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As a result, the Knipovich Ridge is characterized by Underlapping magma centers, with long oblique rifts.This style of basin-dominated segmentation probably evolved in a simple shear detachment . Bathymetric map of the northern part of the Norwegian-Greenland seas and the continental margins, showing the mineral Knipovich and Mohn Ridges. The 1984 survey presented in this paper provided a complete set of bathymetric data from the southernmost section of the Svalbard Transform, including the Molloy Fracture Zone, connecting the Knipovich Ridge to the Molloy Ridge; and the Molloy Deep, a nodal basin formed at the intersection of the Molloy Transform Fault and the Molloy Ridge. The oceanic section exhibits zones of very thin crust (∼1 km) that are interpreted as fracture zones. 86 Subplatform formed as a down-faulted portion of the Selis Ridge in the early to mid-Triassic 87 (Gabrielsen et al. Figure 2a. Senja fracture zones have caused other important transverse ridges to form (Fig . Shaded relief image of magnetic data (Verhoef et al., 1996 . The thickness of the magmatic portion of the crust formed along the Mohns Ridge at ca. rifted crust. boundary comprises the Knipovich Ridge in the Greenland Sea and the Gakkel Ridge in the Eurasia Basin, connected by the complex Spitsbergen Transform System of short ridges and transform faults (Figure 1). The NOAM-EUR plate boundary continues south from the GR though the Fram Strait (east of northernmost Greenland) to the Knipovich Ridge (KR) and thence along the rest of the northern half of the Mid-Atlantic Ridge. Abbreviations: AR=Aegir Ridge, KR=Kolbeinsey Ridge, KnR=Knipovich Ridge, MR=Mohns Ridge, RR=Reyknanes Ridge, EJMFZ=East . The around 500 km long transform free ridge is bound to the north by the Molloy transform fault. while the Norwegian-Greenland Sea marks the western boundary. It lies at the northern extremity of the Pacific spreading axis. (2009) into a magmatic- and a tectonic-dominated part. Mid-Ocean Ridges are geologically strong, with developed magma endless originating onto the ocean floor and into the crust at and near rifts along the ridge axes. In the other end-member model, melt production is normal, but a similar but much thinner lid hampers melt migration to the surface 15. The pole of relative motion between these plates is located in Siberia [17], so the full spreading rate decreases northward from 18 mm/yr on the Kolbeinsey Ridge to less than 10 mm/yr on the eastern Gakkel Ridge. This engine splutters at very low speeds: Isolated volcanoes, capable of vigorous eruptions . A) The Svyatogor Ridge is a 46 km long, ~5 km wide feature at the intersection between the Molloy Transform Fault (MTF) and the Knipovich Ridge (KR). Only in the northernmost cases are some of these off-axial ridges non-linear. In most cases the spreading direction at a divergent boundary is perpendicular to the ridge itself, but at the Knipovich ridge the direction is highly oblique. Knipovich Ridge (Bosse and Fer (2019), see satellite image in Fig. In addition, because no transform fault was detected between the Mohns and Knipovich ridges, we conclude that the Knipovich Ridge must be obliquely spreading to the NW-SE. Here, we present a 340-km-long seismic refraction line acquired during the expedition ARK-XXIV/3 of research vessel Polarstern in 2009, using 18 ocean bottom seismometers. The area is covered by sediments from the Bear Island Fan, and . spreading Knipovich Ridge. Six seismic multichannel profiles and multibeam bathymetric data were collected during 2000 and 2001 from the Mohn‐Knipovich spreading ridge bend in the Norwegian‐Greenland seas. Kolbeinsey Ridge - A segment of the Mid-Atlantic Ridge north of Iceland in the Arctic Ocean Knipovich Ridge - (between Greenland and Spitsbergen) Reykjanes Ridge - (south of Iceland) Mid oceanic ridge volcanoes The most volcanic activity takes place along the mid-ocean ridges. setting has been well known for its importance to paleoceanography, global climate and its ultra-slow mid-ocean ridge system (Knipovich and Molloy Ridges). B05408 MCADOO ET AL. a thick thermal boundary layer (lid) below the ridge axis that shuts off melt production down to 30 km or deeper. Six seismic multichannel profiles and multibeam bathymetric data were collected during 2000 and 2001 from the Mohn‐Knipovich spreading ridge bend in the Norwegian‐Greenland seas. The Aegir Ridge and the ridge underlying the Iceland continental margin are all inactive mid-oceanic ridges. Year of discovery: 1970. side of Knipovich Ridge, 8 mm/yr (Ehlers and Jokat, 2009). Accepted 2006 December 18. 