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Tonga Trench

March 11, 2023

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.

The Tonga Trench constitutes the northern half of the Tonga-Kermadec subduction system, which extends 2,550 km (1,580 mi) between New Zealand and Tonga.[1]

Horizon Deep

 
RV Horizon (1948), used as Auxiliary Fleet Tug USS ATA-180

The deepest point of the Tonga Trench, the Horizon Deep at 23°15′30″S 174°43′36″W / 23.25833°S 174.726667°W / -23.25833; -174.726667, is 10,800 ± 10 m (35,433 ± 33 ft) deep, making it the deepest point in the Southern Hemisphere and the second deepest on Earth after the Challenger Deep in the Mariana Trench. It is named for the research vessel Horizon of the Scripps Institution of Oceanography, the crew of which found the deep in December 1952.[2]

As one of the deepest hadal trenches, the sediment of the Horizon Deep harbours a community of roundworms. A 2016 study found that the abundance of individuals in this community is six times greater than it is at a site on the trench edge approximately 6,250 m (20,510 ft)) near the deep and that the difference in biomass between these locations is even bigger. Species diversity, on the other hand, is twice as big on the trench slope, probably because of a small number of opportunistic species in the trench.[3] Figures for abundance and biomass are similar for the deeps of the Mariana Trench but considerably lower in the Peru–Chile Trench.[4]

Crewed descent

 
Deep Submersible Support Vessel DSSV Pressure Drop and DSV Limiting Factor at its stern

The Tonga Trench and the operating area was surveyed by the support ship, the Deep Submersible Support Vessel DSSV Pressure Drop, with a Kongsberg SIMRAD EM124 multibeam echosounder system. The gathered data will be donated to the GEBCO Seabed 2030 initiative.[5][6] The dive was part of the Five Deeps Expedition.[7] The objective of this expedition is to thoroughly map and visit the deepest points of all five of the world's oceans by the end of September 2019.[7]

As part of the Five Deeps expedition, Sirena Deep, itself 5,750 km (3,570 mi) away from Horizon Deep, was visited by Victor Vescovo on the first crewed descent to the bottom of the Sirena Deep on 5 June 2019 (in the Deep-Submergence Vehicle DSV Limiting Factor, a Triton 36000/2 model submersible) and measured a depth of 10,823 m (35,509 ft) ±10 m (33 ft) by direct CTD pressure measurements.[8] This descent and direct depth measurement of Sirena Deep occurred a month after descending four times to the bottom of the Challenger Deep, which is also approximately 6,000 km away from the Tonga Trench.

Geology

Tonga-Kermadec arc system

The region between the Tonga trench and the Lau back-arc basin, the Tonga-Kermadec Ridge, moves independently from the Australian and Pacific plates and is subdivided into several small plates, the Tonga, Kermadec, and Niuafo'ou plates. The Tonga Plate is facing the Tonga Trench.[9]

The Tonga Trench-Arc system is an extension-dominated, non-accretionary convergent margin. The Pacific Plate is being subducted westward in the trench. The convergence rate has been estimated to 15 cm/year (5.9 in/year) but GPS measurements in the northern trench indicate a convergence rate of 24 cm/year (9.4 in/year) there.[10] This is the fastest plate velocity on Earth, a result is the earth's most active zone of mantle seismicity.[11] Subduction rates decrease southward along the Tonga-Kermadec Arc, from 24 cm/year (9.4 in/year) in the north to 6 cm/year (2.4 in/year) in the south and also become more oblique southward. The high rate in the Tonga Trench is largely due to a reduction in extension in the Lau Basin.[12] Crustal extension in the Miocene Lau-Colville Ridge began at 6 Ma which initiated the opening of the Lau Basin-Havre Trough. This extension has propagated southward since and has developed into a spreading centre in the Lau Basin in front of the Tonga Trench. New crust is thus produced in front of the Tonga-Kermadec trenches while old crust is consumed behind it in the Tonga Trench.[13]

Pacific slab avalanche

While most of the large earthquakes occur at the contact zone between both tectonic plates, related to the friction during subduction, others are produced in the Pacific Plate due to its bending.[14] The Pacific crust that descends into the trench is old, 100–140 Ma, and relatively cold and it can therefore store a lot of elastic energy. As it reaches deep into the mantle, more than 600 km (370 mi), and encounters barriers, it is being contorted, which produces deep mantle earthquakes.[15]

About 500 km (310 mi) beneath the North Fiji Basin, a detached segment of the subducted Australian Plate has collided with the subducted Pacific Plate which produces many large-scale earthquakes. The subducted Pacific Plate is also being deformed in the collision as both slabs settle on the 660 km discontinuity. This slab collision probably occurred 5–4 Ma when the Lau Basin started to open.[16]

Oceanic trenches are important sites for the formation of what will become continental crust and for recycling of material back into the mantle. Along the Tonga Trench mantle-derived melts are transferred to the island arc systems, and abyssal oceanic sediments and fragments of oceanic crust are collected.[10]

Tonga Trench–Lau Basin transition

 
At its northern end the Tonga Trench bends west into the microplates, interconnected spreading centres, and deformation zones of the Lau Basin. But the Tonga Trench also has a continuation in the inactive Vitiaz Trench (north of map area) with which it formed a single continuous trench before the opening of the North Fiji Basin (west of map area).
The Capricorn Seamount (centre right) is sitting on the eastern slope of the trench.

