Caraga Region is located at northeastern part of Mindanao. It includes the five provinces of Dinagat Province, Surigao del Norte, Surigao del Sur, Agusan del Norte and Agusan del Sur. Caraga Region is now hosting several mining projects producing various mineral commodities particularly but not limited to gold, copper, chrome, nickel, iron and limestone for concrete cement production. This makes the Department of Environment and Natural Resources, Mines and Geosciences Bureau, Regional Office No. 13 with Office located in Surigao City plays important role in the region's economy, job generation, social and environmental enhancement and protection and ensuring government shares through royalties and taxes.
Caraga Region is one of the regions notably located in the eastern seaboard of the Philippines. With its geographic location facing the Pacific Ocean and famous Philippine Trench, the Region is prone to various weather conditions and geologic phenomenon like, but not limited to, typhoon, tsunami and other coastal surges and seismic activities. With these, DENR-MGB13 is expeditiously utilizing its human and financial resources to generate geohazard maps as necessary source of information to spatial planners and other government and non-government agencies working for public safety and disaster management.
General geology
In the broader physiographic framework of the Philippine archipelago, Caraga Region occupies the northernmost portion of the Eastern Mindanao Ridge or Mindanao Pacific Cordillera, a more than 400-km, NNW-SSE trending orogenic belt comprising eastern Mindanao. The Mindanao Pacific Cordillera is bounded by two major structures that played a key role in the neotectonic evolution of the Philippine Mobile Belt, namely the Philippine Trench and the Philippine Fault Zone.
The geologic evolution of the Mindanao Pacific Cordillera was largely controlled by convergent and transcurrent tectonics intermittently active during Upper Cretaceous to Pleistocene times. These complex tectonic processes brought about the juxtaposition of older metamorphic basement rocks with ophiolite suite of rocks later superposed by younger multiple stage island arc volcano-sedimentary sequences. The broad geomorphic configuration of the region is largely controlled by these tectonic processes of the past.
Oldest rocks in the region are pre-Tertiary metamorphics and ophiolitic suite of rocks of Cretaceous age. Limited exposures of post-ophiolitic sedimentary rocks of Eocene age suggest dominant erosional processes from Paleocene to Eocene period. On the contrary, the Oligocene to Middle Miocene age is marked by thick accumulation of arc basaltic volcano-sedimentary sequence and turbidites later succeeded by mid-Miocene to Pliocene volcanic flows, pyroclastics and epiclastic of more andesitic composition. Arc magmatism was also active during the mid-Miocene to Pliocene times generating monzonitic and dioritic stocks and plutons and hornblende andesite porphyry intrusions. In areas away from paleo-volcanic centers, thick sedimentary clastic rocks with sporadic limestone horizons and intercalated calcareous sediments, marls and/or coal seams were formed during the Miocene to Pliocene. Reefal limestone, some of dubious stratigraphic position unconformably capped older rocks with age assignment ranging from Miocene to Plio-Pleistocene. The Paco-Maniayao volcanic complex north of Lake Mainit represents the latest Quaternary volcanism in the region.
Mineral resources
The rich mineral heritage of Caraga Region greatly owes its genesis to these complex natural processes operative during a long span of geologic time. Two (2) major geological events are noteworthy in influencing the high mineral endowment of the Region. These are: 1) the emplacement of Upper Cretaceous ophiolites over the eastern Philippines proto-arc during the Paleocene times and 2) island arc calc-alkalic magmatic and volcanic activity during the Miocene to Pliocene times coeval with the inception of the Philippine Trench – Philippine Fault system resulting from the oblique convergence of the Philippine Sea Plate with eastern Mindanao.
The superposition of the younger island arc plutonic and sub-volcanic rocks with associated hydrothermal base and precious metal deposits with an older ophiolite suite of rocks with affiliated nickel and chromite deposits makes Caraga Region as one of the most prolifically endowed belt of the Philippines in terms of mineral resource potential and diversity.