Epithermal and subjacent porphyry mineralization, Acupan, Baguio District, Philippines: a fluid-inclusion and paragenetic study

Cooke, David R.; Bloom, Mark S.

doi:10.1016/0375-6742(90)90042-9

Cited by 67 publications

(25 citation statements)

References 25 publications

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“…Epithermal gold veins in the Baguio district are flanked to the south, west, and north by major late Miocene to Pliocene porphyry Cu-Au deposits, and porphyry Cu-Au prospects occur adjacent to epithermal veins at Acupan South and possibly Kelly (Comsti et al, 1990;Cooke and Bloom, 1990). The late Miocene-Pliocene episode of high K magmatic activity represented by the Virac Complex and coeval Klondyke Formation andesites is responsible for the development of porphyry and epithermal deposits within and around the Baguio district (Cooke, 1990(Cooke, , 1991.…”

Section: Relationships Between Magmatism and Mineralizationmentioning

confidence: 97%

“…The system is one of the most southerly, lying close to the Ampucao dacite porphyry (Fig. 3), allowing the investigation of genetic relationships between the two deposits (Cooke and Bloom, 1990). Furthermore, it was accessible for over 2 km along strike and over a vertical interval of more than 750 in (between level 2600 and the surface).…”

Section: Sampling Programmentioning

confidence: 99%

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Epithermal gold mineralization, Acupan, Baguio District, Philippines; geology, mineralization, alteration, and the thermochemical environment of ore deposition

Cooke

McPhail²,

Bloom³

1996

Economic Geology

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A large gold-rich adularia-sericite-style epithermal vein system formed at 0.65 Ma at Acupan, Baguio district, Philippines, during a period of high K magmatism. Low-salinity (•0.5 wt % NaC1 equiv), gassy (up to 0.41 m CO.2) meteoric fluids with temperatures of up to 300øC or more xvere focused into a series of steeply dipping interconnected faults and joints in the Virac granodiorite, Balatoc diatreme, Lucbuban gabbro, and Zig-Zag Formation. Prolonged and varied geothermal activity resulted in the formation of a series of composite banded epithermal veins with an average width of 1 m that extend to depths of at least i km (relative to the present-day surface). The epithermal event was characteried by periods of hydrothermal brecciation interspersed with more quiescent periods when delicate to coarsely banded vein material was precipitated. Five distinct mineral assemblages have been defined in the epithermal veins: type A (characterized by fine-grained chalcedony), type B (fine-grained gray quartz), type C (coarse-grained white quartz), type D (coarse-grained calcite), and type E (coarse-grained anhydrite). Electrum and Au-Ag tellurides have been recognized in type B, C, and D bands. Interaction of ascending chloride brines with the wall rocks over the lifetime of the system produced intense, symmetrical, meterwide halos of altered rock characterized by sericitic, silicic, and sericite-chlorite mineral assemblages that grade out to a weak, diffuse widespread propylitically altered zone. Minor adularia alteration is restricted to the deeper mine levels.Sulfide-oxide-silicate-carbonate phase relationships in the Acupan vein system constrain the mineralizing fluids to values of logJ•o21 between -28 and -33, logJ•n21 between -1.5 and -3.7, and logJ•H2sl between -0.6 and -1.8 at 300øC. Abundant quartz-K mica-pyrite alteration and vein mineralization are consistent with silica-saturated, reduced, weakly acidic to weakly alkaline fluid compositions. Boiling caused the fluids to evolve to more alkaline conditions, leading to the sporadic precipitation of adularia in the veins and altered wall rocks. Dissolved COs concentrations were sufficiently high (up to 0.41 m) to stabilize calcite at the expense of calc-silicate minerals. Mg •+ concentrations were low in the mineralizing fluids but increased during dissolution of primary hornblende and biotite in the country rocks, resulting in the development of a sericitechlorite alteration assemblage in the deep mine levels. HsS and H.2COa were the predominant sulfur-and carbon-bearing species, and the low-salinity, gassy nature of the fluids favored gold and silver transport as bisulfide complexes. H.2Te and HTe-were the predominant aqueous tellurium species. Entrainment of minor amounts of magmatic volatiles during type C and D mineralization is responsible for Te enrichment in the dominantly meteoric fluids, and log fw•/ ranged between -7.8 and -8.6 at 300øC during periods of hessitc deposition. Magmatic contributions also account for the CO• and H•S-rich nature of the fluids ...