3 km, which is normal for ultra slow spreading ridges. The North Atlantic Mid-Oceanic Ridge is a system of tectonically active fracture zones, ridge-segments and well as minor compressional zones that generate strike-slip earthquakes, normal fault earthquakes and some obliquely thrust fault earthquakes. A mid-ocean ridge demarcates the barrier between two tectonic plates and accordingly is termed a divergent plate boundary. 2010). The boundary between YP-2 and YP-3 lies at an estimated age of 2.7 Ma (Knies et al., 2009). The intracontinental portion of the boundary between the North American and Eurasian plates can be identified ort the basis of seismicity, recent tectonics, and earthquake focal mechanisms. To the south, the ridge axis bends into the Mohns Ridge. A schematic map of the north-east Atlantic, modified from Google Earth, illustrating key regional tectonic elements. Towards the east, it is bounded by the ultraslow mid-ocean Knipovich Ridge. The model depicts the general situation that such ridges are asymmetrical, i.e. (Tucholke et al., 1998; Tani . The model is forced by impos-ing a uniform heat loss north of the sill1 of 150 W m 2 for a period ractureF Zone, Mohns Ridge and lastly Knipovich Ridge together with Spitsbergen ractureF Zone. 1990). The degree of the non-linearities increases slightly with proximity to the Mohns-Knipovich bend. In addition, because no transform fault was detected between the Mohns and Knipovich ridges, we conclude that the Knipovich Ridge must be obliquely spreading to the NW-SE. 2; Talwani and Eldholm, 1977; Eldholm et al., 1990). We demonstrate that the IMU event is linked to onset of uplift and massive shelf-progradation on the NE Greenland margin. that one of the flanks of the axial rift valley The Mohn and Knipovich spreading ridges are in the category of slow-spreading ridges. The simplest plate geometry that can explain these data involves a North American-Eurasian boundary that extends from the Nansen ridge through a broad zone of deformation in northeast Asia to the Sea of . . The present plate boundary is composed from south to north of (1) Kolbeinsey Ridge, an unusually shallow accretion (spreading) axis roughly normal to the present spreading direction; (2) the Jan Mayen F. Z., a classic transform fault formed subsequent to the separation of Norway from Greenland; (3) Mohns Ridge, a spreading axis more or less It is classified as an ultra-slow spreading ridge (Dick et al., 1993). spreading ridge detachment faults form near the ridge axis and are believed to be active over a period of 1-4 m.y. These ridges resemble unique archives for the evolution and . The basal age of . About 75% of all volcanic activity on the planet takes place here. the Knipovich Ridge respectively, have trapped fluids, formed gas hydrate and developed active seepage systems associated with exceptional chemosynthetic communities. The Oceanic crust is formed of rocks much newer than the . 1998; Glørstad-Clark et al. Department of Mineral Deposits; (1987) and White (1988) most workers explain the Early Tertiary volcanism of the North Atlantic Igneous Province (NAIP) in terms of lithospheric impingement of the proto-Iceland mantle plume. 20 Ma decreases gradually to ca. Preliminary analysis of the Knipovich Ridge segmentation: influence of focused magmatism and ridge obliquity on an ultraslow spreading system events on the plate boundary north of Svalbard may have been related and two events on the Knipovich ridge may be related (Figure 2). Continuity from the Mohns Ridge rift valley into the rift valley of the Knipovich Ridge (Talwani and Eldholm, 1977) has been observed. (a) Schematic of the circulation in the Nordic seas and bathymetry. Knipovich Ridge is determined by dextral strike-slip displacements along the Molloy Fracture Zone (315 ° NW). CMR lists about twenty events as occurring in the Norwegian Sea between mid-February and mid-July whereas the QED lists 5 events It