scholarly journals Geological and Chronological Constraints on the Long-Lived Eocene Yulong Porphyry Cu-Mo Deposit, Eastern Tibet: Implications for the Lifespan of Giant Porphyry Cu Deposits

2017 ◽  
Vol 112 (7) ◽  
pp. 1719-1746 ◽  
Author(s):  
Jia Chang ◽  
Jian-Wei Li ◽  
David Selby ◽  
Jia-Cheng Liu ◽  
Xiao-Dong Deng
Keyword(s):  
Early Stage ◽  
Porphyry Copper ◽  
Copper Deposit ◽  
Granite Porphyry ◽  
Radiometric Dating ◽  
Time Interval ◽  
Porphyry Cu ◽  
Economic Significance ◽  
Vein Formation ◽  
Porphyry Cu Deposit

Abstract The Yulong porphyry Cu-Mo deposit, the third largest porphyry Cu deposit in China, contains proven reserves of > 6.5 million metric tons (Mt) Cu and 0.4 Mt Mo. Previous radiometric dating studies have provided numerous ages for this deposit, but the timing and duration of the process governing the deposition of Cu and Mo remains not well constrained. In this paper, we first document multiple stages of mineralization and hydrothermal alteration associated with distinct magmatic pulses at Yulong by field and textural relationships, and then present high-precision molybdenite Re-Os ages of 14 quartz-molybdenite ± chalcopyrite veins representing these stages to precisely constrain the timing and duration of Cu-Mo mineralization. The ore-hosting Yulong composite stock consists of three successive porphyry intrusions: (1) monzonitic granite porphyry (MGP), (2) K-feldspar granite porphyry (KGP), and (3) quartz albite porphyry (QAP). The vein formation, Cu-Mo mineralization, and ore-related alteration are grouped into early, transitional, and late stages with respect to the intrusive history. The first two porphyry intrusions are followed by cyclical sequences of veining that are mainly associated with potassic alteration and have formed (1) ME vein/USTT, (2) EBE/T veins, (3) A1E/T veins, (4) A2E/BT veins, and (5) A3E/T veins. A2E/BT and A3E/T veins of the early and transitional stages are dominated by quartz and chalcopyrite ± pyrite, respectively, and represent the main Cu-Mo mineralization events. More than 80% of Cu and Mo at Yulong were deposited in the early stage with the remainder being formed in the transitional stage. The late-stage pyrite-quartz veins (DL), which are characterized by sericitic alteration halos, postdate the intrusion of QAP dikes and have no economic significance. Molybdenite Re-Os ages of A2E and BT veins indicate that sulfide deposition at Yulong was episodic over a prolonged history lasting over 5.13 ± 0.23 m.y. (1σ). However, the bulk Cu-Mo ores formed in a shorter time interval of 1.36 ± 0.24 m.y. (1σ) with most Cu precipitated in a more restricted timespan of 0.82 ± 0.24 m.y. (1σ) in the early stage. These results, combined with geochronologic data from porphyry copper deposits elsewhere, confirm that multiple magmatic-hydrothermal pulses with a lifespan of tens to hundreds of thousands of years are sufficient to form a giant porphyry copper deposit. Factors such as metal concentration, volume, and focusing efficiency of ore-forming fluids could have played important roles in producing a giant porphyry Cu deposit regardless of a short- or long-lived magmatic-hydrothermal system.

scholarly journals Mapping Hydrothermal Zoning Pattern of Porphyry Cu Deposit Using Absorption Feature Parameters Calculated from ASTER Data

2019 ◽  
Vol 11 (14) ◽  
pp. 1729 ◽  
Author(s):  
Mengjuan Wu ◽  
Kefa Zhou ◽  
Quan Wang ◽  
Jinlin Wang
Keyword(s):  
Thermal Emission ◽  
Porphyry Copper ◽  
Copper Deposit ◽  
Geological Mapping ◽  
Systematic Sampling ◽  
Small Scale ◽  
Absorption Feature ◽  
Porphyry Cu ◽  
Feature Parameters ◽  
Porphyry Cu Deposit

