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Southeast Indian Ridge

April 28, 2023

The Southeast Indian Ridge (SEIR) is a mid-ocean ridge in the southern Indian Ocean. A divergent tectonic plate boundary stretching almost 6,000 km (3,700 mi) between the Rodrigues Triple Junction (25°S 70°E / 25°S 70°E / -25; 70) in the Indian Ocean and the Macquarie Triple Junction (63°S 165°E / 63°S 165°E / -63; 165) in the Pacific Ocean, the SEIR forms the plate boundary between the Australian and Antarctic plates since the Oligocene (anomaly 13).[1]

The Southeast Indian Ridge (denoted by the yellow line)

The SEIR is the spreading centre closest to the Kerguelen and Amsterdam–Saint-Paul hotspot.[2] The SEIR has an intermediate full spreading rate of 65 mm/yr, and, because Antarctica is virtually stationary, this results in a northward ridge migration of half that rate.[3] Spreading rates along the SEIR varies from 69 mm/yr near 88°E to 75 mm/yr near 120°E.[4]

Geology

Amsterdam−St. Paul hotspot

During the past 1 Ma the Amsterdam–St. Paul hotspot (ASP) has produced a 150×200 km plateau straddling on the SEIR.[5] The ASP Plateau covers and area of 30,000 km2 and rises 500 m above the surrounding seafloor.[3]

Both Amsterdam and St. Paul are located on the Antarctic side within 40 km of the SEIR. North-east of the ASP Plateau a string of submarine volcanoes, 1−3 km-high and 40 km-wide, mark the track of the ASP hotspot across the Australian Plate. This track leads to the intersection of the Broken Ridge and Ninety East Ridge west of Australia. The ASP hotspot ceased to produce these volcanoes some 10−5 Ma when the SEIR started to interact with it and the hotspot started to build the shallow plateau. The Kerguelen hotspot, located more than 1,000 km from the SEIR, also influences the MORB composition of the SEIR near the ASP Plateau.[3] Furthermore, there is an active submarine volcano, the 1100 m-high Boomerang Seamount, 18 km north of Amsterdam Island near the SEIR. Analyses of the isotope composition of basalts recovered from its caldera support that the ASP hotspot contributed to the formation of the Ninety East Ridge.[6]

Australian−Antarctic Discordance

Trending east-west between Australia and Antarctica, the SEIR traverses the Australian-Antarctic Discordance (AAD), a morphologically complex region overlying an area of mantle down-welling.[7] Located midway between the ASP-Kerguelen and the Balleny-Tasmantid hotspots, the AAD overlies a region where cooler mantle temperatures have produced a thin oceanic crust and a rough topography with deep valleys.[8]

Between the AAD and the Amsterdam and St. Paul islands, spreading rate is constant at 69–75 mm/yr while axial depth increases by more than 2300 m. This has been interpreted as an eastward decrease in mantle temperature of perhaps 100 °C caused by a magma flow from the Kerguelen–ASP hotspots to the AAD 'cold spot' at 120–128°E. Located at 126°E, the AAD would thus mark the 40 km-long transition between Indian Ocean and Pacific MORBs (mid-ocean ridge basalts), a boundary that has been migrating westward during the past tens of million years.[9]

Between 102°E and the AAD, where the spreading rate is constant, the left-stepping transform faults suggest the presence of oblique extensional forces while the presence of a long, elevated ridge near the 96°E right-stepping transform suggests a compressional force is also active. Together these features indicate the two tectonic plate made a recent counter-clockwise change in relative motion.[4]

Between 88°E and 118°E there are nine transform faults offsetting the SEIR 21–135 km or an age of 0.5–3.6 Ma, accompanied by eight first-order segments (older than 5 Ma) and five east-migrating rifts. These transform faults and migrating rifts are located were the SEIR reaches its maximum axial depths. The first-order transform faults are off-set 2–17 km by 19 non-transform discontinuities, resulting in 18–180 km-long second-order segments. The flanks of the SEIR are dominated by fracture zones perpendicular to the ridge and gravitational lineations oblique to the spreading direction and sometimes zigzag-shaped. This suggests that the SEIR evolves rapidly within the framework of the stable transform faults.[10]

