lies in the southern part of the IBM arc system in the Western Pacific. Guam and The Northern Mariana Islands mark its eastern limit.
Location and Bathymetryedit
The Mariana Trough stretches 1300 km from north to south, about the distance from Los Angeles CA to Portland OR, Tokyo, Japan to Seoul, Korea, or London, England to Rome, Italy. The Mariana Trough has roughly the dimensions and areal extent of Japan or California. The Trough is crudely crescent-shaped, opening on the south; it is bounded to the east by the active Mariana arc, to the west by the remnant arc of the West Mariana Ridge (Karig 1972), and to the south by the Challenger Deep, part of the Mariana Trench. It narrows northward until the Mariana arc and West Mariana Ridge meet at about 24°N. It is widest in the middle, at 18°N, where it is about 240 km wide, and narrows to about half this at its southern, open end. Depths in the basin are distributed asymmetrically, being greater adjacent to the West Mariana Ridge than next to the active arc, due to a westward-thinning wedge of volcaniclastic sediments derived from the active arc, and also less thermal buoyancy of the mantle. Where not covered by sediments, the seafloor is deeper and bathymetry more rugged than normal. The most recent, "zero-age" seafloor of the Philippine Sea, including the Mariana Trough, lies at a mean depth of 3200 m compared to normal zero-age seafloor depths of 2500 m (Park, Tamaki & Kobayashi 1990).
Bathymetry of the Mariana Trough and surroundings. The figure was generated by Dr. F. Martinez University of Hawaii using open source software GMT version 4.14 [1] and data bases (Smith and Sandwell and Smith global measured and predicted bathymetry file topo_9.1.img, [2])
Extension styleedit
The extension axis for the Mariana Trough can be subdivided along strike into a southern two-thirds characterized by slow seafloor spreading and a northern third characterized by rifting. From as far north as 19°45'N south to 13°10’N, the spreading ridge has the typical morphology of a slow-spreading ridge, with an axial graben that is sometimes occupied by a central ridge where volcanic activity is concentrated (neovolcanic zone); south of this the ridge more resembles a fast-spreading ridge, probably because magma supply is enhanced by proximity to the arc (Martinez, Fryer & Becker2000). Spreading half-rates in the region between 16° and 18°N are estimated at 1.5 to 2.2 cm/year (Bibee, Shor & Lu 1980). The ridge becomes punctiform north of 18°30', and true seafloor spreading does not occur north of 19°45'N (but see the different conclusion of Yamazaki, Murakami & Saito 1993). Rifting forms a series of amagmatic deeps between 19°45'N and 21°10'N called the 'Central Graben' (Martinez et al.). These basins have low heatflow, lack igneous activity, and are the deepest parts of the Mariana Trough (>5400 m). The deepest part of the Central Graben is also unique among active back-arc basins in exposing mantle peridotites along the extension axis (Stern et al. 1996). Extension north of the Central Graben occurs by combined tectonic and magmatic processes that are distinct from seafloor spreading, in a region known as the Volcano-Tectonic Zone (VTZ; Martinez et al.). The VTZ corresponds with a part of the Mariana Trough where the crust thickens from 6 to 15 km. The southern VTZ is dominated by fissure eruptions associated with a ridge-like feature, ~30 km long, which rises to less than 2800 m water depth and which is similar to the inflated segment at the southern terminus of the spreading ridge. The northern VTZ is dominated by point-source volcanism, with edifices spaced 50–60 km apart alternating with rift basins. There is no volcanic activity along the adjacent arc segment and it appears that the extension axis has captured the arc magma supply between the Kasuga cross-chain at 22°N and Nikko near 23°N, where the extension axis intersects the arc. North of this, incipient rifting is magmatically manifested by unusual, shoshonitic lavas of the Hiyoshi complex, Fukutoku-oka-no-ba (or Sin Iwo Jima), and Iwo Jima (Stern, Fouch & Klemperer 2003). Rifting and spreading are inferred to be propagating northward at a rate of 10 to 40 cm/year (Martinez et al.), so the variations in tectonic and magmatic style seen along-strike north of 18°N provide an example of the sequence of events that occur at any one section across the back-arc basin as the rift evolves from updoming through rifting to true spreading.
Referencesedit
Bibee, L.D.; Shor Jr., G.G.; Lu, R.S. (1980). "Inter-arc spreading in the Mariana Trough". Marine Geology. 35: 183–197. Bibcode:1980MGeol..35..183B. doi:10.1016/0025-3227(80)90030-4.