The northern end of the Tonga Trench (at 15°10'S) is probably linked to the Fiji Fracture Zone, trending east–west north of Fiji, but the trench ends in a complex transition from subduction to a strike-slip motion and seismicity patterns indicate a presence of a c.  100 km (62 mi)–broad transition zone rather than a simple transform fault. In or near this zone there is a ridge-ridge-ridge triple junction (15°37′S 174°52′W / 15.617°S 174.867°W / -15.617; -174.867), known as the King's or Mangatolu Triple Junction (MTJ), characterised by deformation and recent and intense volcanism (see for example Home Reef). The Tofua volcanic arc on the northern Tonga Ridge extends to less than 40 km (25 mi) of the trench's northern end.[17]

Just north of the MTJ lies the south–north-trending Northeast Lau Spreading Centre (NELSC) which intercepts the northern end of the Tonga Trench and is one of three major spreading centres in the northern Lau Basin (together with the Futuna Spreading Centre and Northwest Lau Spreading Centre.) The maximum spreading rate in the NELSC is 94 mm/a (3.7 in/year) but spreading decreases to zero at either end of the spreading centre. The total spreading rate between the Tongan and Australian plates, however, is 157 mm/a (6.2 in/year), and additional microplates and/or deformations zones must thus exist. The NELSC probably receives magmatic contributions from the Samoa hotspot.[18] The NELSC has a morphology which is similar to those of slow-spreading ridges with many closely packed ridges and troughs reaches. Where it meets the trench, a ridge-transform-transform boundary is developing between the Tonga Ridge, the Pacific Plate, and the Australian Plate.[17]

North-east of the 60° bend in the Tonga Trench the Pacific seafloor is full of parallel lineations. These have been interpreted as remnants of an extinct, east-to-west-trending spreading centre on the Pacific Plate, much older than the Tonga Trench.[17]

Louisville Seamount Chain collision

At its southern end (c. 26°S) the Tonga Trench is colliding with the Louisville Seamount Chain, a chain of guyots and seamounts on the Pacific Plate roughly parallel to the Hawaiian–Emperor seamount chain in the northern pacific. The Louisville collision zone migrates southward at a rate of 18 cm/year (7.1 in/year) because of the difference in the oblique angle between the Louisville Ridge relative the direction of convergence. In the eastern Lau Basin spreading centres are propagating southward at roughly the same rate. The collision zone also offsets the Tonga Trench to the north-west relative to the Kermadec Trench by c. 50 km (31 mi).[10] The subducting Louisville Ridge has caused a significant amount of erosion on the outer edge of the southern Tonga fore-arc and has probably accelerated subsidence in the Tonga Trench, a process which makes the Tonga Trench the second deepest trench on Earth and considerably deeper than the Kermadec Trench.[19]

The oldest and westernmost of the Louisville seamounts, the Osbourn Seamount, is sitting on the edge of the trench and its former flat top is currently tilting towards the trench.[20] West of the Osbourn Seamount a broad zone of faulted blocks shallows the trench by 3,000 m (9,800 ft) while the adjacent fore-arc is elevated by c. 300 m (980 ft) and covered by canyons.[21]

The Louisville collision zone correlates with a zone of seismic quiescence along the Tonga-Kermadec Trench known as the "Louisville Gap". This gap in seismicity indicates that subducting seamounts inhibit or even prevent seismicity at subduction zones, perhaps by increasing intervals between earthquakes, but the mechanism behind this process is poorly understood.[22]

Geochemical evidence suggests that the Louisville chain has been subducting under the Tonga-Kermadec Arc since 4 Ma. Seismic studies have identified a southward, along-arc mantle flow that indicate that Pacific mantle is being replaced by Indo-Australian mantle west of the Tonga Trench.[23]

Osbourn Trough

The Osbourn Trough, located at 25.5°S just north of the Louisville Ridge collision zone, is a 900 km (560 mi)-long extinct spreading ridge located midway between two large oceanic plateaux north and south of the Tonga Trench respectively: Manihiki 1,750 km (1,090 mi) to the north and Hikurangi 1,550 km (960 mi) to the south. These plateaux once formed part of the 100×10^6 km3 (3.5×1018 cu ft) Ontong Java-Manihiki-Hikurangi large igneous province (LIP). Spreading between the plateaux ceased when Hikurangi collided with the Chatham Rise east of New Zealand at 86 Ma.[24] The western end of the Osbourn Trough is bounded by the Tonga Trench and its eastern by the Wishbone–East Manihiki Scarp. In between the Osbourn Trough is divided into three segments separated by dextral offsets. Near the Tonga Trench the bathymetry of these structures is affected by the bending of the Pacific Plate.[25]

