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Hollister Ridge

February 24, 2023

Hollister Ridge is a group of seamounts in the Pacific Ocean. They lie west from the Pacific-Antarctic Ridge and form three ridges that form a line; one of the ridges rises to a depth of 100 metres (330 ft) and in the past formed an island. The seamounts are composed out of basaltic and other rocks and their ages range from about 2.5 million years ago to latest Pleistocene; an acoustic swarm recorded in the southern Pacific Ocean in 1991-1992 is considered to be the manifestation of a historical eruption of the Hollister Ridge.

Hollister Ridge
Hollister Ridge (Pacific Ocean)
Summit depth100 metres (330 ft)
Location
Coordinates53°59′53″S 139°50′42″W / 53.998°S 139.845°W / -53.998; -139.845Coordinates: 53°59′53″S 139°50′42″W / 53.998°S 139.845°W / -53.998; -139.845[1]
Geology
Age of rockPliocene-Pleistocene
Last activity1991-1992

The origin of the Hollister Ridge is unclear, with various proposed mechanisms involving the neighbouring Pacific-Antarctic Ridge, crustal weaknesses and the Louisville hotspot.

History

The ridge was discovered either by gravimetry from satellites[2] or by the research ship Eltanin[3] in 1965 and first named "Hollister Ridge" in a 1995 publication.[4] Rock samples were taken at the ridge in 1996.[2]

Geography and geomorphology

The Hollister Ridge is an aseismic ridge in the Pacific Ocean, west of the Pacific-Antarctic Ridge.[2] It consists of three separate ridges which are lined up in east-southeast to north-northwest direction, starting from the axis of the Pacific-Antarctic Ridge and ending in the direction of the Louisville seamount chain. The eastern ridge is 70 kilometres (43 mi) long and rises to a depth of 1,400 metres (4,600 ft) below sea level, the central ridge is 207 kilometres (129 mi) long and rises to a depth of 100 metres (330 ft) below sea level, the western ridge is 50 kilometres (31 mi) long and rises to a depth of 1,500 metres (4,900 ft) below sea level.[5] The central ridge formed an island in the past.[6]

Geology

The ridge rises from a seafloor whose age decreases from 7-8 to 0-1 million years ago southeastward.[5] Three fracture zones, the Heezen, Tharp and Hollister fracture zones, extend northwestward across the seafloor northeast of the Hollister Ridge;[6] at least the first two are considered to be part of the Eltanin fracture zone.[7] A scarp lies south of the Hollister Ridge,[8] and even farther south lies the Udintsev fracture zone.[9] The Pacific-Antarctic Ridge close to the Hollister Ridge is the site of an isolated geoid anomaly which has been interpreted as a product of magmatic upwelling.[10]

Rocks sampled from the Hollister Ridge have yielded basalts,[6] alkali basalts, hawaiites, picrites and tholeiites[11] as well as granites, which are most likely dropstones transported to the ridge by icebergs. The basalts range from aphyric to porphyric and contain phenocrysts of olivine and plagioclase.[6]

Several mechanisms have been proposed to explain its origin:[2]

  • The ridge may be the present-day location of the Louisville hotspot.[12][2] Petrological differences between the volcanoes formed by this hotspot and the Hollister Ridge make this hypothesis problematic,[13][12] as are misfits between the reconstructed path of the Louisville hotspot and the position of the Hollister Ridge.[14] Even later plate reconstructions have endorsed this model of origin.[15]
  • A "mini-hotspot", which however is not consistent with the geometry of the ridge (which is at an angle to the motion of the Pacific Plate).[8] Such a mini-hotspot may be a branch of the Louisville hotspot.[16]
  • Asthenosphere may be flowing from the Louisville hotspot to the Pacific-Antarctic Ridge.[2] Seamounts and aseismic ridges have been observed in other regions of the world where such flow is expected to occur.[9]
  • Lineaments in the crust allowed the ascent of magma from the mantle.[17] Such lineaments may be produced by tectonic stresses related to crustal spreading; this theory is supported by the geometry of the Hollister Ridge and the ages of its components. There may be some influence by the Louisville hotspot.[18] Pliocene changes in the plate motion patterns of the region may have generated the lineaments.[19]
  • One variation of the "lineament" theory posits that the ridge at first was built by magma ascending through crustal weaknesses; later material from the Louisville hotspot flowed south towards the Hollister Ridge and increasingly interacted with the lineament, thus influencing the composition of the ridge rocks.[20] A change in lithospheric thickness across the Eltanin fracture zone would divert the mantle flow from the Louisville hotspot southward.[21]

