Trobriand Plate | |
---|---|
Type | Microplates |
Movement1 | northwest (rotational) |
Speed1 | 10 mm/year |
Features | New Guinea, Pacific Ocean |
1Relative to the African Plate |
The Trobriand Plate was, and likely is, an independent microplate between New Guinea and the Solomon Islands. It has some unique geology, having the presence of the youngest metamorphic core complexes on earth. If there is presently active subduction between it and the Solomon Plate, at the Trobriand Trough, it continues to be an active microplate. Otherwise in the latest tectonic models it has merged with the Solomon Sea Plate, which becomes somewhat larger than predicted by Bird's 2003 model of Tectonic Plates. As a smaller Solomon Sea Plate is totally underwater, global positioning data can not resolve this issue. The area of the plate is associated with earthquake and volcanic activity as part of the Pacific Ring of Fire.
The Trobriand Plate underlies south eastern parts of Papua New Guinea east of the Owen Stanley Range as it is separated in the range from the Australian Plate by the Owen Stanley Fault Zone [1] [2] This extends along the southern border of the Goodenough Basin and through the southern part of Normanby Island in the D'Entrecasteaux Islands. This fault zone then becomes the Nubara Transform Fault that strikes northeast towards the Solomon Islands but is only related to the Trobriand microplate until the Trobriand Trough is reached. The north eastern plate boundary is the Trobriand Trough. [3] Woodlark Island is on the area of the Trobriand Plate as the Nubara Transform Fault is to its south east. [4] The western end of the New Britain Trench terminates at the Trobriand Plate.
Within the Trobriand Plate is the unigue to today's earth, the youngest (7–5 million year old) metamorphic core complexes formed of sedimentary rocks that have been subject to high and ultra-high-pressure, as well as gneissic domes that are being rapid emplaced at between 1–2 cm/year (0.39–0.79 in/year) vertically. [4] [2] The metamorphic core complexes include the Suckling-Dayman massif of south eastern New Guinea and the Emo Metamorphics which have some characteristics shared with back-arc basin basalts. [5] The gneissic domes along the volcanic front include the D'Entrecasteaux Islands and Misima Island. [3]
The Trobriand Plate is located in a very complex tectonic environment between the current Australian Plate to the south and the South Bismarck Plate and Pacific Plate to the north. [6] This environment has been intensively studied in the last 20 years and these studies have contributed to the resolution of important tectonic theory issues. They have also created inconsistencies with observation as opposed to prediction from historic tectonic modelling. This for example means that the Woodlark Plate must be a small, almost triangular shaped oceanic tectonic plate, rather than one that included continental eastern portions of Papua New Guinea. [7] These portions must now be assigned to either the Trobriand Plate or if it is now fixed with respect to the Solomon Sea Plate, a larger Solomon Sea Plate. [7] GNS data can not resolve this issue as a smaller Solomon Sea Plate is all underwater. [8]
The Trobriand Plate must have been in the fairly recent past an independent microplate, and likely still is. [9] [10] The evidence for a separate Trobriand Plate includes:
Against a current separate Trobriant Plate is the evidence that:
It is important to realise that much of the historic tectonic plate literature up to 2016 in some cases, and later in popular literature, had the Woodlark Plate as originally proposed to be somewhat larger than current proposals, extending to the west along the east coast of New Guinea and subducting beneath the Caroline plate along its northern border. [20] This model had the Maoke Plate with a convergent boundary on its west, the Australian Plate converging on the south, and on the east an undefined compressive zone which that marked the boundary with the adjoining to the north Solomon Sea Plate. It was also in this model contacting the South Bismarck Plate to the northeast. [21] Interestingly subduction at the Trobriand Trough was originally assumed in this historic model, [21] but at a rate that proved to be quite incompatible with actual data.
Most of the Woodlark Plate's originally assigned area and boundary activity are now assigned to a combination of the Australian Plate and Solomon Sea minor plate. The northern Trobriand Plate will assume the subduction at the New Britain Trench that a larger Solomon Sea Plate has assigned. These assignments are partially informed by GNS studies over a decade after the original 2003 Bird model. This showed that the Woodlark Basin region had distinctly different movements from a "Trobriand Block" and multiple eastern New Guinea land "Blocks" so that it was possible to define up to 5 distinct crustal blocks with possible independent movement, [22] that others later interpreted as components of the differing microplates. [7]
A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.
The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately 100 million years ago when India broke away and began moving north. Australia and Antarctica had begun rifting by 96 million years ago and completely separated a while after this, some believing as recently as 45 million years ago, but most accepting presently that this had occurred by 60 million years ago.
The Izu–Bonin–Mariana (IBM) arc system is a tectonic plate convergent boundary in Micronesia. The IBM arc system extends over 2800 km south from Tokyo, Japan, to beyond Guam, and includes the Izu Islands, the Bonin Islands, and the Mariana Islands; much more of the IBM arc system is submerged below sealevel. The IBM arc system lies along the eastern margin of the Philippine Sea Plate in the Western Pacific Ocean. It is the site of the deepest gash in Earth's solid surface, the Challenger Deep in the Mariana Trench.