Capricorn Seamount

Main article: Capricorn Seamount

The Capricorn Seamount is a guyot located on the eastern wall of the northern Tonga Trench (see map above). It is a large guyot, 100 km (62 mi) wide at its base with a small part of its reefal or lagoonal summit reaching 440 m (1,440 ft) below sea level. The bending of the Pacific Plate at the Tonga Trench is currently slicing it like a loaf of bread: inside the guyot a north–south-trending horst and graben system is developing parallel to the trench; the western slope of the guyot has reached the 9,000 m (30,000 ft)-deep trench and has started to fill it; the summit of the guyot is tilted 1.7° towards the trench and its centre is only 45 km (28 mi) from the trench axis.[26] The Capricorn Seamount is expected to be completely consumed by the trench within 500,000 years.[27]

Apollo 13

When the Apollo 13 mission was aborted in 1970 following an explosion in an oxygen tank, as the spacecraft returned to Earth, its radioisotope thermoelectric generator broke up in the atmosphere, and the heat source plunged into an area of the Pacific Ocean that is either in or near the Tonga Trench. However, no release of 238Pu (half-life of 87.7 years) used as heat source in the thermoelectric generator could be detected by atmospheric and oceanic monitoring.[28]

See also

References

Notes

  1. ^ Smith & Price 2006, p. 316
  2. ^ "GEBCO Gazetteer of Undersea Feature Names". GEBCO. 26 April 2015. Retrieved 9 April 2017.
  3. ^ Leduc et al. 2016, Abstract
  4. ^ Leduc et al. 2016, p. 8
  5. ^ The Nippon Foundation-GEBCO Seabed 2030 Project
  6. ^ "Major partnership announced between The Nippon Foundation-GEBCO Seabed 2030 Project and The Five Deeps Expedition". gebco.net. 11 March 2019. Retrieved June 19, 2019.
  7. ^ a b "The Five Deeps Expedition: Home". fivedeeps.com. Retrieved January 9, 2019.
  8. ^ "CONFIRMED: Horizon Deep Second Deepest Point on the Planet" (PDF). fivedeeps.com. Retrieved June 19, 2019.
  9. ^ Bird 2003, Tonga Plate (TO), Kermadec Plate (KE), and Niuafo’ou Plate (NI), p. 28
  10. ^ a b c Wright et al. 2000, Geologic setting, pp. 490–491
  11. ^ Bevis et al. 1995, Abstract
  12. ^ Smith et al. 2003, p. 100
  13. ^ Smith et al. 2003, p. 114
  14. ^ Garcia-Castellanos, Torne & Fernandez 2000
  15. ^ Bevis et al. 1995, p. 251
  16. ^ Richards, Holm & Barber 2011, Abstract
  17. ^ a b c Wright et al. 2000, Map 1: A strike-slip boundary and the termination of the Trench, pp. 499–502
  18. ^ German et al. 2006, pp. 3–4
  19. ^ Contreras‐Reyes et al. 2011, Fig. 1, p. 2; [6], p. 2
  20. ^ Contreras‐Reyes et al. 2011, 4:12; 14:38
  21. ^ Stratford et al. 2015, p. 6, Geological setting
  22. ^ Peirce & Watts 2010, The Louisville Ridge–Tonga Trench collision, pp. 9–11; Fig. 3, p. 10
  23. ^ Timm et al. 2013, p. 2
  24. ^ Worthington et al. 2006, Abstract
  25. ^ Worthington et al. 2006, pp. 686–687
  26. ^ Hill & Glasby 1996, Abstract; Morphology and Seismic Evidence, pp. 21–24
  27. ^ Hill & Glasby 1996, p. 20
  28. ^ Furlong & Wahlquist 1999, p. 27

