Puerto Princesa Subterranean River National Park geologic marker

In the geology of the Philippines, the Philippine Mobile Belt is a complex portion of the tectonic boundary between the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

and the

Philippine Sea Plate The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part o ...

, comprising most of the country of the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

. It includes two subduction zones, the Manila Trench to the west and the

Philippine Trench The Philippine Trench (also Philippine Deep, Mindanao Trench, and Mindanao Deep) is a submarine trench to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean and continues NNW-SSE. It has a ...

to the east, as well as the

Philippine Fault System The Philippine Fault System is a major inter-related system of geological faults throughout the whole of the Philippine Archipelago, primarily caused by tectonic forces compressing the Philippines into what geophysicists call the Philippine Mob ...

. Within the Belt, a number of

crustal block Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relat ...

s or microplates which have been shorn off the adjoining major plates are undergoing massive deformation. Most segments of the

, including northern

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

, are part of the Philippine Mobile Belt, which is bounded by the

to the east, the

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 The tectonic relationship of the Sangihe Plate, Halmahera Plate, ...

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 Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

, the zone of active collision between the North Luzon Trough portion of the

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. The name "Luzon Volcanic Arc" was first proposed by Carl Bowin et al. to describe a series of Miocene to recent volcanoes due to ...

and South China. The Philippine Mobile Belt has also been called the Philippine Microplate and the Taiwan–Luzon–Mindoro Belt.

Palawan and Sulu

Palawan Palawan (), officially the Province of Palawan ( cyo, Probinsya i'ang Palawan; tl, Lalawigan ng Palawan), is an archipelagic province of the Philippines that is located in the region of Mimaropa. It is the largest province in the country in t ...

with the

Calamian Islands The Calamian Islands or the Calamianes is a group of islands in the province of Palawan, Philippines. It includes: * Busuanga Island * Coron Island * Culion Island * Calauit Island * Malcapuya Island * Banana Island * Pass Island * Calumbuyan I ...

and the Sulu Archipelago with the

Zamboanga Peninsula Zamboanga Peninsula ( tl, Tangway ng Zamboanga; cbk, Peninsula de Zamboanga; ceb, Lawis sa Zamboanga) is an administrative region in the Philippines, designated as Region IX. It consists of three provinces (Zamboanga del Norte, Zamboanga Sibu ...

of western

Mindanao Mindanao ( ) ( Jawi: مينداناو) is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of ...

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 inactive

Palawan Trench Palawan (), officially the Province of Palawan ( cyo, Probinsya i'ang Palawan; tl, Lalawigan ng Palawan), is an archipelagic province of the Philippines that is located in the region of Mimaropa. It is the largest province in the country in ...

marks the subduction boundary between the Palawan microblock and the

Spratly Islands The Spratly Islands ( fil, Kapuluan ng Kalayaan; zh, c=南沙群島/南沙群岛, s=, t=, p=Nánshā Qúndǎo; Malay, id, Kepulauan Spratly; vi, Quần đảo Trường Sa) are a disputed archipelago in the South China Sea. Composed ...

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.

Boundaries

The Philippine Mobile Belt is bounded on the west by the Manila Trench and its associates the

Negros Trench The Negros Trench is an oceanic trench located northeast of the Sulu Trench and west of Negros Island Region in Visayas, the trench is located in the Sunda Plate in the southwestern region of the Pacific Ocean. The depth of the Negros Trench ...

and the

Cotabato Trench The Cotabato Trench is an oceanic trench in the Pacific Ocean, off the southwestern coast of Mindanao in the Philippines. Along this trench the oceanic crust of the Sunda Plate beneath the Celebes Sea is being subducted beneath the Philippines ...

, which subducts the Sunda Plate under the Philippine Mobile Belt. To the east is the

and its northern associate, the

East Luzon Trench The Philippine Trench (also Philippine Deep, Mindanao Trench, and Mindanao Deep) is a submarine trench to the east of the Philippines. The trench is located in the Philippine sea of the western North Pacific Ocean and continues NNW-SSE. It has a ...

which subducts

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 Sierra Madre (Spanish, 'mother mountain range') may refer to: Places and mountains Mexico *Sierra Madre Occidental, a mountain range in northwestern Mexico and southern Arizona *Sierra Madre Oriental, a mountain range in northeastern Mexico *S ...

of eastern Luzon. To the north the Philippine Mobile Belt ends in Taiwan, where accreted portions of the Luzon Arc and Luzon forearc form the eastern Coastal Range and the inland

Longitudinal Valley A longitudinal valley is an elongated valley found between two almost-parallel mountain chains in geologically young fold mountains, such as the Alps, Carpathians, Andes, or the highlands of Central Asia. They are often occupied and shaped by a ...

of Taiwan, respectively. To the south the Philippine Mobile Belt terminates in the

, 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 Located in the western Pacific Ocean near Indonesia, the Molucca Sea Plate has been classified by scientists as a fully subducted microplate that is part of the Molucca Sea Collision Complex. The Molucca Sea Plate represents the only known example ...

has been totally subsumed by the arc-arc collision of the

Halmahera Arc Halmahera Arc is the volcanic arc of the Halmahera region of eastern Indonesia. It is considered to belong to the Halmahera Plate within the Molucca Sea Collision Zone. Origin Potassium-argon ages of Neogene to Recent igneous rocks from the Halmah ...

and the Sangihe Arc of eastern Indonesia.