Identifying hydrothermal zoning pattern associated with porphyry copper deposit is important for indicating its economic potential. Traditional approaches like systematic sampling and conventional geological mapping are time-consuming and labor extensive, and with limitations for providing small scale information. Recent developments suggest that remote sensing is a powerful tool for mapping and interpreting the spatial pattern of porphyry Cu deposit. In this study, we integrated in situ spectral measurement taken at the Yudai copper deposit in the Kalatag district, northwestern China, information obtained by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), as well as the spectra of samples (hand-specimen) measured using an Analytical Spectral Device (ASD) FieldSpec4 high-resolution spectrometer in laboratory, to map the hydrothermal zoning pattern of the copper deposit. Results proved that the common statistical approaches, such as relative band depth and Principle Component Analysis (PCA), were unable to identify the pattern accurately. To address the difficulty, we introduced a curve-fitting technique for ASTER shortwave infrared data to simulate Al(OH)-bearing, Fe/Mg(OH)-bearing, and carbonate minerals absorption features, respectively. The results indicate that the absorption feature parameters can effectively locate the ore body inside the research region, suggesting the absorption feature parameters have great potentials to delineate hydrothermal zoning pattern of porphyry Cu deposit. We foresee the method being widely used in the future.

scholarly journals Using Whole Rock and Zircon Geochemistry to Assess Porphyry Copper Potential of the Tonggou Copper Deposit, Eastern Tianshan

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 584
Author(s):  
Xue-Bing Zhang ◽  
Feng-Mei Chai ◽  
Chuan Chen ◽  
Hong-Yan Quan ◽  
Ke-Yong Wang ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Porphyry Copper ◽  
Copper Deposit ◽  
Middle Part ◽  
Orogenic Belt ◽  
Geochemical Data ◽  
Eastern Tianshan ◽  
Porphyry Cu ◽  
Central Asian ◽  
Geochemical Analyses

Eastern Tianshan hosts a number of porphyry Cu deposits. However, these mainly formed in the Jueluotage Belt, in the middle part of Eastern Tianshan. The Tonggou porphyry Cu mineralization is an exception to this, since it is located in the Bogda Orogenic Belt, north of Eastern Tianshan. We obtained new zircon U-Pb ages, whole-rock geochemical data, zircon Hf isotope data, and zircon trace element compositions. LA-ICP-MS zircon U-Pb dating indicates a crystallization age of 302.2–303.0 Ma for the Tonggou mineralized granodiorite (TMG), which suggests that the Tonggou porphyry Cu mineralization formed in the Late Carboniferous period. εHf (t) data (1.8–14.1) for TMG suggests it was sourced from juvenile crustal melts, mixed with some mantle materials. TMG displays low ΣREE, compatible elements (Ba, Sr, Zr, and Hf), Zr/Hf and Nb/Ta ratios, as well as clearly negative Eu anomalies in whole rocks analyses. In addition, TMG is enriched in P, Hf and Th/U ratios in zircon, and has lower crystallization temperatures (734 to 735 °C) than the Daheyan barren granodiorite (DBG) (753 to 802 °C). Whole rock and zircon geochemical analyses show that the TMG was formed by fractional crystallization to a greater extent than the DBG in the Bogda Orogenic Belt. Moreover, zircon grains of the TMG show high Ce4+/Ce3+ ratios (159–286), which are consistent with related values from large porphyry deposits of the Central Asian Orogenic Belt (CAOB). High Ce4+/Ce3+ ratios reflect oxidizing magmas as a result of fractional crystallization, which indicates that the Tonggou deposit has potential to host a large porphyry Cu deposit.

scholarly journals Compositions of Cu-(Fe)-Sulfides in the 109 Reduced Granite-Related Cu Deposit, Xinjiang, Northwest China: Implications to the Characteristics of Ore-Forming Fluids

