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Diorite Porphyry (DP)
Diorite porphyries as 2m-15m wide dikes intrude into the BV. The porphyry dikes most possibly emanate as fingers from the main porphyry body at depth, and form part of the transitional intrusive contact zone between pluton and volcanic country rock. The DP is made up of >50% 2mmX3mm plagioclase phenocrysts set in fine grained to aphanitic hornblende-rich matrix. It looks very similar to the Mabuhay andesite porphyry (MAP) bodies hosting epithermal gold deposits at the MMC mine. However, the MAP at the mine site is observed to truncate porphyry copper-gold mineralization (e.g. Ntina Pit) and hosts only younger epithermal gold.
The intrusion of the DP main body and dikes has caused the mechanical and hydraulic brecciation of the host BV, especially those near the intrusive contacts where some fluidized polymictic breccias are developed.
Microdiorite (MD) and Diorite Porphyry Breccia (DPBx)
On the lower section of MSD 02-1 are medium grained porphyritic to fine grained andesitic bodies that intrude the DP. The contact between the DP and this finer grained body is transitional, where the latter appears as just a finer facies of the DP.
The contacts between the DP and the MD are narrow fluidized breccia zones composed of DP clasts in MD matrix. The crackle breccia zone in the DP generated by this MD intrusion, however, is wide. Because it can be delineated as a mappable unit, this fluidized to crackle breccia with DP clasts in MD matrix is termed as diorite porphyry breccia (DPBx). The MD-DPBx is host to the strongest Cu-Au mineralization intercepted by MSD 02-1 at Kalaya-an. The same is also true at Boyongan, and even at Suyoc. It is most likely that the MD is a late fluid- and metal-rich differentiate of the DP that acts as one of the main progenitor-intrusive of the Porphyry Cu-Au deposits found in Placer.
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