subprovinces. It comprises the world-class Canadian Malartic deposit (25.91 Moz, including past production, reserves, and resources), and smaller gold deposits located along faults and shear zones in volcanic and metasedimentary rocks of the Abitibi subprovince. North of the Larder Lake-Cadillac fault zone, the Malartic camp includes 2714 to 2697 Ma volcanic rocks and ≤2687 Ma turbiditic sedimentary rocks overlain by ≤2679 to 2669 Ma polymictic conglomerate and sandstone of the Timiskaming Group. South of the fault, the Pontiac subprovince comprises ≤2685 Ma turbiditic graywacke and mudstone, and minor ultramafic to mafic volcanic rocks and iron formations of the Pontiac Group. These supracrustal rocks were metamorphosed at peak greenschist to lower amphibolite facies conditions at ~2660 to 2658 Ma, during D2 compressive deformation, and are cut by a variety of postvolcanic intrusions ranging from ~2695 to 2640 Ma. The Canadian Malartic deposit encompasses several past underground operations and is currently mined as a low-grade, open-pit operation that accounts for about 80% of the past production and reserves in the camp. It dominantly consists of disseminated-stockwork replacement-style mineralization in greenschist facies sedimentary rocks of the Pontiac Group. The mineralized zones are spatially associated with the Sladen fault and ~2678 Ma subalkaline to alkaline porphyritic quartz monzodiorite and granodiorite. Field relationships and isotopic age data for ore-related vein minerals indicate that gold mineralization in the Canadian Malartic deposit occurred at ~2665 to 2660 Ma and was contemporaneous with syn- to late-D2 peak metamorphism. The smaller deposits in the camp include auriferous disseminated-stockwork zones of the Camflo deposit (1.9 Moz) and quartz ± carbonate-pyrite veins and breccias (0.6 Moz) along faults in chemically and mechanically favorable rocks. The age of these deposits is poorly constrained, but ~2692 Ma postmineral dikes, and ~2625 Ma hydrothermal titanite and rutile from the Camflo deposit highlight a long and complex hydrothermal history. Crosscutting relationships and regional geochronological constraints suggest that an early episode of pre-Timiskaming mineralization occurred at >2692 Ma, shortly after the end of volcanism in the Malartic camp, and postmetamorphic fluid circulation may have contributed to concentration or remobilization of gold until ~2625 Ma. However, the bulk of the gold was concentrated in the Canadian Malartic deposit during the main phase of compressive deformation and peak regional metamorphism.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79369170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 35: Gold Deposits of the Jiaodong Peninsula, Eastern China","authors":"K. Qiu, R. Goldfarb, Jun Deng, Hao‐Cheng Yu, Zong-Yang Gou, Zhengjiang Ding, Zhaopeng Wang, Da-peng Li","doi":"10.5382/sp.23.35","DOIUrl":"https://doi.org/10.5382/sp.23.35","url":null,"abstract":"The Jiaodong gold province, within the eastern margin of the North China block and the translated northeastern edge of the South China block, has a stated premining gold resource exceeding 4,500 metric tons (t). It is thus one of the world’s largest gold provinces, with a present cumulative annual production estimated at 60 t Au. More than 90% of the Jiaodong gold resource is hosted by batholiths and related bodies of the Linglong (ca. 160–145 Ma) and, to a lesser degree, Guojialing (ca. 130–122 Ma) suites. The intrusions were emplaced into high-grade metamorphic basement rocks of the Precambrian Jiaobei (North China block) and Sulu (South China block) terranes during a 70-m.y.-period of lithospheric delamination, extensional core complex formation, and exhumation. The deposits are located about 20 to 200 km to the east of the continental-scale NNE-striking Tancheng-Lujiang (Tan-Lu) strike-slip fault system. They occur along a series of more regional NNE- to NE-striking brittle and ductile-brittle faults, which appear to intersect the Tan-Lu main structure to the southwest. This system of early to middle Mesozoic regional thrust faults, reactivated during Cretaceous normal motion and ore formation, tends to occur along the margins of the main Linglong batholiths or between intrusions of the two suites of granitoids. Orebodies are mainly present as quartz-pyrite veins (Linglong-type) and as stockwork veinlets and disseminated mineralization (Jiaojia-type). The two mineralization styles are transitional and may be present within the same gold deposit. The ca. 120 Ma timing of gold mineralization correlates with major changes in plate kinematics in the Pacific Basin and the onset of seismicity along the Tan-Lu fault system, with the enormous fluid volumes and associated metal being derived from sediment devolatilization above the westerly subducting Izanagi slab.