Sources

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  • Bird, P. (2003). "An updated digital model of plate boundaries". Geochemistry, Geophysics, Geosystems. 4 (3): 1027. Bibcode:2003GGG.....4.1027B. CiteSeerX 10.1.1.695.1640. doi:10.1029/2001GC000252. S2CID 9127133.
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  • Garcia-Castellanos, D.; Torne, M.; Fernandez, M. (2000). "Slab pull effects from a flexural analysis of the Tonga and Kermadec Trenches (Pacific Plate)" (PDF). Geophysical Journal International. 141 (2): 479–484. Bibcode:2000GeoJI.141..479G. doi:10.1046/j.1365-246x.2000.00096.x. Retrieved 9 April 2017.
  • German, C. R.; Baker, E. T.; Connelly, D. P.; Lupton, J. E.; Resing, J.; Prien, R. D.; Walker, S. L.; Edmonds, H. N.; Langmuir, C. H. (2006). "Hydrothermal exploration of the Fonualei Rift and spreading center and the Northeast Lau spreading center". Geochemistry, Geophysics, Geosystems. 7 (11): Q11022. Bibcode:2006GGG.....711022G. CiteSeerX 10.1.1.846.412. doi:10.1029/2006GC001324. S2CID 59394719.
  • Furlong, R. R.; Wahlquist, E. J. (1999). "US space missions using radioisotope power systems" (PDF). Nuclear News. 42: 26–35. Retrieved 9 April 2017.
  • Hill, P. J.; Glasby, G. P. (1996). "Capricorn Seamount – geology and geophysics of a subducting guyot". In Meylan, M. A.; Glasby, G. P. (eds.). (PDF). SOPAC Technical Bulletin (Report). Vol. 10. pp. 17–29. Archived from the original (PDF) on 2017-04-15. Retrieved 14 April 2017.
  • Leduc, D.; Rowden, A. A.; Glud, R. N.; Wenzhöfer, F.; Kitazato, H.; Clark, M. R. (2016). "Comparison between infaunal communities of the deep floor and edge of the Tonga Trench: Possible effects of differences in organic matter supply" (PDF). Deep Sea Research Part I: Oceanographic Research Papers. 116: 264–275. Bibcode:2016DSRI..116..264L. doi:10.1016/j.dsr.2015.11.003. Retrieved 17 April 2017.
  • Peirce, C.; Watts, T. (2010). Post-Doctoral Researchers in Marine Geophysics Further Particulars (Report). Durham University/University of Oxford. CiteSeerX 10.1.1.619.2915.
  • Richards, S.; Holm, R.; Barber, G. (2011). "When slabs collide: A tectonic assessment of deep earthquakes in the Tonga-Vanuatu region". Geology. 39 (8): 787–790. Bibcode:2011Geo....39..787R. doi:10.1130/G31937.1. S2CID 140706943. Retrieved 24 December 2016.
  • Smith, I. E.; Price, R. C. (2006). "The Tonga–Kermadec arc and Havre–Lau back-arc system: their role in the development of tectonic and magmatic models for the western Pacific". Journal of Volcanology and Geothermal Research. 156 (3): 315–331. Bibcode:2006JVGR..156..315S. doi:10.1016/j.jvolgeores.2006.03.006. Retrieved 19 March 2017.
  • Smith, I. E.; Worthington, T. J.; Stewart, R. B.; Price, R. C.; Gamble, J. A. (2003). "Felsic volcanism in the Kermadec arc, SW Pacific: crustal recycling in an oceanic setting". Geological Society, London, Special Publications. 219 (1): 99–118. Bibcode:2003GSLSP.219...99S. CiteSeerX 10.1.1.972.7814. doi:10.1144/GSL.SP.2003.219.01.05. S2CID 140676351.
  • Stratford, W.; Peirce, C.; Paulatto, M.; Funnell, M.; Watts, A. B.; Grevemeyer, I.; Bassett, D. (2015). (PDF). Geophysical Journal International. 200 (3): 1503–1522. Bibcode:2015GeoJI.200.1503S. doi:10.1093/gji/ggu475. Archived from the original (PDF) on 26 October 2015. Retrieved 16 April 2017.
  • Timm, C.; Bassett, D.; Graham, I. J.; Leybourne, M. I.; De Ronde, C. E.; Woodhead, J.; Layton-Matthews, D.; Watts, A. B. (2013). "Louisville seamount subduction and its implication on mantle flow beneath the central Tonga–Kermadec arc". Nature Communications. 4: 1720. Bibcode:2013NatCo...4.1720T. doi:10.1038/ncomms2702. PMID 23591887.
  • Worthington, Tim J.; Hekinian, Roger; Stoffers, Peter; Kuhn, Thomas; Hauff, Folkmar (30 May 2006). "Osbourn Trough: Structure, geochemistry and implications of a mid-Cretaceous paleospreading ridge in the South Pacific". Earth and Planetary Science Letters. 245 (3–4): 685–701. Bibcode:2006E&PSL.245..685W. doi:10.1016/j.epsl.2006.03.018. Retrieved 17 December 2016.
  • Wright, D. J.; Bloomer, S. H.; MacLeod, C. J.; Taylor, B.; Goodliffe, A. M. (2000). "Bathymetry of the Tonga Trench and Forearc: A Map Series" (PDF). Marine Geophysical Researches. 21 (5): 489–512. Bibcode:2000MarGR..21..489W. doi:10.1023/A:1026514914220. S2CID 6072675. Retrieved 9 April 2017.