Tectonic history

Australia and Antarctica were neighbours before the break-up of Gondwana in the Cretaceous and several conjugate structures exist on either side of the SEIR.[11] In south-western Australia the Albany-Fraser Orogen formed during the Mesoproterozoic collision between the Australian Yilgarn and Antarctic Mawson cratons. The continental basement of the submarine Naturaliste Plateau is also associated with this orogeny. The Darling Fault on the Australian west coast has a possible continuation beneath the Antarctic Denman Glacier.[12] Archaean and Paleoproterzoic rocks in the Kalinjala Mylonite Zone of the Eyre Peninsula, Australia, match those found in Terre Adelie in Eastern Wilkes Land, Antarctica.[13] Faults in Tasmania–Victoria and Northern Victoria Land have been identified as Cambrian remains of the west-dipping subduction zone along the eastern margin of Gondwana.[14]

Australia and Antarctica broke-up around 110 Ma but spreading in the SEIR first began during the Eocene (40 Ma) when the Kerguelen hotspot separated Broken Ridge from the rest of the Kerguelen Plateau. The SEIR has been migrating northeast since and is now located 1400 km from the Kerguelen hotspot. The ASP hotspot was originally located beneath Australia and a chain of seamounts connecting it to the southern end of the Ninety East Ridge, i.e. the ASP hotspot track, indicate it probably contributed to the formation of the Ninety East Ridge before the SEIR opened.[15]

The opening of the Southern Ocean began west of Australia around 100 Ma from where it propagated eastward at about 2 cm/yr. This rifting was not the direct product of hotspot interaction as it occurred over a cooler than normal mantle. Initially spreading was extremely slow, a half rate of 2–6 mm/yr during the period 96–45 Ma after which it accelerated to 30–35 mm/yr.[8]

Oceanography

The SEIR divides the channel between Australia and Antarctica into the South Indian Basin to the south and the South Australian and Tasman basins to the north. The AAD forms a saddle across the channel while also offering the deepest connection between the Australian and South Indian basins.[16]

There is a voluminous contourite drift along the southern flank of SEIR. Volcanic in origin, it is most likely derived from the slopes of the Kerguelen Plateau and Crozet Islands. This redistribution of sediments has occurred during the last 40000 years. Elevated contributions during the Last Glacial Maximum are thought to be caused by the Antarctic Circumpolar Current and Circumpolar Deep Water and their interaction with the Circumpolar Bottom Water.[17]

See also

Notes

  1. ^ Cochran & Sempéré 1997, The Southeast Indian Ridge, pp. 15467, 15469
  2. ^ Graham et al. 1999, Introduction, p. 298
  3. ^ a b c Scheirer et al. 2000, Background, pp. 8244, 8247
  4. ^ a b Sempéré & Cochran 1997, General Characteristics of the Southeast Indian Ridge, p. 15490
  5. ^ Scheirer et al. 2000, Introduction, pp. 8243–8244
  6. ^ Johnson et al. 2000, Conclusions, pp. 256–257
  7. ^ Klein, Langmuir & Staudigel 1991, Introduction, p. 2089
  8. ^ a b West et al. 1997, Introduction, pp. 7783–7785
  9. ^ Mahoney et al. 2002, Introduction, pp. 1155–1156
  10. ^ Sempéré & Cochran 1997, Segmentation Characteristics, pp. 15490–15495
  11. ^ Williams, Whittaker & Müller 2012, Introduction, p. 1
  12. ^ Williams, Whittaker & Müller 2012, Southwest Australia and Western Wilkes Land, p. 3
  13. ^ Williams, Whittaker & Müller 2012, Eyre Peninsula and Eastern Wilkes Land, pp. 3–4
  14. ^ Williams, Whittaker & Müller 2012, Tasmania-Victoria and Northern Victoria Land, pp. 4–5
  15. ^ Johnson et al. 2000, Geologic setting, pp. 246–247
  16. ^ Rodman & Gordon 1982, Bathymetry, p. 5771
  17. ^ Dezileau et al. 2000, Abstract

