The Chagos–Laccadive Ridge (CLR), also known as the Chagos–Laccadive Plateau,[1] is a prominent volcanic ridge and oceanic plateau extending between the Northern and the Central Indian Ocean.
Extending from c. 10°S to 15°N, the CLR includes the Laccadive, Maldives, and Chagos archipelagos and can be divided into three corresponding blocks, of which the first is continental and the two latter are oceanic. The CLR is asymmetrical with a steeper eastern slope and has an average depth of less than 1,000 m (3,300 ft). It formed south of or near the Equator together with the remaining western continental margin of India, when India separated first from Madagascar in the Mid-Cretaceous and then from the Seychelles Islands in the Late Cretaceous.[2]
The CLR extends northward for c. 2,550 km (1,580 mi) from 10°S at the southern end of the Chagos Archipelago to 14°N around the Adas Bank.[3] The second element of the name is for the Laccadive Islands, among the islands of Lakshadweep. ("Laccadive" is a form of the name "Lakshadweep".) The islands of Chagos, Maldives and Lakshadweep are the above-water parts of the Chagos–Laccadive Ridge.
The Laccadive Ridge, the northern part of the CLR, parallels the Indian west coast (8°N–16°N) and has an average width of 270 km (170 mi). It is separated from the flanking basins by fault scarps made of thick, high-density crust. It is made of thinned continental crust marked by the volcanism that occurred near the KT-boundary c. 66 Ma.[4][5]
The western coastal margin of the Indian subcontinent was affected by two large igneous provinces at 85 Ma and 65 Ma. This left a complex of ridges that run parallel to the west coast of which the Laccadive Ridge is the larger. A complex of considerably smaller ridges constitutes a northern extension to the CLR. The Laxmi Ridge, the larger of these, is made of continental crust and formed during the Seychelles-India breakup.[6] East of the Laxmi Ridge in the Laxmi Basin, the Panikkar Ridge is made of stretched continental crust and has a similar tectonic history. In contrast, the Palitana Ridge north of the Panikkar Ridge probably represents an extinct spreading centre and on the nearby shelf and slope a lineament, known as the Prathap Ridge Complex, is similarly made of oceanic crust and both are probably leftovers from the India–Madagascar breakup.[7][8]
Formationedit
The vast Chagos–Laccadive Ridge contains a considerable amount of volcanic rock, as does the southern part of the Mascarene Plateau. Although the Chagos–Laccadive Ridge is an aseismic ridge, between 1965 and 1970 an unusual, isolated swarm of earthquakes occurred on the west side of the Great Chagos Bank at approximately 6°00′S71°20′E / 6.000°S 71.333°E / -6.000; 71.333.[9] It is unknown, but of considerable interest, how much continental crust exists at depth beneath the ridge.
Ajay, K. K.; Chaubey, A. K.; Krishna, K. S.; Rao, D. G.; Sar, D. (2010). "Seaward dipping reflectors along the SW continental margin of India: Evidence for volcanic passive margin" (PDF). Journal of Earth System Science. 119 (6): 803–813. Bibcode:2010JESS..119..803A. doi:10.1007/s12040-010-0061-2. Retrieved 14 July 2018.
Krishna, K. S.; Rao, D. G.; Sar, D. (2006). "Nature of the crust in the Laxmi Basin (14°–20°N), western continental margin of India". Tectonics. 25 (1): TC1006. Bibcode:2006Tecto..25.1006K. CiteSeerX10.1.1.595.6101. doi:10.1029/2004TC001747.
Mukhopadhyay, R.; Ghosh, A. K.; Iyer, S. D. (2017). The Indian Ocean nodule field: geology and resource potential (2nd ed.). Elsevier. ISBN9780444637628. Retrieved 14 July 2018.
Nair, N.; Anand, S. P.; Rajaram, M. (2013). "Tectonic framework of laccadive Ridge in western Continental margin of India" (PDF). Marine Geology. 346: 79–90. Bibcode:2013MGeol.346...79N. doi:10.1016/j.margeo.2013.08.009. Retrieved 15 July 2018.
