Gakkel Ridge

The existence and approximate location of the Gakkel Ridge were predicted by Soviet polar explorer Yakov Yakovlevich Gakkel and confirmed on Soviet expeditions in the Arctic around 1950. The Ridge is named after him, and the name was recognized in April 1987 by SCUFN (under that body's old name, the Sub-Committee on Geographical Names and Nomenclature of Ocean Bottom Features).

Until 1999, it was believed to be non-volcanic; that year, scientists operating from a nuclear submarine discovered active volcanoes along it. The largest, the Gakkel Ridge Caldera, is a supervolcano that erupted approximately 1.1 million years ago during the Pleistocene.{{cite journal |last1=Piskarev |first1=Alexey |last2=Elkina |first2=Daria |title=Giant caldera in the Arctic Ocean: Evidence of the catastrophic eruptive event |journal=Scientific Reports |date=10 April 2017 |volume=7 |issue=1 |pages=46248 |doi=10.1038/srep46248 |pmid=28393928 |pmc=5385544 |bibcode=2017NatSR...746248P }} In 2001 two research icebreakers, the German Polarstern and the American Healy, with several groups of scientists, cruised to the Gakkel Ridge to explore it and collect petrological samples. Among other discoveries, this expedition found evidence of hydrothermal vents. In 2007, Woods Hole Oceanographic Institution conducted the "Arctic Gakkel Vents Expedition" (AGAVE), which made some unanticipated discoveries, including the unconsolidated fragmented pyroclastic volcanic 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.{{cite journal |last1=Sohn |first1=Robert A. |last2=Willis |first2=Claire |last3=Humphris |first3=Susan |last4=Shank |first4=Timothy M. |last5=Singh |first5=Hanumant |last6=Edmonds |first6=Henrietta N. |last7=Kunz |first7=Clayton |last8=Hedman |first8=Ulf |last9=Helmke |first9=Elisabeth |last10=Jakuba |first10=Michael |last11=Liljebladh |first11=Bengt |last12=Linder |first12=Julia |last13=Murphy |first13=Christopher |last14=Nakamura |first14=Ko-ichi |last15=Sato |first15=Taichi |last16=Schlindwein |first16=Vera |last17=Stranne |first17=Christian |last18=Tausenfreund |first18=Maria |last19=Upchurch |first19=Lucia |last20=Winsor |first20=Peter |last21=Jakobsson |first21=Martin |last22=Soule |first22=Adam |title=Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean |journal=Nature |date=June 2008 |volume=453 |issue=7199 |pages=1236–1238 |doi=10.1038/nature07075 |pmid=18580949 |bibcode=2008Natur.453.1236S |hdl=1912/2636 |s2cid=205213845 |hdl-access=free }} Using "free-swimming" robotic submersibles on the Gakkel ridge, the AGAVE expedition also discovered what they called "bizarre 'mats' of microbial communities containing a half dozen or more new species".http://www.ridge2000.org/dls/abstracts.php {{Webarchive|url=https://web.archive.org/web/20080905103630/http://ridge2000.org/dls/abstracts.php |date=2008-09-05 }} "The Arctic Gakkel Vents (AGAVE) Expedition: A High–Stakes Technology Gamble Pays Big Dividends Beneath the Arctic Ice Cap", Ridge 2000 Abstracts 2009 A hydrothermal site, named "Aurora", was discovered in 2014.{{cite web |title=Arctic Hydrothermal Vent Site Could Help in Search for Extraterrestrial Life |url=https://www.whoi.edu/press-room/news-release/arctic-hydrothermal-vent-site-could-help-in-search-for-extraterrestrial-life/ |website=www.whoi.edu/}}{{cite web |title=Aurora: InterRidge Vents Database Ver. 3.4 |url=https://vents-data.interridge.org/ventfield/aurora |website=vents-data.interridge.org |language=en}} Aurora has elevated levels of methane and high temperatures, suggesting interactions between water and ultramafic rock below the vent field (rather than basalt reactions). Aurora's geochemistry may resemble that of the Rainbow Vent Field in the Atlantic Ocean.

