C. Leys, A. Schwarz, M. Cloos, S. Widodo, J. Kyle, J. Sirait
The supergiant Grasberg porphyry deposit in Papua, Indonesia (5.26 Gt @ 0.61% Cu and 0.57 g/t Au, with no cutoff applied) is hosted by the Grasberg Igneous Complex that fills an upward-flared diatreme ~1,800 m wide at the 4,250-m surface elevation. The Grasberg Igneous Complex is emplaced into folded and strike-slip faulted Tertiary and older sediments and comprises 3.6 to 3.3 Ma Dalam monzodiorite intrusions and subordinate volcanic rocks occupying much of the pipe, the central 3.2 Ma Main Grasberg intrusion, and the NW-SE-trending 3.2 to 3.0 Ma Kali dikes. The Grasberg Igneous Complex contains two porphyry systems: Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold. The Gajah Tidur intrusion belongs to the Dalam igneous group and is a 3.4 Ma porphyritic monzonite with its top at a 2,750-m elevation; it is overprinted by an extensive, domal, quartz stockwork, with a low-grade and intensely phyllic-altered core, surrounded by molybdenite-bearing veins, with a pre-Main Grasberg Re-Os age, as well as chalcopyrite and overprinting pyrite-covellite veins. The strongly potassic-altered, Main Grasberg monzodiorite porphyry extends from surface to the 2,700-m elevation and is overprinted by a cylindrical, ~1-km-diameter, intense quartz-magnetite stockwork cut by abundant chalcopyrite-bornite veins with rare molybdenite dated at 3.09 Ma. A 700-m-wide annulus of chalcopyrite overprinted by pyrite-covellite-mineralized phyllic alteration surrounds the stockwork. Altered and mineralized Main Grasberg and surrounding Dalam rocks were subsequently wedged apart by the largely unmineralized Kali dikes. Gold is predominantly associated with the Main Grasberg porphyry system where it occurs as 1- to 150-µm (avg ~15 µm) native gold inclusions within chalcopyrite and bornite. Melt and fluid inclusions from Main Grasberg stockwork quartz veins, which exhibit crack-seal textures, comprise K-feldspar-rich silicate melt, sulfide melt, virtually water-free salt melt, and coexisting hypersaline and vapor-rich fluids. Factors important in forming the Grasberg deposit include the following: (1) generation of highly oxidized fertile magma in a postsubduction tectonic setting; (2) efficient extraction of metals from the parental magma chamber; (3) prolonged maintenance of a fluid-accumulating cupola in a strike-slip structural setting that delivered multiple overlapping discharges of metal-rich fluid; (4) highly focused fluid flow into a narrow, permeable stockwork zone in which a steep temperature gradient enabled highly efficient copper and gold precipitation and led to high ore grades; (5) limited dilution by postmineral intrusions; (6) the youthfulness of the deposit minimized erosion and resulted in preservation of nearly all the high-grade Main Grasberg porphyry orebody; and (7) the proximity of the two porphyry centers enables them to be mined as a single, large deposit. The Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold porphyry centers
{"title":"Chapter 29: Grasberg Copper-Gold-(Molybdenum) Deposit: Product of Two Overlapping Porphyry Systems","authors":"C. Leys, A. Schwarz, M. Cloos, S. Widodo, J. Kyle, J. Sirait","doi":"10.5382/sp.23.29","DOIUrl":"https://doi.org/10.5382/sp.23.29","url":null,"abstract":"The supergiant Grasberg porphyry deposit in Papua, Indonesia (5.26 Gt @ 0.61% Cu and 0.57 g/t Au, with no cutoff applied) is hosted by the Grasberg Igneous Complex that fills an upward-flared diatreme ~1,800 m wide at the 4,250-m surface elevation. The Grasberg Igneous Complex is emplaced into folded and strike-slip faulted Tertiary and older sediments and comprises 3.6 to 3.3 Ma Dalam monzodiorite intrusions and subordinate volcanic rocks occupying much of the pipe, the central 3.2 Ma Main Grasberg intrusion, and the NW-SE-trending 3.2 to 3.0 Ma Kali dikes. The Grasberg Igneous Complex contains two porphyry systems: Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold. The Gajah Tidur intrusion belongs to the Dalam igneous group and is a 3.4 Ma porphyritic monzonite with its top at a 2,750-m elevation; it is overprinted by an extensive, domal, quartz stockwork, with a low-grade and intensely phyllic-altered core, surrounded by molybdenite-bearing veins, with a pre-Main Grasberg Re-Os age, as well as chalcopyrite and overprinting pyrite-covellite veins. The strongly potassic-altered, Main Grasberg monzodiorite porphyry extends from surface to the 2,700-m elevation and is overprinted by a cylindrical, ~1-km-diameter, intense quartz-magnetite stockwork cut by abundant chalcopyrite-bornite veins with rare molybdenite dated at 3.09 Ma. A 700-m-wide annulus of chalcopyrite overprinted by pyrite-covellite-mineralized phyllic alteration surrounds the stockwork. Altered and mineralized Main Grasberg and surrounding Dalam rocks were subsequently wedged apart by the largely unmineralized Kali dikes. Gold is predominantly associated with the Main Grasberg porphyry system where it occurs as 1- to 150-µm (avg ~15 µm) native gold inclusions within chalcopyrite and bornite. Melt and fluid inclusions from Main Grasberg stockwork quartz veins, which exhibit crack-seal textures, comprise K-feldspar-rich silicate melt, sulfide melt, virtually water-free salt melt, and coexisting hypersaline and vapor-rich fluids. Factors important in forming the Grasberg deposit include the following: (1) generation of highly oxidized fertile magma in a postsubduction tectonic setting; (2) efficient extraction of metals from the parental magma chamber; (3) prolonged maintenance of a fluid-accumulating cupola in a strike-slip structural setting that delivered multiple overlapping discharges of metal-rich fluid; (4) highly focused fluid flow into a narrow, permeable stockwork zone in which a steep temperature gradient enabled highly efficient copper and gold precipitation and led to high ore grades; (5) limited dilution by postmineral intrusions; (6) the youthfulness of the deposit minimized erosion and resulted in preservation of nearly all the high-grade Main Grasberg porphyry orebody; and (7) the proximity of the two porphyry centers enables them to be mined as a single, large deposit. The Gajah Tidur copper-(molybdenum) and Main Grasberg copper-gold porphyry centers ","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"106 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72972402","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}
J. A. McDivitt, S. Hagemann, M. Baggott, S. Perazzo
