Breccia characteristics and classification of the GW orebodies, Balatoc Diatreme, Philippines: Insights to breccia facies and distribution across diatremes

Abstract

AbstractA careful descriptive characterization of breccias, including diatremes, is useful for comparative purposes during exploration, rather than the colloquial use of various breccia terminology in ore exploration. Here, we present the first detailed breccia characterization of the Balatoc Diatreme‐hosted GW orebodies in the Acupan deposit, Philippines. Three breccia types are identified from descriptive classification of the GW orebodies. GW 3/13, located at the northwestern rim of the diatreme, is a medium‐ to coarse‐grained rotational, quartz‐cemented diorite breccia, whereas GW 11, at the eastern portion of the diatreme, is a medium‐ to coarse‐grained mosaic calcite‐cemented andesite breccia. Both GW orebodies located at the southwestern portion of the diatreme, GW 4/7 and GW 6, are medium‐ to coarse‐grained rotational quartz‐cemented polymict breccias. The breccia facies and distribution emplaced during a single event include: (a) Crackle breccias proximal to the unbrecciated host rocks. (b) Mosaic breccia facies along the contact between the surrounding host rocks and orebody. (c) Rotational breccia facies near the outline of the diatreme. At Balatoc, the mineralized GW orebodies are characterized by mosaic and rotational clast distributions, suggesting that these breccia types are priority targets in ore exploration. Recognizing these various breccia types in other deposits may serve as an exploration vector to determine their position in a diatreme‐hosted deposit.