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Section: Relationships Between Magmatism and Mineralizationmentioning

confidence: 97%

Section: Sampling Programmentioning

confidence: 99%

Epithermal gold mineralization, Acupan, Baguio District, Philippines; geology, mineralization, alteration, and the thermochemical environment of ore deposition

Cooke

McPhail²,

Bloom³

1996

Economic Geology

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“…Modern interpretations suggest various sources for the mineralizing fluids in the shallow epithermal environment of these systems-from dominantly magmatic to mixed magmaticmeteoric; a consensus exists concerning the prevailing magmatic origin of the fluids in the deeper porphyry environment (Arribas 1995;Sillitoe and Hedenquist 2003;Heinrich 2005;Seedorff et al 2005). The transition between porphyry and epithermal environments, including evolution of the fluid composition and of the sulfidation state of the mineralizing fluids, lateral and vertical zonation in the distribution of wallrock alteration zones, and ore mineral assemblages has been noted in many Tertiary mineral districts, where tectonic and erosional processes did not significantly affect the original architecture of the magmatic-hydrothermal system (e.g., Cooke and Bloom 1990;Muntean and Einaudi 2000, Brathwaite et al 2001Müller et al 2002), while Mesozoic and older systems are rarely well preserved (e.g. Kesler et al 2005;Chambefort and Moritz 2006;Chambefort et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Late Cretaceous porphyry Cu and epithermal Cu–Au association in the Southern Panagyurishte District, Bulgaria: the paired Vlaykov Vruh and Elshitsa deposits

et al. 2009

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Vlaykov Vruh-Elshitsa represents the best example of paired porphyry Cu and epithermal Cu-Au deposits within the Late Cretaceous Apuseni-BanatTimok-Srednogorie magmatic and metallogenic belt of Eastern Europe. The two deposits are part of the NW trending Panagyurishte magmato-tectonic corridor of central Bulgaria. The deposits were formed along the SW flank of the Elshitsa volcano-intrusive complex and are spatially associated with N110-120-trending hypabyssal and subvolcanic bodies of granodioritic composition. At Elshitsa, more than ten lenticular to columnar massive ore bodies are discordant with respect to the host rock and are structurally controlled. A particular feature of the mineralization is the overprinting of an early stage high-sulfidation mineral assemblage (pyrite ± enargite ± covellite ± goldfieldite) by an intermediate-sulfidation paragenesis with a characteristic Cu-Bi-Te-Pb-Zn signature forming the main economic parts of the ore bodies. The two stages of mineralization produced two compositionally different types of ores-massive pyrite and copper-pyrite bodies. Vlaykov Vruh shares features with typical porphyry Cu systems. Their common geological and structural setting, ore-forming processes, and paragenesis, as well as the observed alteration and geochemical lateral and vertical zonation, allow us to interpret the Elshitsa and Vlaykov Vruh deposits as the deep part of a high-sulfidation epithermal system and its spatially and genetically related porphyry Cu counterpart, respectively. The magmatichydrothermal system at Vlaykov Vruh-Elshitsa produced much smaller deposits than similar complexes in the northern part of the Panagyurishte district (Chelopech, Elatsite, Assarel). Magma chemistry and isotopic signature are some of the main differences between the northern and southern parts of the district. Major and trace element geochemistry of the Elshitsa magmatic complex are indicative for the medium-to high-K calc-alkaline character of the magmas. 87 Pb=37.497-38.630) allow attribution of ore-formation in the porphyry and epithermal deposits in the Southern Panagyurishte district to a single metallogenic event with a common source of metals.

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“…About a quarter of these prospects have had some recent exploration to reevaluate historical data; the others are reportedly porphyry copper-type occurrences (C. Manipon, written commun., 2004). The porphyry copper deposits and prospects in the Baguio district are subjacent to major producing epithermal gold-silver deposits, such as Acupan and gold and base-metal skarn deposits such the Thanksgiving deposit (Cooke and Bloom, 1990;Waters and others, 2011).…”

Section: Luzon Central Cordilleramentioning

confidence: 99%

Porphyry copper assessment of East and Southeast Asia: Philippines, Taiwan (Republic of China), Republic of Korea (South Korea), and Japan

Hammarstrom¹,

Bookstrom²,

Demarr³

et al. 2014

Scientific Investigations Report

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Epithermal and subjacent porphyry mineralization, Acupan, Baguio District, Philippines: a fluid-inclusion and paragenetic study

Cited by 67 publications

References 25 publications

Epithermal gold mineralization, Acupan, Baguio District, Philippines; geology, mineralization, alteration, and the thermochemical environment of ore deposition

Epithermal gold mineralization, Acupan, Baguio District, Philippines; geology, mineralization, alteration, and the thermochemical environment of ore deposition

Late Cretaceous porphyry Cu and epithermal Cu–Au association in the Southern Panagyurishte District, Bulgaria: the paired Vlaykov Vruh and Elshitsa deposits

Porphyry copper assessment of East and Southeast Asia: Philippines, Taiwan (Republic of China), Republic of Korea (South Korea), and Japan

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