TheGakkel Ridge(formerly known as theNansen CordilleraandArctic Mid-Ocean Ridge)[1]is amid-oceanic ridge,a divergenttectonicplate boundary between theNorth American Plateand theEurasian Plate.[2]It is located in theEurasian Basinof theArctic Ocean,betweenGreenlandandSiberia.Geologically, it connects the northern end of theMid-Atlantic Ridgewith theLaptev Sea Rift.
History
editThe existence and approximate location of the Gakkel Ridge were predicted bySovietpolar explorerYakov Yakovlevich Gakkeland confirmed on Soviet expeditions in the Arctic around 1950. The Ridge is named after him, and the name was recognized in April 1987 bySCUFN(under that body's old name, the Sub-Committee on Geographical Names and Nomenclature of Ocean Bottom Features).[1]
Until 1999, it was believed to be non-volcanic; that year, scientists operating from a nuclear submarine discovered activevolcanoesalong it. The largest, theGakkel Ridge Caldera,is asupervolcanothat erupted approximately 1.1 million years ago during thePleistocene.[3]In 2001 two research icebreakers, the GermanPolarsternand the AmericanHealy,with several groups of scientists, cruised to the Gakkel Ridge to explore it and collect petrological samples. Among other discoveries, this expedition found evidence ofhydrothermal vents.In 2007,Woods Hole Oceanographic Institutionconducted the "Arctic Gakkel Vents Expedition" (AGAVE), which made some unanticipated discoveries, including the unconsolidated fragmentedpyroclasticvolcanic deposits that cover the axial valley of the ridge (whose area is greater than 10 km2). These suggest volatile substances in concentrations ten times those in the magmas of normal mid-ocean ridges.[4]Using "free-swimming"robotic submersibleson the Gakkel ridge, the AGAVE expedition also discovered what they called "bizarre 'mats' of microbial communities containing a half dozen or more new species".[5]A hydrothermal site, named "Aurora", was discovered in 2014.[6][7]Aurora has elevated levels ofmethaneand high temperatures, suggesting interactions between water andultramaficrock below the vent field (rather thanbasaltreactions). Aurora's geochemistry may resemble that of theRainbow Vent Fieldin the Atlantic Ocean.
Geology
edit
The Gakkel Ridge is approximately 1,800 kilometres (1,100 mi) long and is the slowest known spreading ridge on earth, with a rate of less than one centimeter per year. It continues to the south and connects with the Knipovich Ridge.[8]
The Gakkel ridge is not offset by anytransform faults.The ridge does have segments with variable orientation and varying degrees of volcanism: the Western Volcanic Zone From the Lena trough (7° W, to 3° E longitude), the Sparsely Magmatic Zone (from 3° E to 29° E longitude), and the Eastern Magmatic Zone (from 29° E to 89°E).[9]The gaps of volcanic activity imply very cold crust and mantle, probably related to the very low spreading rate, but it is not yet known why some parts of the ridge are more magmatic than others.[10]Some earthquakes have been detected from the mantle, below the crust, which is very unusual for a mid-ocean ridge.[11]It confirms that the mantle and crust of Gakkel ridge, like some segments of theSouthwest Indian Ridge,are very cold.
Hydrothermal Activity
editThe Gakkel ridge features several confirmed and inferred hydrothermal fields, including Aurora (visually confirmed in 2014) and Lucky B (dredged in 2001).[12][13][14]More sites have been inferred, but not confirmed due to difficulties with ice at higher latitudes.
See also
editReferences
edit- ^ab"IHO-IOC GEBCO Gazetteer"(PDF).International Hydrographic Organization/Intergovernmental Oceanographic Commission.September 2007. Archived fromthe original(PDF)on 2008-09-11.Retrieved2008-05-24.
- ^"GPS Measurements Reveal Imprint of North American Plate in Siberia".Earth Institute at Columbia University.11 November 2003.
- ^Piskarev, Alexey; Elkina, Daria (10 April 2017)."Giant caldera in the Arctic Ocean: Evidence of the catastrophic eruptive event".Scientific Reports.7(1): 46248.Bibcode:2017NatSR...746248P.doi:10.1038/srep46248.PMC5385544.PMID28393928.
- ^Sohn, Robert A.; Willis, Claire; Humphris, Susan; Shank, Timothy M.; Singh, Hanumant; Edmonds, Henrietta N.; Kunz, Clayton; Hedman, Ulf; Helmke, Elisabeth; Jakuba, Michael; Liljebladh, Bengt; Linder, Julia; Murphy, Christopher; Nakamura, Ko-ichi; Sato, Taichi; Schlindwein, Vera; Stranne, Christian; Tausenfreund, Maria; Upchurch, Lucia; Winsor, Peter; Jakobsson, Martin; Soule, Adam (June 2008). "Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean".Nature.453(7199): 1236–1238.Bibcode:2008Natur.453.1236S.doi:10.1038/nature07075.hdl:1912/2636.PMID18580949.S2CID205213845.