Seth, S. (1978). "An earthquake swarm on the Chagos?Laccadive Ridge and its tectonic implications". Geophysical Journal International. 55 (3): 577–588. Bibcode:1978GeoJ...55..577S. CiteSeerX10.1.1.837.7160. doi:10.1111/j.1365-246X.1978.tb05928.x.
Subrahmanyam, C.; Chand, S. (2006). "Evolution of the passive continental margins of India—a geophysical appraisal". Gondwana Research. 10 (1–2): 167–178. doi:10.1016/j.gr.2005.11.024.
Verzhbitsky, E. V. (2003). "Geothermal regime and genesis of the Ninety-East and Chagos-Laccadive ridges". Journal of Geodynamics. 35 (3): 289–302. Bibcode:2003JGeo...35..289V. doi:10.1016/S0264-3707(02)00068-6.
External linksedit
Ashalatha, B.; Subrahmanyam, C.; Singh, R. N. (1991). "Origin and compensation of Chagos-Laccadive Ridge, Indian Ocean, from admittance analysis of gravity and bathymetry data". Earth and Planetary Science Letters. 105 (1–3): 47–54. Bibcode:1991E&PSL.105...47A. doi:10.1016/0012-821X(91)90119-3.
Hydrographic Description (Indian Ocean Pilot)
January 01, 1970
chagos, laccadive, ridge, several, prominent, features, indian, ocean, chagos, laccadive, ridge, upper, left, ninety, east, ridge, centre, central, indian, ridge, left, broken, ridge, bottom, right, also, known, chagos, laccadive, plateau, prominent, volcanic,. 3 48 N 73 24 E 3 800 N 73 400 E 3 800 73 400 Several prominent features of the Indian Ocean Chagos Laccadive Ridge upper left Ninety East Ridge centre Central Indian Ridge left and Broken Ridge bottom right The Chagos Laccadive Ridge CLR also known as the Chagos Laccadive Plateau 1 is a prominent volcanic ridge and oceanic plateau extending between the Northern and the Central Indian Ocean Extending from c 10 S to 15 N the CLR includes the Laccadive Maldives and Chagos archipelagos and can be divided into three corresponding blocks of which the first is continental and the two latter are oceanic The CLR is asymmetrical with a steeper eastern slope and has an average depth of less than 1 000 m 3 300 ft It formed south of or near the Equator together with the remaining western continental margin of India when India separated first from Madagascar in the Mid Cretaceous and then from the Seychelles Islands in the Late Cretaceous 2 Contents 1 Extent 2 Formation 3 See also 4 References 4 1 Notes 4 2 Sources 5 External linksExtent editThe CLR extends northward for c 2 550 km 1 580 mi from 10 S at the southern end of the Chagos Archipelago to 14 N around the Adas Bank 3 The second element of the name is for the Laccadive Islands among the islands of Lakshadweep Laccadive is a form of the name Lakshadweep The islands of Chagos Maldives and Lakshadweep are the above water parts of the Chagos Laccadive Ridge The Laccadive Ridge the northern part of the CLR parallels the Indian west coast 8 N 16 N and has an average width of 270 km 170 mi It is separated from the flanking basins by fault scarps made of thick high density crust It is made of thinned continental crust marked by the volcanism that occurred near the KT boundary c 66 Ma 4 5 The western coastal margin of the Indian subcontinent was affected by two large igneous provinces at 85 Ma and 65 Ma This left a complex of ridges that run parallel to the west coast of which the Laccadive Ridge is the larger A complex of considerably smaller ridges constitutes a northern extension to the CLR The Laxmi Ridge the larger of these is made of continental crust and formed during the Seychelles India