Lau Basin

Last updated
Lau Basin
Approximate surface projection on Pacific Ocean of Lau Basin. Spreading centers are shown in yellow.
The Lau Basin in the upper part of the arc-backarc complex Kermadec Arc.jpg
The Lau Basin in the upper part of the arc-backarc complex

The Lau Basin is a back-arc basin (also addressed as "interarc basin" [1] ) at the Australian-Pacific plate boundary. It is formed by the Pacific plate subducting under the Australian plate. The Tonga-Kermadec Ridge, a frontal arc, and the Lau-Colville Ridge, a remnant arc, sit to the eastern and western sides of the basin, respectively. [2] The basin has a raised transition area to the south where it joins the Havre Trough.

Contents

History

Lau Basin is a young basin (much is less than 5 million years old) [2] that separates a previously continuous island arc by extensional rifting [1] and spreading. [3] During the Pliocene, the Pacific plate was subducting beneath the Australian plate. [2] The slab of the Pacific plate melted as it was thrust down, and then rose to form the original Tonga-Kermadec Ridge. Around 25 million years ago, the Pacific plate started to drift away from the Australian plate, thus splitting the volcanic ridge. The rifting was initially caused by extension until 6 million years ago, by which time seafloor spreading started in this region and eventually formed the Lau Basin between the separated ridges. [4] In the north the basin reaches its maximum width of 500 km (310 mi) with a triangular shape to the south understood to be the result of the southward propagation of the main extensional centers and their asymmetric, predominantly westward opening. [3]

Spreading centers

Spreading centers associated with the Lau Basin. KEY: C-ELSC - Central Eastern Lau Spreading Center CLSC - Central Lau Spreading Center FRSC - Fonualei Rift and Spreading Center FSC - Futuna Spreading Center ILSC - Intermediate Lau Spreading Center LETZ - Lau Extensional Transform Zone MTJ - Mangatolu Triple Junction NELSC - North-East Lau Spreading Center NWLSC - North-West Lau Spreading Center VFR-Valu Fa Ridge Lau Basin-NOAA-Tectonic features hires.jpg
Spreading centers associated with the Lau Basin. KEY:
C-ELSC - Central Eastern Lau Spreading Center
CLSC - Central Lau Spreading Center
FRSC - Fonualei Rift and Spreading Center
FSC - Futuna Spreading Center
ILSC - Intermediate Lau Spreading Center
LETZ - Lau Extensional Transform Zone
MTJ - Mangatolu Triple Junction
NELSC - North-East Lau Spreading Center
NWLSC - North-West Lau Spreading Center
VFR-Valu Fa Ridge

Southward propagating

The V-shaped Lau Basin was opened by two southward propagating spreading centers: the Central Lau Spreading Center (CLSC) and the East Lau Spreading Center (ELSC). [4] The initial ELSC was oriented north–south and has a spreading rate of about 100 mm (3.9 in)/year. It erupts mid-ocean ridge basalt (MORB). [5] The northeastern tip of ELSC propagated southward faster than the other part and produced a pseudofault oriented 170 degree. [6] The ELSC rotated 15–25 degree clockwise and continued to propagate towards the south. Then the CLSC, as well as an extensional transform zone (ETZ) linking the two spreading centers were formed. The CLSC propagated southwards and replaced the northern segment ELSC. [7] The region of overlap of CLSC and ELSC is characterized by strike-slip earthquakes. There is an Intermediate Lau spreading center (ILSC) between the two and to the east of the ELSC which has now four characterised segments. [8] In the 3rd segment of the ELSC there is a transition in ridge morphology, associated with a substantial decrease of basin depth, from 2.7 km (1.7 mi) to 2.1 km (1.3 mi) which has been correlated with the appearance of an axial magma chamber reflector in the southern part of the ELSC. [8] Recent measurements have shown that the opening rates are increasing at ELSC and CLSC. [7] At present, the spreading rate of Lau Basin is about 150 mm (5.9 in)/year and as an example of a fast-spreading back-arc basin [9] much additional study has been undertaken which has identified additional spreading centers. [5] As we come south down the Lau Basin spreading rates decrease being for the CLSC 120 mm (4.7 in)/year, just to the north of the ELSC at the ILSC 102 mm (4.0 in)/year, at the start of the Valu Fa Ridge (VFR) to the south 69 mm (2.7 in)/year, and at its southern end 48 mm (1.9 in)/year. [10] Some authors have combined the VFR as part of the ELSC but the geology is slightly different. [11] The southernmost spreading segment (it has two segments) [8] of the VFR approaches to within 20 km (12 mi) of the arc to its east at about 24°S and is only 1,700 m (5,600 ft) deep. [5] These spreading centers have now partially dismembered the Lau Ridge. [12] South of the VFR, the back-arc region is mainly an area of stretched arc crust with abundant normal faulting but no obvious spreading and is called the Southern Lau Rift (SLR), an area of current active shallow earthquakes. [11] Similarly to the south the Havre Trough has currently only rifting. To the north east is the southern section of the Fonualei Rift and Spreading Center (FRSC) which is southward propagating but to the north the interactions of the FRSC appear more complex and are mentioned below. [13]