- ^http:// ridge2000.org/dls/abstracts.phpArchived2008-09-05 at theWayback Machine"The Arctic Gakkel Vents (AGAVE) Expedition: A High–Stakes Technology Gamble Pays Big Dividends Beneath the Arctic Ice Cap", Ridge 2000 Abstracts 2009
- ^"Arctic Hydrothermal Vent Site Could Help in Search for Extraterrestrial Life".whoi.edu/.
- ^"Aurora: InterRidge Vents Database Ver. 3.4".vents-data.interridge.org.
- ^Zarayskaya, Yu. A. (March 2017). "Segmentation and seismicity of the ultraslow Knipovich and Gakkel mid-ocean ridges".Geotectonics.51(2): 163–175.Bibcode:2017Geote..51..163Z.doi:10.1134/S0016852117010095.
- ^Michael, P. J.; Langmuir, C. H.; Dick, H. J. B.; Snow, J. E.; Goldstein, S. L.; Graham, D. W.; Lehnert, K.; Kurras, G.; Jokat, W.; Mühe, R.; Edmonds, H. N. (June 2003). "Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge, Arctic Ocean".Nature.423(6943): 956–961.Bibcode:2003Natur.423..956M.doi:10.1038/nature01704.PMID12827193.S2CID4312652.
- ^Montési, Laurent G. J.; Behn, Mark D. (25 December 2007). "Mantle flow and melting underneath oblique and ultraslow mid-ocean ridges".Geophysical Research Letters.34(24): L24307.Bibcode:2007GeoRL..3424307M.doi:10.1029/2007GL031067.hdl:1912/3347.
- ^Schlindwein, Vera; Demuth, Andrea; Korger, Edith; Läderach, Christine; Schmid, Florian (March 2015)."Seismicity of the Arctic mid-ocean Ridge system".Polar Science.9(1): 146–157.Bibcode:2015PolSc...9..146S.doi:10.1016/j.polar.2014.10.001.
- ^"Vent Fields".vents-data.interridge.org.
- ^Ramirez-Llodra, Eva; Argentino, Claudio; Baker, Maria; Boetius, Antje; Costa, Carolina; Dahle, Håkon; Denny, Emily; Dessandier, Pierre-Antoine; Eilertsen, Mari; Ferre, Benedicte; German, Christopher; Hand, Kevin; Hilário, Ana; Hislop, Lawrence; Jamieson, John; Kalnitchenko, Dimitri; Mall, Achim; Panieri, Giuliana; Purser, Autun; Ramalho, Sofia; Reeves, Eoghan; Rolley, Leighton; Pereira, Samuel; Ribeiro, Pedro; Fatih Sert, Muhammed; Steen, Ida; Stetzler, Marie; Stokke, Runar; Victorero, Lissette; Vulcano, Francesca; Vågenes, Stig; Waghorn, Kate; Buenz, Stefan (1 March 2023)."Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed".Oceanography.36(1): 6.Bibcode:2023Ocgry..36....6R.doi:10.5670/oceanog.2023.103.hdl:10037/27685.
- ^Snow, J.; Hellebrand, E.; Jokat, W.; Muhe, R. (2001)."Magmatic and hydrothermal activity in Lena Trough, Arctic Ocean".Eos, Transactions American Geophysical Union.82(17): 193.Bibcode:2001EOSTr..82Q.193S.doi:10.1029/01EO00101.
Further reading
edit- Jokat, Wilfried; Schmidt-Aursch, Mechita C. (March 2007)."Geophysical characteristics of the ultraslow spreading Gakkel Ridge, Arctic Ocean".Geophysical Journal International.168(3): 983–998.Bibcode:2007GeoJI.168..983J.doi:10.1111/j.1365-246X.2006.03278.x.
- Edmonds, H. N.; Michael, P. J.; Baker, E. T.; Connelly, D. P.; Snow, J. E.; Langmuir, C. H.; Dick, H. J. B.; Mühe, R.; German, C. R.; Graham, D. W. (January 2003). "Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean".Nature.421(6920): 252–256.Bibcode:2003Natur.421..252E.doi:10.1038/nature01351.PMID12529639.S2CID4392497.
External links
edit- "Arctic Seafloor Expedition: July 1-Aug. 10, 2007".Polar Discovery.
- "AMORE 2001: Arctic Ocean".Archived fromthe originalon 3 August 2003.
- "No hole at the Pole".Geology News.17 October 2001. Archived fromthe originalon 14 May 2003.
- "NOAA SCIENTIST AND COLLEAGUES FIND HOT SPRINGS IN COLD WATERS"(Press release). NOAA. 15 January 2003. Archived fromthe originalon 10 February 2003.
- Lindsay, Jay (22 June 2007)."Robots to look for life in Arctic".NBC News.The Associated Press.[dead link]
- Watson, Kristen (1 March 2001)."Evidence of Recent Volcanic Activity Found Along the Slow-Spreading Gakkel Ridge".Earth Institute at Columbia University.