Occurrences of Ore Minerals and Fluid Inclusion Study on the Kingking Porphyry Copper–Gold Deposit, Eastern Mindanao, Philippines

Abstract

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 .

Adakitic rocks in the Masara gold-silver mine, Compostela Valley, Mindanao, Philippines: Different places, varying mechanisms?

“…Eastern Mindanao is host to several precious metal -base metal mines and prospects (e.g. Sillitoe, 1989;Suerte et al, 2007;Imai et al, 2009;Sonntag et al, 2011) (Figure 2). The general tectonic grain in the minesite is NW-SE consistent with the general direction of the Philippine Fault Zone.…”

Origin of Bornite Pods in Intrusive Rocks at the Kingking Porphyry Copper‐gold Deposit, Southeastern Mindanao, Philippines

“…3). Suerte et al (2007) reported the occurrence of bornite clots/pods in the brecciated parts of the biotite diorite porphyry overprinted by K-silicate alteration. They occur together with the andesite and diorite fragments without associated stockworks of quartz veinlets (Fig.…”

“…Ore minerals and fluid inclusions at the Kingking deposit were studied by Suerte et al (2007). In addition, Suerte et al (2007) reported the occurrence of bornite pods in the brecciated parts of the biotite diorite porphyry, overprinted by K-silicate alteration, together with volcanic rock and diorite fragments without associated stockworks of quartz veinlets. Bornite pods are also reported in the Endeavor porphyry copper-gold deposit in Northparkes, Australia (Lickfold et al, 2003).…”

About the Special Issue: Collection of Achievements on Earth Resources from AUN/SEED‐Net, Part II

“…In addition to the porphyry copper deposits that have been mined already such as the Batu Hijau deposit, there are still a number of porphyry-type deposits and prospects remaining undeveloped in the ASEAN region. Suerte et al (2007) present the occurrences of ore minerals and fl uid inclusion study on the Kingking porphyry copper -gold deposit, Mindanao, Philippines. They demonstrate that bornite solid solution and intermediate solid solution ( iss ) were deposited as primary phases.…”

“…Most papers were presented at the AUN/SEED-Net eighth Fieldwise Seminar on Geological Engineering Field and the third International Symposium and Exhibition entitled "Contribution of Science and Engineering for Geo-Hazard and Geo-Resources Management Toward Sustainable Development" held on 3 -4 August 2006 at Yogyakarta, Indonesia. Three papers describe magmatic and hydrothermal systems of porphyry-type mineralization ( Idrus et al , 2007;Imai et al , 2007;Suerte et al , 2007 ), while seven papers including one short communication report on hydrothermal systems associated with gold mineralization ( Ariffi n & Hewson, 2007;Crisostomo et al , 2007;Harijoko et al , 2007;Jimenez et al , 2007;Syafrizal et al, 2007;Warmada et al , 2007 ). In addition, one paper discusses temporal evolution of island arc magmatism ( Polve et al , 2007 ).…”