A rift valley is a linear shaped lowland between several highlands or mountain ranges produced by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear depression may subsequently be further deepened by the forces of erosion. More generally the valley is likely to be filled with sedimentary deposits derived from the rift flanks and the surrounding areas. In many cases rift lakes are formed. One of the best known examples of this process is the East African Rift.[1] On Earth, rifts can occur at all elevations, from the sea floor to plateaus and mountain ranges in continental crust or in oceanic crust. They are often associated with a number of adjoining subsidiary or co-extensive valleys, which are typically considered part of the principal rift valley geologically.
Many existing continental rift valleys are the result of a failed arm (aulacogen) of a triple junction, although there are two, the East African Rift and the Baikal Rift Zone, which are currently active, as well as a third which may be, the West Antarctic Rift System. In these instances, not only the crust but entire tectonic plates are in the process of breaking apart forming new plates. If they continue, continental rifts will eventually become oceanic rifts.
Other rift valleys are the result of bends or discontinuities in horizontally-moving (strike-slip) faults. When these bends or discontinuities are in the same direction as the relative motions along the fault, extension occurs. For example, for a right lateral-moving fault, a bend to the right will result in stretching and consequent subsidence in the area of the irregularity. In the view of many geologists today, the Dead Sea lies in a rift which results from a leftward discontinuity in the left lateral-moving Dead Sea Transform fault. Where a fault breaks into two strands, or two faults run close to each other, crustal extension may also occur between them, as a result of differences in their motions. Both types of fault-caused extension commonly occur on a small scale, producing such features as sag ponds or landslides.
Rift valleys are also known to occur on other terrestrial planets and natural satellites. The 4,000 km long Valles Marineris on Mars is believed by planetary geologists to be a large rift system.[7][8] Some features of Venus, most notably, the 4,000 km Devana Chasma[9] and a part of the western Eistla, and possibly also Alta and Bell Regio have been interpreted by some planetary geologists as rift valleys.[10][11] Some natural satellites also have prominent rift valleys. The 2,000 km long Ithaca Chasma on Tethys in the Saturn system is a prominent example. Charon's Nostromo Chasma is the first confirmed in the Pluto system, however large chasms up to 950 km wide observed on Charon have also been tentatively interpreted by some as giant rifts, and similar formations have also been noted on Pluto.[12] A recent study suggests a complex system of ancient lunar rift valleys, including Vallis Rheita and Vallis Alpes.[13] The Uranus system also has prominent examples, with large 'chasma' believed to be giant rift valley systems, most notably the 1492 km long Messina Chasma on Titania, 622 km Kachina Chasmata on Ariel, Verona Rupes on Miranda,[14] and Mommur Chasma on Oberon.[15]
^. Archived from the original on 2020-06-19. Retrieved 2020-06-18.
^"Lake Baikal – World Heritage Site". World Heritage. Retrieved 2007-01-13.
^. Alaska Science Forum. Archived from the original on 2012-04-19. Retrieved 2007-01-07.
^Siegert, Martin J. (1999). "Antarctica's Lake Vostok". American Scientist. 87 (6): 510. Bibcode:1999AmSci..87..510S. doi:10.1511/1999.6.510. S2CID 209833822. The best explanation is that Lake Vostok may lie in a rift valley, as does Lake Tanganyika in East Africa and Lake Baikal in Russia. The geography of Lake Vostok is indeed consistent with this notion, in that the lake has a crescent shape, just like Tanganyika and Baikal, and the side walls of the lake are relatively steep, at least on one side.
^John Grotzinger .... (2006). Understanding Earth. New York: W. H. Freeman. ISBN0-7167-7696-0.
^Anderson, Scott; Grimm, Robert E. (1998). "Rift processes at the Valles Marineris, Mars: Constraints from gravity on necking and rate-dependent strength evolution". Journal of Geophysical Research. 103 (E5): 11113. Bibcode:1998JGR...10311113A. doi:10.1029/98JE00740. ISSN 0148-0227.