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90339538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 34: The Paleoproterozoic (Rhyacian) Gold Deposits of West Africa","authors":"N. Thébaud, A. Allibone, Q. Masurel, A. Eglinger, James Davis, A. André-Mayer, J. Miller, Morou François Ouedrago, M. Jessell","doi":"10.5382/sp.23.34","DOIUrl":"https://doi.org/10.5382/sp.23.34","url":null,"abstract":"Paleoproterozoic terranes of the Man-Leo Shield in the southern part of the West African craton host one of the world’s largest gold provinces with an overall endowment >10,000 metric tons (t). Although gold deposition commenced by ca. 2170 Ma, most deposits formed later, either during the inversion and metamorphism of intraorogenic sedimentary basins between ca. 2110 and 2095 Ma, or during later transcurrent deformation and associated widespread high K plutonism following docking of Archean and Paleoproterozoic domains within the craton at ca. 2095 Ma. Deposits formed between ca. 2110 and 2095 Ma include those with free gold in quartz veins and refractory gold in arsenopyrite and/or pyrite, and are associated with halos of carbonate, sericite, chlorite, and albite alteration. Most are located in bends and intersections between shear zones, minor faults, folds, and entrained blocks of relatively reactive igneous rock. Conglomerate-hosted gold deposits of the Tarkwa district formed early in the 15-m.y.-long period. Gold deposits that formed subsequently between ca. 2095 and 2060 Ma have a wider variety of styles, geologic settings, and metal assemblages. District-scale albite, carbonate, and tourmaline alteration, hydrothermal breccias, and a close relationship to high K granitoids characterize some of these deposits, whereas others are more typical orogenic gold deposits that are similar to those formed earlier during the craton evolution.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80649627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 28: Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea","authors":"D. Cooke, S. Sykora, Erin Lawlis, J. L. Blackwell, M. Ageneau, N. Jansen, A. Harris, D. Selley","doi":"10.5382/sp.23.28","DOIUrl":"https://doi.org/10.5382/sp.23.28","url":null,"abstract":"The Lihir gold deposit, Papua New Guinea, is the world’s largest alkalic low-sulfidation epithermal gold deposit in terms of contained gold (50 Moz). The deposit formed over the past million years and records a progression from porphyry- to epithermal-style hydrothermal activity. The early porphyry stage was characterized by biotite-anhydrite-pyrite ± K-feldspar ± magnetite alteration and weak gold ± copper mineralization and produced abundant anhydrite ± carbonate veins and anhydrite ± biotite-cemented breccias. These features collectively characterize the deep-seated anhydrite zone at Lihir. Several hundred thousand years ago, one or more catastrophic mass-wasting events unroofed the porphyry system after porphyry-stage hydrothermal activity ceased. Mass wasting may have been facilitated in part by dissolution of porphyry-stage anhydrite veins. Epithermal mineralization occurred after sector collapse, resulting in phreatic and hydraulic brecciation and veining, widespread adularia-pyrite ± carbonate alteration, and formation of mineralized zones at Lienetz, Minifie, Kapit, Kapit NE, Coastal, and Borefields. A NE- to ENE-striking fault array localized several of these orebodies. The pyrite-rich veins and pyrite-cemented breccias that formed during epithermal-stage hydrothermal activity define the sulfide zone at Lihir. This zone mostly contains refractory gold in pyrite, with minor free gold and precious metal tellurides hosted in late-stage quartz veins. A period of diatreme volcanism disrupted the Luise amphitheater during the latter stages of epithermal mineralization. The diatreme breccia complex truncated several of the epithermal ore zones and was crosscut locally by late-stage epithermal veins. Recent geothermal activity produced a steam-heated clay alteration blanket that has overprinted the refractory sulfide-rich epithermal assemblage near the present-day land surface. Gold was remobilized downward from the steam-heated zone into the sulfide zone during argillic and advanced argillic alteration, producing thin gold-rich rims around pyrite grains. This process produced a high-grade tabular enrichment zone immediately beneath the base of the clay blanket.