crosses the central Boreas Basin from the Knipovich Ridge to the Northeast Greenland margin. The Pacific-Antarctic Ridge is the southern extension of the East Pacific Rise. (b) Sea surface temperature (SST) Oceanic crust each side of the Knipovich Ridge is thin (∼3.5 km) and is characterised by the absence of oceanic layer 3 (3.5/4.1 to 4.7 km s−1). KnR: Knipovich Ridge. This stress field is superimposed by a system related to rifting and latitudinal opening. Thermal development and rejuvenation of the marginal plateaus. . Top insert (left) shows a geological profile from the Knipovich Ridge to the Kara Sea (A-A ). The curved stress trajectories create arcuate faults and subsiding elongate basins while focusing most of the volcanism through the boundary faults. By the middle Triassic the Selis Ridge became expressed as a 88 pronounced north-south striking, elongated structural high acting as a barrier to sediments 89 (Gudlaugsson et al. comprises the high-Arctic portion of the North American-Eurasian (NOAM-EUR) plate boundary. The role of the Spitsbergen shear zone in determining morphology, segmentation and evolution of the Knipovich Ridge. The axial crustal thickness on the central Mohns Ridge has been examined by both REE-inversion methods and seismic Geer Zone), and has formed the northward trending Knipovich Ridge, among the slowest spreading cen- ters in the world. Therefore,changes inthe properties and dynamics of the Nordic seas impact not only the local climate and over the Mohn Ridge. 1b). The BSR appears It is a relatively young divergent boundary and ridge in the Northern Mid-Atlantic Ridge system. Bathymetry image showing the crest of Southern Explorer Ridge. History: Named after the Russian Academician N. M. Knipovich (1862-1939), ichthyologist and hydro-biologist. By Nilgun Okay. In the sedimentary cover above the basement of the oceanic crust, we can distinguish several stratigraphic complexes, whose thicknesses increase toward the Barents-Kara continental margin. At mid-ocean ridges, the lithospheric plates drift apart, magma fills the gap to form new crust. The western flank is fringed with a deep sea basin which is several times wider. We explain the thermo-mechanical coupling and the deposition of contourites by the formation of a continuous plate boundary along the Mohns and Knipovich ridges, leading to an accelerated widening of the Fram Strait. . Figure 1. Only in the northernmost cases are some of these off-axial ridges non-linear. Its segmentation follows Bruvoll et al. Mid-Ocean Ridges are geologically strong, with developed magma endless originating onto the ocean floor and into the crust at and near rifts along the ridge axes. The 1984 survey presented in this paper provided a complete set of bathymetric data from the southernmost section of the Svalbard Transform, including the Molloy Fracture Zone, connecting the Knipovich Ridge to the Molloy Ridge; and the Molloy Deep, a nodal basin formed at the intersection of the Molloy Transform Fault and the Molloy Ridge. The bathymetry is also By Yuichi Nishimura. Ehlers and Jokat (2009) claimed that the Knipovich Ridge has been an ultraslow ridge throughout its history with no major changes in spreading rates. It is a segmented, sheared transform margin partly characterized by under-plating of thinned oceanic crust (Ritzmann et al., 2004) which may generate together with magmatic intrusions at the continent-ocean boundary a higher geothermal gradient (Vanneste et al. In this thesis, I synthesize my research on the seismicity of ultraslow spreading ridges describing the overarching theme of 10 peer-reviewed publications. The area is covered by sediments from the Bear Island Fan, and . In the Quater nary, the boundary of plate interaction along the ten sion crack has been straightened to form the contem porary Knipovich Ridge, which crosses the previously existing magmatic. 1. The presently active plate boundary is manifested successively from south to north as the Reykjanes Ridge, the Neovolcanic Zone of Iceland, the Kolbeinsey Ridge, the Mohns Ridge, and the Knipovich Ridge (Fig. We modelled the tectonic stress regime due to oblique spreading along the Molloy and Knipovich ridges to investigate whether spatial variations in the tectonic regime . Flickr photos, groups, and tags related to the "gakkel" Flickr tag. Plio-Pleistocene boundary which is at ca. The latter has a prominent central rift, 3200-3400 m deep, somewhat deeper than The Pacific-Antarctic Ridge (PAR) is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. 