The Kalgoorlie gold camp in the Yilgarn craton of Western Australia comprises the supergiant Golden Mile and the smaller Mt. Charlotte, Mt. Percy, and Hidden Secret deposits. Since the camp’s discovery in 1893, ~1,950 metric tons (t) of Au have been produced from a total estimated endowment of ~2,300 t. The camp is located within Neoarchean rocks of the Kalgoorlie terrane, within the Eastern Goldfields superterrane of the eastern Yilgarn craton. Gold mineralization is distributed along an 8- × 2-km, NNW-trending corridor, which corresponds to the Boulder Lefroy-Golden Mile fault system. The host stratigraphic sequence, dated at ca. 2710 to 2660 Ma, comprises lower ultramafic and mafic lava flow rocks, and upper felsic to intermediate volcaniclastic, epiclastic, and lava flow rocks intruded by highly differentiated dolerite sills such as the ca. 2685 Ma Golden Mile Dolerite. Multiple sets of NNW-trending, steeply dipping porphyry dikes intruded this sequence from ca. 2675 to 2640 Ma. From ca. 2685 to 2640 Ma, rocks of the Kalgoorlie gold camp were subjected to multiple deformation increments and metamorphism. Early D1 deformation from ca. 2685 to 2675 Ma generated the Golden Mile fault and F1 folds. Prolonged sinistral transpression from ca. 2675 to 2655 Ma produced overprinting, NNW-trending sets of D2-D3 folds and faults. The last deformation stage (D4; < ca. 2650 Ma) is recorded by N- to NNE-trending, dextral faults which offset earlier structures. The main mineralization type in the Golden Mile comprises Fimiston lodes: steeply dipping, WNW- to NNW-striking, gold- and telluride-bearing carbonate-quartz veins with banded, colloform, and crustiform textures surrounded by sericite-carbonate-quartz-pyrite-telluride alteration zones. These lodes were emplaced during the earlier stages of regional sinistral transpression (D2) as Riedel shear-type structures. During a later stage of regional sinistral transpression (D3), exceptionally high grade Oroya-type mineralization developed as shallowly plunging ore shoots with “Green Leader” quartz-sericite-carbonate-pyrite-telluride alteration typified by vanadium-bearing muscovite. In the Hidden Secret orebody, ~3 km north-northwest of the Golden Mile, lode mineralization is a silver-rich variety characterized by increased abundance of hessite and petzite and decreased abundance of calaverite. At the adjacent Mt. Charlotte deposit, the gold-, silver-, and telluride-bearing lodes become subordinate to the Mt. Charlotte-type stockwork veins. The stockwork veins occur as planar, 2- to 50-cm thick, auriferous quartz-carbonate-sulfide veins that define steeply NW- to SE-dipping and shallowly N-dipping sets broadly coeval with D4 deformation. Despite extensive research, there is no consensus on critical features of ore formation in the camp. Models suggest either (1) distinct periods of mineralization over a protracted, ca. 2.68 to 2.64 Ga orogenic history; or (2) broadly synchronous formation of the different
{"title":"Chapter 12: Geologic Setting and Gold Mineralization of the Kalgoorlie Gold Camp, Yilgarn Craton, Western Australia","authors":"J. A. McDivitt, S. Hagemann, M. Baggott, S. Perazzo","doi":"10.5382/sp.23.12","DOIUrl":"https://doi.org/10.5382/sp.23.12","url":null,"abstract":"The Kalgoorlie gold camp in the Yilgarn craton of Western Australia comprises the supergiant Golden Mile and the smaller Mt. Charlotte, Mt. Percy, and Hidden Secret deposits. Since the camp’s discovery in 1893, ~1,950 metric tons (t) of Au have been produced from a total estimated endowment of ~2,300 t. The camp is located within Neoarchean rocks of the Kalgoorlie terrane, within the Eastern Goldfields superterrane of the eastern Yilgarn craton. Gold mineralization is distributed along an 8- × 2-km, NNW-trending corridor, which corresponds to the Boulder Lefroy-Golden Mile fault system. The host stratigraphic sequence, dated at ca. 2710 to 2660 Ma, comprises lower ultramafic and mafic lava flow rocks, and upper felsic to intermediate volcaniclastic, epiclastic, and lava flow rocks intruded by highly differentiated dolerite sills such as the ca. 2685 Ma Golden Mile Dolerite. Multiple sets of NNW-trending, steeply dipping porphyry dikes intruded this sequence from ca. 2675 to 2640 Ma. From ca. 2685 to 2640 Ma, rocks of the Kalgoorlie gold camp were subjected to multiple deformation increments and metamorphism. Early D1 deformation from ca. 2685 to 2675 Ma generated the Golden Mile fault and F1 folds. Prolonged sinistral transpression from ca. 2675 to 2655 Ma produced overprinting, NNW-trending sets of D2-D3 folds and faults. The last deformation stage (D4; < ca. 2650 Ma) is recorded by N- to NNE-trending, dextral faults which offset earlier structures. The main mineralization type in the Golden Mile comprises Fimiston lodes: steeply dipping, WNW- to NNW-striking, gold- and telluride-bearing carbonate-quartz veins with banded, colloform, and crustiform textures surrounded by sericite-carbonate-quartz-pyrite-telluride alteration zones. These lodes were emplaced during the earlier stages of regional sinistral transpression (D2) as Riedel shear-type structures. During a later stage of regional sinistral transpression (D3), exceptionally high grade Oroya-type mineralization developed as shallowly plunging ore shoots with “Green Leader” quartz-sericite-carbonate-pyrite-telluride alteration typified by vanadium-bearing muscovite. In the Hidden Secret orebody, ~3 km north-northwest of the Golden Mile, lode mineralization is a silver-rich variety characterized by increased abundance of hessite and petzite and decreased abundance of calaverite. At the adjacent Mt. Charlotte deposit, the gold-, silver-, and telluride-bearing lodes become subordinate to the Mt. Charlotte-type stockwork veins. The stockwork veins occur as planar, 2- to 50-cm thick, auriferous quartz-carbonate-sulfide veins that define steeply NW- to SE-dipping and shallowly N-dipping sets broadly coeval with D4 deformation. Despite extensive research, there is no consensus on critical features of ore formation in the camp. Models suggest either (1) distinct periods of mineralization over a protracted, ca. 2.68 to 2.64 Ga orogenic history; or (2) broadly synchronous formation of the different ","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":"78238146","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}
P. Dirks, I. Sanislav, M. R. van Ryt, J. Huizenga, T. Blenkinsop, S. L. Kolling, S. Kwelwa, G. Mwazembe
