Geology of the Municipalities of Tuba and Itogon,
Benguet Province, Philippines


Jason Agdeppa, Melezra Amora, Eloisa Bulalacao, Zaymon Calucin, Anna Paola Beatrice Canto,

Michelle dela Cruz, Mariefe de Guzman, Ricardo Escanlar III, Margueret Fajilago, Stephanie Anne Frogoso, Ranee Joshi, Loraine Pastoriza, Nick Vily Primaleon, Kristine Joy Taguibao, Justin Vidamo, Emmanuelle Villaflor

UP NIGS Geology 170 Students




Geologic mapping is conducted in selected areas in the towns of Tuba and Itogon, Benguet in compliance with the requirements for undergraduate geology students. The study area is composed mostly of intrusive igneous rock units. Volcanic and sedimentary rocks are also observed. Based on field observations, the oldest rocks are meta-andesites which are part of the Pugo Formation. These meta-andesites are intruded by the Middle Miocene Central Cordillera Diorite Complex (CCDC), which is composed of different diorite facies. Another set of intrusions, composed of dacites, andesites, and volcanic breccias, may have contributed to the uplift of the area. This event led to erosion and eventually deposition forming the younger conglomerate unit identified to be part of the Late Miocene Klondyke Formation and limestone unit. Efforts to determine its absolute age and to identify as to what formation it belongs are still on going. The youngest rock unit observed is a breccia body based on stratigraphic position and cross-cutting relationship.


Structures observed in the area can be related to the regional tectonic setting. Variations in the trends of the structures are attributed to the tectonic history and nature of emplacement of most of these rocks. This involves intrusion, uplift and the effect of regional stresses.


Mineralization is also observed in the form of disseminations and veinlets of sulphides. Quartz veins are relatively numerous in specific areas. Sulphides which are common in the andesites include pyrite, chalcopyrite and bornite. Molybdenite occurs in less significant amounts. These are also observed in the diorites but not as extensive as in the andesites.

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