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"126 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85398246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 18: Geology of Round Mountain, Nevada: A Giant Low-Sulfidation Epithermal Gold Deposit","authors":"D. Rhys, Nadia St. Jean, R. Lagos, David L. Emmons, G. Schroer, R. Friedman","doi":"10.5382/sp.23.18","DOIUrl":"https://doi.org/10.5382/sp.23.18","url":null,"abstract":"The Round Mountain low-sulfidation epithermal Au deposit occurs within the rhyolitic tuff of Round Mountain (26.86 Ma) on the northeast side of an elliptical volcanic center that has morphology and volcanic facies suggesting it originated as a caldera. The hosting tuff comprises three pyroclastic flow and fall deposits (units T1 to T3). These are overlain successively by lacustrine sediments and volcaniclastic rocks. which may contain paleowater table levels formed at the time of ore formation and a 26.4 Ma postmineralization tuff unit. A linear vertical drop in the basement contact coincides with thick tuff fill and megabreccia, which is interpreted to follow the position of a WNW-trending ring fissure or vent wall that may have focused the locations of subsequent hydrothermal upflow zones. Orebodies are developed in strata-bound zones that are most extensive in poorly welded tuff, focused below overlying impermeable welded tuff in a WNW-trending, gently NW-plunging corridor above and mantling the SW-dipping paleoslope of basement rocks. Ore comprises disseminated pervasive adularia-quartz-pyrite ± illite alteration with electrum. The disseminated mineralization surrounds, and is most intensely developed in association with, a low-displacement extensional fault-vein network composed of conjugate NE- and SW-dipping faults and steeply dipping extensional veins. Vein orientations and kinematic indicators suggest ore formation occurred during localized NE-SW-directed extension that may have been related to late stages of volcanic subsidence, potentially in association with deep resurgent magmatism into ring fissures approximately 0.5 m.y. after deposition of the host tuff sequence.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80493376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 10: Olympiada Gold Deposit, Yenisei Ridge, Russia","authors":"A. M. Sazonov, K. Lobanov, E. Zvyagina, S. I. Leontiev, S. A. Sil’yanov, N. Nekrasova, A. Nekrasov, A. B. Borodushkin, V. A. Poperekov, V. Zhuravlev, S. S. Ilyin, Y. Kalinin, A. Savichev, A. Yakubchuk","doi":"10.5382/sp.23.10","DOIUrl":"https://doi.org/10.5382/sp.23.10","url":null,"abstract":"The Olympiada deposit, containing >1,560 metric tons (t; 50 Moz) of gold at an average grade of 4 to 4.6 g/t Au, occurs in central Siberia, Russia. Over 30 years, the deposit produced more than 580 t of gold, including 200 t from oxidized ore grading 11.1 g/t. The deposit forms a 2-km-long, steeply dipping system, which is traced downdip for 1.7 km. It occurs in the Neoproterozoic orogen of the Yenisei Ridge at the western margin of the Siberian craton. This and other gold deposits in the district are controlled by the large, long-lived Tatarka-Ishimbino tectonic zone, marking a suture between terranes chiefly consisting of deformed Meso- to Neoproterozoic carbonate-clastic sedimentary rocks. The combination of lithologic and structural factors was critical for localization of gold mineralization associated with calcic and siliceous alteration accompanied by early arsenic and late antimony sulfides. As a result, very fine (10 μm) and high fineness (910–997) gold associates with diverse sulfides, especially arsenopyrite, and commonly contains mercury, similar to some characteristics of Carlin-type deposits. Geochronologic studies suggest that mineralization was formed during several stages between 817 and 660 Ma. The isotopic composition of Os and He, along with presence of anomalous Ni, Co, and Pt, points to a mantle mafic source, whereas isotopic composition of Pb and S suggest a contaminated crustal source, i.e., originating from a mix of mantle and crustal fluids.