Eruptive history

Argon-argon dating has yielded ages ranging from a mean age of 2.531 ± 0.036 million years ago for the western ridge[22] over 0.487 ± 0.03 million years ago and 0.343 ± 0.008 million years ago for the eastern ridge to 91,000 ± 12,000 and 0 years ago for the central ridge. This implies that volcanism is still active[23] at the central ridge, which is also the shallowest sector of the Hollister Ridge.[22]

There is evidence of historical eruptions at the Hollister Ridge.[14] Between 10 March 1991 and 12 June 1992 a strong acoustic swarm was recorded in the southern Pacific Ocean from several stations in French Polynesia[24] and its source identified with a segment of the Hollister Ridge.[25] Anthropogenic and biological origins were considered unlikely sources for the swarm,[26] and it is thus interpreted to be a volcanic swarm.[1] The acoustic swarm may have resulted from the interaction between seawater and a subaqueous lava lake;[27] the acoustic patterns are not consistent with a simple explosive eruption.[1]

References

  1. ^ a b c "Hollister Ridge". Global Volcanism Program. Smithsonian Institution.
  2. ^ a b c d e f Vlastelic et al. 1998, p. 777.
  3. ^ Castillo et al. 1998, p. 111.
  4. ^ Okal & Langenhorst 2000, p. 185.
  5. ^ a b Vlastelic et al. 1998, p. 778,779.
  6. ^ a b c d Vlastelic et al. 1998, p. 779.
  7. ^ Vlastélic & Dosso 2005, p. 11.
  8. ^ a b Géli et al. 1998, p. 35.
  9. ^ a b Vlastélic & Dosso 2005, p. 2.
  10. ^ Talandier & Okal 1996, p. 1533.
  11. ^ Vlastelic et al. 1998, p. 780.
  12. ^ a b Okal & Langenhorst 2000, p. 186.
  13. ^ Vlastelic et al. 1998, p. 792.
  14. ^ a b Géli et al. 1998, p. 32.
  15. ^ Morgan, W. Jason; Morgan, Jason Phipps (2007). "Plate velocities in hotspot reference frame: electronic supplement". geosociety.org: 55–57. doi:10.1130/2007090.
  16. ^ Vlastélic & Dosso 2005, p. 10.
  17. ^ Vlastelic et al. 1998, p. 791.
  18. ^ Géli et al. 1998, p. 37.
  19. ^ Peive, A. A. (1 July 2007). "Linear volcanic chains in oceans: Possible formation mechanisms". Geotectonics. 41 (4): 288. Bibcode:2007Geote..41..281P. doi:10.1134/S0016852107040024. ISSN 0016-8521. S2CID 128409663.
  20. ^ Vlastélic & Dosso 2005, p. 12.
  21. ^ Castillo et al. 1998, p. 121.
  22. ^ a b Vlastelic et al. 1998, p. 783.
  23. ^ Vlastelic et al. 1998, p. 781.
  24. ^ Talandier & Okal 1996, p. 1530.
  25. ^ Talandier & Okal 1996, p. 1532.
  26. ^ Talandier & Okal 1996, p. 1536.
  27. ^ Talandier & Okal 1996, p. 1542.

