Reduced granitic magmas in an arc setting: The Catface porphyry Cu–Mo deposit of the Paleogene Cascade Arc

Smith, Colin Michael; Canil, Dante; Rowins, Stephen M.; Friedman, Richard M.

doi:10.1016/j.lithos.2012.08.001

Cited by 63 publications

(16 citation statements)

References 62 publications

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“…Porphyry Mo and Sn-W deposits are associated with A-type and S-type granites, respectively, which form in back-arc continental environments (Christiansen and Keith, 1996;Newberry, 1998). Porphyry Cu-Mo and Cu-Au deposits are derived from I-type granites (Loucks, 2014;Dilles et al, 2014) that possess variable alkalinity (e.g., Barr et al, 1976;Lang et al, 1995), degrees of silica saturation (Seedorff et al, 2005), and oxidation states (Rowins, 2000;Smith et al, 2012;Cao et al, 2014). Porphyry deposits are rare in Proterozoic and Archean rocks, possibly due to differences in the style of plate tectonics and diminished preservation potential of older orogens (e.g., Groves et al, 2005;Richards and Mumin, 2014).…”

Section: Porphyry Depositsmentioning

confidence: 99%

Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

et al. 2016

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Section: Porphyry Depositsmentioning

confidence: 99%

Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

et al. 2016

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“…The data of the CAOB and Pacific Rim metallogenic belt are from Lee (); Smith et al . (); Shen and Pan (); Shen et al . (2015); Xiao et al .…”

Section: Resultsmentioning

confidence: 97%

“…An elevated oxygen fugacity will facilitate the extraction of Cu into the melts at the source because melts have a much higher solubility of metal and sulfur due to S as

{SO}_{4}^{2 -}

under oxidizing conditions (Carroll & Rutherford, ). However, there are several porphyry Cu (Mo‐Au) systems associated with low oxygen fugacity (≤QFM buffer) granitic rocks (Rowins, ), such as the Catface porphyry Cu‐Mo‐Au deposit (Smith et al, ), the Pulang porphyry Cu deposit (Liu et al, ), and the Baogutu porphyry Cu deposit (Cao et al, ). Therefore, other factors (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Dilles, ; Shen et al ., ; Sun et al, ; Zhang et al, ). However, the oxygen fugacity in some porphyry Cu (Mo–Au) systems is lower (≤Quartz‐Fayalite‐Magnetite buffer) (Rowins, ), such as in the Catface porphyry Cu–Mo–Au deposit located in Canada (Smith et al, ), the Pulang porphyry Cu deposit situated in southwestern China (Liu et al, ), and the Baogutu porphyry Cu deposit located in northwestern China (Cao et al, ). Therefore, in addition to oxygen fugacity, there are other factors that control the formation of porphyry Cu deposits, especially for the porphyry Cu deposits with a low oxygen fugacity.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Rare Earth Elements, Zr, and Hf in Ore‐Bearing Porphyries from the Western Awulale Metallogenic Belt, Northwestern China and their Application in Determining Metal Fertility of Granitic Magma

Chen

2018

Resource Geology

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The western Awulale metallogenic belt in northwestern China hosts a number of small-to medium-sized porphyry Cu deposits that are associated with albite porphyry. The common presence of plagioclase (albite) as phenocrysts and the absence of hydrous minerals (amphibole and biotite) indicate that the water content of albite porphyry is low. Trace-element compositions of whole rocks and zircon grains from these orebearing porphyries were measured. Zircon grains from albite porphyries exhibit Ce 4+ /Ce 3+ ratios ranging from 7.75 to 95.1, which indicate that these porphyries have a low oxygen fugacity. Trace element compositions of ore-bearing porphyries exhibit (La/Yb) N ratios ranging from 1.09 to 11.1 and Eu/Eu * ratios ranging from 0.10 to 0.66. These ore-bearing porphyries have Zr values ranging from 171 to 707 ppm and Hf values ranging from 8.30 to 18.9 ppm. Combining these porphyries with other ore-bearing porphyries that formed in the Central Asian Orogenic Belt (CAOB) and the Pacific Rim metallogenic belt, we found that the (La/Yb) N and Eu/Eu * ratios of ore-bearing porphyries in western Awulale are low, while the Zr and Hf values are high. Specifically, REEs can be used to evaluate the degree of differentiation and degree of partial melting, and Zr and Hf can be used to evaluate the redox conditions and water content of magmatic rocks. Our findings indicate that ore-bearing porphyries in western Awulale have a lower oxygen fugacity, degree of differentiation, and water content than do others in the CAOB and the Pacific Rim metallogenic belt. Compared to those of ore-bearing porphyries with lower zircon Ce 4+ /Ce 3+ ratios, the (La/Yb) N ratios of orebearing porphyries in our study are low, and the Zr and Hf values are high. This finding indicates that, under reducing conditions, the degree of evolution and water content may have an important influence on the metal abundance in magmas. There is also a clear relationship between (La/Yb) N , Eu/Eu * , Zr, Hf, and the size of the deposits. Large-(>4 Mt Cu) and intermediate (1.5-4 Mt Cu)-sized porphyry Cu deposits are associated with granitic intrusions that have higher (La/Yb) N and Eu/Eu * ratios and lower Zr and Hf values. This finding indicates that, in addition to oxygen fugacity, the degree of evolution and water content are controlling parameters for metal abundance in magmas, especially in low oxygen fugacity porphyry Cu

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“…Therefore, comparison of the distribution of trace elements may reveal factors that control the trace element distribution in different Cu-(Fe)-sulfides, particularly for reduced porphyry Cu deposit. Previous studies have indicated that the Cu-(Fe)sulfides in reduced porphyry Cu deposits, which include chalcopyrite, bornite, and chalcocite, are similar to those in classic porphyry Cu deposits [5,[16][17][18][19]. However, owing to the limited number of the reduced porphyry Cu deposits, fewer studies have been conducted on sulfides in this type of deposit.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Yang

2020

Geofluids

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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.

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Reduced granitic magmas in an arc setting: The Catface porphyry Cu–Mo deposit of the Paleogene Cascade Arc

Cited by 63 publications

References 62 publications

Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

Apatite Trace Element Compositions: A Robust New Tool for Mineral Exploration

Characteristics of Rare Earth Elements, Zr, and Hf in Ore‐Bearing Porphyries from the Western Awulale Metallogenic Belt, Northwestern China and their Application in Determining Metal Fertility of Granitic Magma

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

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