^Andrews-Hanna, Jeffrey C. (2012). "The formation of Valles Marineris: 3. Trough formation through super-isostasy, stress, sedimentation, and subsidence". Journal of Geophysical Research. 117 (E6): n/a. Bibcode:2012JGRE..117.6002A. doi:10.1029/2012JE004059. ISSN 0148-0227.
^Kiefer, W. S.; Swafford, L. C. (2006). "Topographic Analysis Of Devana Chasma, Venus; Implications For Rift System Segmentation And Propagation". Journal of Structural Geology. 28 (12): 2144–2155. Bibcode:2006JSG....28.2144K. doi:10.1016/j.jsg.2005.12.002.
^Senske, D. A.; Schaber, G. G.; Stofan, E. R. (1992). "Regional topographic rises on Venus: Geology of Western Eistla Regio and comparison to Beta Regio and Atla Regio". Journal of Geophysical Research. 97 (E8): 13395. Bibcode:1992JGR....9713395S. doi:10.1029/92JE01167. ISSN 0148-0227.
^Solomon, Sean C.; Smrekar, Suzanne E.; Bindschadler, Duane L.; Grimm, Robert E.; Kaula, William M.; McGill, George E.; Phillips, Roger J.; Saunders, R. Stephen; Schubert, Gerald; Squyres, Steven W.; Stofan, Ellen R. (1992). "Venus tectonics: An overview of Magellan observations". Journal of Geophysical Research. 97 (E8): 13199. Bibcode:1992JGR....9713199S. doi:10.1029/92JE01418. ISSN 0148-0227. S2CID 129537658.
^Dunn, Marcia (16 July 2015). "'Blowing my mind': Peaks on Pluto, canyons on Charon". PhysOrg.
^Andrews-Hanna, Jeffrey C.; Besserer, Jonathan; Head III, James W.; Howett, Carly J. A.; Kiefer, Walter S.; Lucey, Paul J.; McGovern, Patrick J.; Melosh, H. Jay; Neumann, Gregory A.; Phillips, Roger J.; Schenk, Paul M.; Smith, David E.; Solomon, Sean C.; Zuber, Maria T. (2014). "Structure and evolution of the lunar Procellarum region as revealed by GRAIL gravity data". Nature. 514 (7520): 68–71. Bibcode:2014Natur.514...68A. doi:10.1038/nature13697. ISSN 0028-0836. PMID 25279919. S2CID 4452730.
^ Chaikin, Andrew (2001-10-16). . space.com. Imaginova Corp. p. 1. Archived from the original on July 9, 2008. Retrieved 2007-07-23.
^ Smith, B. A.; Soderblom, L. A.; Beebe, A.; Bliss, D.; Boyce, J. M.; Brahic, A.; Briggs, G. A.; Brown, R. H.; Collins, S. A. (4 July 1986). "Voyager 2 in the Uranian System: Imaging Science Results". Science. 233 (4759): 43–64. Bibcode:1986Sci...233...43S. doi:10.1126/science.233.4759.43. PMID 17812889. S2CID 5895824.
Further readingedit
Bonatti, E (1985). "Punctiform initiation of seafloor spreading in the Red Sea during transition from a continental to an oceanic rift". Nature. 316 (6023): 33–37. Bibcode:1985Natur.316...33B. doi:10.1038/316033a0. S2CID 4355790.
Mart, Y.; Dauteuil, O. (2000). "Analogue experiments of propagation of oblique rifts". Tectonophysics. 316 (1–2): 121–132. Bibcode:2000Tectp.316..121M. doi:10.1016/s0040-1951(99)00231-0.