References

  • Cochran, J. R.; Sempéré, J. C. (1997). "The Southeast Indian Ridge between 88 E and 118 E: Gravity anomalies and crustal accretion at intermediate spreading rates" (PDF). Journal of Geophysical Research: Solid Earth. 102 (B7): 15463–15487. Bibcode:1997JGR...10215463C. doi:10.1029/97JB00511.
  • Dezileau, L.; Bareille, G.; Reyss, J. L.; Lemoine, F. (2000). "Evidence for strong sediment redistribution by bottom currents along the southeast Indian ridge". Deep Sea Research Part I: Oceanographic Research Papers. 47 (10): 1899–1936. Bibcode:2000DSRI...47.1899D. doi:10.1016/S0967-0637(00)00008-X. Retrieved 25 September 2016.
  • Graham, D. W.; Johnson, K. T. M.; Priebe, L. D.; Lupton, J. E. (1999). "Hotspot–ridge interaction along the Southeast Indian Ridge near Amsterdam and St. Paul islands: helium isotope evidence" (PDF). Earth and Planetary Science Letters. 167 (3): 297–310. Bibcode:1999E&PSL.167..297G. doi:10.1016/s0012-821x(99)00030-8. Retrieved 14 August 2016.
  • Johnson, K. T. M.; Graham, D. W.; Rubin, K. H.; Nicolaysen, K.; Scheirer, D. S.; Forsyth, D. W.; Baker, E. T.; Douglas-Priebe, L. M. (2000). "Boomerang Seamount: The active expression of the Amsterdam–St. Paul hotspot, Southeast Indian Ridge". Earth and Planetary Science Letters. 183 (1): 245–259. Bibcode:2000E&PSL.183..245J. doi:10.1016/s0012-821x(00)00279-x. Retrieved 24 September 2016.
  • Klein, E. M.; Langmuir, C. H.; Staudigel, H. (1991). "Geochemistry of basalts from the Southeast Indian Ridge, 115°E–138°E" (PDF). Journal of Geophysical Research. 96 (B2): 2089–2107. Bibcode:1991JGR....96.2089K. doi:10.1029/90jb01384. Retrieved 14 August 2016.
  • Mahoney, J. J.; Graham, D. W.; Christie, D. M.; Johnson, K. T. M.; Hall, L. S.; Vonderhaar, D. L. (2002). "Between a hotspot and a cold spot: isotopic variation in the Southeast Indian Ridge asthenosphere, 86°E–118°E". Journal of Petrology. 43 (7): 1155–1176. Bibcode:2002JPet...43.1155M. doi:10.1093/petrology/43.7.1155.
  • Rodman, M. R.; Gordon, A. L. (1982). "Southern Ocean bottom water of the Australian‐New Zealand sector". Journal of Geophysical Research: Oceans. 87 (C8): 5771–5778. Bibcode:1982JGR....87.5771R. doi:10.1029/jc087ic08p05771. Retrieved 25 September 2016.
  • Scheirer, D. S.; Forsyth, D. W.; Conder, J. A.; Eberle, M.; Hung, S. H.; Johnson, K.; Graham, D. W. (2000). "Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam-St. Paul plateau" (PDF). Journal of Geophysical Research. 105 (B4): 8243–8262. Bibcode:2000JGR...105.8243S. doi:10.1029/1999jb900407. Retrieved 14 August 2016.
  • Sempéré, J. C.; Cochran, J. R. (1997). "The Southeast Indian Ridge between 88°E and 118°E: Variations in crustal accretion at constant spreading rate". Journal of Geophysical Research: Solid Earth. 102 (B7): 15489–15505. Bibcode:1997JGR...10215489S. doi:10.1029/97jb00171.
  • West, B. P.; Wilcock, W. S.; Sempéré, J. C.; Géli, L. (1997). "Three‐dimensional structure of asthenospheric flow beneath the Southeast Indian Ridge" (PDF). Journal of Geophysical Research: Solid Earth. 102 (B4): 7783–7802. Bibcode:1997JGR...102.7783W. doi:10.1029/96jb03895.
  • Williams, S. E.; Whittaker, J. M.; Müller, R. D. (2012). Full-fit reconstructions of the southern Australian margin and Antarctica — implications for correlating geology between Australia and Antarctica. Proceedings of the Eastern Australasian Basins Symposium IV. Brisbane, QLD. Retrieved 24 September 2016.

