Philippine Mobile Belt
Encyclopedia
The Philippine Mobile Belt is a complex portion of the tectonic boundary between the Eurasian Plate
and the Philippine Sea Plate, comprising most of the country of the Philippines
. It includes two subduction zones, the Manila Trench
to the west and the Philippine Trench
to the east, as well as the Philippine Fault System. Within the Belt, a number of crustal blocks or microplates which have been sheared off the adjoining major plates are undergoing massive deformation.
Most segments of the Philippines
, including northern Luzon
, are part of the Philippine Mobile Belt, which is separate from the Philippine Sea Plate to the east, the Molucca Sea Collision Zone
to the south, Sunda Plate
to the southwest, and the South China Sea Basin to the west and north-west. To the north it ends in eastern Taiwan
, the zone of active collision between the North Luzon Trough portion of the Luzon Volcanic Arc
and South China. The Philippine Mobile Belt has also been called the Philippine Microplate and the Taiwan-Luzon-Mindoro Belt.
with the Calamian Islands, plus the Sulu Archipelago
with the Zamboanga Peninsula
of western Mindanao
, are the tops of two protruding north-eastern arms of the Sunda Plate
. They are not part of the Philippine Mobile Belt but are in collision with it. The Sulu Trench marks the boundary of the Sulu micro-block with the Sulu Sea basin and the Palawan micro-block. The Palawan Trench marks the subduction boundary between the Palawan microblock and the Spratly Islands
plateau of the South China Sea basin. The Palawan/Calamian arm was also known in 1981 as the Palawan block and Palawan microcontinent, and in 1989 as the Palawan Micro-Block.
and its associates the Negros Trench and the Cotabato Trench, which absorb the subducting Sunda Plate
under the Philippine Mobile Belt. To the east is the Philippine Trench
and its northern associate, the East Luzon Trench which absorb the subducting Philippine Sea Plate under the Philippine Mobile Belt. The continuity of the Philippine-East Luzon Trench is interrupted and displaced by Benham Plateau
on the Philippine Sea Plate, which collided and is still colliding with the Sierra Madre
of eastern Luzon.
portions of the Luzon Arc and Luzon forearc form the eastern Coastal Range
and the inland Longitudinal Valley
of Taiwan, respectively.
, which is itself part of the elongated zone of convergence extending north through the Philippines into Taiwan. Within the Molucca Sea Collision Zone, the Molucca Sea Plate
has been totally subsumed by the arc-arc collision of the Halmahera Arc
and the Sangihe Arc of eastern Indonesia.
. Luzon is not bisected E-W, and illustrations showing anything similar are erroneous. Northern Luzon is integral with southern Luzon. Any suggestion that Northern Luzon is not part of the Philippine Mobile Belt is not borne out by the detailed fault mapping of Pinet and Stephan (1989), and others. A common tectonic plate illustration for the Philippines is incorrect in this regard.
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
and the Philippine Sea Plate, comprising most of the country of the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
. It includes two subduction zones, the Manila Trench
Manila Trench
The Manila Trench is an ocean trench in the South China Sea, west of the Philippines. It reaches a depth of about 5,400 m, in contrast with the average depth of the South China Sea of about 1,500 m...
to the west and the Philippine Trench
Philippine Trench
The Philippine Trench is a submarine trench to the east of the Philippines. It has a length of approximately 1,320 km and a width of about 30 km from the centre of the Philippine island of Luzon trending southeast to the northern Maluku island of Halmahera in Indonesia...
to the east, as well as the Philippine Fault System. Within the Belt, a number of crustal blocks or microplates which have been sheared off the adjoining major plates are undergoing massive deformation.
Most segments of the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, including northern Luzon
Luzon
Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...
, are part of the Philippine Mobile Belt, which is separate from the Philippine Sea Plate to the east, the Molucca Sea Collision Zone
Molucca Sea Collision Zone
The Molucca Sea Collision Zone is postulated by paleogeologists to explain the tectonics of the area based on the Molucca Sea in Indonesia, and adjacent involved areas.-Tectonics:...
to the south, Sunda Plate
Sunda Plate
The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...
to the southwest, and the South China Sea Basin to the west and north-west. To the north it ends in eastern Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, the zone of active collision between the North Luzon Trough portion of the Luzon Volcanic Arc
Luzon Volcanic Arc
The Luzon Volcanic Arc is a chain of volcanoes in a north south line across the Luzon Strait from Taiwan to Luzon. It is the northern extension of the Philippine Mobile Belt...
and South China. The Philippine Mobile Belt has also been called the Philippine Microplate and the Taiwan-Luzon-Mindoro Belt.
Palawan and Sulu
Although they are parts of the Republic of the Philippines, PalawanPalawan
Palawan is an island province of the Philippines located in the MIMAROPA region or Region 4. Its capital is Puerto Princesa City, and it is the largest province in the country in terms of total area of jurisdiction. The islands of Palawan stretch from Mindoro in the northeast to Borneo in the...
with the Calamian Islands, plus the Sulu Archipelago
Sulu Archipelago
The Sulu Archipelago is a chain of islands in the southwestern Philippines. This archipelago is considered to be part of the Moroland by the local rebel independence movement. This island group forms the northern limit of the Celebes Sea....
with the Zamboanga Peninsula
Zamboanga Peninsula
Zamboanga Peninsula / Western Mindanao is a peninsula and an administrative region in the Philippines. Designated as Region IX, the region consists of three provinces, namely, Zamboanga del Norte, Zamboanga del Sur, and Zamboanga Sibugay, its component cities of Dipolog, Dapitan, Pagadian, and...
of western Mindanao
Mindanao
Mindanao is the second largest and easternmost island in the Philippines. It is also the name of one of the three island groups in the country, which consists of the island of Mindanao and smaller surrounding islands. The other two are Luzon and the Visayas. The island of Mindanao is called The...