February 16, 2024
rift, valley, other, uses, disambiguation, confused, with, rift, zone, rift, valley, linear, shaped, lowland, between, several, highlands, mountain, ranges, produced, action, geologic, rift, rifts, formed, result, pulling, apart, lithosphere, extensional, tect. For other uses see Rift valley disambiguation Not to be confused with Rift zone A rift valley is a linear shaped lowland between several highlands or mountain ranges produced by the action of a geologic rift Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics The linear depression may subsequently be further deepened by the forces of erosion More generally the valley is likely to be filled with sedimentary deposits derived from the rift flanks and the surrounding areas In many cases rift lakes are formed One of the best known examples of this process is the East African Rift 1 On Earth rifts can occur at all elevations from the sea floor to plateaus and mountain ranges in continental crust or in oceanic crust They are often associated with a number of adjoining subsidiary or co extensive valleys which are typically considered part of the principal rift valley geologically African Rift Valley From left to right Lake Upemba Lake Mweru Lake Tanganyika largest and Lake Rukwa A rift valley near Quilotoa Ecuador The Ottawa Bonnechere GrabenTHingvallavatn Contents 1 Earth s rift valleys 1 1 Rift valley lakes 2 Extraterrestrial rift valleys 3 References 3 1 Further readingEarth s rift valleys editThe most extensive rift valley is located along the crest of the mid ocean ridge system and is the result of sea floor spreading Examples of this type of rift include the Mid Atlantic Ridge and the East Pacific Rise Many existing continental rift valleys are the result of a failed arm aulacogen of a triple junction although there are two the East African Rift and the Baikal Rift Zone which are currently active as well as a third which may be the West Antarctic Rift System In these instances not only the crust but entire tectonic plates are in the process of breaking apart forming new plates If they continue continental rifts will eventually become oceanic rifts Other rift valleys are the result of bends or discontinuities in horizontally moving strike slip faults When these bends or discontinuities are in the same direction as the relative motions along the fault extension occurs For example for a right lateral moving fault a bend to the right will result in stretching and consequent subsidence in the area of the irregularity In the view of many geologists today the Dead Sea lies in a rift which results from a leftward discontinuity in the left lateral moving Dead Sea Transform fault Where a fault breaks into two strands or two faults run close to each other crustal extension may also occur between them as a result of differences in their motions Both types of fault caused extension commonly occur on a small scale producing such features as sag ponds or landslides Rift valley lakes edit Main article Rift lake Many of the world s largest lakes are located in rift valleys 2 Lake Baikal in Siberia a World Heritage Site 3 lies in an active rift valley Baikal is both the deepest lake in the world and with 20 of all of the liquid freshwater on earth has the greatest volume 4 Lake Tanganyika second by both measures is in the Albertine Rift the westernmost arm of the active East African Rift Lake Superior in North America the largest freshwater lake by area lies in the ancient and dormant Midcontinent Rift The largest subglacial lake Lake Vostok may also lie in an ancient rift valley 5 Lake Nipissing and Lake Timiskaming in Ontario and Quebec Canada lie inside a rift valley called the Ottawa Bonnechere Graben 6 THingvallavatn Iceland s largest natural lake is also an example of a rift lake Extraterrestrial rift valleys editRift valleys are also known to occur on other terrestrial planets and natural satellites The 4 000 km long Valles Marineris on Mars is believed by planetary geologists to be a large rift system 7 8 Some features of Venus most notably the 4 000 km Devana Chasma 9 and a part of the western Eistla and possibly also Alta and Bell Regio have been interpreted by some planetary geologists as rift valleys 10 11 Some natural satellites also have prominent rift valleys The 2 000 km long Ithaca Chasma on Tethys in the Saturn system is a