700 mbsf. common perception that the Greenland-Faroes Ridge is a hot spot track related to the Iceland plume, we consider it a symmetric construction that formed above an upper-mantle upwelling maintained at the plate boundary. The Explorer Ridge is a mid-ocean ridge, a divergent tectonic plate boundary located about 241 km (150 mi) west of Vancouver Island, British Columbia, Canada. than that found along the western boundary of the Greenland Sea between 12W and 5 W. There is also a 1200 m deep ridge that separates the marginal sea into two sub-basins, mimicking the Mohn and Knipovich ridge system. Given . The ridge is unaffected by any transform fault zones The axis is a detachment zone intersecting the oceanic basement having formed from the Late Oligocene. The Knipovich Ridge is a very young divergent plate boundary, built within the framework of the opening of the North Atlantic (Kokhan et al., 2012; Okino et al., 2002 ). The normal thickness of the crust . The ultraslow Gakkel Ridge seafloor spreading, at 0.3-0.7 cm/yr [Eld- holm et al., 1990], is the slowest of the global mid-oceanic Along a 73.5 N section [Mauritzen 1996, Figure 11] the AW is shallower and extends about 300 km offshore with a distinct Polar Front over the Knipovich Ridge. The map of their spatial distribution shows that the faults are grouped into domains a few tens of kilometers in size and are a result of superposition of several inequivalent geodynamic factors: the shear zone oriented parallel to the Hornsunn Fault and superposed on the . Coordinates in ACUF (en): Latitude: 76; Longitude: 7.5 : ACUF unique id (UFI) (en): -154042 : Relations Crustal transect from the North Atlantic Knipovich Ridge to the Svalbard Margin west of Hornsund. ridges in water depths of 1000-2000 m and exhibits a well-developed rift valley between 2600 and 3400 m (Perry, 1986). Preliminary analysis of the Knipovich Ridge segmentation: influence of focused magmatism and ridge obliquity on an ultraslow spreading system The Knipovich Ridge as it has been mentioned above, is drastically displaced eastward. For both sets, the two events occurred within a few minutes of each other. A wide variety of beliefs on the size and morphology of the plume exist, from a single point (e.g., Forsyth, 1986; Lawver & Müller . flow across the Greenland-Scotland Ridge into the Atlantic via the overflows and contribute to the lower limb of the Atlantic meridional overturning circulation (AMOC;DicksonandBrown1994;HansenandØsterhus 2000). A mid-ocean ridge demarcates the barrier between two tectonic plates and accordingly is termed a divergent plate boundary. Information on 8 felt earthquakes is available even on nearly uninhabited Canadian Arctic Archipelago. Directly to the north of the tip of the Knipovich The modern location of the axis of the Knipovich Ridge straightens the complicate divergent boundary between the plates in the strike-slip conditions between the spreading centers of the Mohns and Gakkel ridges. Due to the position of the Vestnesa Ridge with respect to the Molloy and Knipovich mid-ocean ridges, it has been suggested that seepage along the ridge has a tectonic control. There, massive volcanoes form, like Logachev Seamount that we examine in detail in this project. A widely accepted tectonic model for the plate separation process in such slow-spreading ridges is shown in this slide. Ridge extends roughly 550 km with an axial strike direction of 060° NE, has a full spreading rate of 16 mm/yr (Dubinin et al., 2013; Klingelhöfer et al., 2000) and represents the boundary between the Eurasian and North American plates (Dauteuil & Brun, 1993). The degree of the non-linearities increases slightly with proximity to the Mohns-Knipovich bend. The full spreading rate is slow to ultraslow (15-17 mm a−1), characterized by both magmatic and amagmatic spreading and lack of transform faults. Following White et al. and YP is just west of Svalbard. The Arctic Mid-ocean Ridge system extends northward from the MAR and is the boundary between the Eurasian and North