Sources

  • Castillo, Paterno R.; Natland, James H.; Niu, Yaoling; Lonsdale, Peter F. (January 1998). "Sr, Nd and Pb isotopic variation along the Pacific–Antarctic risecrest, 53–57°S: Implications for the composition and dynamics of the South Pacific upper mantle". Earth and Planetary Science Letters. 154 (1–4): 109–125. Bibcode:1998E&PSL.154..109C. CiteSeerX 10.1.1.331.8707. doi:10.1016/S0012-821X(97)00172-6. ISSN 0012-821X.
  • Géli, Louis; Aslanian, Daniel; Olivet, Jean-Louis; Vlastelic, Ivan; Dosso, Laure; Guillou, Hervé; Bougault, Henri (December 1998). "Location of Louisville hotspot and origin of Hollister Ridge: geophysical constraints". Earth and Planetary Science Letters. 164 (1–2): 31–40. Bibcode:1998E&PSL.164...31G. doi:10.1016/S0012-821X(98)00217-9. ISSN 0012-821X.
  • Okal, Emile A.; Langenhorst, Amy R. (May 2000). "Seismic properties of the Eltanin Transform System, South Pacific". Physics of the Earth and Planetary Interiors. 119 (3–4): 185–208. Bibcode:2000PEPI..119..185O. doi:10.1016/S0031-9201(99)00169-7. ISSN 0031-9201.
  • Talandier, Jacques; Okal, Emile A. (1 October 1996). "Monochromatic T waves from underwater volcanoes in the pacific ocean: Ringing witnesses to geyser processes?". Bulletin of the Seismological Society of America. 86 (5). ISSN 0037-1106.
  • Vlastélic, Ivan; Dosso, Laure (May 2005). "Initiation of a plume-ridge interaction in the South Pacific recorded by high-precision Pb isotopes along Hollister Ridge". Geochemistry, Geophysics, Geosystems. 6 (5): n/a. Bibcode:2005GGG.....6.5011V. doi:10.1029/2004GC000902.
  • Vlastelic, I.; Dosso, L.; Guillou, H.; Bougault, H.; Geli, L.; Etoubleau, J.; Joron, J.L. (August 1998). "Geochemistry of the Hollister Ridge: relation with the Louisville hotspot and the Pacific–Antarctic Ridge". Earth and Planetary Science Letters. 160 (3–4): 777–793. Bibcode:1998E&PSL.160..777V. doi:10.1016/S0012-821X(98)00127-7. ISSN 0012-821X.