The Geita mine is operated by AngloGold Ashanti and currently comprises four gold deposits mined as open pits and underground operations in the Geita greenstone belt, Tanzania. The mine produces ~0.5 Moz of gold a year and has produced ~8.3 Moz since 2000, with current resources estimated at ~6.5 Moz, using a lower cut-off of 0.5 g/t. The geologic history of the Geita greenstone belt involved three tectonic stages: (I) early (2820–2700 Ma) extension (D1) and formation of the greenstone sequence in an oceanic plateau environment; (II) shortening of the greenstone sequence (2700–2660 Ma) involving ductile folding (D2–5) and brittle-ductile shearing (D6), coincident with long-lived igneous activity concentrated in five intrusive centers; and (III) renewed extension (2660–2620 Ma) involving strike-slip and normal faulting (D7–8), basin formation, and potassic magmatism. Major gold deposits in the Geita greenstone belt formed late in the history of the greenstone belt, during D8 normal faulting at ~2640 Ma, and the structural framework, mineral paragenesis, and timing of gold precipitation is essentially the same in all major deposits. Gold is hosted in iron-rich lithologies along contacts between folded metaironstone beds and tonalite-trondhjemite-granodiorite (TTG) intrusions, particularly where the contacts were sheared and fractured during D6–7 faulting. The faults, together with damage zones created along D3 fold hinges and D2–3 hydrothermal breccia zones near intrusions, formed microfracture networks that were reactivated during D8. The fracture networks served as conduits for gold-bearing fluids; i.e., lithologies and structures that trap gold formed early, but gold was introduced late. Fluids carried gold as Au bisulfide complexes and interacted with Fe-rich wall rocks to precipitate gold. Fluid-rock interaction and mineralization were enhanced as a result of D8 extension, and localized hydrofracturing formed high-grade breccia ores. Gold is contained in electrum and gold-bearing tellurides that occur in the matrix and as inclusions in pyrrhotite and pyrite. The gold mineralization is spatially linked to long-lived, near-stationary intrusive centers. Critical factors in forming the deposits include the (syn-D2–6) formation of damage zones in lithologies that enhance gold precipitation (Fe-rich lithologies); late tectonic reactivation of the damage zones during extensional (D8) faulting with the introduction of an S-rich, gold-bearing fluid; and efficient fluid-rock interaction in zones that were structurally well prepared.
{"title":"Chapter 8: The World-Class Gold Deposits in the Geita Greenstone Belt, Northwestern Tanzania","authors":"P. Dirks, I. Sanislav, M. R. van Ryt, J. Huizenga, T. Blenkinsop, S. L. Kolling, S. Kwelwa, G. Mwazembe","doi":"10.5382/SP.23.08","DOIUrl":"https://doi.org/10.5382/SP.23.08","url":null,"abstract":"The Geita mine is operated by AngloGold Ashanti and currently comprises four gold deposits mined as open pits and underground operations in the Geita greenstone belt, Tanzania. The mine produces ~0.5 Moz of gold a year and has produced ~8.3 Moz since 2000, with current resources estimated at ~6.5 Moz, using a lower cut-off of 0.5 g/t. The geologic history of the Geita greenstone belt involved three tectonic stages: (I) early (2820–2700 Ma) extension (D1) and formation of the greenstone sequence in an oceanic plateau environment; (II) shortening of the greenstone sequence (2700–2660 Ma) involving ductile folding (D2–5) and brittle-ductile shearing (D6), coincident with long-lived igneous activity concentrated in five intrusive centers; and (III) renewed extension (2660–2620 Ma) involving strike-slip and normal faulting (D7–8), basin formation, and potassic magmatism. Major gold deposits in the Geita greenstone belt formed late in the history of the greenstone belt, during D8 normal faulting at ~2640 Ma, and the structural framework, mineral paragenesis, and timing of gold precipitation is essentially the same in all major deposits. Gold is hosted in iron-rich lithologies along contacts between folded metaironstone beds and tonalite-trondhjemite-granodiorite (TTG) intrusions, particularly where the contacts were sheared and fractured during D6–7 faulting. The faults, together with damage zones created along D3 fold hinges and D2–3 hydrothermal breccia zones near intrusions, formed microfracture networks that were reactivated during D8. The fracture networks served as conduits for gold-bearing fluids; i.e., lithologies and structures that trap gold formed early, but gold was introduced late. Fluids carried gold as Au bisulfide complexes and interacted with Fe-rich wall rocks to precipitate gold. Fluid-rock interaction and mineralization were enhanced as a result of D8 extension, and localized hydrofracturing formed high-grade breccia ores. Gold is contained in electrum and gold-bearing tellurides that occur in the matrix and as inclusions in pyrrhotite and pyrite. The gold mineralization is spatially linked to long-lived, near-stationary intrusive centers. Critical factors in forming the deposits include the (syn-D2–6) formation of damage zones in lithologies that enhance gold precipitation (Fe-rich lithologies); late tectonic reactivation of the damage zones during extensional (D8) faulting with the introduction of an S-rich, gold-bearing fluid; and efficient fluid-rock interaction in zones that were structurally well prepared.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80460547","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}
N. Oliver, B. Thomson, F. H. Freitas-Silva, R. Holcombe
The Paracatu deposit in Brazil is a shallowly dipping, bulk-tonnage, low-grade, vein-style orogenic Au orebody hosted in very strongly deformed Neoproterozoic carbonaceous phyllite of the southern Brasília fold belt. At regional to district scales, the gold orebody lies along the eastern, hanging-wall edge of a major thrust of the ~630 Ma Brasiliano orogeny. This thrust cuts through a facies transition between clastic-dominated rocks of the Canastra Group and carbonate-dominant rocks of the Vazante Group, deposited at ~1000 Ma in a rift to passive-margin environment on the flank of the São Francisco craton. At the same scales, the footwall of this major thrust system hosts numerous structurally controlled zinc deposits including Vazante and Morro Agudo. At Paracatu, ore genesis occurred primarily by the formation of early tectonic quartz sulfide-carbonate veins, prior to substantial ductile deformation (boudinage), local physico-chemical reworking of these veins, and redistribution of some gold. Structural, geochemical, and isotopic data indicate a strong influence of the local rocks (cm to 100-m scales) on many ore ingredients, and the quartz and carbonate in ore veins were most likely derived locally (cm to m scales). However, the coassociation of gold and arsenic with the boudinaged veins and a major thrust, and the absence of metal enrichments normally associated with syngenetic metalliferous black shales, supports a model of far-field derivation of gold within this metasedimentary package (km to 10-km scales). Transport of metal-bearing fluids toward a favorable structural and chemical site during thrusting and orogenesis was possibly focused, during precipitation to ore grades, by the position of transverse structures in the basement, which also influenced deposition of the adjacent zinc deposits. Successful mining of the low-grade resource was initially favored by the subhorizontal orebody geometry and weathering characteristics, and subsequently by high production rates from the 100-m-thick mineralized zone.