Coordinates: 47°20′47″S 97°23′48″E / 47.346294°S 97.396675°E / -47.346294; 97.396675

April 28, 2023
southeast, indian, ridge, seir, ocean, ridge, southern, indian, ocean, divergent, tectonic, plate, boundary, stretching, almost, between, rodrigues, triple, junction, indian, ocean, macquarie, triple, junction, pacific, ocean, seir, forms, plate, boundary, bet. The Southeast Indian Ridge SEIR is a mid ocean ridge in the southern Indian Ocean A divergent tectonic plate boundary stretching almost 6 000 km 3 700 mi between the Rodrigues Triple Junction 25 S 70 E 25 S 70 E 25 70 in the Indian Ocean and the Macquarie Triple Junction 63 S 165 E 63 S 165 E 63 165 in the Pacific Ocean the SEIR forms the plate boundary between the Australian and Antarctic plates since the Oligocene anomaly 13 1 The Southeast Indian Ridge denoted by the yellow line The SEIR is the spreading centre closest to the Kerguelen and Amsterdam Saint Paul hotspot 2 The SEIR has an intermediate full spreading rate of 65 mm yr and because Antarctica is virtually stationary this results in a northward ridge migration of half that rate 3 Spreading rates along the SEIR varies from 69 mm yr near 88 E to 75 mm yr near 120 E 4 Contents 1 Geology 1 1 Amsterdam St Paul hotspot 1 2 Australian Antarctic Discordance 2 Tectonic history 3 Oceanography 4 See also 5 Notes 6 ReferencesGeology EditAmsterdam St Paul hotspot Edit During the past 1 Ma the Amsterdam St Paul hotspot ASP has produced a 150 200 km plateau straddling on the SEIR 5 The ASP Plateau covers and area of 30 000 km2 and rises 500 m above the surrounding seafloor 3 Both Amsterdam and St Paul are located on the Antarctic side within 40 km of the SEIR North east of the ASP Plateau a string of submarine volcanoes 1 3 km high and 40 km wide mark the track of the ASP hotspot across the Australian Plate This track leads to the intersection of the Broken Ridge and Ninety East Ridge west of Australia The ASP hotspot ceased to produce these volcanoes some 10 5 Ma when the SEIR started to interact with it and the hotspot started to build the shallow plateau The Kerguelen hotspot located more than 1 000 km from the SEIR also influences the MORB composition of the SEIR near the ASP Plateau 3 Furthermore there is an active submarine volcano the 1100 m high Boomerang Seamount 18 km north of Amsterdam Island near the SEIR Analyses of the isotope composition of basalts recovered from its caldera support that the ASP hotspot contributed to the formation of the Ninety East Ridge 6 Australian Antarctic Discordance Edit Trending east west between Australia and Antarctica the SEIR traverses the Australian Antarctic Discordance AAD a morphologically complex region overlying an area of mantle down welling 7 Located midway between the ASP Kerguelen and the Balleny Tasmantid hotspots the AAD overlies a region where cooler mantle temperatures have produced a thin oceanic crust and a rough topography with deep valleys 8 Between the AAD and the Amsterdam and St Paul islands spreading rate is constant at 69 75 mm yr while axial depth increases by more than 2300 m This has been interpreted as an eastward decrease in mantle temperature of perhaps 100 C caused by a magma flow from the Kerguelen ASP hotspots to the AAD cold spot at 120 128 E Located at 126 E the AAD would thus mark the 40 km long transition between Indian Ocean and Pacific MORBs mid ocean ridge basalts a boundary that has been migrating westward during the past tens of million years 9 Between 102 E and the AAD where the spreading rate is constant the left stepping transform faults suggest the presence of oblique extensional forces while the presence of a long elevated ridge near the 96 E right stepping transform suggests a compressional force is also active Together these features indicate the two tectonic plate made a recent counter clockwise