American Plates. Awell-defined axial valley characterizes the ridges, with depth variations generally between 2 8 and 3 8km, increasing from the Jan Mayen area to the Knipovich Ridge (Crane et al., 2001; Hellevang, 2003). The Iceland anomaly through geological history. In total, 680 1-D . The full spreading rate is slow to ultraslow (15-17 mm a−1), characterized by both magmatic and amagmatic spreading and lack of transform faults. The walls of the Knipovich Ridge are complicated by normal and reverse faults revealed by a high-frequency profilograph. The Oceanic crust is formed of rocks much newer than the . The width of the oceanic basin between the Knipovich Ridge and the Spitsbergen continental slope does not exceed 100 km narrowing northward down to 20-30 km. In the following, we refer to the orthogonally spreading, central part of the ridge bend as the MKB, with southern boundary at 73.5°N and northern end at 73.83°N. These half-spreading . We interpret the increased magmatism as a passive response to the (extensional) bending of this southernmost part of the Knipovich Ridge. Several authors have proposed an unstable plate boundary north of GSFZ until Late Cenozoic time, when the ridge obtained the continuous, unsegmented structure observed today ( Engen et al., 2008 . Only very small amounts of melt form, the young ocean lithosphere is very cold and melt freezes so rapidly that it can only make its way to the seafloor at few locations. As a consequence,the Atlantic Water that flows through the Nordic seas takes different paths; FIG. Oceanic crust each side of the Knipovich Ridge is thin (∼3.5 km) and is characterised by the absence of oceanic layer 3 (3.5/4.1 to The oceanic section exhibits zones of very thin crust (∼1 km) that are interpreted as fracture zones. In the Quaternary, the boundary of plate interaction along the tension crack has been straightened to form the contemporary Knipovich Ridge, which crosses the previously existing magmatic spreading substrate and sedimentary cover at an angle of about 45° relative to the direction of accretion. Image from Rolf Mjelde, University of Bergen. Received 2006 December 18; in original form 2006 February 28 . Kathleen Crane, Hany Doss, Peter Vogt, Eirik Sundvor, Georgy Cherkashov, Irina Poroshina, Devorah Joseph. The Gakkel SMZ data thus indicate a sharp geochemical boundary in the absence of any tectonic boundary. Knipovich Ridge belongs to the slowest spreading ridges world-wide. GEBCO: discoverer and year of discovery (en): Discoverer: Russian research vessel "Akademik Knipovich". Patterns (in . Two felt earthquakes dated January 18, 1976 and July 17, 1977 are known from Svalbard. In the Quaternary, the boundary of plate interaction along the ten sion crack has been straightened to form the contemporary Knipovich Ridge, which crosses the previously existing magmatic spreading substrate and sedimentary cover at an angle of about 45 ° relative to the direction of accretion. The hydrographic sections agree with the SST field in Figure 1, which in combination with drifter observations substantiate this pathway as a topographically . Deep convective cooling should form a thick low-resistivity layer (30 km) extending below the ridge. The Knipovich Ridge has a spreading rate of ~8 mm/yr [Ehlers & Jokat, 2009].Svyatogor Ridge is located between Chrons 5 and 2A (C2A, C5), correlating to 9.8 Ma and 2.8 Ma respectively [Engen et The Knipovich ridge to the southwest of the Gakkel ridge is also isotopically distinct from . shown by grey 500, 1000, 2000, 3000 and 4000 m contours. The rift valley of the Gakkel Ridge is formed by rocks from the oceanic basement, which supposedly had velocities of more than 7.5 km/s . Purple and dark blue colors indicate deepest depths. : 2005). Rifting and spreading across the paleo-shear zone has led to the extremely oblique and asymmetric opening about the Knipovich Ridge. More recent work discovered large gas hydrate and fluid flow systems situated on young and hot oceanic crust extending from the upper continental slope off Svalbard to the mid-ocean ridge. According to the acting map of seismic zonation of the USSR published in 1978, 7-8 MSK areas include the Lena River Delta and adjacent areas located in the . .

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