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

• Published in: Journal of Asian earth sciences 2017-07, Vol.142, p.45-55
• Main Authors: Yumul, Graciano P., Brown, Walter W., Dimalanta, Carla B., Ausa, Carlito A., Faustino-Eslava, Decibel V., Payot, Betchaida D., Ramos, Noelynna T., Lizada, Adrian Nicol L., Buena, Alfred Elmer, Villaplaza, Barbie Ross B., Manalo, Pearlyn C., Queaño, Karlo L., Guotana, Juan Miguel R., Pacle, Nichole Anthony D.
• Format: Article
• Language: English
• Subjects: Adakite; Crystallization; Gold-silver; Island arc; Masara; Mindanao; Philippines
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2016.06.005

•Adakitic rocks are reported for the first time in the Masara gold-silver mine.•The generation of these adakitic rocks are due to fractional crystallization.•The presence of adakitic rocks does not necessarily indicate mineralization. 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.