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91299341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 9: Orogenic Gold Deposits of the Kibali District, Neoarchean Moto Belt, Northeastern Democratic Republic of Congo","authors":"A. Allibone, C. Vargas, E. Mwandale, Justus Kwibisa, R. Jongens, Sarah Quick, Nathan Komarnisky, M. Fanning, P. Bird, D. MacKenzie, R. Turnbull, J. Holliday","doi":"10.5382/sp.23.09","DOIUrl":"https://doi.org/10.5382/sp.23.09","url":null,"abstract":"The Kibali district in the Democratic Republic of Congo hosts the large Karagba-Chaffeur-Durba (KCD) deposit and smaller satellite deposits that together contained 20 million ounces (Moz) of gold when mining recommenced in 2013. An additional 3 Moz of gold was probably mined from the district before 2013. Gold deposits in the Kibali district are located along the KZ trend, a series of folds, contractional shear zones, and altered lithostratigraphic units that coincide with the margin of an earlier 2630 to 2625 Ma intraorogenic basin within the Neoarchean Moto belt. Fluids first responsible for barren carbonate-quartz-sericite alteration, and later for siderite and/or ankerite (±quartz, magnetite, pyrite, and/or chlorite) alteration with associated auriferous pyrite ± rare arsenopyrite veinlets, infiltrated and replaced the siliciclastic, banded iron formation (BIF), and chert host rocks via fold axes, shear zones, and reactive BIF horizons. The complex shape and gentle northeast plunge of the lodes across the Kibali district reflect the shape and plunge of coincident folds that formed during early barren alteration. Many other folded BIF horizons across the wider Moto belt remain barren or only weakly mineralized, suggesting deep extensional structures that may have developed in the vicinity of the KZ trend during basin opening and prior to gold mineralization, were important fluid pathways during later contractional deformation and mineralization.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88972165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 36: Carlin-Type Gold Deposits in Nevada: Geologic Characteristics, Critical Processes, and Exploration","authors":"John L. Muntean","doi":"10.5382/sp.23.36","DOIUrl":"https://doi.org/10.5382/sp.23.36","url":null,"abstract":"Carlin-type gold deposits in Nevada account for ~5% of worldwide annual gold production, typically about ~135 metric tons (t) (~4.5 Moz) per year. They are hydrothermal epigenetic replacement bodies hosted predominantly in carbonate-bearing sedimentary rocks. They are known for their “invisible” gold that occurs in the crystal structure of pyrite. Over 95% of the production from these deposits is from four clusters of deposits, which include the Carlin trend and the Cortez, Getchell, and Jerritt Canyon camps. Despite differences in the local geologic settings, the characteristics of the deposits are very similar in the four clusters. Shared characteristics include: (1) alteration characterized by carbonate dissolution, silicate argillization, and silicification; (2) ore formation characterized by auriferous arsensian pyrite, typically as rims on preore pyrite, followed by late open-space deposition of orpiment, realgar, stibnite, and other minerals; (3) Ag/Au ratios of <1 in ore; (4) an As-Hg-Sb-Tl geochemical signature; (5) low temperatures (~160°–240°C) and salinities of ore fluids (~1–6 wt % NaCl equiv) and fairly shallow depths of formation (<~2–3 km); and (6) lack of mineral and elemental zoning around ore. The four clusters share regional geologic controls related to formation as follows: (1) along the rifted margin of a craton, (2) within the slope facies of a passive margin sequence dominated by carbonates, (3) in the lower plate of a regional thrust fault, and (4) during a narrow time interval in the late Eocene (~42–34 Ma). The geometries and ore controls of the deposits in the four clusters are also very similar. At the deposit scale, ore and hydrothermal alteration are commonly associated with high-angle faults and preore low-angle contractional structures, including thrust faults and folds. The high-angle faults acted as fluid pathways for upwelling ore fluids, which were then diverted into lower angle favorable strata and contractional structures, where fluid-rock interaction led to replacement of carbonate and formation of ore. Rheologic contrasts between lithologies were also critical in diverting fluids into wall rocks. Common rheologic contrasts include contacts between thin- and thick-bedded lithologic units and the margins of contact metamorphic aureoles associated with Mesozoic intrusions. The similarities suggest common processes. Four critical processes are apparent: (1) development of source(s) for gold and other critical components of the ore fluids, (2) formation of fluid pathways, (3) water-rock interaction and gold deposition, and (4) a tectonic trigger, which was renewal of magmatism and a change from contraction to extension in the late Eocene. Consensus exists on these processes, except for the source of gold and other components of the ore fluid, with most models calling upon either a magmatic-hydrothermal source or a crustal source, where metals were scavenged by either meteoric or metamorphic fluids. Future res","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82884214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 7: Paleoproterozoic Gold Deposits of the Loulo District, Western Mali","authors":"A. Allibone, D. M. Lawrence, J. Scott, M. Fanning, J. Lambert-Smith, P. Stenhouse, Reinet Harbidge, C. Vargas, R. Turnbull, J. Holliday","doi":"10.5382/sp.23.07","DOIUrl":"https://doi.org/10.5382/sp.23.07","url":null,"abstract":"Paleoproterozoic (Rhyacian) gold deposits of the Loulo district in western Mali contain >17 million ounces (Moz) Au and form part of the second most highly endowed region within West Africa. The deposits are located within siliciclastic, marble, and evaporitic rocks of the ca. 2110 Ma greenschist facies Kofi series, which were folded and inverted between ca. 2100 and 2070 Ma, prior to gold mineralization. Deposits at Yalea and Gounkoto are located along discontinuous, low-displacement, albite- and carbonate-altered shear zones, whereas Gara is confined to a tourmaline-altered quartz sandstone unit. Lodes typically plunge gently to moderately, reflecting the attitude of folds in the adjacent rocks and bends in the host shear zones, both of which influenced their location. Gold mineralization in the Loulo district was broadly synchronous with emplacement of the Falémé batholith and associated Fe skarn mineralization, which intrude and overprint the western margin of the Kofi series, respectively. However, hydrothermal fluids generated during metamorphic devolatilization of the Kofi series rocks appear responsible for gold mineralization, albeit within a district-wide thermal gradient associated with emplacement of the Falémé batholith. The regional-scale Senegal-Mali shear zone, commonly cited as an important control on the location of gold deposits in western Mali, is absent in the Loulo district.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78932146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 26: Geology of the Hishikari Gold Deposit, Kagoshima, Japan","authors":"Takayuki Seto, Y. Yamato, Ryota Sekine, E. Izawa","doi":"10.5382/sp.23.26","DOIUrl":"https://doi.org/10.5382/sp.23.26","url":null,"abstract":"The bonanza-grade, low-sulfidation epithermal Hishikari gold deposit is located in the Plio-Pleistocene volcanic area of southern Kyushu, Japan. The concealed veins were discovered in 1981 and the mine has since produced 5.462 million metric tons (Mt) of ore averaging 44.3 g/t Au (242 t Au) from 1985 to the end of 2018, at which time reserves were 7.98 Mt at 20.9 g/t Au. The Hishikari deposit consists of the Honko, Sanjin, and Yamada ore zones, which occur in a NE-trending area 2.8 km long and 1.0 km wide. The veins are hosted by basement sedimentary rocks of the Cretaceous Shimanto Supergroup and by overlying Hishikari Lower Andesites of Pleistocene age. Sinter occurs about 100 m above the Yamada ore zone. Temperature-controlled hydrothermal alteration zones occupy an area of >5 km long and 2 km wide. The Honko and Sanjin veins occur within a chlorite-illite alteration zone (paleotemperature >230°C), whereas the Yamada veins occur within an interstratified clay mineral zone (150°–230°C). The marginal alteration comprises quartz-smectite (100°–150°C) and cristobalite-smectite (<100°C) zones. Ore-grade veins are located between –60- and 120-m elev, with the paleowater table over the Honko-Sanjim veins at ~300-m elev. Overall, the Ag/Au wt ratio is about 0.6. Vein-forming minerals consist of quartz, adularia, and clay minerals plus truscottite, with electrum and minor pyrite, chalcopyrite, naumannite, galena, and sphalerite. The major veins formed from repeated episodes of boiling and strong fluid flow inferred from bands of quartz, adularia, and smectite with bladed quartz, columnar adularia, and truscottite.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"98 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76060552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}