Coordinates: 22°56′41″S 174°43′59″W / 22.94472°S 174.73306°W / -22.94472; -174.73306

March 11, 2023
tonga, trench, oceanic, trench, located, southwestern, pacific, ocean, deepest, trench, southern, hemisphere, second, deepest, earth, after, mariana, trench, fastest, plate, tectonic, velocity, earth, occurring, this, location, pacific, plate, being, subducted. 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 The Tonga Trench constitutes the northern half of the Tonga Kermadec subduction system which extends 2 550 km 1 580 mi between New Zealand and Tonga 1 Contents 1 Horizon Deep 1 1 Crewed descent 2 Geology 2 1 Tonga Kermadec arc system 2 1 1 Pacific slab avalanche 2 2 Tonga Trench Lau Basin transition 2 3 Louisville Seamount Chain collision 2 4 Osbourn Trough 2 5 Capricorn Seamount 3 Apollo 13 4 See also 5 References 5 1 Notes 5 2 SourcesHorizon Deep Edit RV Horizon 1948 used as Auxiliary Fleet Tug USS ATA 180 The deepest point of the Tonga Trench the Horizon Deep at 23 15 30 S 174 43 36 W 23 25833 S 174 726667 W 23 25833 174 726667 is 10 800 10 m 35 433 33 ft deep making it the deepest point in the Southern Hemisphere and the second deepest on Earth after the Challenger Deep in the Mariana Trench It is named for the research vessel Horizon of the Scripps Institution of Oceanography the crew of which found the deep in December 1952 2 As one of the deepest hadal trenches the sediment of the Horizon Deep harbours a community of roundworms A 2016 study found that the abundance of individuals in this community is six times greater than it is at a site on the trench edge approximately 6 250 m 20 510 ft near the deep and that the difference in biomass between these locations is even bigger Species diversity on the other hand is twice as big on the trench slope probably because of a small number of opportunistic species in the trench 3 Figures for abundance and biomass are similar for the deeps of the Mariana Trench but considerably lower in the Peru Chile Trench 4 Crewed descent Edit Deep Submersible Support Vessel DSSV Pressure Drop and DSV Limiting Factor at its stern The Tonga Trench and the operating area was surveyed by the support ship the Deep Submersible Support Vessel DSSV Pressure Drop with a Kongsberg SIMRAD EM124 multibeam echosounder system The gathered data will be donated to the GEBCO Seabed 2030 initiative 5 6 The dive was part of the Five Deeps Expedition 7 The objective of this expedition is to thoroughly map and visit the deepest points of all five of the world s oceans by the end of September 2019 7 As part of the Five Deeps expedition Sirena Deep itself 5 750 km 3 570 mi away from Horizon Deep was visited by Victor Vescovo on the first crewed descent to the bottom of the Sirena Deep on 5 June 2019 in the Deep Submergence Vehicle DSV Limiting Factor a Triton 36000 2 model submersible and measured a depth of 10 823 m 35 509 ft 10 m 33 ft by direct CTD pressure measurements 8 This descent and direct depth measurement of Sirena Deep occurred a month after descending four times to the bottom of the Challenger Deep which is also approximately 6 000 km away from the Tonga Trench Geology EditTonga Kermadec arc system Edit The region between the Tonga trench and the Lau back arc basin the Tonga Kermadec Ridge moves independently from the Australian and Pacific plates and is subdivided into several small plates the Tonga Kermadec and Niuafo ou plates The Tonga Plate is facing the Tonga Trench 9 The Tonga Trench Arc system is an extension dominated non accretionary convergent margin The Pacific Plate is being subducted westward in the trench The convergence rate has been estimated to 15 cm year 5 9 in year but GPS measurements in the northern trench indicate a convergence rate of 24 cm year 9 4 in year there 10 This is the fastest plate velocity on Earth a result is the earth s most active zone of mantle seismicity 11 Subduction rates decrease southward along the Tonga Kermadec Arc from 24 cm year 9 4 in year in the north to 6 cm year 2 4 in year in the south and also become more oblique southward The high rate in the Tonga Trench is largely due to a reduction in extension in the Lau Basin 12 Crustal extension in the Miocene Lau Colville Ridge began at 6 Ma which initiated the opening of the Lau Basin Havre Trough This extension has propagated southward since and has developed into a spreading centre in the Lau Basin in front of the Tonga Trench New crust is thus produced in front of the Tonga Kermadec trenches while old crust is consumed behind it in the Tonga Trench 13 Pacific slab avalanche Edit While most of the large earthquakes occur at the contact zone between both tectonic