Sangihe Plate
Encyclopedia
Sangihe Plate has recently (1990s) been postulated to be a microplate within the Molucca Sea Collision Zone
of eastern Indonesia
.
region is unique. It is the only global example of an active arc-arc collision consuming an oceanic basin via subduction
in two directions. The Molucca Sea Plate
has been subsumed by tectonic microplates, the Halmahera Plate
and the Sangihe Plate. The whole complexity is now known as the Molucca Sea Collision Zone
.
The existence of Sangihe as a tectonic plate separate from the Molucca Sea Plate
is not yet entirely agreed upon by geologists. Some see Sangihe as a western slab of the Molucca Sea Plate, just as they regard Halmahera as an eastern slab of the Molucca Sea Plate. What is apparent to date is that Sangihe was part of the Molucca Sea slab subducted during the Neogene
between 45 Ma and 25 Ma.
Seismicity
shows the west-dipping Sangihe reaches a depth of about 650 kilometres (403.9 mi). Both Sangihe and Halmahera are exposed to the surface while the Molucca Sea plate is completely subsumed below these two microplates. The southern boundary of the Molucca Sea Plate is also the boundary of the Philippine Sea Plate and the Australian Plate, and is moving northwards. Since the Sangihe Plate and the Halmahera Plate are in continuity with the Molucca Sea Plate, this implies all three slabs are moving northward in mantle with the Australian Plate.
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:...
of eastern Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
.
Regional tectonics
The tectonic setting of the Molucca SeaMolucca Sea
The Molucca Sea is located in the western Pacific Ocean, within the country of Indonesia. The region is rich in coral and has many diving sites.-Location:...
region is unique. It is the only global example of an active arc-arc collision consuming an oceanic basin via subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
in two directions. 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 subsumed by tectonic microplates, the Halmahera Plate
Halmahera Plate
Halmahera Plate has recently been postulated to be a microplate within the Molucca Sea Collision Zone of eastern Indonesia.-Regional tectonics:...
and the Sangihe Plate. The whole complexity is now known as 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:...
.
The existence of Sangihe as a tectonic plate separate from 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...
is not yet entirely agreed upon by geologists. Some see Sangihe as a western slab of the Molucca Sea Plate, just as they regard Halmahera as an eastern slab of the Molucca Sea Plate. What is apparent to date is that Sangihe was part of the Molucca Sea slab subducted during the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
between 45 Ma and 25 Ma.
Seismicity
Seismology
Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,...
shows the west-dipping Sangihe reaches a depth of about 650 kilometres (403.9 mi). Both Sangihe and Halmahera are exposed to the surface while the Molucca Sea plate is completely subsumed below these two microplates. The southern boundary of the Molucca Sea Plate is also the boundary of the Philippine Sea Plate and the Australian Plate, and is moving northwards. Since the Sangihe Plate and the Halmahera Plate are in continuity with the Molucca Sea Plate, this implies all three slabs are moving northward in mantle with the Australian Plate.