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Rui Liu ◽  
Genwen Chen ◽  
Jianxing Yang
Keyword(s):  
Trace Elements ◽  
Oxygen Fugacity ◽  
Porphyry Copper ◽  
Northwest China ◽  
Low Oxygen ◽  
Concentration Data ◽  
Porphyry Cu ◽  
Western Tianshan ◽  
Forming Characteristics ◽  
Porphyry Cu Deposit

In general, porphyry Cu deposit is related to the highly oxidized ore-forming system. However, there are many porphyry Cu deposits that are related to the reduced ore-forming system, and the ore-forming characteristics of reduced porphyry Cu deposit are unclear. Cu-(Fe)-sulfides are the main Cu-hosting minerals in porphyry Cu deposits and are also economically important, and the composition of Cu-(Fe)-sulfides has closely relationship with ore-forming characteristics. In this study, concentration data obtained via laser ablation inductively coupled plasma mass spectrometry are reported for chalcopyrite, bornite, and chalcocite from the 109 porphyry Cu deposit formed in a reduced granite-related mineralization system in western Tianshan, Xinjiang, northwest China. The results show that the chalcopyrite hosts several trace elements including Zn, Ge, Se, In, and Sn; the bornite hosts Mo, Ag, Zn, Se, and Bi; and the chalcocite hosts Mo, Ag, Zn, Sn, Se, and Bi. The smooth time-resolved depths profiles and limited variations of trace element concentrations in these sulfides suggest that their presence is isomorphic. The microstructures of the chalcopyrite and bornite were observed by high-resolution transmission electron microscopy. Their lattices are neatly arranged, also indicating that the trace elements exist mainly as isomorphisms in the chalcopyrite and bornite. Ge, Sn, and In are hosted in the chalcopyrite but absent in bornite and chalcocite, indicating that chalcopyrite has a high potential for hosting these elements. Ge and Sn are preferentially hosted in the chalcopyrite, possibly due to relatively high temperatures and low oxygen fugacity during its formation. Indium is preferentially hosted in the chalcopyrite, possibly due to the In2+ substitution for Fe2+ controlled by Goldschmidt’s rules, which state that substitution occurs between a substituent and host owing to similarities in their radii and charges. However, the concentration of Ag is low in chalcopyrite but significantly high in bornite and chalcocite, indicating that this element is preferentially hosted in the latter two minerals. The abundance of Ag, a low-temperature element, in Cu-(Fe)-sulfides may largely be dependent on temperature. The Au content is below the minimum level of detection in all sulfides, which is obviously different from the classic porphyry copper deposits. In addition, the concentrations of Zn, Ge, As, Sb, and Te in the chalcopyrite and those of Zn, Se, As, Sb, and Bi in the bornite from the 109 porphyry Cu deposit show obvious differences from those of classic porphyry Cu deposits. Therefore, some elements in Cu-(Fe)-sulfides can be used as indicators of ore-forming oxygen fugacity. Bornite and chalcocite are generally enriched in Ag, indicating that the mining of porphyry Cu deposits may be concerned with the precious metal Ag in bornite and chalcocite. In addition, chalcopyrite may host sufficient Se and Zn, and bornite and chalcocite could host sufficient Se, Zn, and Bi, suggesting that sulfides may be hosts for deleterious elements.

Carmacks Copper Cu-Au-Ag Deposit: Mineralization and Postore Migmatization of a Stikine Arc Porphyry Copper System in Yukon, Canada

2020 ◽  
Vol 115 (7) ◽  
pp. 1413-1442
Author(s):  
Nikolett Kovacs ◽  
Murray M. Allan ◽  
James L. Crowley ◽  
Maurice Colpron ◽  
Craig J.R. Hart ◽  
...  
Keyword(s):  
British Columbia ◽  
Porphyry Copper ◽  
Copper Deposit ◽  
Early Jurassic ◽  
Amphibolite Facies ◽  
Late Triassic ◽  
Ionization Mass ◽  
Sulfide Mineralization ◽  
Porphyry Cu ◽  
South Central