change in relative motion 4 Between 88 E and 118 E there are nine transform faults offsetting the SEIR 21 135 km or an age of 0 5 3 6 Ma accompanied by eight first order segments older than 5 Ma and five east migrating rifts These transform faults and migrating rifts are located were the SEIR reaches its maximum axial depths The first order transform faults are off set 2 17 km by 19 non transform discontinuities resulting in 18 180 km long second order segments The flanks of the SEIR are dominated by fracture zones perpendicular to the ridge and gravitational lineations oblique to the spreading direction and sometimes zigzag shaped This suggests that the SEIR evolves rapidly within the framework of the stable transform faults 10 Tectonic history EditAustralia and Antarctica were neighbours before the break up of Gondwana in the Cretaceous and several conjugate structures exist on either side of the SEIR 11 In south western Australia the Albany Fraser Orogen formed during the Mesoproterozoic collision between the Australian Yilgarn and Antarctic Mawson cratons The continental basement of the submarine Naturaliste Plateau is also associated with this orogeny The Darling Fault on the Australian west coast has a possible continuation beneath the Antarctic Denman Glacier 12 Archaean and Paleoproterzoic rocks in the Kalinjala Mylonite Zone of the Eyre Peninsula Australia match those found in Terre Adelie in Eastern Wilkes Land Antarctica 13 Faults in Tasmania Victoria and Northern Victoria Land have been identified as Cambrian remains of the west dipping subduction zone along the eastern margin of Gondwana 14 Australia and Antarctica broke up around 110 Ma but spreading in the SEIR first began during the Eocene 40 Ma when the Kerguelen hotspot separated Broken Ridge from the rest of the Kerguelen Plateau The SEIR has been migrating northeast since and is now located 1400 km from the Kerguelen hotspot The ASP hotspot was originally located beneath Australia and a chain of seamounts connecting it to the southern end of the Ninety East Ridge i e the ASP hotspot track indicate it probably contributed to the formation of the Ninety East Ridge before the SEIR opened 15 The opening of the Southern Ocean began west of Australia around 100 Ma from where it propagated eastward at about 2 cm yr This rifting was not the direct product of hotspot interaction as it occurred over a cooler than normal mantle Initially spreading was extremely slow a half rate of 2 6 mm yr during the period 96 45 Ma after which it accelerated to 30 35 mm yr 8 Oceanography EditThe SEIR divides the channel between Australia and Antarctica into the South Indian Basin to the south and the South Australian and Tasman basins to the north The AAD forms a saddle across the channel while also offering the deepest connection between the Australian and South Indian basins 16 There is a voluminous contourite drift along the southern flank of SEIR Volcanic in origin it is most likely derived from the slopes of the Kerguelen Plateau and Crozet Islands This redistribution of sediments has occurred during the last 40000 years Elevated contributions during the Last Glacial Maximum are thought to be caused by the Antarctic Circumpolar Current and Circumpolar Deep Water and their interaction with the Circumpolar Bottom Water 17 See also EditCentral Indian Ridge Southwest Indian Ridge Rodrigues Triple JunctionNotes Edit Cochran amp Sempere 1997 The Southeast Indian Ridge pp 15467 15469 Graham et al 1999 Introduction p 298 a b c Scheirer et al 2000 Background pp 8244 8247 a b Sempere amp Cochran 1997 General Characteristics of the Southeast Indian Ridge p 15490 Scheirer et al 2000 Introduction pp 8243 8244 Johnson et al 2000 Conclusions pp 256 257 Klein Langmuir amp Staudigel 1991 Introduction p 2089 a b West et al 1997 Introduction pp 7783 7785 Mahoney et