巴西Paracatu矿床是一个浅倾、大吨位、低品位脉状造山金矿体，赋存于Brasília褶皱带南部新元古代碳质千层岩中变形剧烈。在区域至地区尺度上，金矿体沿~630 Ma Brasiliano造山带主逆冲东侧上盘边缘发育。该逆冲断断了以碎屑岩为主的Canastra群与以碳酸盐岩为主的Vazante群之间的相转换，这些岩石沉积于~1000 Ma的裂谷-被动边缘环境中，位于 o Francisco克拉通侧翼。在相同的规模下，这个主要逆冲系统的下盘拥有许多受构造控制的锌矿床，包括Vazante和Morro Agudo。在Paracatu，成矿主要发生于早期构造石英硫化物-碳酸盐脉体的形成，在此之前，这些脉体发生了大量的韧性变形(断裂)，并发生了局部的物化改造和部分金的再分布。构造、地球化学和同位素数据表明，当地岩石(厘米至100米尺度)对许多矿石成分有很强的影响，矿脉中的石英和碳酸盐很可能来自当地(厘米至100米尺度)。然而，金和砷与边界脉和主逆冲的共同作用，以及通常与同生含金属黑色页岩相关的金属富集的缺乏，支持了在该变质沉积岩包内远场衍生金的模型(公里至10公里尺度)。在冲断和造山过程中，含金属流体向有利的构造和化学部位的运移可能集中在基底横向构造的位置，这也影响了相邻锌矿床的沉积。低品位资源的成功开采最初得益于亚水平矿体的几何形状和风化特征，随后得益于100m厚矿化带的高产。
{"title":"Chapter 5: The Low-Grade, Neoproterozoic, Vein-Style, Carbonaceous Phyllite-Hosted Paracatu Gold Deposit, Minas Gerais, Brazil","authors":"N. Oliver, B. Thomson, F. H. Freitas-Silva, R. Holcombe","doi":"10.5382/sp.23.05","DOIUrl":"https://doi.org/10.5382/sp.23.05","url":null,"abstract":"The Paracatu deposit in Brazil is a shallowly dipping, bulk-tonnage, low-grade, vein-style orogenic Au orebody hosted in very strongly deformed Neoproterozoic carbonaceous phyllite of the southern Brasília fold belt. At regional to district scales, the gold orebody lies along the eastern, hanging-wall edge of a major thrust of the ~630 Ma Brasiliano orogeny. This thrust cuts through a facies transition between clastic-dominated rocks of the Canastra Group and carbonate-dominant rocks of the Vazante Group, deposited at ~1000 Ma in a rift to passive-margin environment on the flank of the São Francisco craton. At the same scales, the footwall of this major thrust system hosts numerous structurally controlled zinc deposits including Vazante and Morro Agudo. At Paracatu, ore genesis occurred primarily by the formation of early tectonic quartz sulfide-carbonate veins, prior to substantial ductile deformation (boudinage), local physico-chemical reworking of these veins, and redistribution of some gold. Structural, geochemical, and isotopic data indicate a strong influence of the local rocks (cm to 100-m scales) on many ore ingredients, and the quartz and carbonate in ore veins were most likely derived locally (cm to m scales). However, the coassociation of gold and arsenic with the boudinaged veins and a major thrust, and the absence of metal enrichments normally associated with syngenetic metalliferous black shales, supports a model of far-field derivation of gold within this metasedimentary package (km to 10-km scales). Transport of metal-bearing fluids toward a favorable structural and chemical site during thrusting and orogenesis was possibly focused, during precipitation to ore grades, by the position of transverse structures in the basement, which also influenced deposition of the adjacent zinc deposits. Successful mining of the low-grade resource was initially favored by the subhorizontal orebody geometry and weathering characteristics, and subsequently by high production rates from the 100-m-thick mineralized zone.","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":"81266837","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}
G. Tripp, R. Tosdal, T. Blenkinsop, J. Rogers, S. Halley
Neoarchean greenstone-hosted gold deposits in the Eastern Goldfields Superterrane of the Yilgarn craton of Western Australia are diverse in style, timing with respect to magmatic activity, structural environment, host rocks, and geochemical character. Geologic constraints for the range of gold deposits indicate deposit formation synchronous with volcanism, synchronous with syn- and postvolcanic intrusion, synchronous with postvolcanic deformation in faults and shear zones, or some combination of superposed events over time. The gold deposits are distributed as clusters along linear belt-parallel fault zones internal to greenstone belts but show no association with major terrane boundary faults. World-class gold districts are associated with the thickest, internal parts of the greenstone belts identified by stratigraphic preservation and low metamorphic grades. Ore-proximal faults in those regions are more commonly associated with syn- and postvolcanic structures related to greenstone construction and deformation rather than major terrane amalgamation. Using the Kalgoorlie district as a template, the gold deposits show a predictable regional association with thicker greenstone rocks overlain unconformably by coarse clastic rock sequences in the uppermost units of the greenstone stratigraphy. At a camp scale, major gold deposits show a spatial association with unconformable epiclastic and volcaniclastic rocks located above an unconformity internal to the Black Flag Group. Distinct episodes of gold deposition in coincident locations suggest fundamental crustal structural controls provided by the fault architecture. Late penetrative deformation and metamorphism overprinted the greenstone rocks and the older components of many gold deposits and were accompanied by major gold deposition in late quartz-carbonate veins localized in crustal shear zones or their higher order fault splays.