Abstract Late Triassic to Early Jurassic porphyry Cu mineralization is common in British Columbia, yet there are few age-equivalent porphyry occurrences in Yukon. This study presents new data for the enigmatic Carmacks Copper Cu-Au-Ag deposit in south-central Yukon, Canada, which is hosted in amphibolite facies metamorphic inliers within the Early Jurassic Granite Mountain batholith. Sulfide mineralization occurs mainly as net-textured bornite and chalcopyrite in leucosome, and as chalcopyrite ± pyrite blebs and disseminations in amphibolite and quartz-plagioclase-biotite schist. Several studies suggest that the Carmacks Copper deposit and the nearby Minto deposit are related to porphyry belts in British Columbia, but constraining the timing of alteration, mineralization, and metamorphism has been difficult. This study establishes a geologic and high-precision geochronologic framework for sulfide mineralization and its host rocks at the Carmacks Copper deposit, using Re-Os dating of molybdenite, and chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) analysis of both whole zircon grains and laser-cut fragments of complexly zoned zircon grains. Our data indicate that the igneous protolith of the metamorphic inliers formed at 217.53 ± 0.16 Ma, followed by peak metamorphism at amphibolite facies at 205.82 ± 0.23 Ma, which occurred prior to Granite Mountain batholith emplacement but subsequent to Cu-Au-Ag mineralization of the protolith. An early phase of the Granite Mountain batholith was emplaced at 199.84 ± 0.14 Ma, followed by the main phase at 195 to 194 Ma. A second generation of metamorphic zircon in migmatite at 196.01 ± 0.12 Ma represents a partial melting event associated with Granite Mountain batholith emplacement. Two petrographically distinct populations of molybdenite are present in unstrained, net-textured copper sulfides. A sample dominated by strained molybdenite yielded an 187Re/187Os age of 212.5 ± 1.0 Ma, which represents the minimum mineralization age of the protolith. A sample dominated by euhedral grains yielded an 187Re/187Os age of 198.5 ± 0.9 Ma, constraining the maximum age of sulfide remobilization. These results indicate that primary mineralization is >212.5 Ma and potentially coeval with the ~217.5 Ma generation of Late Triassic magmatism. The mineralized protolith, best interpreted as the potassic alteration zone of a Late Triassic (~217–213 Ma) porphyry Cu-Au system, was metamorphosed to amphibolite facies at ~206 Ma, and subsequently migmatized during 200 to 194 Ma intrusion of the Granite Mountain batholith. The chalcopyrite-bornite-dominant assemblage in neosome precipitated from an immiscible Cu-Fe-S melt phase that partly consumed xenocrystic molybdenite and reprecipitated new molybdenite grains. The Carmacks Copper deposit and the related Minto deposit are remnants of a Late Triassic porphyry belt, where a significant fraction of the original metal endowment was likely lost through digestion of mineralized rocks by midcrustal magma in the Early Jurassic. These Yukon deposits are rare examples of metamorphosed porphyry Cu systems in the global geologic record, where rapid tectonic burial following mineralization was the principal factor in their preservation.

scholarly journals Petrochemical characteristics of late Paleozoic magmatic rocks of the Mandakh area, southeast Mongolia

2018 ◽  
pp. 5-21
Author(s):  
Undarmaa Batsaikhan ◽  
Tsuchiya Noriyoshi ◽  
Chimedtseren Anaad ◽  
Batkhishig Bayaraa
Keyword(s):  
Porphyry Copper ◽  
Copper Deposit ◽  
Porphyry Copper Deposit ◽  
Late Paleozoic ◽  
Calc Alkaline ◽  
Porphyry Cu ◽  
Magmatic Rocks ◽  
Mineral Assemblages ◽  
Intrusive Rocks ◽  
Quartz Monzonite