Otherwise propagating

From the north of the CLSC we have a northeast orientated Lau Extensional Transform Zone (LETZ) which joins up to the Peggy Ridge which is a fairly linear SW to NE orientated ridge greater than 200 km (120 mi) in the central Lau Basin [14] (Labelled PR in diagram of basin on this page). The LETZ accommodates east to west extension but so does the FRSC to its east and such a double parallel arrangement has not been identified in any other back-arc basin. [15] There is considerable complexity at the northern part of the Lau Basin where presently five independent oceanic tetectonic plates are interacting. The northwest aspect of the Lau basin has the Northwest Lau Spreading Center (NWLSC). This is spreading at 75 mm (3.0 in)/year. [10] The Rochambeau Rifts to the NWLSC's northeast are moving apart at 110 mm (4.3 in)/year. [10] To the east of the Rochambeau Rifts is an area of sea floor spreading between the Niuafo'ou Plate and northern Tonga Plate. From the north south we have the Northeast Lau Spreading Center (NELSC) separating at 42 mm (1.7 in)/year, the area south of the Mangatolu Triple Junction (MTJ, also known as the Kings Triple Junction [16] ) which is separating at 30 mm (1.2 in)/year and the FRSC whose first northern segment is propagating northwards [17] with a spreading rate of 28 mm (1.1 in)/year in the north east Lau Basin but down to 9 mm (0.35 in)/year [10] where the last segment of the FRCS intercepts the Tofua volcanic arc to the west of the Tonga Ridge. [17] A prominent NW-trending formation of young volcanic structures that includes the Niuafo'ou shield volcano crosses the northern Lau Basin approximately 75 km (47 mi) west of the MTJ and is called the Western Rift Margin (WRM). [3] To the east of the WRM the seafloor has multiple NNW trending elongated ridges of roughly the same orientation as the WRM, while to its west the seafloor is more chaotic with much volcanism. [3]

Petrology

Lau Basin volcanics are mainly andesites and dacites that were erupted 6.4 to 9.0 Ma. Most mafic rocks found are 55% SiO2 basaltic andesites. [2] The whole basin floor is mostly composed of MORB-like rocks, but the westmost 80~120 km of the basin floor contains a mixture of MORB, transitional and arc-like basalts. This western region has a different composition because it was formed by extension and rifting between the Lau and Tonga ridges before seafloor spreading started. The grabens in this region was then filled by fresh magma from a mantle source that is different from the mantle source for CLSC/ELSC. [2] In the north eastern portion of the basin there is over 402 km2 (155 sq mi)) of dacite lava north of the Niuatahi seafloor caldera which appears to have come from seafloor activity not associated with the caldera which on its flanks also has some dacite eruptives. [18] The southern basin volcanics and that of the ʻAta volcano can be associated with recycling from the subducted portions of the Louisville Seamount Chain. [19] Dredged lavas from the FRSC are almost identical to lavas from the nearby arc volcanoes. [13] To the south the lavas in this part of the Lau Basin are more arc-like than the MORB at the ELSC, with basalt and andesite present. [5] Further south the eruptives of the rift valley east of the SLR are mainly andesitic and/or dacitic while the western margin of the SLR has andesites and basalts. [11]