Karig, D.E. (1972). "Remnant Arcs". Geological Society of America Bulletin. 83 (4): 1057–1068. Bibcode:1972GSAB...83.1057K. doi:10.1130/0016-7606(1972)83[1057:RA]2.0.CO;2. ISSN 0016-7606.
Martinez, F.; Fryer, P.; Baker, N.A.; Yamazaki, T. (1995). "Evolution of Backarc Rifting: Mariana Trough, 20°-24°N". Journal of Geophysical Research: Solid Earth. 100: 3807–3827. Bibcode:1995JGR...100.3807M. doi:10.1029/94JB02466.
Martinez, F.; Fryer, P.; Becker, N. (2000). "Geophysical characteristics of the southern Mariana Trough, 11°50'N-13°40'N". Journal of Geophysical Research: Solid Earth. 105: 16591–16607. Bibcode:2000JGR...10516591M. doi:10.1029/2000JB900117.
Park, C.-H.; Tamaki, K.; Kobayashi, K. (1990). "Age-depth correlation of the Philippine Sea back-arc basins and other marginal basins in the world". Tectonophysics. 181: 351–371. Bibcode:1990Tectp.181..351C. doi:10.1016/0040-1951(90)90028-7.
Stern, R.J.; Bloomer, S.H.; Martinez, F.; Yamazaki, T.; Harrison, T.M. (1996). "The composition of back-arc basin lower crust and upper mantle in the Mariana Trough: A first report". Island Arc. 5 (3): 354–372. doi:10.1111/j.1440-1738.1996.tb00036.x.
Stern, R.J.; Fouch, M.J.; Klemperer, S. (2003). "An Overview of the Izu–Bonin–Mariana Subduction Factory". In J. Eiler; M. Hirschmann (eds.). Inside the Subduction Factory(PDF). Geophysical Monograph. Vol. 138. American Geophysical Union. pp. 175–222. ISBN0-87590-997-3.
Yamazaki, T.; Murakami, F.; Saito, E. (1993). "Mode of seafloor spreading in the northern Mariana Trough". Tectonophysics. 221 (2): 207–221. Bibcode:1993Tectp.221..207Y. doi:10.1016/0040-1951(93)90333-F.
January 01, 1970
mariana, trough, active, back, basin, western, pacific, ocean, stern, fouch, klemperer, 2003, integral, part, bonin, mariana, system, lies, southern, part, system, western, pacific, guam, northern, mariana, islands, mark, eastern, limit, location, bathymetry, . The Mariana Trough is an active back arc basin in the western Pacific Ocean Stern Fouch amp Klemperer 2003 It is an integral part of the Izu Bonin Mariana Arc system The Mariana Trough lies in the southern part of the IBM arc system in the Western Pacific Guam and The Northern Mariana Islands mark its eastern limit Location and Bathymetry editThe Mariana Trough stretches 1300 km from north to south about the distance from Los Angeles CA to Portland OR Tokyo Japan to Seoul Korea or London England to Rome Italy The Mariana Trough has roughly the dimensions and areal extent of Japan or California The Trough is crudely crescent shaped opening on the south it is bounded to the east by the active Mariana arc to the west by the remnant arc of the West Mariana Ridge Karig 1972 and to the south by the Challenger Deep part of the Mariana Trench It narrows northward until the Mariana arc and West Mariana Ridge meet at about 24 N It is widest in the middle at 18 N where it is about 240 km wide and narrows to about half this at its southern open end Depths in the basin are distributed asymmetrically being greater adjacent to the West Mariana Ridge than next to the active arc due to a westward thinning wedge of volcaniclastic sediments derived from the active arc and also less thermal buoyancy of the mantle Where not covered by sediments the seafloor is deeper and bathymetry more rugged than normal The most recent zero age seafloor of the Philippine Sea including the Mariana Trough lies at a mean depth of 3200 m compared to normal zero age seafloor depths of 2500 m Park Tamaki amp Kobayashi 1990 nbsp Bathymetry of the Mariana Trough and surroundings The figure was generated by Dr F Martinez University of Hawaii using open source software GMT version 4 14 1 and data bases Smith and Sandwell and Smith global measured and predicted bathymetry file topo 9 1 img 2 Extension style editThe extension axis for the Mariana Trough can be subdivided along strike into a southern two thirds characterized by slow seafloor spreading and a northern third characterized by rifting From as far north as 19 45 N south to 13 10 N the spreading ridge has the typical morphology of a slow spreading ridge with an axial graben