breakup 6 East of the Laxmi Ridge in the Laxmi Basin the Panikkar Ridge is made of stretched continental crust and has a similar tectonic history In contrast the Palitana Ridge north of the Panikkar Ridge probably represents an extinct spreading centre and on the nearby shelf and slope a lineament known as the Prathap Ridge Complex is similarly made of oceanic crust and both are probably leftovers from the India Madagascar breakup 7 8 Formation editThe vast Chagos Laccadive Ridge contains a considerable amount of volcanic rock as does the southern part of the Mascarene Plateau Although the Chagos Laccadive Ridge is an aseismic ridge between 1965 and 1970 an unusual isolated swarm of earthquakes occurred on the west side of the Great Chagos Bank at approximately 6 00 S 71 20 E 6 000 S 71 333 E 6 000 71 333 9 It is unknown but of considerable interest how much continental crust exists at depth beneath the ridge See also editCentral Indian RidgeReferences editNotes edit Geographical Names 2003 Nair Anand amp Rajaram 2013 Morpho tectonic elements of the WCMI pp 80 81 Mukhopadhyay Ghosh amp Iyer 2017 pp 43 44 Ajay et al 2010 Physiographic and tectonic settings pp 804 806 Nair Anand amp Rajaram 2013 Discussion pp 89 90 Subrahmanyam amp Chand 2006 p 170 Krishna Rao amp Sar 2006 Origin of the Panikkar Ridge pp 2 8 9 Figg 1 9 pp 24 35 Subrahmanyam amp Chand 2006 p 169 Seth 1978 Abstract Sources edit Ajay K K Chaubey A K Krishna K S Rao D G Sar D 2010 Seaward dipping reflectors along the SW continental margin of India Evidence for volcanic passive margin PDF Journal of Earth System Science 119 6 803 813 Bibcode 2010JESS 119 803A doi 10 1007 s12040 010 0061 2 Retrieved 14 July 2018 Chagos Laccadive Plateau Undersea Features Geographical Names 2003 09 17 Retrieved 14 July 2018 Krishna K S Rao D G Sar D 2006 Nature of the crust in the Laxmi Basin 14 20 N western continental margin of India Tectonics 25 1 TC1006 Bibcode 2006Tecto 25 1006K CiteSeerX 10 1 1 595 6101 doi 10 1029 2004TC001747 Mukhopadhyay R Ghosh A K Iyer S D 2017 The Indian Ocean nodule field geology and resource potential 2nd ed Elsevier ISBN 9780444637628 Retrieved 14 July 2018 Nair N Anand S P Rajaram M 2013 Tectonic framework of laccadive Ridge in western Continental margin of India PDF Marine Geology 346 79 90 Bibcode 2013MGeol 346 79N doi 10 1016 j margeo 2013 08 009 Retrieved 15 July 2018 Seth S 1978 An earthquake swarm on the Chagos Laccadive Ridge and its tectonic implications Geophysical Journal International 55 3 577 588 Bibcode 1978GeoJ 55 577S CiteSeerX 10 1 1 837 7160 doi 10 1111 j 1365 246X 1978 tb05928 x Subrahmanyam C Chand S 2006 Evolution of the passive continental margins of India a geophysical appraisal Gondwana Research 10 1 2 167 178 doi 10 1016 j gr 2005 11 024 Verzhbitsky E V 2003 Geothermal regime and genesis of the Ninety East and Chagos Laccadive ridges Journal of Geodynamics 35 3 289 302 Bibcode 2003JGeo 35 289V doi 10 1016 S0264 3707 02 00068 6 External links editAshalatha B Subrahmanyam C Singh R N 1991 Origin and compensation of Chagos Laccadive Ridge Indian Ocean from admittance analysis of gravity and bathymetry data Earth and Planetary Science Letters 105 1 3 47 54 Bibcode 1991E amp PSL 105 47A doi 10 1016 0012 821X 91 90119 3 Hydrographic Description Indian Ocean Pilot Retrieved from https en wikipedia org w index php title Chagos Laccadive Ridge amp oldid 1175223952, wikipedia, wiki, book, books, library,