Regional geology

The belt's basement rock complex consists of oceanic crust from the

, including

ophiolite An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level and often emplaced onto continental crustal rocks. The Greek word ὄφις, ''ophis'' (''snake'') is found ...

s in North Luzon, or continental crust from the Sunda Plate. On top of which are

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

to Quaternary magmatic arcs. These magmatic arcs are exposed in the western Central Cordillera, and the northern

. The

Cagayan River The Cagayan River, also known as the Río Grande de Cagayán, is the longest river and the largest river by discharge volume of water in the Philippines. It has a total length of approximately and a drainage basin covering . It is located in t ...

Basin is an intra-arc

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

. Subduction of

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

South China sea oceanic crust occurs at the Manila Trench. Subduction of

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

Philippine Sea oceanic crust occurs at the East Luzon Trough –

system. The strike-slip,

left lateral fault Sinistral and dextral, in some scientific fields, are the two types of chirality ("handedness") or relative direction. The terms are derived from the Latin words for "left" (''sinister'') and "right" (''dexter''). Other disciplines use different ...

is associated with the northward movement of the belt.

Collision zones

* ''Taiwan: Continent-Arc Collision'' – 400 km-long island dominated by mountain ranges. Represents an active orogenic belt resulting from the collision of the western edge of the Philippine Sea Plate where the Luzon arc has developed, with the continental margin of Eurasia. Start of collision is associated with the kinematic reorganization of the Philippine Sea Plate 4 Ma (

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Arc-Continent A continental arc is a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet, and where one plate has cont ...

Collision'' – Southern termination of the Manila Trench. North Palawan Block enters into collision with the central portion of the Philippine Mobile Belt within

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

times after cessation of the accretion of South China Sea oceanic crust between 32 and 17 Ma ( Oligocene - Miocene). * ''Moluccas Sea: Arc-Arc Collision'' – South of Mindanao Island in the Moluccas Sea. Subducting into 2 directions: to the East and to the West. This double-vergent subduction causes consequently the convergence/collision of the 2 corresponding active volcanic arcs. Start of collision in Upper Miocene. Corresponding arcs, the Sangihe and Halmahera, are presently separated by at least 100 km.

Luzon

The island of Luzon is bisected by the braided N-S trending

. 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.

Collage of 17 principal blocks

The composition of the Philippine Mobile Belt is generally interpreted as a collage of a large variety of blocks or terrane of diverse origin amalgamated before collision with the Eurasian margin. Seven principal blocks have been identified in Luzon: the Sierra Madre Oriental, Angat,

Zambales Zambales, officially the Province of Zambales ( fil, Lalawigan ng Zambales; ilo, Probinsia ti Zambales; Pangasinan: ''Luyag/Probinsia na Zambales''; xsb, Probinsya nin Zambales), is a province in the Philippines located in the Central Luzon re ...

, Central Cordillera of Luzon, Bicol and Catanduanes Island blocks. In the Central Philippines four principal blocks have been identified: Panay, Mindoro, Cebu and Bohol. In Mindanao six principal blocks have been identified: Pacific Cordillera, Surigao, Pujada peninsular, Central Cordillera of Mindanao, Daguma range and Zamboanga.

Well-known micro-continental blocks

* North Palawan Block * Mindoro Block

Magmatic arcs

Ancient arcs

In Luzon, the Middle Oligocene to Late Miocene age of the arc is well constrained stratigraphically as well as radiometrically. Most of the intrusive rocks are dioritic in composition, although alkali rocks also occur. In the Central Cordillera of Luzon, intrusive rocks include Paleogene rocks related to an ancient arc and Neogene intrusive and volcanic rocks related to eastward subduction from the Manila Trench. In Visayas, oldest known magmatic rocks in the Philippines are found in Cebu Island, where dioritic rocks have been dated at

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eig ...

(Walther and others, 1981), similar rocks have been recognized in neighboring Bohol Island. In Mindanao, interpretation of the age of these rocks is further complicated by their petrographic diversity. Sajona and others (1993) analyzed Pliocene-Pleistocene adakitic rocks in Zamboanga Peninsula and mention a possible association with activity along the Philippine Fault in Surigao and northern Davao.

Active arcs

The distribution of Philippine Pliocene-Quaternary volcanoes generally reflects the activity along subduction zones presently bounding the archipelago. *Five distinct volcanic belts can be defined, namely: **

corresponding to the Manila Trench ** East-Philippine Volcanic Arc associated with the Philippine Trench ** Negros-Panay Arc linked to the

** Sulu-Zamboanga Arc formed by the Sulu Trench ** Cotabato Arc related to the

Sedimentary basins

The archipelago has 16

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subside ...

s formed by tectonic processes. Here are the following sedimentary basins: * Luzon ** Bicol Shelf ** Cagayan Valley Basin ** Central Luzon Basin ** Ilocos Trough ** Mindoro–Cuyo Basin ** East Palawan Basin ** Northwest Palawan Basin ** Reed Bank Basin ** Southeast Luzon Basin ** Southwest Palawan Basin ** West Luzon Basin * Visayas ** Visayan Basin (or in Luzon) ** West Masbate–Iloilo Basin * Mindanao ** Agusan–Davao Basin ** Cotabato Basin ** Sulu Sea Basin

Stratigraphic groupings

References

{{DEFAULTSORT:Philippine Mobile Belt Philippine tectonics Tectonic plates Geology of the Pacific Ocean Volcanic belts Geology of the Philippines Geology of Taiwan