Balog-balog, Tarlac; Mayantoc, Tarlac
Villones and others (1979)
In the western flank of Zambales Range is a diorite complex originally called Balog-Balog Diorite by Villones and others (1979) for the diorite exposures at Balog-Balog, Tarlac. It is also well exposed at Mayantoc, Tarlac. The complex is a dike system intruding the gabbro and diabase dike swarms of the ophiolite suite. It appears to be late differentiates of the gabbro of the ophiolite and is an intrinsic part of the ophiolite complex. The Balog-Balog consists of diorite, quartz diorite, pegmatite, plagiogranite and possibly tonalite and monzonite. The diorite is fine to coarse grained and pegmatitic. The main diorite is light to dark gray, equigranular and contains abundant hornblende crystals. The quartz diorite is light colored and pinkish with crystals of free quartz and potash feldspars. The coarse crystalline pegmatite contains large euhedral crystals of hornblende in a felsic matrix.