Trobriand plate

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Trobriand plate
Trobriand plate
Approximate surface projections of active tectonic plates. Key: '"`UNIQ--templatestyles-00000000-QINU`"'  South Bismarck Plate, '"`UNIQ--templatestyles-00000001-QINU`"'  Solomon Sea Plate, '"`UNIQ--templatestyles-00000002-QINU`"'  Trobriand Plate, '"`UNIQ--templatestyles-00000003-QINU`"'  Woodlark Plate, '"`UNIQ--templatestyles-00000004-QINU`"'  Active trench subduction boundaries, '"`UNIQ--templatestyles-00000005-QINU`"'  Inactive trench subduction boundaries, '"`UNIQ--templatestyles-00000006-QINU`"'  current spreading boundary. The Australian Plate to the south-east and the Pacific Plate to the north-west are not shown, but their complex collision has created these microplates. Click and then mouse over shows feature names.
Type Microplates
Movement1north-west (rotational)
Speed110 mm/year
Features New Guinea, Pacific Ocean
1Relative to the African Plate
Coral Sea Topography.jpg
Trobriand
   Plate
Coral Sea Topography.jpg
Seafloor topographic map of area of Trobriand Plate. The location of the Solomon Sea Plate (S. P.) and Woodlark Plate (W. P.) are also labelled.

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.

Contents

Geography

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 north-east 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.

Geology

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]

Tectonics

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:

Other Tectonic relationships

Much of the historic academic 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 north-east. [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]

See also

Related Research Articles

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The Cayman Trough is a complex transform fault zone pull-apart basin which contains a small spreading ridge, the Mid-Cayman Rise, on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate. It extends from the Windward Passage, going south of the Sierra Maestra of Cuba toward Guatemala. The transform fault continues onshore as the Polochic-Motagua fault system, which consists of the Polochic and Motagua faults. This system continues on until the Chiapas massif where it is part of the diffuse triple junction of the North American, Caribbean and Cocos plates.

<span class="mw-page-title-main">North American plate</span> Large tectonic plate including most of North America, Greenland and part of Siberia

The North American Plate is a tectonic plate containing most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of 76 million km2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific Plate.

<span class="mw-page-title-main">Australian plate</span> Major tectonic plate separated from Indo-Australian Plate about 3 million years ago

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.

<span class="mw-page-title-main">Okhotsk microplate</span> Minor tectonic plate in Asia

The Okhotsk microplate is a proposed minor tectonic plate covering the Kamchatka Peninsula, Magadan Oblast, and Sakhalin Island of Russia; Hokkaido, Kantō and Tōhoku regions of Japan; the Sea of Okhotsk, as well as the disputed Kuril Islands.

<span class="mw-page-title-main">Izu–Bonin–Mariana Arc</span> Convergent boundary in Micronesia

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.

<span class="mw-page-title-main">Macquarie Fault Zone</span> Lateral-moving transform fault south of New Zealand

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 23 May 1989, of at least Mw8.0

<span class="mw-page-title-main">Caroline plate</span> Minor oceanic tectonic plate north of New Guinea

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.

<span class="mw-page-title-main">Maoke plate</span> Small tectonic plate in western New Guinea

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.

<span class="mw-page-title-main">North Bismarck plate</span> Small tectonic plate in the Bismarck Sea north of New Guinea

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.

<span class="mw-page-title-main">Shetland plate</span> Tectonic microplate off the tip of the Antarctic Peninsula

The Shetland Plate, or South Shetland Plate, is a tectonic microplate located off the tip of the Antarctic Peninsula that contains the South Shetland Islands. The plate is bordered on three sides by the Antarctic Plate, while the fourth side is bordered by the Scotia Plate. The northwestern border is defined by the South Shetland Trench, separating the Shetland Plate to the south from the Antarctic Plate to the north. This trench is the remnant of a subduction zone where the defunct Phoenix Plate, now part of the Antarctic Plate, subducted under the Antarctic Peninsula and the Shetland Islands. The southeastern border is a rift zone, with the Antarctic Plate creating the Bransfield Basin. The southwestern and northeastern boundaries are each part of larger fracture zones. The southwestern border is the Hero Fracture Zone and separates the Antarctic Plate to the southwest from the Shetland Plate to the northeast. The northeastern boundary is the Shackleton Fracture Zone and separates the Shetland Plate to the southwest from the Scotia 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.

<span class="mw-page-title-main">Woodlark plate</span> Small tectonic plate located to the east of the island of New Guinea

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.