The Solomon Sea Plate is a minor tectonic plate to the northwest of the Solomon Islands archipelago in the south Pacific Ocean. It roughly corresponds with the Solomon Sea east of Papua New Guinea. The plate boundaries are associated with high earthquake activity as part of the New Britain subduction zone.
The 1,600 kilometres (990 mi) long Macquarie Fault Zone is a major right lateral-moving transform fault along the seafloor of the south Pacific Ocean which runs from New Zealand southwestward towards the Macquarie Triple Junction. It is also the tectonic plate boundary between the Australian Plate to the northwest and the Pacific Plate to the southeast. As such it is a region of high seismic activity and recorded the largest strike-slip event on record up to May 23, 1989, of at least Mw8.0
The New Hebrides Plate, sometimes called the Neo-Hebridean Plate, is a minor tectonic plate located in the Pacific Ocean. While most of it is submerged as the sea bottom of the North Fiji Basin, the island country of Vanuatu, with multiple arc volcanoes, is on the western edge of the plate. It is bounded on the south-west by the Australian Plate, which is subducting below it at the New Hebrides Trench. The Vanuatu subduction zone is seismically active, producing many earthquakes of magnitude 7 or higher. To its north is the Pacific Plate, north-east the Balmoral Reef Plate and to its east the Conway Reef Plate.
The Caroline Plate is a minor tectonic plate that straddles the Equator in the eastern hemisphere located north of New Guinea. It forms a subduction zone along the border with the Bird's Head Plate and other minor plates of the New Guinea region to the south. A transform boundary forms the northern border with the Pacific Plate. Along the border with the Philippine Sea Plate is a convergent boundary that transitions into a rift.
The Maoke Plate is a small tectonic plate located in western New Guinea underlying the Sudirman Range from which the highest mountain on the island- Puncak Jaya rises. To its east was proposed a convergent boundary with the Woodlark Plate, although this is now best modelled after further studies as a boundary with an enlarged Solomon Sea Plate or a new microplate called the Trobriand Plate. To the south lies a transform boundary with the Australian Plate and the Bird's Head Plate lies to the west.
The Mariana Plate is a micro tectonic plate located west of the Mariana Trench which forms the basement of the Mariana Islands which form part of the Izu–Bonin–Mariana Arc. It is separated from the Philippine Sea Plate to the west by a divergent boundary with numerous transform fault offsets. The boundary between the Mariana and the Pacific Plate to the east is a subduction zone with the Pacific Plate subducting beneath the Mariana. This eastern subduction is divided into the Mariana Trench, which forms the southeastern boundary, and the Izu–Ogasawara Trench the northeastern boundary. The subduction plate motion is responsible for the shape of the Mariana plate and back arc.
The North Bismarck Plate is a small tectonic plate located in the Bismarck Sea off the northeast coast of New Guinea. It is currently regarded as a relic or inactive plate by most. At one time it was called the Manus Plate, but this term was later used for a modelled microplate at the south east boundary of the North Bismarck Plate.
The South Bismarck Plate is a small tectonic plate located mainly in the southern Bismarck Sea. The eastern part of New Guinea and the island of New Britain are on this plate. It is associated with high earthquake and volcanic activity as part of the New Britain subduction zone within the Pacific Ring of Fire.
The 2000 New Ireland earthquakes occurred off the coast of New Ireland Province, Papua New Guinea on November 16 and 17.
The Woodlark Plate is a small almost triangular shaped tectonic plate located east of the island of New Guinea and situated mainly within the northern half of the Woodlark Basin. It is located in a very complex tectonic environment, that because of associated features, has been extensively studied since it was first proposed to exist. It is now known to be much smaller than originally proposed, mainly because of information from GPS stations on islands and sea floor studies that have fully defined its margins.
The West Melanesian Trench is an oceanic trench in the Bismarck Sea north of Papua New Guinea delineating the plate tectonic boundary between the Caroline and North Bismarck plates.
The New Britain Trench has formed due to subduction of the floor of the Solomon Sea and has some of the highest current seismic activity in the world.
The Woodlark Basin is a young geologic structural basin located in the southwestern Pacific Ocean, found to the southeast of the island country of Papua New Guinea. The basin is an extensional basin that is actively spreading and has a seafloor spreading center. The basin formed between the then Indo-Australian Plate and the Solomon microplate creating the presently independent Woodlark Plate. The Woodlark Basin has a complex geologic history dating back twenty million years to the initial opening of the basin but most of the spreading has happened in the last 3.6 million years.
The subduction tectonics of the Philippines is the control of geology over the Philippine archipelago. The Philippine region is seismically active and has been progressively constructed by plates converging towards each other in multiple directions. The region is also known as the Philippine Mobile Belt due to its complex tectonic setting.
The Vanuatu subduction zone is currently one of the most active subduction zones on earth, producing great earthquakes, with potential for tsunami hazard to all coastlines of the Pacific ocean. There are active volcanoes associated with arc volcanism.
The New Britain subduction zone is one of the most recently formed and most active subduction zones on earth, producing great earthquakes, with potential for tsunami hazard, and being associated with active volcanism, as part of the Pacific Ring of Fire. It has a close relationship to an area of subduction tectonic activity that extends south eastward from New Britain to the Vanuatu subduction zone, involving the north eastern portion of the Australian Plate and its complicated collision dynamics with the south-western portion of the Pacific Plate.