plates related to the friction during subduction others are produced in the Pacific Plate due to its bending 14 The Pacific crust that descends into the trench is old 100 140 Ma and relatively cold and it can therefore store a lot of elastic energy As it reaches deep into the mantle more than 600 km 370 mi and encounters barriers it is being contorted which produces deep mantle earthquakes 15 About 500 km 310 mi beneath the North Fiji Basin a detached segment of the subducted Australian Plate has collided with the subducted Pacific Plate which produces many large scale earthquakes The subducted Pacific Plate is also being deformed in the collision as both slabs settle on the 660 km discontinuity This slab collision probably occurred 5 4 Ma when the Lau Basin started to open 16 Oceanic trenches are important sites for the formation of what will become continental crust and for recycling of material back into the mantle Along the Tonga Trench mantle derived melts are transferred to the island arc systems and abyssal oceanic sediments and fragments of oceanic crust are collected 10 Tonga Trench Lau Basin transition Edit At its northern end the Tonga Trench bends west into the microplates interconnected spreading centres and deformation zones of the Lau Basin But the Tonga Trench also has a continuation in the inactive Vitiaz Trench north of map area with which it formed a single continuous trench before the opening of the North Fiji Basin west of map area The Capricorn Seamount centre right is sitting on the eastern slope of the trench The northern end of the Tonga Trench at 15 10 S is probably linked to the Fiji Fracture Zone trending east west north of Fiji but the trench ends in a complex transition from subduction to a strike slip motion and seismicity patterns indicate a presence of a c 100 km 62 mi broad transition zone rather than a simple transform fault In or near this zone there is a ridge ridge ridge triple junction 15 37 S 174 52 W 15 617 S 174 867 W 15 617 174 867 known as the King s or Mangatolu Triple Junction MTJ characterised by deformation and recent and intense volcanism see for example Home Reef The Tofua volcanic arc on the northern Tonga Ridge extends to less than 40 km 25 mi of the trench s northern end 17 Just north of the MTJ lies the south north trending Northeast Lau Spreading Centre NELSC which intercepts the northern end of the Tonga Trench and is one of three major spreading centres in the northern Lau Basin together with the Futuna Spreading Centre and Northwest Lau Spreading Centre The maximum spreading rate in the NELSC is 94 mm a 3 7 in year but spreading decreases to zero at either end of the spreading centre The total spreading rate between the Tongan and Australian plates however is 157 mm a 6 2 in year and additional microplates and or deformations zones must thus exist The NELSC probably receives magmatic contributions from the Samoa hotspot 18 The NELSC has a morphology which is similar to those of slow spreading ridges with many closely packed ridges and troughs reaches Where it meets the trench a ridge transform transform boundary is developing between the Tonga Ridge the Pacific Plate and the Australian Plate 17 North east of the 60 bend in the Tonga Trench the Pacific seafloor is full of parallel lineations These have been interpreted as remnants of an extinct east to west trending spreading centre on the Pacific Plate much older than the Tonga Trench 17 Louisville Seamount Chain collision Edit At its southern end c 26 S the Tonga Trench is colliding with the Louisville Seamount Chain a chain of guyots and seamounts on the Pacific Plate roughly parallel to the Hawaiian Emperor seamount chain in the northern pacific The Louisville collision zone migrates southward at a rate of 18 cm year 7 1 in year because of the difference in the oblique angle between the Louisville Ridge relative the direction of convergence In the eastern Lau Basin spreading centres are propagating southward at roughly the same rate The collision zone also offsets the Tonga Trench to the north west relative to the Kermadec Trench by c 50 km 31 mi 10 The subducting Louisville Ridge has caused a significant amount of erosion on the outer edge of the southern Tonga fore arc and has probably accelerated subsidence in the Tonga Trench a process which makes the Tonga Trench the second deepest trench on Earth and considerably deeper than the Kermadec Trench 19 The oldest and westernmost of the Louisville seamounts the Osbourn Seamount is sitting on the edge of the trench and its former flat top is currently tilting towards the trench 20 West of the Osbourn Seamount a broad zone of faulted