Mantle source

The source of mantle melt to the Lau Basin is centered west of the spreading centers at shallow depth. This source may have directly supplied the western part of Lau Basin. The MORB-type basalt filled the grabens that were originally formed by extension in western Lau Basin. Asymmetric melt supply gave rise to the asymmetric thickness of crust at different sections of the basin. This melt supply may still be continuing today as indicated by a low-velocity anomaly in the upper mantle beneath the western Lau Basin. [4]

Mantle convection

At the subduction boundary between Pacific plate and the Tonga and Kermadec plates, the roll-back of the Tonga Trench and Pacific slab caused compensating flow of the mantle beneath the Lau Basin. This fertile mantle then encounters the water released from the dehydrated subducting Pacific slab and undergoes partial melting. This results in the creation of a batch of depleted mantle between the fertile mantle and subducting slab. An upward flow of the depleted layer is then induced by back-arc spreading and slab subduction towards corner region where the mantle is hydrated. The enhanced melting in this region prevents the depleted mantle from getting re-enriched and thus allows it to flow until it overturns. It is then carried back down beneath the back-arc as subduction continues. The ELSC located right on top of the highly depleted mantle thus experiences a diminished magma supply which results in a thinner layer of crust and a faster spreading rate. The CLSC, on the other hand, has thicker crust because it overlies the fertile mantle that is largely removed from effect of the volcanic front. Unlike ELSC, CLSC has characteristics that are much more similar to a mid-ocean ridge. [9]

Crustal structure

Crustal structure in the region. The back-arc marked on the far left is the Lau Basin. Map00382 (28005000220).jpg
Crustal structure in the region. The back-arc marked on the far left is the Lau Basin.

Crustal thickness increases from 6 km (3.7 mi) in the east to 9 km (5.6 mi) in the west. All of the Lau basin crust has a thicker midcrustal section than is seen in the pacific plate. The Lau Basin crust can be divided into eastern, central and western sections according to their thickness (5.5–6.5, 7.5–8.5 and 9 km, respectively). crust in the eastern section is similar to the one in the Pacific Plate with a thicker midcrustal layer and a thinner lower crustal layer. This suggests that it is composed of oceanic crust that was created more than 1.5 million years ago at the ELSC. The boundary between the eastern and central sections coincides with the boundary between the ELSC crust and CLSC crust, implying the internal structures in these two spreading ridges are, or were different. The central section has relatively thicker crust that formed within the past 1.5 million years at the CLSC. The boundary between the central and western crustal sections lies in the middle of ELSC crust, suggesting that the western section contains crust created both by oceanic spreading at ELSC and by island arc extension from the original Lau Basin. [1] In the ELSC further studies have shown that the back-arc crust created at less than 50 km (31 mi) from the volcanic arc front is unusually thick at 8 to 9 km) and has a thick upper crustal layer and a lower crustal layer ("Domain II crust", “hydrous” crust) due to slab-derived water input into the subaxial melting regime of the back-arc spreading center. [20] Seismic studies show that back-arc crust created at distances greater than 70 km (43 mi) from the volcanic arc front is thinner and more similar to typical oceanic crust ("Domain III crust"). [20] The crust in the southern FRSC was created by extension of arc crust with variable input of magmatism and magmatic underplating is found in some parts of the southern Niuafo'ou microplate. [21]

Tectonics

The northern red lines of spreading centers in this diagram of the Kermadec and Tonga Plates are those in the Lau Basin Kermadec and Tonga Plates.jpg
The northern red lines of spreading centers in this diagram of the Kermadec and Tonga Plates are those in the Lau Basin

The processes of back-arc basin formation were first proposed by Daniel (Dan) Karig in 1970 [1] from studies of the Lau Basin. [15] The possibility of there being in this region several tectonic plates and triple junctions was suggested by Clement Chase the next year. [15] The Lau Basin presently has oceanic crust from the Australian Plate to its east, the Niuafo'ou Plate to its north east and the clockwise rotating Tonga Plate to its west. [22] The Futuna microplate is in close relationship to the north in this most active tectonic area. [22] In the northern Lau Basin, the extensional motion between the reference points of Australia and Tonga is accommodated by multiple zones of active rifting and spreading that are located along the boundaries of the Niuafo'ou microplate. [3] These are so complex, especially towards the north that other smaller microplates may currently exist and certainly some of the plate boundaries are zones of deformation or for other reassons are ill defined. [23] There is a overlapping spreading center from the northernmost segment of the FRSC in the east to the southernmost segment of the Mangatolu Triple Junction in the west. [3] The relationships between seafloor and crustal properties, that were established based on observations made at mid-ocean ridges such as distance to spreading center, water depth and crustal age may not be strictly applicable in the back-arc basin setting. [24] In particular the complexity of the northern section is best explained if the spreading in back-arc basins is not as linear a process as it is along mid-ocean ridges and rather back arc spreading has the potential for newly emerging or jumping spreading centers. [25]

