- Molucca Sea Collision Zone
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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.
Contents
Tectonics
The tectonic relationship of the Sangihe Plate, Halmahera Plate, and the Molucca Sea Plate, plus the volcanic Halmahera Arc and the Sangihe Arc is complex. Their interrelationship constitutes the Molucca Sea Collision Zone. The north of this zone interlinks with the Philippine Mobile Belt. Some call this linkage the Philippine-Halmahera Arc and consider it an integral part of the elongated zone of convergence extending north through the Philippines into eastern Taiwan. In the Molucca Sea Collision Zone model, the Molucca Sea Plate has been totally consumed by the arc-arc collision of the Halmahera Arc and the Sangihe Arc of eastern Indonesia.[1]
Arc-arc collision
The Molucca Sea Collision Zone is the site of an orthogonal collision between two active subduction systems. Both the Halmahera subduction system to the east, and the Sangihe subduction system to the west, have subducted oceanic lithosphere of the Molucca Sea plate, which has been completely consumed, with the Sangihe arc now over-riding the Halmahera forearc.[2] Both volcanic arcs have been active since the Neogene. Both arcs show increased evidence for sediment recycling as the collision progressed, but for differing reasons. In Halmahera, this may represent an increased sediment flux through the arc front, while in Sangihe it may simply reflect a greater opportunity for melting of sediment-fluxed portions of the mantle wedge. In both cases the change in arc geochemistry can be related to the evolving architecture of that particular subduction zone. The Halmahera lavas also record a temporal change in the chemistry of the mantle component that resulted from induced convection above the falling Molucca Sea Plate drawing compositionally distinct peridotite into the mantle wedge. [3]
Single collision zones
The magmatic systems are reaching the end of their life as island arcs and are becoming a single collision zone,[4] lending weight to the contention that Halmahera and Sangihe should be regarded as tectonic plates rather than volcanic arcs.
Northern extension
Seismic and tomographic discrepancies in the mantle up to 400 km below Mindanao in the Philippines, indicate it is a more advanced northern extension of the Molucca Sea Collision Zone. [5]
References
- ^ Macpherson, Forde, Hall and Thirlwall (2003) in Intra-Oceanic Subduction Systems: Tectonic and Magmatic Processes, ISBN 1-86239-147-5 p208
- ^ Colin G Macpherson et ors, Geochemical evolution of magmatism in an arc-arc collision: the Halmahera and Sangihe arcs, eastern Indonesia, in Robert D Larter, ed, (2003) Intra-oceanic Subduction Systems, Geological Society of London. p208
- ^ Colin G Macpherson et ors, Geochemical evolution of magmatism in an arc-arc collision: the Halmahera and Sangihe arcs, eastern Indonesia, in Robert D Larter, ed, (2003) Intra-oceanic Subduction Systems, Geological Society of London. p207
- ^ Colin G Macpherson et ors, Geochemical evolution of magmatism in an arc-arc collision: the Halmahera and Sangihe arcs, eastern Indonesia, in Robert D Larter, ed, (2003) Intra-oceanic Subduction Systems, Geological Society of London. p208
- ^ Colin G Macpherson et ors, Geochemical evolution of magmatism in an arc-arc collision: the Halmahera and Sangihe arcs, eastern Indonesia, in Robert D Larter, ed, (2003) Intra-oceanic Subduction Systems, Geological Society of London. p215
See also
Large Small West: Burma Plate · Philippines: Philippine Mobile Belt · Indonesia: Banda Sea Plate · Molucca Sea Collision Zone · Bird's Head Plate · Halmahera Plate · Sangihe Plate · Timor Plate · New Guinea: Maoke Plate · Woodlark Plate · North Bismarck Plate · South Bismarck Plate · Manus Plate · Solomon Sea PlateFaults Philippine Fault System · Sorong Fault · Ramu-Markham Fault · Great Sumatran fault · New Britain Subduction ZoneTrenches and troughs Java Trench (Sunda) with Mentawai Trough · Sunda Trough · Timor Trough · Philippines: North Luzon Trough · Manila Trench · Philippine Trench · Cotabato Trench · East Luzon Trench · Sulu Trench · Negros Trench · Palawan Trench · Moluccas: Banda Trench · Ceram Trough · Ternate Trough · Talaud Trough · Sangihe Trough · Salajar Trough · Ayu Trough · West Caroline Trough · Timor: Aur Trough · Tanimbar Trough · New Guinea: New Guinea Trench · Manokwari Trough · West Melanesian Trench · Lyra Trough · Mussau Trench · New Britain Trench (Bougainville) · Pocklington TroughSubsea plateaus and basins Benham Plateau · Weber Basin · North Australian BasinCategories:- Philippine tectonics
- Geology of the Pacific Ocean
- Volcanic belts
- Geology of Indonesia
- Geology of the Philippines
- Molucca Sea
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