The late Paleozoic magmatic rocks are widely distributed in the Mandakh area which is located in the Gurvansaikhan and Manlai terrains, where porphyry Cu deposits occur. In this paper we discuss petrochemical features and mineral assemblages of magmatic rocks in the Mandakh area. Furthermore, we compared petrochemical characteristics of magmatic rocks in the Mandakh area with host magmatic rocks of the Tampakan deposit (Philippines), Cerro Colorado deposit (Chili) and negative criteria of Cu deposits (Japan) due to try to characterize potential of the porphyry copper deposit related to magmatic rocks in Mandakh area. Geochemical features of magmatic rocks in Mandakh area are calc-alkaline, magnetite-series, I-type and similar to adakite type. The Devonian intrusive rocks comprised of syenite and syenogranite, while the Carboniferous intrusive rocks consist of granodiorite, monzodiorite, quartz-monzonite and hornblende granite. Devonian magmatic rocks are more alkaline in composition. Although, Devonian and Carboniferous magmatic rocks are slightly different from each other. Comparing with bonanza copper deposits in the world, they are possible to host porphyry mineralization.

The Tongkuangyu Cu Deposit, Trans-North China Orogen: A Metamorphosed Paleoproterozoic Porphyry Cu Deposit

2020 ◽  
Vol 115 (1) ◽  
pp. 51-77
Author(s):  
Xuyang Meng ◽  
Jeremy Richards ◽  
Jingwen Mao ◽  
Huishou Ye ◽  
S. Andrew DuFrane ◽  
...  
Keyword(s):  
North China ◽  
Porphyry Copper ◽  
Volcanic Rocks ◽  
Copper Deposit ◽  
Granitic Rocks ◽  
Weighted Mean ◽  
Porphyry Cu ◽  
Copper Mineralization ◽  
Biotite Schist ◽  
Granodiorite Porphyry

Abstract The Tongkuangyu copper deposit in the Zhongtiaoshan region, southern Trans-North China orogen, is hosted by a poorly constrained sequence of Paleoproterozoic volcano-sedimentary (quartz-sericite schist and biotite schist) and granitic rocks that have been metamorphosed to lower greenschist facies and variably deformed. The deposit has previously been proposed to be either a porphyry-type or a sediment-hosted stratiform Cu deposit, and its age of formation has been debated. The quartz-sericite schist is interpreted to be a felsic crystal tuff and consists of angular quartz crystals in a fine-grained sericite-altered matrix. Two quartz-sericite schist samples yielded zircon U-Pb upper concordia intercept ages of 2512 ± 12 (2σ, mean square of weighted deviates [MSWD] = 0.19) and 2335 ± 16 Ma (2σ, MSWD = 0.80). Biotite schist, which is interleaved locally with the quartz-sericite schist and is interpreted to be a basaltic-andesitic sill, yielded a younger zircon U-Pb upper concordia intercept age of 2191 ± 10 Ma (2σ, MSWD = 1.7). Five samples of granodiorite and granodiorite porphyry that intruded the schist sequence yielded similar zircon U-Pb ages, with a weighted mean upper concordia intercept age of 2182 ± 7 Ma (2σ, MSWD = 1.3). These results suggest that the volcanic sequence was deposited between ∼2.5 and 2.3 Ga and was intruded by basaltic-andesitic sills and a suite of granodiorite and granodiorite porphyry intrusions at ∼2.19 to 2.18 Ga. Two stages of copper mineralization are interpreted to have formed after pervasive sericite alteration of the felsic volcanic rocks. Stage 1 mineralization includes disseminated and deformed quartz veinlets containing chalcopyrite ± pyrite ± magnetite ± molybdenite associated with biotite ± K-feldspar alteration in granodiorite porphyry and schist. Stage 2 comprises undeformed quartz-chlorite-carbonate veins with bornite ± chalcopyrite ± magnetite associated with local chlorite and silicic alteration. Allanite crystals intergrown with chalcopyrite in the granodiorite porphyry yielded an approximate concordia U-Pb age of 2115 ± 31 Ma (2σ, MSWD = 2.3). Two molybdenite samples in a deformed quartz-chalcopyrite-molybdenite vein yielded Re-Os model ages of 2106 ± 9 and 2089 ± 9 Ma (2σ), consistent with previously published results. Hydrothermal monazite grains with Cu-Fe sulfide inclusions in the granodiorite porphyry, quartz-sericite schist, and undeformed chlorite-bornite-quartz veins yielded much younger U-Pb upper concordia intercept ages of 1832 ± 16 (2σ, MSWD = 0.48), 1810 ± 14 (2σ, MSWD = 0.92), and 1809 ± 12 Ma (2σ, MSWD = 0.38), respectively. The results are in agreement with four Re-Os model ages for pyrite mineral separates from undeformed quartz-sulfide veins, which yielded a weighted mean age of 1807 ± 4 Ma (2σ, n = 4, MSWD = 0.42). In contrast, hydrothermal rutile crystals in the quartz-sericite schist and biotite schist yielded a range of roughly concordant ages between 2.1 and 1.8 Ga, reflecting isotopic disturbance. We interpret these results to indicate original copper mineralization at ∼2.1 Ga that is significantly later than the granodiorite (∼2.18 Ga) and schists (∼2.5–2.2 Ga), followed by hydrothermal remobilization and metamorphism at ∼1.8 Ga. The metavolcanic and granodiorite porphyry host rocks, alteration styles, and disseminated and veinlet form of the earlier mineralization are strongly reminiscent of porphyry Cu deposits, and ages of ∼2.1 Ga have been reported for one intrusion and three volcanic rock samples from the district. The Tongkuangyu, therefore, represents one of the oldest known porphyry copper deposits. Remobilization of copper occurred at ∼1.8 Ga during the Zhongtiao orogeny.