<span class="mw-page-title-main">West Melanesian Trench</span> Oceanic trench in the Bismarck Sea north of Papua New Guinea

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.

<span class="mw-page-title-main">New Britain Trench</span> Oceanic trench in the southern Pacific Ocean

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.

<span class="mw-page-title-main">Woodlark Basin</span> Oceanic basin located to the east of the island of New Guinea

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.

<span class="mw-page-title-main">Oblique subduction</span> Tectonic process

Oblique subduction is a form of subduction for which the convergence direction differs from 90° to the plate boundary. Most convergent boundaries involve oblique subduction, particularly in the Ring of Fire including the Ryukyu, Aleutian, Central America and Chile subduction zones. In general, the obliquity angle is between 15° and 30°. Subduction zones with high obliquity angles include Sunda trench and Ryukyu arc.

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.

References

  1. ↑ Sun & Mann 2021 , FIGURE 1
  2. 1 2 Wallace et al. 2014 , Figure 1, Sections: 1 Introduction, 2 Tectonic Setting
  3. 1 2 3 Benyshek & Taylor 2021 , Section:2.1 Geologic Background, Figure 2
  4. 1 2 Benyshek & Taylor 2021 , Introduction, Figure 1.Geology and tectonics of the Papuan Peninsula-Woodlark Basin region
  5. ↑ Worthing, M.A.; Crawford, A.J. (1996). "The igneous geochemistry and tectonic setting of metabasites from the emo metamorphics, Papua New Guinea; A record of the evolution and destruction of a backarc basin". Mineralogy and Petrology. 58 (1–2): 79–100. doi:10.1007/BF01165765. S2CID   129618443.
  6. ↑ Benyshek & Taylor 2021 , 3.1.Woodlark Basin Spreading Center
  7. 1 2 3 4 5 Benyshek & Taylor 2021 , Abstract,9 Conclusions
  8. ↑ Wallace et al. 2014 , 4.2 Preferred Elastic Block Model Results
  9. ↑ Cameron 2014 , Section:Abstract ii P4
  10. 1 2 Benyshek & Taylor 2021 , 2.2 Gravity, Figure 3.Seismicity and focal mechanisms of the Papua New Guinea–Solomon Islands region
  11. 1 2 Taylor, Brian; Goodliffe, Andrew (2009). "Plate boundaries in the Woodlark Basin and Solomon Sea Region, Papua New Guinea". AGU Fall Meeting Abstracts. 2009. Bibcode:2009AGUFM.T31C1834G . Retrieved 12 August 2023.
  12. ↑ Tiffin, D. L.; Honza, E.; Keene, J. (1984). Shipboard Scientists (ed.). "A GEOLOGICAL AND GEOPHYSICAL INVESTIGATION OF THE WESTERN SOLOMON SEA, TROBRIAND BASIN, AND ADJACENT AREAS – CRUISE REPORT OF THE R/V NATSUSHIMA 5 Dec. 1983 – Jan. 1984" (PDF). United Nations Development Programme. Retrieved 13 August 2023.
  13. 1 2 3 Benyshek & Taylor 2021 , 3.3 Trobriand Trough and Papuan Arc, Figure 7, Figure 8
  14. ↑ "USGS:Seismotectonics of the New Guinea Region and Vicinity:Historic Seismicity" . Retrieved 12 August 2023.
  15. 1 2 Benyshek & Taylor 2021 , 2.3 Seismicity and Arc Volcanism
  16. ↑ Cameron 2014 , Section:2.0.1. PLATE BOUNDARIES P31
  17. 1 2 Benyshek & Taylor 2021 , 6.3.1.Case 2: Four-Plate Solution, Figure 11
  18. ↑ Holm, RJ; Rosenbaum, G; Richards, SW (1 May 2016). "Post 8 Ma reconstruction of Papua New Guinea and Solomon Islands: Microplate tectonics in a convergent plate boundary setting". Earth-Science Reviews. 156: 66–81. doi:10.1016/j.earscirev.2016.03.005.
  19. 1 2 Benyshek & Taylor 2021 , 6.3.1.Case 1: Three-Plate Solution
  20. ↑ Boulart et al. 2022 , Fig. 1: Regional map of the Woodlark Basin, Section:Introduction
  21. 1 2 Bird, Peter (2003). "An updated digital model of plate boundaries". Geochemistry, Geophysics, Geosystems. 4 (3): 1027. Bibcode:2003GGG.....4.1027B. doi: 10.1029/2001GC000252 .
  22. ↑ Wallace et al. 2014 , Section:4 Interpretation of the GPS Results

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