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[Display omitted] • The Suyoc vein prospect is an intermediate sulfidation epithermal. • δD and δ18O compositions indicate typical late stage formation. • There is potential presence of cogenetic porphyry Cu and high sulfidation epithermal. The Suyoc prospect is an epithermal vein-type mineralization located at the southern part of the Mankayan Mineral District, Northern Luzon, Philippines. The prospect's epithermal veins are hosted in volcaniclastic rocks and conglomerate, which belong to the Late Oligocene to Early Miocene Balili Formation and the Middle to Late Miocene Suyoc Conglomerate, respectively. These veins are classified into three major types: quartz vein, quartz-sulfide vein, and quartz-carbonate vein. The quartz vein exhibits massive and cockade textures associated with pyrite + chalcopyrite. The quartz-sulfide vein consists of massive and comb quartz associated with pyrite + chalcopyrite + sphalerite. The quartz-carbonate vein has massive quartz associated with rhodochrosite and chalcopyrite + sphalerite + galena + Au/Ag ± bournonite. In addition, massive gypsum ± pyrite occurs as a minor vein-type. Fluid inclusion measurements in quartz from the three major vein-types revealed 230–250 °C formation temperatures and 1.0–3.5 wt. % NaCl equivalent salinity, which are values consistent with epithermal deposits. Quartz textures (e.g., massive, cockade, comb, crustiform) and dominance of liquid-rich fluid inclusions do not suggest that boiling is a primary mechanism of vein deposition. Possible mechanisms are inferred as meteoric water dilution based on homogenization versus salinity trend in quartz vein and presence of rhodochrosite in quartz-carbonate vein, and wall rock interaction based on FeS trend in sphalerite crystals of the quartz-carbonate vein. The presence of pyrite and chalcopyrite in the major vein-types and the FeS mole percent values (0.51 to 8.30) in quartz-carbonate vein indicate an intermediate sulfidation state. The alteration minerals illite, chlorite, pyrite and quartz indicate near-neutral pH condition. δ34S values, which vary from −1.1 to +3.9‰, suggest reduced condition when compared to the representative bulk δ34S value for the Mankayan Mineral District. The characteristics and conditions strongly indicate an intermediate sulfidation epithermal (ISE) style of mineralization. Moreover, the δD water (−63 to −66‰) and δ18O water (−3.9 to −1.1‰) values from the major vein-types suggest late stage formation in a magmatic-hydrothermal system similar to other ISE deposits in the Northern Luzon Segment (e.g., Victoria, Acupan and Antamok). Given these, the presence of the Suyoc ISE veins in the underexplored southern part of the Mankayan Mineral District implies potential presence of undiscovered cogenetic porphyry Cu and high sulfidation epithermal mineralization in the area. [ABSTRACT FROM AUTHOR]

• Early Miocene, Middle Miocene and Pliocene magmatic events were identified in Sangilo. • Middle Miocene fertile magmatism is attributed to MASH zone development. • Pliocene mineralization is from increased fertility due to rapid ascent of basaltic melt. In the Baguio Mineral District (BMD), porphyry Cu ± Au deposition and associated epithermal mineralization are attributed to the highly evolved magmatism during the Pliocene. It has been well-documented that the interaction between silicic crustal melts and primitive mantle melts formed water-rich, oxidized magmas that resulted to hydrothermal mineralization. However, there are very few studies on the Early to Middle Miocene calc-alkaline magmatism which is considered to be barren of mineralization. This magmatic event is represented by phases of the Central Cordillera Diorite Complex (CCDC), which also serve as host rocks to the Sangilo epithermal deposit. The Sangilo quartz-carbonate veins in the BMD are hosted by an Early Miocene hornblende diorite (22.33 ± 0.63 Ma) intruded by a Middle Miocene quartz diorite (15.91 ± 0.6 Ma) which are, in turn, penetrated by Pliocene basaltic andesite dikes. The Miocene magmatic units with hybrid crust-mantle source affinity were formed from varying degrees of interaction within the MASH (mixing, assimilation, storage, and homogenization) zone during the formation of the CCDC. The basaltic andesite dikes, part of the Pliocene Mafic Dike Complex, represent direct differentiates of basaltic melts that experienced ponding at the base of the lower crust before ascending to shallow crustal levels. Based on the assessment of the physico-chemical conditions, three distinct magmatic events were identified: a barren Early Miocene event, a fertile Middle Miocene event and a fertile Pliocene event. The Middle Miocene fertile magmatism is attributed to further development of the MASH zone under the Luzon arc from the Early to Middle Miocene. On the other hand, the enhanced fertility during the Pliocene is associated with the subduction of the Scarborough Ridge. [ABSTRACT FROM AUTHOR]

The presence of adakites has been used as an indicator for the occurrence of gold mineralization in many mineral prospecting works. Traditionally, the unique geodynamic controls to adakite formation, particularly the high temperature gradient and other slab-melting requirements, have been taken as key elements that must be present during their formation. However, several studies have suggested alternative mechanisms. This paper presents fractional crystallization as the most viable mechanism for the generation of adakitic rocks in the Masara gold-silver mine in Eastern Mindanao, Philippines. Furthermore, this paper also argues that the occurrence of adakitic rocks does not necessarily indicate the presence of mineralization. Depending on the scale, their occurrence may be an exploration marker at a regional or district level, but at the mine-level, other more localized parameters will have to be considered. [ABSTRACT FROM AUTHOR]

• Cu-Au deposition is related to calc-alkaline and adakitic magmas with high fO2. • Deposits in Baguio and Pacific Cordillera are Miocene to Plio-Pleistocene. • Crustal thickening and bathymetric high subduction contribute to mineralization. The Baguio Mineral District in Luzon, Philippines is known to host several world-class epithermal gold – porphyry copper deposits. The interplay of tectonic setting, magma composition, structural control and hydrothermal systems contributed to the generation of these deposits. Ridge subduction (Scarborough seamount) resulting to flat subduction and a transpressional regime could also be related to the formation of epithermal gold - porphyry copper deposits in Baguio. Subduction processes leading to the formation of calc-alkaline rocks associated with high water pressure, oxygen fugacity and late sulfur saturation are almost always associated with the gold-copper deposits in the district. Compared to the Baguio Mineral District, less exploration work, mine development and production were done in the Pacific Cordillera Mineral District, Mindanao in southern Philippines. It is worth noting, however, that both mineral districts show similarities and overlapping features in terms of geological, geophysical and geochemical characteristics. This leads one to conclude that the Pacific Cordillera Mineral District has ore deposits waiting to be discovered. [ABSTRACT FROM AUTHOR]