scholarly journals Porphyry copper deposit formation in arcs: What are the odds?

Geosphere ◽  
2021 ◽  
Author(s):  
Jeremy P. Richards ◽  
Matthew Leybourne
Keyword(s):  
Hydrothermal Fluid ◽  
Subduction Zones ◽  
Porphyry Copper ◽  
Fluid Phase ◽  
Copper Deposit ◽  
Ore Deposits ◽  
Water Soluble ◽  
Cumulative Probability ◽  
High Threshold ◽  
Porphyry Cu

Arc magmas globally are H2O-Cl-S–rich and moderately oxidized (ΔFMQ = +1 to +2) relative to most other mantle-derived magmas (ΔFMQ ≤ 0). Their relatively high oxidation state limits the extent to which sulfide phases separate from the magma, which would otherwise tend to deplete the melt in chalcophile elements such as Cu (highly siderophile elements such as Au and especially platinum-group elements are depleted by even small amounts of sulfide segregation). As these magmas rise into the crust and begin to crystallize, they will reach volatile saturation, and a hydrous, saline, S-rich, moderately oxidized fluid is released, into which chalcophile and any remaining siderophile metals (as well as many other water-soluble elements) will strongly partition. This magmatic-hydrothermal fluid phase has the potential to form ore deposits (most commonly porphyry Cu ± Mo ± Au deposits) if its metal load is precipitated in economic concentrations, but there are many steps along the way that must be successfully negotiated before this can occur. This paper seeks to identify the main steps along the path from magma genesis to hydrothermal mineral precipitation that affect the chances of forming an ore deposit (defined as an economically mineable resource) and attempts to estimate the probability of achieving each step. The cumulative probability of forming a large porphyry Cu deposit at any given time in an arc magmatic system (i.e., a single batholith-linked volcanoplutonic complex) is estimated to be ~0.001%, and less than 1/10 of these deposits will be uplifted and exposed at shallow enough depths to mine economically (0.0001%). Continued uplift and ero­sion in active convergent tectonic regimes rapidly remove these upper-crustal deposits from the geological record, such that the probability of finding them in older arc systems decreases further with age, to the point that porphyry Cu deposits are almost nonexistent in Precambrian rocks. A key finding of this paper is that most volcanoplutonic arcs above subduction zones are prospective for porphyry ore formation, with prob­abilities only falling to low values at late stages of magmatic-hydrothermal fluid exsolution, focusing, and metal deposition. This is in part because of the high threshold required in terms of grade and tonnage for a deposit to be considered economic. Thus, the probability of forming a porphyry-type system in any given arc segment is relatively high, but the probability that it will be a large economic deposit is low, dictated to a large extent by mineral economics and metal prices.

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