blocks shallows the trench by 3 000 m 9 800 ft while the adjacent fore arc is elevated by c 300 m 980 ft and covered by canyons 21 The Louisville collision zone correlates with a zone of seismic quiescence along the Tonga Kermadec Trench known as the Louisville Gap This gap in seismicity indicates that subducting seamounts inhibit or even prevent seismicity at subduction zones perhaps by increasing intervals between earthquakes but the mechanism behind this process is poorly understood 22 Geochemical evidence suggests that the Louisville chain has been subducting under the Tonga Kermadec Arc since 4 Ma Seismic studies have identified a southward along arc mantle flow that indicate that Pacific mantle is being replaced by Indo Australian mantle west of the Tonga Trench 23 Osbourn Trough Edit The Osbourn Trough located at 25 5 S just north of the Louisville Ridge collision zone is a 900 km 560 mi long extinct spreading ridge located midway between two large oceanic plateaux north and south of the Tonga Trench respectively Manihiki 1 750 km 1 090 mi to the north and Hikurangi 1 550 km 960 mi to the south These plateaux once formed part of the 100 10 6 km3 3 5 1018 cu ft Ontong Java Manihiki Hikurangi large igneous province LIP Spreading between the plateaux ceased when Hikurangi collided with the Chatham Rise east of New Zealand at 86 Ma 24 The western end of the Osbourn Trough is bounded by the Tonga Trench and its eastern by the Wishbone East Manihiki Scarp In between the Osbourn Trough is divided into three segments separated by dextral offsets Near the Tonga Trench the bathymetry of these structures is affected by the bending of the Pacific Plate 25 Capricorn Seamount Edit Main article Capricorn Seamount The Capricorn Seamount is a guyot located on the eastern wall of the northern Tonga Trench see map above It is a large guyot 100 km 62 mi wide at its base with a small part of its reefal or lagoonal summit reaching 440 m 1 440 ft below sea level The bending of the Pacific Plate at the Tonga Trench is currently slicing it like a loaf of bread inside the guyot a north south trending horst and graben system is developing parallel to the trench the western slope of the guyot has reached the 9 000 m 30 000 ft deep trench and has started to fill it the summit of the guyot is tilted 1 7 towards the trench and its centre is only 45 km 28 mi from the trench axis 26 The Capricorn Seamount is expected to be completely consumed by the trench within 500 000 years 27 Apollo 13 EditWhen the Apollo 13 mission was aborted in 1970 following an explosion in an oxygen tank as the spacecraft returned to Earth its radioisotope thermoelectric generator broke up in the atmosphere and the heat source plunged into an area of the Pacific Ocean that is either in or near the Tonga Trench However no release of 238Pu half life of 87 7 years used as heat source in the thermoelectric generator could be detected by atmospheric and oceanic monitoring 28 See also Edit Oceans portalGeology of the Pacific Ocean List of submarine topographical featuresReferences EditNotes Edit Smith amp Price 2006 p 316 GEBCO Gazetteer of Undersea Feature Names GEBCO 26 April 2015 Retrieved 9 April 2017 Leduc et al 2016 Abstract Leduc et al 2016 p 8 The Nippon Foundation GEBCO Seabed 2030 Project Major partnership announced between The Nippon Foundation GEBCO Seabed 2030 Project and The Five Deeps Expedition gebco net 11 March 2019 Retrieved June 19 2019 a b The Five Deeps Expedition Home fivedeeps com Retrieved January 9 2019 CONFIRMED Horizon Deep Second Deepest Point on the Planet PDF fivedeeps com Retrieved June 19 2019 Bird 2003 Tonga Plate TO Kermadec Plate KE and Niuafo ou Plate NI p 28 a b c Wright et al 2000 Geologic setting pp 490 491 Bevis et al 1995 Abstract Smith et al 2003 p 100 Smith et al 2003 p 114 Garcia Castellanos Torne amp Fernandez 2000 Bevis et al 1995 p 251 Richards Holm amp Barber 2011 Abstract a b c Wright et al 2000 Map 1 A strike slip boundary and the termination of the Trench pp 499 502 German et al 2006 pp 3 4 Contreras Reyes et al 2011 Fig 1 p 2 6 p 2 Contreras Reyes et al 2011 4 12 14 38 Stratford et al 2015 p 6 Geological setting Peirce amp Watts 2010 The Louisville Ridge Tonga Trench collision pp 9 11 Fig 3 p 10 Timm et al 2013 p 2 Worthington et al 2006 Abstract Worthington et al 2006 pp 686 687 Hill amp Glasby 1996 Abstract Morphology and Seismic Evidence pp 21 24 Hill amp Glasby 1996 p 20 Furlong amp Wahlquist 1999 p 27 Sources Edit Bevis M Taylor F W Schutz B E Recy J Isacks B L Helu S Singh R Kendrick E Stowell J Taylor B Calmant S 1995 Geodetic observations of very rapid convergence and back arc extension