Fluid inclusions in porphyry and skarn ore at Santa Rita, New Mexico

Ahmad, Shujaat; Rose, Arthur W.

doi:10.2113/gsecongeo.75.2.229

Cited by 109 publications

(47 citation statements)

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“…In some hypersaline inclusions in the stockwork quartz, a vapor phase with high reflection index is observed at higher temperature after the primary bubble vanished during heating experiment (Fig. 14), as reported from the Santa Rita deposit (Ahmad and Rose, 1980). Such complicated phase rela-…”

Section: Principal Cu and Au Mineralization (Stages 1-2)supporting

confidence: 61%

Genesis of the Mamut Porphyry Copper Deposit, Sabah, East Malaysia

Imai¹

2000

Resource Geology

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: The Mamut deposit of Sabah, East Malaysia, is a porphyry type Cu‐Au deposit genetically related to a quartz monzonite (“adamellite”) porphyry stock associated with upper Miocene Mount Kinabalu plutonism. The genesis of the Mamut deposit is discussed based on petrology of the intrusives in the Mount Kinabalu area combined with ore– and alteration–petrography, fluid inclusion and sulfur isotope studies. Groundmass of the adamellite porphyry at Mamut is rich in K which suggests vapor transport of alkaline elements during the mineralizing magmatic process, while the groundmass of the post‐ore “granodiorite” porphyry at Mamut contains small amounts of normative corundum suggesting depletion in alkaline elements at the root zone of the magma column. Sub‐dendritic tremolitic amphibole rims on hornblende phenocrysts in the Mamut adamellite porphyry suggest interaction between the mineralizing magma and the exsolved fluids. Occurrences of clinopyroxene microphenocrysts and pseudomor‐phic aggregates of shredded biotite and clinopyroxene after hornblende phenocrysts in the barren intrusives imply lower water fugacity and decreasing in water fugacity, respectively. Compositional gap between the core of hornblende phenocrysts and the tremolitic amphibole rims and those in the groundmass of the Mamut adamellite porphyry suggests a decrease in pressure. Higher XMg (=Mg/(Mg+Fe) atomic ratio) in the tremolitic amphibole rims in the Mamut adamellite porphyry compared to those of the barren intrusions suggests high oxygen fugacity. High halogen contents of igneous hydrous minerals such as amphiboles, biotite and apatite in the Mamut adamellite porphyry suggest the existence of highly saline fluids during the intrusion and solidification of the mineralizing magma. Fluid inclusions found in quartz veinlet stockworks are characterized by abundant hypersaline polyphase inclusions associated with subordinate amounts of immiscible gaseous vapor. Both Cu and Au are dispersed in disseminated and quartz stockwork ores. Chalcopyrite and pyrrhotite as well as magnetite are the principal ore minerals in the biotitized disseminated ores. Primary assemblage of intermediate solid solution (iss) and pyrrhotite converted to the present assemblage of chalcopyrite and pyrrhotite during cooling. Subsequent to biotitization, quartz veinlet stockworks formed associated with retrograde chlorite alteration. The Cu‐Fe sul–fides associated with stockwork quartz veinlet are chalcopyrite and pyrite. Overlapping Pb and Zn and subsequent Sb mineralizations were spatially controlled by NNE‐trending fractures accompanying the phyllic and advanced argillic alteration envelope. Sulfur isotopic composition of ore sulfides are homogeneous (about +2%) throughout the mineralization stages. These are identical to those of the magmatic sulfides of Mount Kinabalu adamellitic rocks.

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Section: Principal Cu and Au Mineralization (Stages 1-2)supporting

confidence: 61%

Genesis of the Mamut Porphyry Copper Deposit, Sabah, East Malaysia

Imai¹

2000

Resource Geology

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“…NaCl), and gas, and this phase separation was responsible for ore deposition. The initial high temperatures (>420°C), an immiscibility of mineralizing fluids, the presence of chloride brines in inclusions, a wide range of homogenization temperatures and salinity, and a combination of various types of inclusions all show the similarity of the ore-forming process in the Mramorny cluster to PTX conditions at typical porphyry-copper deposits (Roedder 1971, Nash 1976, Eastoe 1978, Ahmad & Rose 1980, Bloom 1981, Ruggieri et al 1997, Harris et al 2005, Frikken et al 2005. As seen from the aforementioned evidence, there are several identical characteristic features at the three locations: (1) relation to hydrothermally altered porphyritic rhyolite or brecciation zones in rhyolite; (2) at Sukhoi and Nadezhda, cassiterite was identified, and the Mount Seraya occurrence is characterized by anomalous concentrations of tin in the alluvium of first-order streams; (3) identical minerals are associated with tourmaline; (4) similar chemical compositions of tourmalines are found in different locations, and (5) the ratio Fe 3+ /Fe tot is relatively high in the tourmalines.…”