{"title":"Chapter 33: Neoarchean Eastern Goldfields of Western Australia","authors":"G. Tripp, R. Tosdal, T. Blenkinsop, J. Rogers, S. Halley","doi":"10.5382/sp.23.33","DOIUrl":"https://doi.org/10.5382/sp.23.33","url":null,"abstract":"Neoarchean greenstone-hosted gold deposits in the Eastern Goldfields Superterrane of the Yilgarn craton of Western Australia are diverse in style, timing with respect to magmatic activity, structural environment, host rocks, and geochemical character. Geologic constraints for the range of gold deposits indicate deposit formation synchronous with volcanism, synchronous with syn- and postvolcanic intrusion, synchronous with postvolcanic deformation in faults and shear zones, or some combination of superposed events over time. The gold deposits are distributed as clusters along linear belt-parallel fault zones internal to greenstone belts but show no association with major terrane boundary faults. World-class gold districts are associated with the thickest, internal parts of the greenstone belts identified by stratigraphic preservation and low metamorphic grades. Ore-proximal faults in those regions are more commonly associated with syn- and postvolcanic structures related to greenstone construction and deformation rather than major terrane amalgamation. Using the Kalgoorlie district as a template, the gold deposits show a predictable regional association with thicker greenstone rocks overlain unconformably by coarse clastic rock sequences in the uppermost units of the greenstone stratigraphy. At a camp scale, major gold deposits show a spatial association with unconformable epiclastic and volcaniclastic rocks located above an unconformity internal to the Black Flag Group. Distinct episodes of gold deposition in coincident locations suggest fundamental crustal structural controls provided by the fault architecture. Late penetrative deformation and metamorphism overprinted the greenstone rocks and the older components of many gold deposits and were accompanied by major gold deposition in late quartz-carbonate veins localized in crustal shear zones or their higher order fault splays.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85023859","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}
Paul J. Dobak, F. Robert, S. Barker, Jeremy R. Vaughan, Douglas Eck
The Eocene Goldstrike system on the Carlin Trend in Nevada is the largest known Carlin-type gold system, with an endowment of 58 million ounces (Moz) distributed among several coalesced deposits in a structural window of gently dipping carbonate rocks below the regional Roberts Mountains thrust. The 3.5- × 2.5-km Goldstrike system is bounded to the east by the Post normal fault system and to the south by the Jurassic Goldstrike diorite stock and is partly hosted in the favorable slope-facies apron of the Bootstrap reef margin that passes through the system. The carbonate and clastic sedimentary sequence is openly folded, cut by sets of reverse and normal faults, and intruded by the Jurassic Goldstrike stock and swarms of Jurassic and Eocene dikes, establishing the structural architecture that controlled fluid flow and distribution of Eocene mineralization. A proximal zone of permeability-enhancing decarbonatization with anomalous gold (>0.1 ppm) extends a few hundreds of meters beyond the ore footprint and lies within a carbonate δ18O depletion anomaly extending ~1.4 km farther outboard. The full extent of the larger hydrothermal system hosting Goldstrike and adjacent deposits on the northern Carlin Trend is outlined by a 20- × 40-km thermal anomaly defined by apatite fission-track analyses. The bulk of the mineralization is hosted in decarbonatized sedimentary units with elevated iron contents and abundant diagenetic pyrite relative to background. Gold is associated with elevated concentrations of As, Tl, Hg, and Sb, and occurs in micron-sized arsenian pyrite grains or in arsenian pyrite overgrowths on older, principally diagenetic pyrite, with sulfidation of available iron as the main gold precipitation mechanism. The intersection of a swarm of Jurassic lamprophyre dikes with the edge of the limestone reef provided a favorable deeply penetrating structural conduit within which a Jurassic stock acted as a structural buttress, whereas the reef’s slope-facies apron of carbonate units, with high available iron content, provided a fertile setting for Carlin-type mineralization. The onset of Eocene extension coupled with a southwestward-sweeping Cenozoic magmatic front acted as the trigger for main-stage gold mineralization at 40 to 39 Ma. All these factors contributed to the exceptional size and grade of Goldstrike.
