The Dent Peninsula ( ms, Semenanjung Dent) is a

peninsula A peninsula (; ) is a landform that extends from a mainland and is surrounded by water on most, but not all of its borders. A peninsula is also sometimes defined as a piece of land bordered by water on three of its sides. Peninsulas exist on all ...

in eastern Sabah, Malaysia. It consists of hills and broad coastal areas. The Peninsula is also previously considered as a

volcanic arc A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc lo ...

of the region which have since migrated southward to

Semporna Peninsula The Semporna Peninsula ( ms, Semenanjung Semporna) is a peninsula in Tawau Division, Sabah, Malaysia. It consists of coastal areas and numerous isolated hills and mountains rising to over . The Peninsula is also considered as a volcanic arc of ...

Geology

Volcanic activity in the

tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

causing rise to

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...

and

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

in the area around Bakapit in the southern area of the peninsula. The rocks in east of

Lahad Datu Lahad Datu ( ms, Bandar Lahad Datu) is the capital of the Lahad Datu District in the Dent Peninsula on Tawau Division of Sabah, Malaysia. Its population was estimated to be around 27,887 in 2010. The town is surrounded by stretches of cocoa and ...

are mixed

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

and

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

: tuffaceous

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s and conglomerate mixed with Ayer, Tabanak and Tungku formations materials of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

s and sandstones. Inner neritic to littoral deposits at the east of the peninsula consist of mudstone, clay and coral limestone with Sabahat (

Middle Miocene The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene. The sub-epoch lasted from 15.97 ± 0.05 Ma to 11.608 ± 0.005 Ma (million y ...

and

Early Pliocene Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...

) and Ganduman (Early Pliocene to

Late Pliocene Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

) formations materials of

lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

and conglomerate. The Ganduman formation displays well preserved outcrops of delta plain deposits grading to shallow marine

deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarel ...

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 The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5&nbs ...

sedimentary sequences which have a relatively high

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

diversity. Based on organic

geochemical Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...

and

petrological Petrology () is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together ...

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 Semporna ( ms, Pekan Semporna) is the capital of the Semporna District in the Tawau Division of Sabah, Malaysia. Its population was estimated to be around 35,301 in 2010. History Semporna was founded soon after the British North Borneo Ch ...

Peninsulas also could be exposed to future

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

s with the active fault in the eastern coast.

Climate and biodiversity

The peninsula especially in the northern generally received mean annual rainfall ranging from 2,000 millimetres to 2,500 millimetres. In the southern coast, the area received annual rainfall ranging from 1,500 millimetres to 2,000 millimetres while the Tungku area received less than 1,500 millimetres. Located in the centre of the peninsula is the

Tabin Wildlife Reserve The Tabin Wildlife Reserve ( ms, Taman Hidupan Liar Tabin) is a nature preserve in Sabah, Malaysia. It was created in 1984 to preserve Sabah's disappearing wild animals. Occupying a large part of the peninsula forming the northern headland of D ...

which is a forest reserve area with variety of protected species.

References

{{Geography of Sabah Peninsulas of Asia Landforms of Sabah