Other major outcrops were observed in the middle

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Balete River west of Pinamalayan. Other major outcrops were observed in the middle reaches of Bongabong River and also in the western portion of Roxas in Oriental Mindoro. Paleocene Mamburao Group This Group is composed of basic volcanic rock, mainly basalt. Exposures of this rock are confined mainly along the lowland of Mamburao and Abra de Ilog. Late Eocene to Late Miocene Sablayan Group - This is given to the clastic beds which predominantly include limestone, calcareous sandstone, calcareous mudstone with andesite and andesitic tuff. These rocks are extensively distributed from Sablayan to Bulalacao. Other exposures are found in the lower and upper reaches of Mamburao River, and also in the upper reaches of Magasawang Tubig River, the Banus River, the Sumagui River and the Tangon River in Oriental Mindoro Pliocene Bongabong Group – The Bongabong Group consists mostly of Pliocence conglomerate, tuffaceous sandstone and mudstone-siltstone. This is scatteredly distributed in Rizal and Calintaan , Occidental Mindoro while major exposures are found from Bgy. Villacerveza in Victoria up to Bongabong River in Bongabong and Mansalay municipalities. Quaternary Socorro Group The groupis composed mainly of terrace gravel and sand deposits; tuffaceous silt and andesitic tuff; and limestone. Major outcrops are distributed in the lowland of Oriental Mindoro from Puerto Galera in the north to Roxas municipality in the south. It also covers portions San Jose, Magsaysay, Sablayan and Mamburao in Occidental Mindoro. Quaternary Alluvium These are detrital deposits formed on valleys by stream action and essentially made up of silt, sand, and gravel. They are extensively distributed along the shores, river channels, broad floodplains and delta of Occidental Mindoro and Oriental Mindoro. Intrusive rocks consist of big Ultramafic complex, a small body of acidic to intermediate rocks such as granodiorite, quartz diorite and dioite porphyry, and small-scale basic rocks of dolerite and gabbro are also present. The major geologic structure in Mindoro Island is the north-south trending Central Mindoro Fault that stretches about 100 kilometers from Mansalay to Puerto Galera ( See attached map ). Previous works by the Mines & Geosciences Bureau (MGB) are vague on the recent activity of the Central Mindoro Fault, although topographic expressions along its trace seem to suggest that it is an active fault. The Aglubang River Fault appears to branch out of the Central Mindoro Fault south of Alcate, Victoria. The older pre-Jurassic to Jurassic formations are distributed in the central area of the island while younger formations accumulate zonally on both sides of the central mountain ranges showing an anticlinal structure. The other major structure is the Lubang Fault that traverses immediately the northern portions of Mindoro Island. This fault trends east west and is located between Mindoro and the Luzon mainland.
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  • Spring '18
  • Coal, Provinces of the Philippines, Oriental Mindoro, Occidental Mindoro, MINDORO ISLAND

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