Features resulting from the interplay of arc magmatism, ophiolite accretion, ocean basin closure and other subsequent tectonic processes are preserved in the Philippine island arc system. Subduction of ocean floor along the trenches surrounding the Philippines is a major factor in shaping the geologic history of this island arc system. Stress-strain relationships, as manifest in both the regional and local setting of the archipelago, are derived from the interaction of at least four major plates: Sundaland, Philippine Mobile Belt, Philippine Sea and, to a certain extent, the Indo-Australian plate. Collision zones in this island arc system are characterized by the involvement of oceanic bathymetric highs (seamounts, spreading ridge, submerged continental fragment). A major strike-slip fault, the Philippine Fault Zone, with compressional and extensional components, traverses the whole archipelago where all excess stress not accommodated by the surrounding trenches is taken up. Tholeiitic through adakitic to calc-alkaline rock suites characterize the different magmatic arcs. Exposed oceanic lithospheric fragments exhibit transitional mid-ocean ridge, back arc basin to island arc geochemical characteristics. The observed crustal thickness in the Philippines resulted from combined magmatic (volcanism) and amagmatic (ophiolite accretion) processes, with the former being the dominant factor.

Mindanao Island in the southern Philippines is made up of two blocks: the islandarc-related eastern-central Mindanao block and the continental Zamboanga Peninsula, which contains several ophiolitic bodies and m61anges. The Middle Miocene Siayan-Sindangan Suture Zone represents the tectonic boundary between the island-arc and continental blocks.

The Kingking deposit is a gold-rich porphyry copper deposit and the southernmost deposit at the eastern Mindanao mineralized belt, Philippines. It is underlain by Cretaceous -Paleogene sedimentary and volcanic rocks that are intruded by mineralized Miocene diorite porphyries and by barren Miocene -Pliocene dacite and diorite porphyries. The main alteration zones in the deposit are the inner potassic zone and the outer propylitic zone. The biotite-bearing diorite and hornblende diorite porphyries are the primary host rocks of mineralization. Two dominant copper minerals, bornite and chalcopyrite, which usually occur as fracture fi llings, are associated with fi ne crystalline quartz veinlet stockworks in the mineralized diorites. Minor secondary covellite, chalcocite and digenite are also observed. The primary Cu-Fe sulfi de phases initially deposited from ore fl uids consisted of bornite solid solution ( bnss ) and intermediate solid solution ( iss ), which decomposed to form the bornite and chalcopyrite. Peculiar bornite pods that are different from dissemination and are associated with volcanic rock xenoliths in biotite-bearing diorite porphyry are noted in a drill hole. These pods of bornite are not associated with quartz veinlet stockworks. Fluid inclusion analyses show three types of inclusions contained in Kingking samples: two-phase fl uid-rich and vapor-rich inclusions and polyphase hypersaline inclusions from porphyry-type quartz veinlet stockworks. The liquid -vapor homogenization temperatures (T H ) and the dissolution temperature of halite daughter crystals (T M ) from the polyphase hypersaline inclusions predominantly range from 400°C up to >500°C. The wide range of T H and T M may be due to heterogeneous trapping of variable ratios of vapor and brine. For some inclusions, T H > T M and in some cases, T H < T M , indicating that some of the brine was supersaturated or saturated with NaCl at the time of entrapment. Calculated salinity of the polyphase hypersaline inclusions ranges from 40 to 60% NaCl equivalent. Temperature and vapor pressure of mineralized fl uid were estimated to be 400°C and 16 MPa .

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High seismic activity in the Philippines originates from tectonic convergence related to surface and subsurface seismotectonic features. Based on earthquake data, the archipelago can be divided into the seismically-active Philippine Mobile Belt and the aseismic North Palawan Block. The latter represents a rifted continental fragment of the Eurasian margin that juxtaposed with the rest of island arc units in central Philippines. Earthquake hypocenter plots on planar and in vertical profiles show that the seismic events are associated with known seismotectonic features. In addition, data suggest that the collision zone between the North Palawan Block and the Philippine Mobile Belt is characterized by a decreased amount of hypocenters at >100 km depths. Although field evidence favors the presence of a subducted slab or slabs beneath western central Philippines, these are difficult to image using the present seismicity distribution dataset.