al 2002 Introduction pp 1155 1156 Sempere amp Cochran 1997 Segmentation Characteristics pp 15490 15495 Williams Whittaker amp Muller 2012 Introduction p 1 Williams Whittaker amp Muller 2012 Southwest Australia and Western Wilkes Land p 3 Williams Whittaker amp Muller 2012 Eyre Peninsula and Eastern Wilkes Land pp 3 4 Williams Whittaker amp Muller 2012 Tasmania Victoria and Northern Victoria Land pp 4 5 Johnson et al 2000 Geologic setting pp 246 247 Rodman amp Gordon 1982 Bathymetry p 5771 Dezileau et al 2000 AbstractReferences EditCochran J R Sempere J C 1997 The Southeast Indian Ridge between 88 E and 118 E Gravity anomalies and crustal accretion at intermediate spreading rates PDF Journal of Geophysical Research Solid Earth 102 B7 15463 15487 Bibcode 1997JGR 10215463C doi 10 1029 97JB00511 Dezileau L Bareille G Reyss J L Lemoine F 2000 Evidence for strong sediment redistribution by bottom currents along the southeast Indian ridge Deep Sea Research Part I Oceanographic Research Papers 47 10 1899 1936 Bibcode 2000DSRI 47 1899D doi 10 1016 S0967 0637 00 00008 X Retrieved 25 September 2016 Graham D W Johnson K T M Priebe L D Lupton J E 1999 Hotspot ridge interaction along the Southeast Indian Ridge near Amsterdam and St Paul islands helium isotope evidence PDF Earth and Planetary Science Letters 167 3 297 310 Bibcode 1999E amp PSL 167 297G doi 10 1016 s0012 821x 99 00030 8 Retrieved 14 August 2016 Johnson K T M Graham D W Rubin K H Nicolaysen K Scheirer D S Forsyth D W Baker E T Douglas Priebe L M 2000 Boomerang Seamount The active expression of the Amsterdam St Paul hotspot Southeast Indian Ridge Earth and Planetary Science Letters 183 1 245 259 Bibcode 2000E amp PSL 183 245J doi 10 1016 s0012 821x 00 00279 x Retrieved 24 September 2016 Klein E M Langmuir C H Staudigel H 1991 Geochemistry of basalts from the Southeast Indian Ridge 115 E 138 E PDF Journal of Geophysical Research 96 B2 2089 2107 Bibcode 1991JGR 96 2089K doi 10 1029 90jb01384 Retrieved 14 August 2016 Mahoney J J Graham D W Christie D M Johnson K T M Hall L S Vonderhaar D L 2002 Between a hotspot and a cold spot isotopic variation in the Southeast Indian Ridge asthenosphere 86 E 118 E Journal of Petrology 43 7 1155 1176 Bibcode 2002JPet 43 1155M doi 10 1093 petrology 43 7 1155 Rodman M R Gordon A L 1982 Southern Ocean bottom water of the Australian New Zealand sector Journal of Geophysical Research Oceans 87 C8 5771 5778 Bibcode 1982JGR 87 5771R doi 10 1029 jc087ic08p05771 Retrieved 25 September 2016 Scheirer D S Forsyth D W Conder J A Eberle M Hung S H Johnson K Graham D W 2000 Anomalous seafloor spreading of the Southeast Indian Ridge near the Amsterdam St Paul plateau PDF Journal of Geophysical Research 105 B4 8243 8262 Bibcode 2000JGR 105 8243S doi 10 1029 1999jb900407 Retrieved 14 August 2016 Sempere J C Cochran J R 1997 The Southeast Indian Ridge between 88 E and 118 E Variations in crustal accretion at constant spreading rate Journal of Geophysical Research Solid Earth 102 B7 15489 15505 Bibcode 1997JGR 10215489S doi 10 1029 97jb00171 West B P Wilcock W S Sempere J C Geli L 1997 Three dimensional structure of asthenospheric flow beneath the Southeast Indian Ridge PDF Journal of Geophysical Research Solid Earth 102 B4 7783 7802 Bibcode 1997JGR 102 7783W doi 10 1029 96jb03895 Williams S E Whittaker J M Muller R D 2012 Full fit reconstructions of the southern Australian margin and Antarctica implications for correlating geology between Australia and Antarctica Proceedings of the Eastern Australasian Basins Symposium IV Brisbane QLD Retrieved 24 September 2016 Coordinates 47 20 47 S 97 23 48 E 47 346294 S 97 396675 E 47 346294 97 396675 Retrieved from https en wikipedia org w index php title Southeast Indian Ridge amp oldid 1134228302, wikipedia, wiki, book, books, library,

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