The west dipping Pacific slab whose bed rock is about 110 millions years old is presently being subducted under the independent Tonga microplate whose spreading center from the Australian Plate are those of the southern Lau Basin. [12] The seismogenic zone below the Lau Basin is very displaced from the Tonga Trench, so that the slab is at about 250 km (160 mi) depth under the Lau Basin spreading axis. [12] The southern limit of the basin is related to the subduction of the Louisville Ridge below the Kermadec-Tonga subduction zone.

Volcanoes

Spreading ridges volcanoes map-en.svg
Spreading ridges volcanoes map-en.svg
Map of current volcanic activity near the Lau Basin. The spreading centers are shown as red lines.

At present, the Lau Basin is still an active back-arc that is rapidly evolving in time. Six of the seven volcanoes in the Lau Basin are still active. [26] The island volcano of Niuafoʻou has erupted multiple times since historic records began. To the east some islands of Tonga are located in the latitudinal range of the ELSC, notably in view of its recent eruptive history Hunga Tonga–Hunga Haʻapai, 80 km (50 mi) away. [8] It has been suggested that carbonate sediments deposited on a previously subducted Louisville Seamount Chain volcano may have been a factor in the explosive nature of the 2022 eruption. [27] ʻAta is about 50 km (31 mi) east of the Valu Fa Ridge [8] and compositional analysis of its volcanics have identified that these are associated with the subducted portions of the Louisville seamounts. [28] [19] Kao which has the highest point of Tonga and Tofua are about 95 km (59 mi) to the east of the most northern segment of the ELSC. [8] The large Niuatahi caldera is in the northeast of the basin. [18] The eastern side of the basin has the Tofua volcanic arc along the western side of the Tonga Ridge.

Earthquakes

Earthquakes in this region are mostly crustal earthquakes. Small earthquakes from the basin are barely recorded on land because of high mantle attenuation. [9] However low‐magnitude seismicity (i.e. mainly Mw less than 5) has been recorded along the active spreading centers in the Lau Basin by ocean bottom seismometers. [29] Most of the earthquakes, as well as volcanic activities locate at the east boundary of Lau Basin, along the Tonga Ridge which is very volcanically active. [2] In the Southern Lau Rift shallow earthquake swarms have occurred. [11] In terms of shallow and thus crustal earthquakes greater than Mw 5 it has been possible to group the earthquakes into stress domains:

Related Research Articles

<span class="mw-page-title-main">Tonga Trench</span> Deepest oceanic trench in the southwestern Pacific Ocean

The Tonga Trench is an oceanic trench located in the southwestern Pacific Ocean. It is the deepest trench in the Southern hemisphere and the second deepest on Earth after the Mariana Trench. The fastest plate-tectonic velocity on Earth is occurring at this location, as the Pacific Plate is being subducted westward in the trench.

<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.

The Tonga Plate is a small southwest Pacific tectonic plate or microplate. It is centered at approximately 19° S. latitude and 173° E. longitude. The plate is an elongated plate oriented NNE - SSW and is a northward continuation of the Kermadec linear zone north of New Zealand. The plate is bounded on the east and north by the Pacific Plate, on the northwest by the Niuafo’ou Microplate, on the west and south by the Indo-Australian Plate. The Tonga plate is subducting the Pacific plate along the Tonga Trench. This subduction turns into a transform fault boundary north of Tonga. An active rift or spreading center separates the Tonga Plate from the Australian Plate and the Niuafo’ou microplate to the west. The Tonga Plate is seismically very active and is rotating clockwise.

<span class="mw-page-title-main">Back-arc basin</span> Submarine features associated with island arcs and subduction zones

A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics.