at the Tonga arc Nature 374 6519 249 251 Bibcode 1995Natur 374 249B doi 10 1038 374249a0 S2CID 4331835 Retrieved 9 April 2017 Bird P 2003 An updated digital model of plate boundaries Geochemistry Geophysics Geosystems 4 3 1027 Bibcode 2003GGG 4 1027B CiteSeerX 10 1 1 695 1640 doi 10 1029 2001GC000252 S2CID 9127133 Contreras Reyes E Grevemeyer I Watts A B Flueh E R Peirce C Moeller S Papenberg C 2011 Deep seismic structure of the Tonga subduction zone Implications for mantle hydration tectonic erosion and arc magmatism Journal of Geophysical Research Solid Earth 116 B10 B10103 Bibcode 2011JGRB 11610103C CiteSeerX 10 1 1 725 500 doi 10 1029 2011JB008434 Garcia Castellanos D Torne M Fernandez M 2000 Slab pull effects from a flexural analysis of the Tonga and Kermadec Trenches Pacific Plate PDF Geophysical Journal International 141 2 479 484 Bibcode 2000GeoJI 141 479G doi 10 1046 j 1365 246x 2000 00096 x Retrieved 9 April 2017 German C R Baker E T Connelly D P Lupton J E Resing J Prien R D Walker S L Edmonds H N Langmuir C H 2006 Hydrothermal exploration of the Fonualei Rift and spreading center and the Northeast Lau spreading center Geochemistry Geophysics Geosystems 7 11 Q11022 Bibcode 2006GGG 711022G CiteSeerX 10 1 1 846 412 doi 10 1029 2006GC001324 S2CID 59394719 Furlong R R Wahlquist E J 1999 US space missions using radioisotope power systems PDF Nuclear News 42 26 35 Retrieved 9 April 2017 Hill P J Glasby G P 1996 Capricorn Seamount geology and geophysics of a subducting guyot In Meylan M A Glasby G P eds Manihiki Plateau Machias and Capricorn Seamounts Niue and Tofua Trough Results of Tui Cruises PDF SOPAC Technical Bulletin Report Vol 10 pp 17 29 Archived from the original PDF on 2017 04 15 Retrieved 14 April 2017 Leduc D Rowden A A Glud R N Wenzhofer F Kitazato H Clark M R 2016 Comparison between infaunal communities of the deep floor and edge of the Tonga Trench Possible effects of differences in organic matter supply PDF Deep Sea Research Part I Oceanographic Research Papers 116 264 275 Bibcode 2016DSRI 116 264L doi 10 1016 j dsr 2015 11 003 Retrieved 17 April 2017 Peirce C Watts T 2010 Post Doctoral Researchers in Marine Geophysics Further Particulars Report Durham University University of Oxford CiteSeerX 10 1 1 619 2915 Richards S Holm R Barber G 2011 When slabs collide A tectonic assessment of deep earthquakes in the Tonga Vanuatu region Geology 39 8 787 790 Bibcode 2011Geo 39 787R doi 10 1130 G31937 1 S2CID 140706943 Retrieved 24 December 2016 Smith I E Price R C 2006 The Tonga Kermadec arc and Havre Lau back arc system their role in the development of tectonic and magmatic models for the western Pacific Journal of Volcanology and Geothermal Research 156 3 315 331 Bibcode 2006JVGR 156 315S doi 10 1016 j jvolgeores 2006 03 006 Retrieved 19 March 2017 Smith I E Worthington T J Stewart R B Price R C Gamble J A 2003 Felsic volcanism in the Kermadec arc SW Pacific crustal recycling in an oceanic setting Geological Society London Special Publications 219 1 99 118 Bibcode 2003GSLSP 219 99S CiteSeerX 10 1 1 972 7814 doi 10 1144 GSL SP 2003 219 01 05 S2CID 140676351 Stratford W Peirce C Paulatto M Funnell M Watts A B Grevemeyer I Bassett D 2015 Seismic velocity structure and deformation due to the collision of the Louisville Ridge with the Tonga Kermadec Trench PDF Geophysical Journal International 200 3 1503 1522 Bibcode 2015GeoJI 200 1503S doi 10 1093 gji ggu475 Archived from the original PDF on 26 October 2015 Retrieved 16 April 2017 Timm C Bassett D Graham I J Leybourne M I De Ronde C E Woodhead J Layton Matthews D Watts A B 2013 Louisville seamount subduction and its implication on mantle flow beneath the central Tonga Kermadec arc Nature Communications 4 1720 Bibcode 2013NatCo 4 1720T doi 10 1038 ncomms2702 PMID 23591887 Worthington Tim J Hekinian Roger Stoffers Peter Kuhn Thomas Hauff Folkmar 30 May 2006 Osbourn Trough Structure geochemistry and implications of a mid Cretaceous paleospreading ridge in the South Pacific Earth and Planetary Science Letters 245 3 4 685 701 Bibcode 2006E amp PSL 245 685W doi 10 1016 j epsl 2006 03 018 Retrieved 17 December 2016 Wright D J Bloomer S H MacLeod C J Taylor B Goodliffe A M 2000 Bathymetry of the Tonga Trench and Forearc A Map Series PDF Marine Geophysical Researches 21 5 489 512 Bibcode 2000MarGR 21 489W doi 10 1023 A 1026514914220 S2CID 6072675 Retrieved 9 April 2017 Coordinates 22 56 41 S 174 43 59 W 22 94472 S 174 73306 W 22 94472 174 73306 Retrieved from https en wikipedia org w index php title Tonga Trench amp oldid 1137851095 Horizon Deep, wikipedia, wiki, book, books, library,

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