, are the tops of two protruding north-eastern arms of the Sunda Plate
Sunda Plate
The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...
. They are not part of the Philippine Mobile Belt but are in collision with it. The Sulu Trench marks the boundary of the Sulu micro-block with the Sulu Sea basin and the Palawan micro-block. The Palawan Trench marks the subduction boundary between the Palawan microblock and the Spratly Islands
Spratly Islands
The Spratly Islands are a group of more than 750 reefs, islets, atolls, cays and islands in the South China Sea. The archipelago lies off the coasts of the Philippines and Malaysia , about one third of the way from there to southern Vietnam. They comprise less than four square kilometers of land...
plateau of the South China Sea basin. The Palawan/Calamian arm was also known in 1981 as the Palawan block and Palawan microcontinent, and in 1989 as the Palawan Micro-Block.
East and west boundaries
The Philippine Mobile Belt is bounded on the west by the Manila TrenchManila Trench
The Manila Trench is an ocean trench in the South China Sea, west of the Philippines. It reaches a depth of about 5,400 m, in contrast with the average depth of the South China Sea of about 1,500 m...
and its associates the Negros Trench and the Cotabato Trench, which absorb the subducting Sunda Plate
Sunda Plate
The Sunda Plate is the tectonic plate on which the majority of Southeast Asia is located. It was formerly considered a part of the Eurasian Plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia...
under the Philippine Mobile Belt. To the east is the Philippine Trench
Philippine Trench
The Philippine Trench is a submarine trench to the east of the Philippines. It has a length of approximately 1,320 km and a width of about 30 km from the centre of the Philippine island of Luzon trending southeast to the northern Maluku island of Halmahera in Indonesia...
and its northern associate, the East Luzon Trench which absorb the subducting Philippine Sea Plate under the Philippine Mobile Belt. The continuity of the Philippine-East Luzon Trench is interrupted and displaced by Benham Plateau
Benham Plateau
Benham Plateau , also known as the Benham Rise, is a seismically active undersea region and extinct volcanic ridge east of the Philippines, in the Philippine Sea. Under the Philippine Sea lies a number of Basins including the West Philippine Basin of which inside the Basin is located the Central...
on the Philippine Sea Plate, which collided and is still colliding with the Sierra Madre
Sierra Madre (Philippines)
The Sierra Madre is a mountain range in The Philippines. It is located along the north-eastern coast of Luzon Island, running north/south. Quezon National Forest Park is situated in the range.-Geography:...
of eastern Luzon.
Northern terminus
To the north the Philippine Mobile Belt ends in Taiwan, where accretedAccretion (geology)
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
portions of the Luzon Arc and Luzon forearc form the eastern Coastal Range
Haian Range
The Hai-an Range , also known as the Coastal Range, is a mountain range lies on the east seashore of Taiwan and crossed the border of counties of Hualien and Taitung. Distinct from western lands of Taiwan, it is a part of Philippine Mobile Belt instead of the Yangtze Plate.The Huatung Valley, a...
and the inland Longitudinal Valley
Huatung Valley
Huatung Valley or Hualien-Taitung Valley , also known as East Rift Valley or the Longitudinal Valley, is a long and narrow valley located at the between Chungyang Range and Haian Range...
of Taiwan, respectively.
Southern terminus
To the south the Philippine Mobile Belt terminates in the Molucca Sea Collision ZoneMolucca Sea Collision Zone
The Molucca Sea Collision Zone is postulated by paleogeologists to explain the tectonics of the area based on the Molucca Sea in Indonesia, and adjacent involved areas.-Tectonics:...
, which is itself part of the elongated zone of convergence extending north through the Philippines into Taiwan. Within the Molucca Sea Collision Zone, the Molucca Sea Plate
Molucca Sea Plate
-Earlier theory:The Molucca Sea Plate was theorised to be a small tectonic plate carrying northern Sulawesi, the Molucca Sea and a portion of the Banda Sea in a region littered with numerous small plates. The theory suggested a subduction zone lies along its northern border with the Sunda Plate...
has been totally subsumed by the arc-arc collision of the Halmahera Arc
Halmahera Arc
Halmahera Arc is the volcanic arc of the Halmahera region of eastern Indonesia. It is considered to belong to the Halmahera Plate tectonics, within the Molucca Sea Collision Zone.-Origin:...
and the Sangihe Arc of eastern Indonesia.
Luzon
The island of Luzon is bisected by the braided N-S trending Philippine Fault SystemPhilippine Fault System
The Philippine Fault System is an inter-related system of faults throughout the whole of the Philippine Archipelago, primarily caused by tectonic forces compressing the Philippines into what tectonic geophysicists call the Philippine Mobile Belt....
. Luzon is not bisected E-W, and illustrations showing anything similar are erroneous. Northern Luzon is integral with southern Luzon. Any suggestion that Northern Luzon is not part of the Philippine Mobile Belt is not borne out by the detailed fault mapping of Pinet and Stephan (1989), and others. A common tectonic plate illustration for the Philippines is incorrect in this regard.