<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.

<span class="mw-page-title-main">Kermadec-Tonga subduction zone</span> Convergent plate boundary that stretches from the North Island of New Zealand northward

The Kermadec-Tonga subduction zone is a convergent plate boundary that stretches from the North Island of New Zealand northward. The formation of the Kermadec and Tonga Plates started about 4–5 million years ago. Today, the eastern boundary of the Tonga Plate is one of the fastest subduction zones, with a rate up to 24 cm/yr. The trench formed between the Kermadec-Tonga and Pacific Plates is also home to the second deepest trench in the world, at about 10,800 m, as well as the longest chain of submerged volcanoes.

<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 May 23, 1989, of at least Mw8.0

<span class="mw-page-title-main">Mariana Plate</span> Small tectonic plate west of the Mariana Trench

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.

<span class="mw-page-title-main">West Mata</span> Submarine volcano in Tonga

West Mata is an active submarine volcano located in the northeastern Lau Basin, roughly 200 km (124 mi) southwest of the Samoan Islands. It is part of the Tonga-Kermadec volcanic arc, which stretches from the North Island of New Zealand to Samoa. The volcano was first discovered in 2008 by scientists aboard the R/V Thompson research vessel, using sonar mapping and a remotely operated vehicle (ROV) to explore the seafloor. At the same time West Mata was discovered, multiple neighboring volcanoes—most of them hydrothermally active—were discovered as well, including Volcano O, Tafu-Maka, Northern Matas and East Mata.

<span class="mw-page-title-main">Geology of the Pacific Ocean</span> Overview about the geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.

<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">North Fiji Basin</span>

The North Fiji Basin (NFB) is an oceanic basin west of Fiji in the south-west Pacific Ocean. It is an actively spreading back-arc basin delimited by the Fiji islands to the east, the inactive Vitiaz Trench to the north, the Vanuatu/New Hebrides island arc to the west, and the Hunter fracture zone to the south. Roughly triangular in shape with its apex located at the northern end of the New Hebrides Arc, the basin is actively spreading southward and is characterised by three spreading centres and an oceanic crust younger than 12 Ma. The opening of the NFB began when a slab roll-back was initiated beneath the New Hebrides and the island arc started its clockwise rotation. The opening of the basin was the result of the collision between the Ontong Java Plateau and the Australian Plate along the now inactive Solomon–Vitiaz subduction system north of the NFB. The NFB is the largest and most developed back-arc basin of the south-west Pacific. It is opening in a complex geological setting between two oppositely verging subduction systems, the New Hebrides/Vanuatu and Tonga trenches and hence its ocean floor has the World's largest amount of spreading centres per area.

<span class="mw-page-title-main">Tonga-Kermadec Ridge</span> Oceanic ridge in the south-west Pacific Ocean underlying the Tonga-Kermadec island arc

The Tonga-Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga-Kermadec island arc. It is a result of the most linear, fastest converging, and seismically active subduction boundary on Earth, the Kermadec-Tonga subduction zone, and consequently has the highest density of submarine volcanoes.

<span class="mw-page-title-main">Monowai (seamount)</span> Volcanic seamount north of New Zealand

Monowai Seamount is a volcanic seamount to the north of New Zealand. It is formed by a large caldera and a volcanic cone just south-southeast from the caldera. The volcanic cone rises to depths of up to 100 metres (330 ft) but its depth varies with ongoing volcanic activity, including sector collapses and the growth of lava domes. The seamount and its volcanism were discovered after 1877, but only in 1980 was it named "Monowai" after a research ship of the same name.

<span class="mw-page-title-main">Plate theory (volcanism)</span>

The plate theory is a model of volcanism that attributes all volcanic activity on Earth, even that which appears superficially to be anomalous, to the operation of plate tectonics. According to the plate theory, the principal cause of volcanism is extension of the lithosphere. Extension of the lithosphere is a function of the lithospheric stress field. The global distribution of volcanic activity at a given time reflects the contemporaneous lithospheric stress field, and changes in the spatial and temporal distribution of volcanoes reflect changes in the stress field. The main factors governing the evolution of the stress field are:

  1. Changes in the configuration of plate boundaries.
  2. Vertical motions.
  3. Thermal contraction.
<span class="mw-page-title-main">Niuatahi</span> Submarine volcano in Tonga

Niuatahi or also called Volcano O is a submarine volcano located in the far northern territory of Tonga. Since the cone in the middle is named Motutahi, the volcano is sometimes referred to as Niuatahi-Motutahi. Despite not having any record of any eruption, Niuatahi does have a record of recent hydrothermal activity.