{"title":"Chapter 15: Goldstrike Gold System, North Carlin Trend, Nevada, USA","authors":"Paul J. Dobak, F. Robert, S. Barker, Jeremy R. Vaughan, Douglas Eck","doi":"10.5382/sp.23.15","DOIUrl":"https://doi.org/10.5382/sp.23.15","url":null,"abstract":"The Eocene Goldstrike system on the Carlin Trend in Nevada is the largest known Carlin-type gold system, with an endowment of 58 million ounces (Moz) distributed among several coalesced deposits in a structural window of gently dipping carbonate rocks below the regional Roberts Mountains thrust. The 3.5- × 2.5-km Goldstrike system is bounded to the east by the Post normal fault system and to the south by the Jurassic Goldstrike diorite stock and is partly hosted in the favorable slope-facies apron of the Bootstrap reef margin that passes through the system. The carbonate and clastic sedimentary sequence is openly folded, cut by sets of reverse and normal faults, and intruded by the Jurassic Goldstrike stock and swarms of Jurassic and Eocene dikes, establishing the structural architecture that controlled fluid flow and distribution of Eocene mineralization. A proximal zone of permeability-enhancing decarbonatization with anomalous gold (>0.1 ppm) extends a few hundreds of meters beyond the ore footprint and lies within a carbonate δ18O depletion anomaly extending ~1.4 km farther outboard. The full extent of the larger hydrothermal system hosting Goldstrike and adjacent deposits on the northern Carlin Trend is outlined by a 20- × 40-km thermal anomaly defined by apatite fission-track analyses. The bulk of the mineralization is hosted in decarbonatized sedimentary units with elevated iron contents and abundant diagenetic pyrite relative to background. Gold is associated with elevated concentrations of As, Tl, Hg, and Sb, and occurs in micron-sized arsenian pyrite grains or in arsenian pyrite overgrowths on older, principally diagenetic pyrite, with sulfidation of available iron as the main gold precipitation mechanism. The intersection of a swarm of Jurassic lamprophyre dikes with the edge of the limestone reef provided a favorable deeply penetrating structural conduit within which a Jurassic stock acted as a structural buttress, whereas the reef’s slope-facies apron of carbonate units, with high available iron content, provided a fertile setting for Carlin-type mineralization. The onset of Eocene extension coupled with a southwestward-sweeping Cenozoic magmatic front acted as the trigger for main-stage gold mineralization at 40 to 39 Ma. All these factors contributed to the exceptional size and grade of Goldstrike.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86758377","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}
G. L. Vursiy, I. A. Zibrov, S. Lobov, A. Yakubchuk
Sukhoi Log, Russia’s largest gold deposit, containing 1,960 metric tons (t) of gold within the deformed Neoproterozoic sedimentary sequences of the Patom passive margin, can be classified as an orogenic gold system. This giant and nearby smaller deposits occur in black shale horizons at several stratigraphic levels. The understanding of Sukhoi Log evolved from a small quartz vein occurrence to a large disseminated gold resource. The genesis of the deposit, originally considered to be related to a granitic intrusion, was later reinterpreted as metamorphogenic, with a significant contribution of synsedimentary gold in pyrite. Recent isotopic studies showed that there may have been more than one early Paleozoic synmetamorphic gold-mineralizing event, so the deposit most likely has a multistage origin. Black shales might have acted either as a synsedimentary and/or synmetamorphic geochemical trap for auriferous fluids. Structurally, the mineralization is confined to the axial portion of the recumbent Sukhoi Log anticline, conjugate with the Kadali-Sukhoi Log shear zone. This imbricate thrust zone marks a major boundary between the Chuya-Nechera anticlinorium and Bodaibo synclinorium, two regional tectonic features in the Patom Highlands.
{"title":"Chapter 25: The Sukhoi Log Gold Deposit, Russia","authors":"G. L. Vursiy, I. A. Zibrov, S. Lobov, A. Yakubchuk","doi":"10.5382/sp.23.25","DOIUrl":"https://doi.org/10.5382/sp.23.25","url":null,"abstract":"Sukhoi Log, Russia’s largest gold deposit, containing 1,960 metric tons (t) of gold within the deformed Neoproterozoic sedimentary sequences of the Patom passive margin, can be classified as an orogenic gold system. This giant and nearby smaller deposits occur in black shale horizons at several stratigraphic levels. The understanding of Sukhoi Log evolved from a small quartz vein occurrence to a large disseminated gold resource. The genesis of the deposit, originally considered to be related to a granitic intrusion, was later reinterpreted as metamorphogenic, with a significant contribution of synsedimentary gold in pyrite. Recent isotopic studies showed that there may have been more than one early Paleozoic synmetamorphic gold-mineralizing event, so the deposit most likely has a multistage origin. Black shales might have acted either as a synsedimentary and/or synmetamorphic geochemical trap for auriferous fluids. Structurally, the mineralization is confined to the axial portion of the recumbent Sukhoi Log anticline, conjugate with the Kadali-Sukhoi Log shear zone. This imbricate thrust zone marks a major boundary between the Chuya-Nechera anticlinorium and Bodaibo synclinorium, two regional tectonic features in the Patom Highlands.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84367500","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}
W. Board, D. McLeish, C. Greig, Octavia E. Bath, Joel E. Ashburner, T. Murphy, R. Friedman
The Brucejack intermediate-sulfidation epithermal Au-Ag deposit, located 65 km north of Stewart, BC, forms part of a well-mineralized, structurally controlled, north-south gossanous trend associated with Early Jurassic intrusions straddling the Late Triassic-Early Jurassic Stuhini-Hazelton Group unconformity in the Sulphurets mineral district. Mining of the deposit commenced in mid-2017 after a long history of exploration dating back to the 1880s. Mineralization is hosted in deformed Lower Jurassic island-arc volcanic rocks of the Hazelton Group exposed on the eastern limb of the Cretaceous McTagg anticlinorium. High-grade Au-Ag mineralization was formed from ~184 to 183 Ma in association with a telescoped, multipulsed magmatic-hydrothermal system beneath an active local volcanic center. Precious metal mineralization occurs as coarse aggregates of electrum and silver sulfosalts in steeply dipping, E- to SE-trending quartz-carbonate vein stockwork zones cutting low-grade intrusion-related phyllic alteration. Epithermal vein development is interpreted to have occurred during the waning stages of Early Jurassic sinistral transpression in a compressive arc environment, followed by a limited Cretaceous deformation overprint.