that is sometimes occupied by a central ridge where volcanic activity is concentrated neovolcanic zone south of this the ridge more resembles a fast spreading ridge probably because magma supply is enhanced by proximity to the arc Martinez Fryer amp Becker2000 Spreading half rates in the region between 16 and 18 N are estimated at 1 5 to 2 2 cm year Bibee Shor amp Lu 1980 The ridge becomes punctiform north of 18 30 and true seafloor spreading does not occur north of 19 45 N but see the different conclusion of Yamazaki Murakami amp Saito 1993 Rifting forms a series of amagmatic deeps between 19 45 N and 21 10 N called the Central Graben Martinez et al These basins have low heatflow lack igneous activity and are the deepest parts of the Mariana Trough gt 5400 m The deepest part of the Central Graben is also unique among active back arc basins in exposing mantle peridotites along the extension axis Stern et al 1996 Extension north of the Central Graben occurs by combined tectonic and magmatic processes that are distinct from seafloor spreading in a region known as the Volcano Tectonic Zone VTZ Martinez et al The VTZ corresponds with a part of the Mariana Trough where the crust thickens from 6 to 15 km The southern VTZ is dominated by fissure eruptions associated with a ridge like feature 30 km long which rises to less than 2800 m water depth and which is similar to the inflated segment at the southern terminus of the spreading ridge The northern VTZ is dominated by point source volcanism with edifices spaced 50 60 km apart alternating with rift basins There is no volcanic activity along the adjacent arc segment and it appears that the extension axis has captured the arc magma supply between the Kasuga cross chain at 22 N and Nikko near 23 N where the extension axis intersects the arc North of this incipient rifting is magmatically manifested by unusual shoshonitic lavas of the Hiyoshi complex Fukutoku oka no ba or Sin Iwo Jima and Iwo Jima Stern Fouch amp Klemperer 2003 Rifting and spreading are inferred to be propagating northward at a rate of 10 to 40 cm year Martinez et al so the variations in tectonic and magmatic style seen along strike north of 18 N provide an example of the sequence of events that occur at any one section across the back arc basin as the rift evolves from updoming through rifting to true spreading References editBibee L D Shor Jr G G Lu R S 1980 Inter arc spreading in the Mariana Trough Marine Geology 35 183 197 Bibcode 1980MGeol 35 183B doi 10 1016 0025 3227 80 90030 4 Karig D E 1972 Remnant Arcs Geological Society of America Bulletin 83 4 1057 1068 Bibcode 1972GSAB 83 1057K doi 10 1130 0016 7606 1972 83 1057 RA 2 0 CO 2 ISSN 0016 7606 Martinez F Fryer P Baker N A Yamazaki T 1995 Evolution of Backarc Rifting Mariana Trough 20 24 N Journal of Geophysical Research Solid Earth 100 3807 3827 Bibcode 1995JGR 100 3807M doi 10 1029 94JB02466 Martinez F Fryer P Becker N 2000 Geophysical characteristics of the southern Mariana Trough 11 50 N 13 40 N Journal of Geophysical Research Solid Earth 105 16591 16607 Bibcode 2000JGR 10516591M doi 10 1029 2000JB900117 Park C H Tamaki K Kobayashi K 1990 Age depth correlation of the Philippine Sea back arc basins and other marginal basins in the world Tectonophysics 181 351 371 Bibcode 1990Tectp 181 351C doi 10 1016 0040 1951 90 90028 7 Stern R J Bloomer S H Martinez F Yamazaki T Harrison T M 1996 The composition of back arc basin lower crust and upper mantle in the Mariana Trough A first report Island Arc 5 3 354 372 doi 10 1111 j 1440 1738 1996 tb00036 x Stern R J Fouch M J Klemperer S 2003 An Overview of the Izu Bonin Mariana Subduction Factory In J Eiler M Hirschmann eds Inside the Subduction Factory PDF Geophysical Monograph Vol 138 American Geophysical Union pp 175 222 ISBN 0 87590 997 3 Yamazaki T Murakami F Saito E 1993 Mode of seafloor spreading in the northern Mariana Trough Tectonophysics 221 2 207 221 Bibcode 1993Tectp 221 207Y doi 10 1016 0040 1951 93 90333 F Retrieved from https en wikipedia org w index php title Mariana Trough amp oldid 1033772263, wikipedia, wiki, book, books, library,