Section: Discussionmentioning

confidence: 99%

Tourmaline of the Mramorny Tin Cluster, Chukotka Peninsula, Russia

Бакшеев

Тихомиров

Yapaskurt

et al. 2009

The Canadian Mineralogist

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Porphyry-related deposits are the fourth type of tin deposits in importance after pegmatite, greisen and granite-related hydrothermal veins. We have studied tourmalines and associated minerals from the several porphyry-tin occurrences related to rhyolite dikes in the Mramorny tin cluster, located in Chukotka, the second large tin province in Russia after the Far East province. Two types of tourmaline were identified in the occurrences of the Mramorny tin cluster: (1) early pre-ore tourmaline, and (2) ore-stage tourmaline, which is associated with chamosite. The early-stage tourmaline can be classed as an intermediate member of the schorl-foitite and "oxy-schorl" -"oxy-foitite" series. Its compositions are characterized by their values of X-site vacancy and Fe tot / (Fe tot + Mg) ranging from 0.147 to 0.665 apfu and from 0.85 to 1.00, respectively. The ratio Fe 3+ / Fe tot in the tourmaline is about 19-25%. The ore-stage tourmaline is characterized by a more complex composition distinguished by lower values of X-site vacancy and Fe tot / (Fe tot + Mg), ranging from 0.018 to 0.437 apfu and from 0.49 to 0.75, respectively. The Fe 3+ / Fe tot value in the tourmaline is about 11-23%. The early and ore-stage tourmalines are characterized by different types of Al substitutions: AlO[R(OH)] -1 and Al(RNa) -1 in the former, and FeAl -1 , taking into account the higher Mg concentration, in the latter. The precipitation of cassiterite and the higher activity of H 2 S during the ore stage resulted in the deposition of Fe-bearing sulfides, and the Fe tot / (Fe tot + Mg) value in the ore-stage tourmaline is lower than that of the early tourmaline. The pattern is similar in the associated early and ore-stage chamosite, i.e., the Fe tot / (Fe tot + Mg) ratio decreases like in tourmaline. On the basis of fluid inclusions, the ore-stage tourmaline started to crystallize at temperature about 385°C and at a pressure of 23 MPa. The fluid responsible for tourmaline formation and ore deposition did boil and was similar to that of porphyry-copper deposits, confirming that the occurrences studied are related to a porphyry environment. The oxygen isotopic data indicate a significant admixture of meteoric water at the ore-stage tourmaline deposition (d 18 O H2O from -8.4 to +0.6‰). The comparison of the tourmalines studied here with tourmalines from porphyry-copper and porphyry-gold deposits indicates that the FeAl -1 substitution is typical of tourmaline in the porphyry environment.Keywords: porphyry-Sn deposit, foitite, schorl, Mramorny cluster, Chukotka, Russia. SOMMaIrELes gisements d'étain liés aux venues porphyriques constituent le quatrième groupe de gisements stannifères en importance après ceux associés aux pegmatites, aux greisens et aux veines hydrothermales issues de granites. Nous avons étudié les tourmalines et les minéraux associés provenant de plusieurs indices minéralisés associés à des filons de rhyolite du camp stannifère de Mramorny, situé à Chukotka, le deuxième camp en importance en Russie après la province ...

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“…have been intensively studied in the Mesozoic-Cenozoic orogenic belts of the American Cordillera and East Pacific Rim (e.g., Ahmad & Rose, 1980;Dilles & Einaudi, 1992;Sillitoe, 1973) and their properties is relatively well understood. Several conceptual models have been proposed to explain the different styles of Cu Porphyry mineralization (Bliss, 1992;Gruen, Heinrich, & Schroeder, 2010;Sillitoe, 1999Sillitoe, , 2010Sillitoe & Gappe, 1984;Volkov et al, 2006;Xu et al, 2009).…”

Section: Conceptual Modelmentioning

confidence: 99%

Predictive Cu porphyry potential mapping using fuzzy modelling in Ahar–Arasbaran zone, Iran

Pazand

Hezarkhani

2018

Geology, Ecology, and Landscapes

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Fuzzy set theory was successfully used to map areas of copper porphyry mineralization potential in the Ahar-Arasbaran district of Iran. Proximity to geological features is translated into fuzzy membership functions based upon qualitative and quantitative knowledge of spatial associations between known Cu porphyry occurrences and geological features in the area. Fuzzy sets of favourable lithology, geochemical anomaly, geophysical anomaly, structural feature, and alterations are combined using fuzzy logic as the inference engine. The fuzzy predictive maps delineate 84% of the known Cu porphyry occurrences. The results demonstrate the usefulness of a geologically constrained fuzzy set approach to map mineral potential and to redirect surficial exploration work in the search for yet undiscovered Cu porphyry mineralization in the mining district. The method described is applicable to other mining districts elsewhere.

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Fluid inclusions in porphyry and skarn ore at Santa Rita, New Mexico

Cited by 109 publications

References 0 publications

Genesis of the Mamut Porphyry Copper Deposit, Sabah, East Malaysia

Genesis of the Mamut Porphyry Copper Deposit, Sabah, East Malaysia

Tourmaline of the Mramorny Tin Cluster, Chukotka Peninsula, Russia

Predictive Cu porphyry potential mapping using fuzzy modelling in Ahar–Arasbaran zone, Iran

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