{"title":"Chapter 14: The Brucejack Au-Ag Deposit, Northwest British Columbia, Canada: Multistage Porphyry to Epithermal Alteration, Mineralization, and Deposit Formation in an Island-Arc Setting","authors":"W. Board, D. McLeish, C. Greig, Octavia E. Bath, Joel E. Ashburner, T. Murphy, R. Friedman","doi":"10.5382/sp.23.14","DOIUrl":"https://doi.org/10.5382/sp.23.14","url":null,"abstract":"The Brucejack intermediate-sulfidation epithermal Au-Ag deposit, located 65 km north of Stewart, BC, forms part of a well-mineralized, structurally controlled, north-south gossanous trend associated with Early Jurassic intrusions straddling the Late Triassic-Early Jurassic Stuhini-Hazelton Group unconformity in the Sulphurets mineral district. Mining of the deposit commenced in mid-2017 after a long history of exploration dating back to the 1880s. Mineralization is hosted in deformed Lower Jurassic island-arc volcanic rocks of the Hazelton Group exposed on the eastern limb of the Cretaceous McTagg anticlinorium. High-grade Au-Ag mineralization was formed from ~184 to 183 Ma in association with a telescoped, multipulsed magmatic-hydrothermal system beneath an active local volcanic center. Precious metal mineralization occurs as coarse aggregates of electrum and silver sulfosalts in steeply dipping, E- to SE-trending quartz-carbonate vein stockwork zones cutting low-grade intrusion-related phyllic alteration. Epithermal vein development is interpreted to have occurred during the waning stages of Early Jurassic sinistral transpression in a compressive arc environment, followed by a limited Cretaceous deformation overprint.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80842230","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}
B. Dubé, P. Mercier-Langevin, J. Ayer, J. Pilote, T. Monecke
The Timmins-Porcupine camp, with >2,190 metric tons Au (70.5 Moz) produced between 1906 and 2019, is the world’s largest Archean orogenic gold camp. The gold deposits of the camp are distributed over ~50 km of strike length along the Destor-Porcupine fault zone. This includes the world-class Hollinger-McIntyre and Dome deposits, which represent archetypal examples of large orogenic quartz-carbonate gold systems. The Dome deposit, where the ore is centered on a folded unconformity between Tisdale volcanic rocks and Timiskaming sedimentary units, also illustrates the spatial relationship between large gold deposits and a regional unconformity. Ore-forming hydrothermal activity in the camp spanned a prolonged period of time, as illustrated by early-stage, low-grade ankerite veins formed between ca. 2690 and 2674 Ma. This was prior to or very early relative to the development of the regional unconformity and sedimentation of the Timiskaming assemblage, and subsequent main-stage gold deposition. The bulk of the gold in the district is younger than the Three Nations Formation of the upper part of the Timiskaming assemblage (i.e., ≤2669 ± 1 Ma) and was deposited syn- to late-main phase of shortening (D3) in the Timmins-Porcupine camp from about 2660 to 2640 ± 10 Ma. The early carbonatization represents a significant early-stage hydrothermal event in the formation of large structurally controlled gold deposits such as Dome and illustrates the protracted nature of the large-scale CO2-rich metasomatism occurring before and during gold deposition. Ores in the Timmins-Porcupine camp mainly consist of networks of steeply to moderately dipping fault-fill quartz-carbonate ± tourmaline ± pyrite veins and associated extensional, variably deformed, shallowly to moderately dipping arrays of sigmoidal veins hosted in highly carbonatized and sericitized rocks and formed during main regional shortening (D3). In contrast, at the Timmins West mine, the Thunder Creek and 144 GAP deposits are early- to syn-Timiskaming intrusion-associated deposits that slightly predate to overlap the main phase of D3 horizontal shortening in which the associated intrusions mainly played a passive role as an older mechanical and chemical trap rock. The formation of the gold deposits of the Timmins-Porcupine camp is due to several key factors. The Destor-Porcupine fault zone represents a deeply rooted first-order structure and tapped auriferous metamorphic fluids and melts from the upper mantle-lower crust. The fault zone has channeled large volumes of auriferous H2O-CO2-rich fluids to the upper crust late in the evolution of the belt. Several of the gold deposits of the camp are spatially associated with the regional Timiskaming unconformity. The current level of erosion is deep enough to expose the unconformity and to maximize the chance of discovering the quartz-carbonate style of orogenic deposits or the associated hydrothermal footprint, but also allowed for preservation of at least
{"title":"Chapter 3: Gold Deposits of the World-Class Timmins-Porcupine Camp, Abitibi Greenstone Belt, Canada","authors":"B. Dubé, P. Mercier-Langevin, J. Ayer, J. Pilote, T. Monecke","doi":"10.5382/sp.23.03","DOIUrl":"https://doi.org/10.5382/sp.23.03","url":null,"abstract":"The Timmins-Porcupine camp, with >2,190 metric tons Au (70.5 Moz) produced between 1906 and 2019, is the world’s largest Archean orogenic gold camp. The gold deposits of the camp are distributed over ~50 km of strike length along the Destor-Porcupine fault zone. This includes the world-class Hollinger-McIntyre and Dome deposits, which represent archetypal examples of large orogenic quartz-carbonate gold systems. The Dome deposit, where the ore is centered on a folded unconformity between Tisdale volcanic rocks and Timiskaming sedimentary units, also illustrates the spatial relationship between large gold deposits and a regional unconformity. Ore-forming hydrothermal activity in the camp spanned a prolonged period of time, as illustrated by early-stage, low-grade ankerite veins formed between ca. 2690 and 2674 Ma. This was prior to or very early relative to the development of the regional unconformity and sedimentation of the Timiskaming assemblage, and subsequent main-stage gold deposition. The bulk of the gold in the district is younger than the Three Nations Formation of the upper part of the Timiskaming assemblage (i.e., ≤2669 ± 1 Ma) and was deposited syn- to late-main phase of shortening (D3) in the Timmins-Porcupine camp from about 2660 to 2640 ± 10 Ma. The early carbonatization represents a significant early-stage hydrothermal event in the formation of large