prominent example Charon s Nostromo Chasma is the first confirmed in the Pluto system however large chasms up to 950 km wide observed on Charon have also been tentatively interpreted by some as giant rifts and similar formations have also been noted on Pluto 12 A recent study suggests a complex system of ancient lunar rift valleys including Vallis Rheita and Vallis Alpes 13 The Uranus system also has prominent examples with large chasma believed to be giant rift valley systems most notably the 1492 km long Messina Chasma on Titania 622 km Kachina Chasmata on Ariel Verona Rupes on Miranda 14 and Mommur Chasma on Oberon 15 References edit The Ethiopian Rift Valley Giacomo Corti CNR The World s Greatest Lakes Archived from the original on 2020 06 19 Retrieved 2020 06 18 Lake Baikal World Heritage Site World Heritage Retrieved 2007 01 13 The Oddities of Lake Baikal Alaska Science Forum Archived from the original on 2012 04 19 Retrieved 2007 01 07 Siegert Martin J 1999 Antarctica s Lake Vostok American Scientist 87 6 510 Bibcode 1999AmSci 87 510S doi 10 1511 1999 6 510 S2CID 209833822 The best explanation is that Lake Vostok may lie in a rift valley as does Lake Tanganyika in East Africa and Lake Baikal in Russia The geography of Lake Vostok is indeed consistent with this notion in that the lake has a crescent shape just like Tanganyika and Baikal and the side walls of the lake are relatively steep at least on one side John Grotzinger 2006 Understanding Earth New York W H Freeman ISBN 0 7167 7696 0 Anderson Scott Grimm Robert E 1998 Rift processes at the Valles Marineris Mars Constraints from gravity on necking and rate dependent strength evolution Journal of Geophysical Research 103 E5 11113 Bibcode 1998JGR 10311113A doi 10 1029 98JE00740 ISSN 0148 0227 Andrews Hanna Jeffrey C 2012 The formation of Valles Marineris 3 Trough formation through super isostasy stress sedimentation and subsidence Journal of Geophysical Research 117 E6 n a Bibcode 2012JGRE 117 6002A doi 10 1029 2012JE004059 ISSN 0148 0227 Kiefer W S Swafford L C 2006 Topographic Analysis Of Devana Chasma Venus Implications For Rift System Segmentation And Propagation Journal of Structural Geology 28 12 2144 2155 Bibcode 2006JSG 28 2144K doi 10 1016 j jsg 2005 12 002 Senske D A Schaber G G Stofan E R 1992 Regional topographic rises on Venus Geology of Western Eistla Regio and comparison to Beta Regio and Atla Regio Journal of Geophysical Research 97 E8 13395 Bibcode 1992JGR 9713395S doi 10 1029 92JE01167 ISSN 0148 0227 Solomon Sean C Smrekar Suzanne E Bindschadler Duane L Grimm Robert E Kaula William M McGill George E Phillips Roger J Saunders R Stephen Schubert Gerald Squyres Steven W Stofan Ellen R 1992 Venus tectonics An overview of Magellan observations Journal of Geophysical Research 97 E8 13199 Bibcode 1992JGR 9713199S doi 10 1029 92JE01418 ISSN 0148 0227 S2CID 129537658 Dunn Marcia 16 July 2015 Blowing my mind Peaks on Pluto canyons on Charon PhysOrg Andrews Hanna Jeffrey C Besserer Jonathan Head III James W Howett Carly J A Kiefer Walter S Lucey Paul J McGovern Patrick J Melosh H Jay Neumann Gregory A Phillips Roger J Schenk Paul M Smith David E Solomon Sean C Zuber Maria T 2014 Structure and evolution of the lunar Procellarum region as revealed by GRAIL gravity data Nature 514 7520 68 71 Bibcode 2014Natur 514 68A doi 10 1038 nature13697 ISSN 0028 0836 PMID 25279919 S2CID 4452730 Chaikin Andrew 2001 10 16 Birth of Uranus provocative moon still puzzles scientists space com Imaginova Corp p 1 Archived from the original on July 9 2008 Retrieved 2007 07 23 Smith B A Soderblom L A Beebe A Bliss D Boyce J M Brahic A Briggs G A Brown R H Collins S A 4 July 1986 Voyager 2 in the Uranian System Imaging Science Results Science 233 4759 43 64 Bibcode 1986Sci 233 43S doi 10 1126 science 233 4759 43 PMID 17812889 S2CID 5895824 Further reading edit Bonatti E 1985 Punctiform initiation of seafloor spreading in the Red Sea during transition from a continental to an oceanic rift Nature 316 6023 33 37 Bibcode 1985Natur 316 33B doi 10 1038 316033a0 S2CID 4355790 Mart Y Dauteuil O 2000 Analogue experiments of propagation of oblique rifts Tectonophysics 316 1 2 121 132 Bibcode 2000Tectp 316 121M doi 10 1016 s0040 1951 99 00231 0 Retrieved from https en wikipedia org w index php title Rift valley amp oldid 1182047766, wikipedia, wiki, book, books, library,