February 24, 2023
hollister, ridge, group, seamounts, pacific, ocean, they, west, from, pacific, antarctic, ridge, form, three, ridges, that, form, line, ridges, rises, depth, metres, past, formed, island, seamounts, composed, basaltic, other, rocks, their, ages, range, from, a. Hollister Ridge is a group of seamounts in the Pacific Ocean They lie west from the Pacific Antarctic Ridge and form three ridges that form a line one of the ridges rises to a depth of 100 metres 330 ft and in the past formed an island The seamounts are composed out of basaltic and other rocks and their ages range from about 2 5 million years ago to latest Pleistocene an acoustic swarm recorded in the southern Pacific Ocean in 1991 1992 is considered to be the manifestation of a historical eruption of the Hollister Ridge Hollister RidgeHollister Ridge Pacific Ocean Summit depth100 metres 330 ft LocationCoordinates53 59 53 S 139 50 42 W 53 998 S 139 845 W 53 998 139 845 Coordinates 53 59 53 S 139 50 42 W 53 998 S 139 845 W 53 998 139 845 1 GeologyAge of rockPliocene PleistoceneLast activity1991 1992The origin of the Hollister Ridge is unclear with various proposed mechanisms involving the neighbouring Pacific Antarctic Ridge crustal weaknesses and the Louisville hotspot Contents 1 History 2 Geography and geomorphology 3 Geology 4 Eruptive history 5 References 5 1 SourcesHistory EditThe ridge was discovered either by gravimetry from satellites 2 or by the research ship Eltanin 3 in 1965 and first named Hollister Ridge in a 1995 publication 4 Rock samples were taken at the ridge in 1996 2 Geography and geomorphology EditThe Hollister Ridge is an aseismic ridge in the Pacific Ocean west of the Pacific Antarctic Ridge 2 It consists of three separate ridges which are lined up in east southeast to north northwest direction starting from the axis of the Pacific Antarctic Ridge and ending in the direction of the Louisville seamount chain The eastern ridge is 70 kilometres 43 mi long and rises to a depth of 1 400 metres 4 600 ft below sea level the central ridge is 207 kilometres 129 mi long and rises to a depth of 100 metres 330 ft below sea level the western ridge is 50 kilometres 31 mi long and rises to a depth of 1 500 metres 4 900 ft below sea level 5 The central ridge formed an island in the past 6 Geology EditThe ridge rises from a seafloor whose age decreases from 7 8 to 0 1 million years ago southeastward 5 Three fracture zones the Heezen Tharp and Hollister fracture zones extend northwestward across the seafloor northeast of the Hollister Ridge 6 at least the first two are considered to be part of the Eltanin fracture zone 7 A scarp lies south of the Hollister Ridge 8 and even farther south lies the Udintsev fracture zone 9 The Pacific Antarctic Ridge close to the Hollister Ridge is the site of an isolated geoid anomaly which has been interpreted as a product of magmatic upwelling 10 Rocks sampled from the Hollister Ridge have yielded basalts 6 alkali basalts hawaiites picrites and tholeiites 11 as well as granites which are most likely dropstones transported to the ridge by icebergs The basalts range from aphyric to porphyric and contain phenocrysts of olivine and plagioclase 6 Several mechanisms have been proposed to explain its origin 2 The ridge may be the present day location of the Louisville hotspot 12 2 Petrological differences between the volcanoes formed by this hotspot and the Hollister Ridge make this hypothesis problematic 13 12 as are misfits between the reconstructed path of the Louisville hotspot and the position of the Hollister Ridge 14 Even later plate reconstructions have endorsed this model of origin 15 A mini hotspot which however is not consistent with the geometry of the ridge which is at an angle to the motion of the Pacific Plate 8 Such a mini hotspot may be a branch of the Louisville hotspot 16 Asthenosphere may be flowing from the Louisville hotspot to the Pacific Antarctic Ridge 2 Seamounts and aseismic ridges have been observed in other regions of the world where such flow is expected to occur 9 Lineaments in the crust allowed the ascent of magma from the mantle 17 Such lineaments may be produced by tectonic stresses related to crustal spreading this theory is supported by the geometry of the Hollister Ridge and the ages of its components There may be some influence by the Louisville hotspot 18 Pliocene changes in the plate motion patterns of the region may have generated the lineaments 19 One variation of the lineament theory posits