structurally controlled gold deposits such as Dome and illustrates the protracted nature of the large-scale CO2-rich metasomatism occurring before and during gold deposition. Ores in the Timmins-Porcupine camp mainly consist of networks of steeply to moderately dipping fault-fill quartz-carbonate ± tourmaline ± pyrite veins and associated extensional, variably deformed, shallowly to moderately dipping arrays of sigmoidal veins hosted in highly carbonatized and sericitized rocks and formed during main regional shortening (D3). In contrast, at the Timmins West mine, the Thunder Creek and 144 GAP deposits are early- to syn-Timiskaming intrusion-associated deposits that slightly predate to overlap the main phase of D3 horizontal shortening in which the associated intrusions mainly played a passive role as an older mechanical and chemical trap rock. The formation of the gold deposits of the Timmins-Porcupine camp is due to several key factors. The Destor-Porcupine fault zone represents a deeply rooted first-order structure and tapped auriferous metamorphic fluids and melts from the upper mantle-lower crust. The fault zone has channeled large volumes of auriferous H2O-CO2-rich fluids to the upper crust late in the evolution of the belt. Several of the gold deposits of the camp are spatially associated with the regional Timiskaming unconformity. The current level of erosion is deep enough to expose the unconformity and to maximize the chance of discovering the quartz-carbonate style of orogenic deposits or the associated hydrothermal footprint, but also allowed for preservation of at least ","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":"83321804","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}
Alan J. Wilson, N. Lisowiec, Cameron Switzer, A. Harris, R. Creaser, C. Fanning
The giant (>20 Moz) Telfer Au-Cu deposit is located in the Paterson Province of Western Australia and is hosted by complexly deformed marine Neoproterozoic metasedimentary siltstones and quartz arenites. The Telfer district also contains magnetite- and ilmenite-series granitoids dated between ca. 645 and 600 Ma and a world-class W skarn deposit associated with the reduced, ~604 Ma O’Callaghans granite. Based on monazite and xenotime U-Pb geochronology, Telfer is estimated to be older than O’Callaghans, forming between 645 and 620 Ma. Au-Cu mineralization at Telfer is hosted in multistage, bedding-parallel quartz-dolomite-pyrite-chalcopyrite reefs and related discordant veins and stockworks of similar composition that were emplaced into two NW-striking doubly plunging anticlines or domes. Mineralization is late orogenic in timing, with hot (≤460°C), saline (<50 wt % NaCl equiv) ore fluids channeled into preexisting domes along a series of shallow, ENE-verging thrust faults and associated fault-propagated fold corridors. A combination of fault-propagated fold corridors acting as fluid conduits below the apex of the Telfer domes and the rheology and chemical contrast between interbedded siltstone and quartz arenite units within the dome are considered key parameters in the formation of the Telfer deposit. Based on the presence of the reduced Au-Cu-W-Bi-Te-Sn-Co-As assemblage, saline and carbonic, high-temperature hydrothermal fluids in Telfer ore, and widespread ilmenite-series granites locally associated with W skarn mineralization, Telfer is considered to be a distal, intrusion-related gold deposit, the high copper content of which may be explained by the predominance of highly saline, magmatic fluids in gangue assemblages cogenetic with ore.
超大型(>20 Moz)特尔弗金铜矿床位于澳大利亚西部帕特森省，由复杂变形的海相新元古代变质沉积粉砂岩和石英砂质组成。特尔弗地区还含有磁铁矿和钛铁矿系列花岗岩，花岗岩的年代约为645 - 600 Ma，与604 Ma O 'Callaghans花岗岩有关的世界级W矽卡岩矿床。根据独居石和xenotime U-Pb年代学，估计Telfer比O 'Callaghans更古老，形成于645 - 620 Ma之间。特尔弗的金-铜矿化赋存于多期、层理平行的石英-白云岩-黄铁矿-黄铜矿礁体和相关的不协调脉体及组成相似的网体中，这些脉体和网体位于两个北西走向的双俯冲背斜或穹窿中。成矿时间为晚造山期，热(≤460°C)、含盐(NaCl当量<50 wt %)矿液沿一系列浅层逆冲断层和相关的断层扩展褶皱走廊流入已存在的球壳。断裂传播的褶皱走廊组合在特尔弗圆顶顶端下方充当流体管道，以及圆顶内互层粉砂岩和石英砂质单元之间的流变学和化学对比被认为是特尔弗矿床形成的关键参数。根据特尔弗矿石中存在还原的Au-Cu-W-Bi-Te-Sn-Co-As组合、盐性和碳性高温热液流体，以及广泛分布的与W矽卡岩成矿有关的钛铁矿系列花岗岩，认为特尔弗是一个与侵入体有关的远端金矿床，其高铜含量可能与与矿石同生的脉石组合中高盐性岩浆流体占主导地位有关。
{"title":"Chapter 11: The Telfer Gold-Copper Deposit, Paterson Province, Western Australia","authors":"Alan J. Wilson, N. Lisowiec, Cameron Switzer, A. Harris, R. Creaser, C. Fanning","doi":"10.5382/sp.23.11","DOIUrl":"https://doi.org/10.5382/sp.23.11","url":null,"abstract":"The giant (>20 Moz) Telfer Au-Cu deposit is located in the Paterson Province of Western Australia and is hosted by complexly deformed marine Neoproterozoic metasedimentary siltstones and quartz arenites. The Telfer district also contains magnetite- and ilmenite-series granitoids dated between ca. 645 and 600 Ma and a world-class W skarn deposit associated with the reduced, ~604 Ma O’Callaghans granite. Based on monazite and xenotime U-Pb geochronology, Telfer is estimated to be older than O’Callaghans, forming between 645 and 620 Ma. Au-Cu mineralization at Telfer is hosted in multistage, bedding-parallel quartz-dolomite-pyrite-chalcopyrite reefs and related discordant veins and stockworks of similar composition that were emplaced into two NW-striking doubly plunging anticlines or domes. Mineralization is late orogenic in timing, with hot (≤460°C), saline (<50 wt % NaCl equiv) ore fluids channeled into preexisting domes along a series of shallow, ENE-verging thrust faults and associated fault-propagated fold corridors. A combination of fault-propagated fold corridors acting as fluid conduits below the apex of the Telfer domes and the rheology and chemical contrast between interbedded siltstone and quartz arenite units within the dome are considered key parameters in the formation of the Telfer deposit. Based on the presence of the reduced Au-Cu-W-Bi-Te-Sn-Co-As assemblage, saline and carbonic, high-temperature hydrothermal fluids in Telfer ore, and widespread ilmenite-series granites locally associated with W skarn mineralization, Telfer is considered to be a distal, intrusion-related gold deposit, the high copper content of which may be explained by the predominance of highly saline, magmatic fluids in gangue assemblages cogenetic with ore.","PeriodicalId":12540,"journal":{"name":"Geology of the World’s Major Gold Deposits and Provinces","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88736326","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}
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