<span class="mw-page-title-main">Osbourn Trough</span> Deep oceanic basin in the southwestern Pacific Ocean

The Osbourn Trough, is a 900 km (560 mi)-long extinct mid-ocean ridge, that may have stopped spreading as recently as 79 million years ago. It is a west-to-east oriented sea floor feature, located to the east of the present Tonga-Kermadec Ridge where the present Pacific Plate is under going subduction under a micro-plate of the Australian Plate. The Osbourn Trough is key to understanding the postulated breakup mechanism of the historic massive Ontong Java-Manihiki-Hikurangi large igneous province (LIP), as it has been shown to be the spreading centre that lead to the separation of the Manihiki Plateau to its north and the Hikurangi Plateau to its south close to New Zealand.

<span class="mw-page-title-main">Lau-Colville Ridge</span> Oceanic ridge in the south-west Pacific Ocean between Fiji and New Zealand

The Lau-Colville Ridge is an extinct oceanic ridge located on the oceanic Australian Plate in the south-west Pacific Ocean extending about 2,700 km (1,700 mi) from the south east of Fiji to the continental shelf margin of the North Island of New Zealand. It was an historic subduction boundary between the Australian Plate and the Pacific Plate and has important tectonic relationships to its east where very active spreading and subduction processes exist today. It is now the inactive part of an eastward-migrating, 100 million year old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex and is important in understanding submarine arc volcanism because of these relationships. To its west is the South Fiji Basin whose northern bedrock is Oligocene in origin.

<span class="mw-page-title-main">Havre Trough</span> Oceanic rift valley in the south-west Pacific Ocean to the north of New Zealand

The Havre Trough is a currently actively rifting back-arc basin about 100 km (62 mi) to 120 km (75 mi) wide, between the Australian Plate and Kermadec microplate. The trough extends northward from New Zealand's offshore Taupō Volcanic Zone commencing at Zealandia's continental shelf margin and continuing as a tectonic feature, as the Lau Basin which currently contains active seafloor spreading centers. Its eastern margin is defined by the Kermadec Ridge created by Pacific Plate subduction under the Kermadec microplate, while the western margin is the remnant Lau-Colville Ridge.

<span class="mw-page-title-main">South Fiji Basin</span> Oceanic basin in the south-west Pacific Ocean between Fiji and New Zealand

The South Fiji Basin is a large 4 to 4.7 km deep oceanic basin in the south-west Pacific Ocean, south of Fiji. It was formed from the then Indo-Australian Plate and is delimited to the north west by the New Hebrides Trench, and the Hunter Fracture Zone, to the west by the Three Kings Ridge, to the east by the Lau-Colville Ridge, and to the south by the continental shelf of Zealandia.