that the ridge at first was built by magma ascending through crustal weaknesses later material from the Louisville hotspot flowed south towards the Hollister Ridge and increasingly interacted with the lineament thus influencing the composition of the ridge rocks 20 A change in lithospheric thickness across the Eltanin fracture zone would divert the mantle flow from the Louisville hotspot southward 21 Eruptive history EditArgon argon dating has yielded ages ranging from a mean age of 2 531 0 036 million years ago for the western ridge 22 over 0 487 0 03 million years ago and 0 343 0 008 million years ago for the eastern ridge to 91 000 12 000 and 0 years ago for the central ridge This implies that volcanism is still active 23 at the central ridge which is also the shallowest sector of the Hollister Ridge 22 There is evidence of historical eruptions at the Hollister Ridge 14 Between 10 March 1991 and 12 June 1992 a strong acoustic swarm was recorded in the southern Pacific Ocean from several stations in French Polynesia 24 and its source identified with a segment of the Hollister Ridge 25 Anthropogenic and biological origins were considered unlikely sources for the swarm 26 and it is thus interpreted to be a volcanic swarm 1 The acoustic swarm may have resulted from the interaction between seawater and a subaqueous lava lake 27 the acoustic patterns are not consistent with a simple explosive eruption 1 References Edit a b c Hollister Ridge Global Volcanism Program Smithsonian Institution a b c d e f Vlastelic et al 1998 p 777 Castillo et al 1998 p 111 Okal amp Langenhorst 2000 p 185 a b Vlastelic et al 1998 p 778 779 a b c d Vlastelic et al 1998 p 779 Vlastelic amp Dosso 2005 p 11 a b Geli et al 1998 p 35 a b Vlastelic amp Dosso 2005 p 2 Talandier amp Okal 1996 p 1533 Vlastelic et al 1998 p 780 a b Okal amp Langenhorst 2000 p 186 Vlastelic et al 1998 p 792 a b Geli et al 1998 p 32 Morgan W Jason Morgan Jason Phipps 2007 Plate velocities in hotspot reference frame electronic supplement geosociety org 55 57 doi 10 1130 2007090 Vlastelic amp Dosso 2005 p 10 Vlastelic et al 1998 p 791 Geli et al 1998 p 37 Peive A A 1 July 2007 Linear volcanic chains in oceans Possible formation mechanisms Geotectonics 41 4 288 Bibcode 2007Geote 41 281P doi 10 1134 S0016852107040024 ISSN 0016 8521 S2CID 128409663 Vlastelic amp Dosso 2005 p 12 Castillo et al 1998 p 121 a b Vlastelic et al 1998 p 783 Vlastelic et al 1998 p 781 Talandier amp Okal 1996 p 1530 Talandier amp Okal 1996 p 1532 Talandier amp Okal 1996 p 1536 Talandier amp Okal 1996 p 1542 Sources Edit Castillo Paterno R Natland James H Niu Yaoling Lonsdale Peter F January 1998 Sr Nd and Pb isotopic variation along the Pacific Antarctic risecrest 53 57 S Implications for the composition and dynamics of the South Pacific upper mantle Earth and Planetary Science Letters 154 1 4 109 125 Bibcode 1998E amp PSL 154 109C CiteSeerX 10 1 1 331 8707 doi 10 1016 S0012 821X 97 00172 6 ISSN 0012 821X Geli Louis Aslanian Daniel Olivet Jean Louis Vlastelic Ivan Dosso Laure Guillou Herve Bougault Henri December 1998 Location of Louisville hotspot and origin of Hollister Ridge geophysical constraints Earth and Planetary Science Letters 164 1 2 31 40 Bibcode 1998E amp PSL 164 31G doi 10 1016 S0012 821X 98 00217 9 ISSN 0012 821X Okal Emile A Langenhorst Amy R May 2000 Seismic properties of the Eltanin Transform System South Pacific Physics of the Earth and Planetary Interiors 119 3 4 185 208 Bibcode 2000PEPI 119 185O doi 10 1016 S0031 9201 99 00169 7 ISSN 0031 9201 Talandier Jacques Okal Emile A 1 October 1996 Monochromatic T waves from underwater volcanoes in the pacific ocean Ringing witnesses to geyser processes Bulletin of the Seismological Society of America 86 5 ISSN 0037 1106 Vlastelic Ivan Dosso Laure May 2005 Initiation of a plume ridge interaction in the South Pacific recorded by high precision Pb isotopes along Hollister Ridge Geochemistry Geophysics Geosystems 6 5 n a Bibcode 2005GGG 6 5011V doi 10 1029 2004GC000902 Vlastelic I Dosso L Guillou H Bougault H Geli L Etoubleau J Joron J L August 1998 Geochemistry of the Hollister Ridge relation with the Louisville hotspot and the Pacific Antarctic Ridge Earth and Planetary Science Letters 160 3 4 777 793 Bibcode 1998E amp PSL 160 777V doi 10 1016 S0012 821X 98 00127 7 ISSN 0012 821X Retrieved from https en wikipedia org w index php title Hollister Ridge amp oldid 1136409501, wikipedia, wiki, book, books, library,

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