File:Awi-Pillowlava hg.jpg from the Gakkel Ridge]]

The Gakkel Ridge is approximately {{convert|1800|km|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.{{cite journal |last1=Zarayskaya |first1=Yu. A. |title=Segmentation and seismicity of the ultraslow Knipovich and Gakkel mid-ocean ridges |journal=Geotectonics |date=March 2017 |volume=51 |issue=2 |pages=163–175 |doi=10.1134/S0016852117010095|bibcode=2017Geote..51..163Z }}

The Gakkel ridge is not offset by any transform 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).{{cite journal |last1=Michael |first1=P. J. |last2=Langmuir |first2=C. H. |last3=Dick |first3=H. J. B. |last4=Snow |first4=J. E. |last5=Goldstein |first5=S. L. |last6=Graham |first6=D. W. |last7=Lehnert |first7=K. |last8=Kurras |first8=G. |last9=Jokat |first9=W. |last10=Mühe |first10=R. |last11=Edmonds |first11=H. N. |title=Magmatic and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge, Arctic Ocean |journal=Nature |date=June 2003 |volume=423 |issue=6943 |pages=956–961 |doi=10.1038/nature01704 |pmid=12827193 |bibcode=2003Natur.423..956M |s2cid=4312652 }} 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.{{cite journal |last1=Montési |first1=Laurent G. J. |last2=Behn |first2=Mark D. |title=Mantle flow and melting underneath oblique and ultraslow mid-ocean ridges |journal=Geophysical Research Letters |date=25 December 2007 |volume=34 |issue=24 |pages=L24307 |doi=10.1029/2007GL031067 |bibcode=2007GeoRL..3424307M |hdl=1912/3347 |hdl-access=free }} Some earthquakes have been detected from the mantle, below the crust, which is very unusual for a mid-ocean ridge.{{cite journal |last1=Schlindwein |first1=Vera |last2=Demuth |first2=Andrea |last3=Korger |first3=Edith |last4=Läderach |first4=Christine |last5=Schmid |first5=Florian |title=Seismicity of the Arctic mid-ocean Ridge system |journal=Polar Science |date=March 2015 |volume=9 |issue=1 |pages=146–157 |doi=10.1016/j.polar.2014.10.001 |bibcode=2015PolSc...9..146S |doi-access=free }} It confirms that the mantle and crust of Gakkel ridge, like some segments of the Southwest Indian Ridge, are very cold.

The Gakkel ridge features several confirmed and inferred hydrothermal fields, including Aurora (visually confirmed in 2014) and Lucky B (dredged in 2001).{{cite web |title=Vent Fields |url=https://vents-data.interridge.org/ |website=vents-data.interridge.org}}{{cite journal |last1=Ramirez-Llodra |first1=Eva |last2=Argentino |first2=Claudio |last3=Baker |first3=Maria |last4=Boetius |first4=Antje |last5=Costa |first5=Carolina |last6=Dahle |first6=Håkon |last7=Denny |first7=Emily |last8=Dessandier |first8=Pierre-Antoine |last9=Eilertsen |first9=Mari |last10=Ferre |first10=Benedicte |last11=German |first11=Christopher |last12=Hand |first12=Kevin |last13=Hilário |first13=Ana |last14=Hislop |first14=Lawrence |last15=Jamieson |first15=John |last16=Kalnitchenko |first16=Dimitri |last17=Mall |first17=Achim |last18=Panieri |first18=Giuliana |last19=Purser |first19=Autun |last20=Ramalho |first20=Sofia |last21=Reeves |first21=Eoghan |last22=Rolley |first22=Leighton |last23=Pereira |first23=Samuel |last24=Ribeiro |first24=Pedro |last25=Fatih Sert |first25=Muhammed |last26=Steen |first26=Ida |last27=Stetzler |first27=Marie |last28=Stokke |first28=Runar |last29=Victorero |first29=Lissette |last30=Vulcano |first30=Francesca |last31=Vågenes |first31=Stig |last32=Waghorn |first32=Kate |last33=Buenz |first33=Stefan |title=Hot Vents Beneath an Icy Ocean: The Aurora Vent Field, Gakkel Ridge, Revealed |journal=Oceanography |date=1 March 2023 |volume=36 |issue=1 |page=6 |doi=10.5670/oceanog.2023.103|doi-access=free |bibcode=2023Ocgry..36....6R |hdl=10037/27685 |hdl-access=free }}{{cite journal |last1=Snow |first1=J. |last2=Hellebrand |first2=E. |last3=Jokat |first3=W. |last4=Muhe |first4=R. |title=Magmatic and hydrothermal activity in Lena Trough, Arctic Ocean |journal=Eos, Transactions American Geophysical Union |date=2001 |volume=82 |issue=17 |pages=193 |doi=10.1029/01EO00101|doi-access=free |bibcode=2001EOSTr..82Q.193S }} More sites have been inferred, but not confirmed due to difficulties with ice at higher latitudes.