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: The Bulawan deposit is located in the porphyry copper belt of southwest Negros island, Philippines. Propylitic, K–feldspar, sericitic, and carbonate alteration types can be distinguished in the deposit. Propylite alteration occurs mainly in Cretaceous‐Eocene andesitic lavas and agglomerates while K–feldspar, sericite and carbonate alteration types occur mostly in the Middle Miocene dacite porphyry breccia pipes and stocks which were intruded into the andesites. K‐feldspar zones occur in the inner parts of the sericitized zone. Sericite alteration overprinted the propylitized and K‐feldspar alteration zones, at lower temperature than epidote and chlorite in the propylitized zone. Carbonate alteration is associated with the mineralization in the center of the breccia pipes and along faults. Mineralization consists of gold‐silver telluride ores that are hosted by the carbonate– and sericite‐altered dacite porphyry breccia pipes. The Bulawan ores occur mainly as disseminations, but unlike many epithermal gold deposits, lack classical epithermal colloform and crustiform quartz veins. The ore minerals are sphalerite, galena, chalcopyrite, pyrite and tetrahedite‐tennantite with minor amounts of electrum, calaverite, petzite, sylvanite, hessite, tellurobismuthite, coloradoite, altaite, and rucklidgeite. Electrum and telluride minerals are associated mostly with calcite and dolomite‐ankerite minerals. Fluid inclusions in quartz and calcite in clasts of propylitized andesite in the breccia pipes homogenize from about 300° to 400°C while fluid inclusions in quartz, calcite and sphalerite within the dacite porphyry breccia pipes homogenize between 300° to 310°C. The ores were formed around 300°C from hydrothermal solutions with salinity of about 6. 6 wt % NaCl equivalent. The presence of sylvanite and calaverite as intergrowths with each other, and the Ag content of calaverite are consistent with the above temperature estimate. Based on paragenesis, the Bulawan deposit formed in a pyrite‐stable environment, with pH between 3. 4 and 5. 5, fO2 between 10‐32 to 10‐30 atm, fS2 between 10‐9.8 to 10‐7.8 atm, fTe2 between 10‐8.9 to 10‐6.5 atm, and total sulfur content about 10‐2.8 molal. The dominant reduced sulfur species in the ore solutions may have been H2S(aq), and the likely aqueous tellurium species were H2Te(aq) and H2TeO3(aq). The ore minerals in the Bulawan deposit were probably formed by mixing of slightly saline and low salinity fluids.

Three calcareous sedimentary rock-hosted Carlin type-like gold prospects were mapped in a mineral production sharing agreement area of Philex Gold Philippines Inc. in Taganaan municipality, Surigao del Norte province in Mindanao island in the Philippines. They occur along a 20-25 km long trend of known epigenetic gold and porphyry copper deposits that lie close to several splays of the Philippine Fault Zone. The gold district forms part of the Late Cretaceous Eastern Mindanao Range that hosts early Paleogene and late Pliocene to Quaternary intrusive rocks.Gold is invisible in the jasperoid outcrops in Lascogon, Napo, and Danao prospects. The jasperoids occur in lenses of marls belonging to the Taganaan Marl Member that is associated to a turbiditic member of the Middle Miocene Mabuhay Formation. The marl lenses include gently dipping interbedded silty limestones and calcareous shales. The "invisible gold" mineralization in silicified calcareous rocks resembles Carlin-type deposits. Based on the mapped igneous and sedimentary rocks, a possible heat source for the gold mineralization is either or both of the two main phases of intrusion, Mabuhay Andesite or Alipao Andesite Porphyry. Forty-eight rock samples, fifteen stream sediment samples, and one soil sample were critical in delineating the general features of the potential Carlin-type prospects. The gold grades of jasperoids in the three prospects range from trace amounts to 20 g/t Au. Regional studies of gold and porphyry copper mineralization in the Surigao del Norte mineral district are important in delineating ore targets for drilling in the three prospects.