Dent Peninsula

Geology

Volcanic activity in the tertiary causing rise to andesite and dacite in the area around Bakapit in the southern area of the peninsula. The rocks in east of Lahad Datu are mixed volcanic and sedimentary: tuffaceous sandstones and conglomerate mixed with Ayer, Tabanak and Tungku formations materials of shales, mudstones and sandstones. Inner neritic to littoral deposits at the east of the peninsula consist of mudstone, clay and coral limestone with Sabahat (Middle Miocene and Early Pliocene) and Ganduman (Early Pliocene to Late Pliocene) formations materials of lignite, marl and conglomerate. The Ganduman formation displays well preserved outcrops of delta plain deposits grading to shallow marine deltaic and holomarine eastward while the Sabahat is represented by the clinoform and downlap seismic packages. The Togopi formation on the onshore of the peninsula is mainly made of marls and preserves Plio-Pleistocene sedimentary sequences which have a relatively high coral diversity. Based on organic geochemical and petrological analyses, both formations of Sabahat and Ganduman found to be gas-prone source rocks. The narrow continental shelf fronting the coastal areas of both Dent and Semporna Peninsulas also could be exposed to future tsunamis with the active fault in the eastern coast.