• Balagan-Tas
• Lomonosov Ridge

{{Reflist}}

{{Refbegin}}

• {{cite journal |last1=Jokat |first1=Wilfried |last2=Schmidt-Aursch |first2=Mechita C. |title=Geophysical characteristics of the ultraslow spreading Gakkel Ridge, Arctic Ocean |journal=Geophysical Journal International |date=March 2007 |volume=168 |issue=3 |pages=983–998 |doi=10.1111/j.1365-246X.2006.03278.x |bibcode=2007GeoJI.168..983J |doi-access=free }}
• {{cite journal |last1=Edmonds |first1=H. N. |last2=Michael |first2=P. J. |last3=Baker |first3=E. T. |last4=Connelly |first4=D. P. |last5=Snow |first5=J. E. |last6=Langmuir |first6=C. H. |last7=Dick |first7=H. J. B. |last8=Mühe |first8=R. |last9=German |first9=C. R. |last10=Graham |first10=D. W. |title=Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean |journal=Nature |date=January 2003 |volume=421 |issue=6920 |pages=252–256 |doi=10.1038/nature01351 |pmid=12529639 |bibcode=2003Natur.421..252E |s2cid=4392497 }}

{{Refend}}

• {{cite web |title=Arctic Seafloor Expedition: July 1-Aug. 10, 2007 |url=http://polardiscovery.whoi.edu/expedition2/index.html |website=Polar Discovery }}
• {{cite web |archive-url=https://web.archive.org/web/20030803025730/http://diotima.mpch-mainz.mpg.de/~geo/Arctic/index.html |title=AMORE 2001: Arctic Ocean |archive-date=3 August 2003 |url=http://diotima.mpch-mainz.mpg.de/~geo/Arctic/index.html }}
• {{cite web |archive-url=https://web.archive.org/web/20030514042609/http://www.geolsoc.org.uk/template.cfm?name=Gakkel |title=No hole at the Pole |website=Geology News |date=17 October 2001 |archive-date=14 May 2003 |url=http://www.geolsoc.org.uk/template.cfm?name=Gakkel }}
• {{cite press release |url=http://www.noaanews.noaa.gov/stories/s1081.htm |title=NOAA SCIENTIST AND COLLEAGUES FIND HOT SPRINGS IN COLD WATERS |archive-url=https://web.archive.org/web/20030210035032/http://www.noaanews.noaa.gov/stories/s1081.htm |archive-date=10 February 2003 |date=15 January 2003 |publisher=NOAA }}
• {{cite news |last1=Lindsay |first1=Jay |title=Robots to look for life in Arctic |url=https://www.nbcnews.com/id/wbna19370252 |work=NBC News |agency=The Associated Press |date=22 June 2007 }}{{dead link|date=August 2024|bot=medic}}{{cbignore|bot=medic}}
• {{cite web |url=http://www.earthinstitute.columbia.edu/news/story2_4_01.html |first1=Kristen |last1=Watson |date=1 March 2001 |title=Evidence of Recent Volcanic Activity Found Along the Slow-Spreading Gakkel Ridge |website=Earth Institute at Columbia University }}

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Category:Underwater ridges of the Arctic Ocean