References

  1. 1 2 3 4 Karig, D. E. (1970). "Ridges and basins of the Tonga-Kermadec island arc system". Journal of Geophysical Research. 75 (2): 239–254. Bibcode:1970JGR....75..239K. doi:10.1029/JB075i002p00239.
  2. 1 2 3 4 5 6 Gill, J. B. 1976. "Composition and Age of Lau Basin and Ridge Volcanic Rocks: Implications for Evolution of an Interarc Basin and Remnant Arc." Bulletin of the Geological Society of America 87 (10): 1384–1395.
  3. 1 2 3 4 5 6 Jegen et al. 2023 , Section:2 Geological Background
  4. 1 2 3 Crawford, W. C.; Hildebrand, J. A.; Dorman, L. M.; Webb, S. C.; Wiens, D. A. (2003). "Tonga Ridge and Lau Basin Crustal Structure from Seismic Refraction Data". Journal of Geophysical Research: Solid Earth. 108 (4): 2195. Bibcode:2003JGRB..108.2195C. doi: 10.1029/2001JB001435 . Retrieved 26 December 2016.
  5. 1 2 3 4 Gray 2022 , p14
  6. ↑ Taylor, B.; Zellmer, K.; Martinez, F.; Goodliffe, A. (1996). "Sea-floor Spreading in the Lau Back-arc Basin". Earth and Planetary Science Letters. 144 (1–2): 35–40. Bibcode:1996E&PSL.144...35T. doi:10.1016/0012-821X(96)00148-3 . Retrieved 26 December 2016.
  7. 1 2 Parson, L. M.; Pearce, J. A.; Murton, B. J.; Hodkinson, R. A. (1990). "Role of Ridge Jumps and Ridge Propagation in the Tectonic Evolution of the Lau Back-Arc Basin, Southwest Pacific". Geology. 18 (5): 470–473. Bibcode:1990Geo....18..470P. doi:10.1130/0091-7613(1990)018<0470:RORJAR>2.3.CO;2.
  8. 1 2 3 4 5 6 Escrig et al. 2009 , Figure 1, Section:2. Geological Setting
  9. 1 2 3 Martinez, Fernando; Taylor, Brian (2002). "Mantle wedge control on back-arc crustal accretion". Nature. 416 (6879): 417–420. Bibcode:2002Natur.416..417M. doi:10.1038/416417a. PMID   11919628. S2CID   4341911.
  10. 1 2 3 4 Gray 2022 , Fig 2.1, p37
  11. 1 2 3 4 Ruellan et al. 2003 , Section:5. Rifting and Spreading Propagation in Southern Lau Back-Arc Basin 23°–25°S
  12. 1 2 3 Artemieva 2023 , Section:#17. Lau Basin
  13. 1 2 Schmid et al. 2020 , Section:Fonualei Rift and Spreading Center
  14. ↑ Baxter et al. 2020 , Section:3.7 PR and Lau Extensional Transform Zone
  15. 1 2 3 Schmid et al. 2020 , Section:Introduction
  16. ↑ Paropkari, Anil; Ray, Durbar; Balaram, V; Lankalapalli, Surya; Mirza, Imran; Satyanarayana, M; Rao, T; Kaisary, Sujata (2010-04-01). "Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives". Journal of Asian Earth Sciences. 38 (3–4): 121–130. Bibcode:2010JAESc..38..121P. doi:10.1016/j.jseaes.2009.12.003.
  17. 1 2 Jegen et al. 2023 , Section:Crustal Zonation of the Lau Basin
  18. 1 2 Embley & Rubin 2018 , Abstract
  19. 1 2 Timm et al. 2013 , Section:Discussion
  20. 1 2 Schmid et al. 2020 , Section:Crustal Structure at the ELSC
  21. ↑ Schmid et al. 2020 , Sections:Abstract, 6 Conclusions
  22. 1 2 Baxter et al. 2020 , Figure 1, Section:Introduction
  23. ↑ Baxter et al. 2020 , Section:4.7. Implications for Microplate Boundaries
  24. ↑ Jegen et al. 2023 , Section:Comparison to Previous Work
  25. ↑ Jegen et al. 2023 , Section:7 Conclusions
  26. ↑ "NOAA Vents Program expeditions: Neovolcanic activity in the NE Lau Basin". NOAA. 2010-05-10. Retrieved 24 December 2012.
  27. ↑ Tian, F; Wang, K; Xie, G; Sun, W (2023). "The formation of explosive volcanos at the circum-Pacific convergent margin during the last century". Journal of Oceanology and Limnology. 41 (1): 75–83. Bibcode:2023JOL....41...75T. doi:10.1007/s00343-022-2276-x. S2CID   254669697.
  28. ↑ Escrig et al. 2009 , Section:5 Conclusion
  29. ↑ Baxter et al. 2020 , 2.3. Assigning CMTs to Lineaments
  30. 1 2 3 4 5 Baxter et al. 2020 , Figure 6, Figure 7: Section:3. Results
  31. 1 2 3 Baxter et al. 2020 , Figure 8, Figure 9a,9b: Section:3. Results
  32. 1 2 3 Baxter et al. 2020 , Figure 10, Figure 9c,9d: Section:3. Results
  33. 1 2 3 Baxter et al. 2020 , Figure 11, Figure 9e,9f: Section:3. Results
Sources

19°S176°W / 19°S 176°W / -19; -176

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.