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. The western flank is fringed with a deep sea basin which is several times wider. 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. We interpret the increased magmatism as a passive response to the (extensional) bending of this southernmost part of the Knipovich Ridge. Crustal transect from the North Atlantic Knipovich Ridge to the Svalbard Margin west of Hornsund. Knipovich Ridge is determined by dextral strike-slip displacements along the Molloy Fracture Zone (315 ° NW). 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. ractureF Zone, Mohns Ridge and lastly Knipovich Ridge together with Spitsbergen ractureF Zone. CMR lists about twenty events as occurring in the Norwegian Sea between mid-February and mid-July whereas the QED lists 5 events Shaded relief image of magnetic data (Verhoef et al., 1996 . and YP is just west of Svalbard. The latter has a prominent central rift, 3200-3400 m deep, somewhat deeper than The boundary between YP-2 and YP-3 lies at an estimated age of 2.7 Ma (Knies et al., 2009). Received 2006 December 18; in original form 2006 February 28 . . 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. 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. The Mohn and Knipovich spreading ridges are in the category of slow-spreading ridges. Given . For both sets, the two events occurred within a few minutes of each other. (b) Sea surface temperature (SST) Knipovich Ridge (Bosse and Fer (2019), see satellite image in Fig. 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. 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 The area is covered by sediments from the Bear Island Fan, and . while the Norwegian-Greenland Sea marks the western boundary. 1. . A mid-ocean ridge demarcates the barrier between two tectonic plates and accordingly is termed a divergent plate boundary. 20 Ma decreases gradually to ca. Geer Zone), and has formed the northward trending Knipovich Ridge, among the slowest spreading cen- ters in the world. GEBCO: discoverer and year of discovery (en): Discoverer: Russian research vessel "Akademik Knipovich". 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 . 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. 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. 1990). 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. Following White et al. At mid-ocean ridges, the lithospheric plates drift apart, magma fills the gap to form new crust. It is a relatively young divergent boundary and ridge in the Northern Mid-Atlantic Ridge system. 1b). The axis is a detachment zone intersecting the oceanic basement having formed from the Late Oligocene. Image from Rolf Mjelde, University of Bergen. About 75% of all volcanic activity on the planet takes place here. 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). 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. The Iceland anomaly through geological history. The Gakkel SMZ data thus indicate a sharp geochemical boundary in the absence of any tectonic boundary. A wide variety of beliefs on the size and morphology of the plume exist, from a single point (e.g., Forsyth, 1986; Lawver & Müller . The role of the Spitsbergen shear zone in determining morphology, segmentation and evolution of the Knipovich Ridge. 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. The model is forced by impos-ing a uniform heat loss north of the sill1 of 150 W m 2 for a period 2005). Kathleen Crane, Hany Doss, Peter Vogt, Eirik Sundvor, Georgy Cherkashov, Irina Poroshina, Devorah Joseph. 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. 700 mbsf. Two felt earthquakes dated January 18, 1976 and July 17, 1977 are known from Svalbard. 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. The thickness of the magmatic portion of the crust formed along the Mohns Ridge at ca. 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. 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. It lies at the northern extremity of the Pacific spreading axis. 2010). 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 . Information on 8 felt earthquakes is available even on nearly uninhabited Canadian Arctic Archipelago. The ridge is unaffected by any transform fault zones 86 Subplatform formed as a down-faulted portion of the Selis Ridge in the early to mid-Triassic 87 (Gabrielsen et al. (a) Schematic of the circulation in the Nordic seas and bathymetry. In the other end-member model, melt production is normal, but a similar but much thinner lid hampers melt migration to the surface 15. Preliminary analysis of the Knipovich Ridge segmentation: influence of focused magmatism and ridge obliquity on an ultraslow spreading system Ehlers and Jokat (2009) claimed that the Knipovich Ridge has been an ultraslow ridge throughout its history with no major changes in spreading rates. Flickr photos, groups, and tags related to the "gakkel" Flickr tag. KnR: Knipovich Ridge. (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. Bathymetry image showing the crest of Southern Explorer Ridge. (2009) into a magmatic- and a tectonic-dominated part. The oceanic section exhibits zones of very thin crust (∼1 km) that are interpreted as fracture zones. The degree of the non-linearities increases slightly with proximity to the Mohns-Knipovich bend. Department of Mineral Deposits; Senja fracture zones have caused other important transverse ridges to form (Fig . The Oceanic crust is formed of rocks much newer than the . Top insert (left) shows a geological profile from the Knipovich Ridge to the Kara Sea (A-A ). The axial crustal thickness on the central Mohns Ridge has been examined by both REE-inversion methods and seismic 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. 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. 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. Figure 1. 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 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. over the Mohn Ridge. Thermal development and rejuvenation of the marginal plateaus. As a consequence,the Atlantic Water that flows through the Nordic seas takes different paths; FIG. These half-spreading . (Tucholke et al., 1998; Tani . : 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. 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). The curved stress trajectories create arcuate faults and subsiding elongate basins while focusing most of the volcanism through the boundary faults. A schematic map of the north-east Atlantic, modified from Google Earth, illustrating key regional tectonic elements. 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 . History: Named after the Russian Academician N. M. Knipovich (1862-1939), ichthyologist and hydro-biologist. 2; Talwani and Eldholm, 1977; Eldholm et al., 1990). Towards the east, it is bounded by the ultraslow mid-ocean Knipovich Ridge. 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. 1998; Glørstad-Clark et al. 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. It crosses the central Boreas Basin from the Knipovich Ridge to the Northeast Greenland margin. rifted crust. Year of discovery: 1970. Abbreviations: AR=Aegir Ridge, KR=Kolbeinsey Ridge, KnR=Knipovich Ridge, MR=Mohns Ridge, RR=Reyknanes Ridge, EJMFZ=East . 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. . 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. events on the plate boundary north of Svalbard may have been related and two events on the Knipovich ridge may be related (Figure 2). Knipovich Ridge belongs to the slowest spreading ridges world-wide. Directly to the north of the tip of the Knipovich setting has been well known for its importance to paleoceanography, global climate and its ultra-slow mid-ocean ridge system (Knipovich and Molloy Ridges). The model depicts the general situation that such ridges are asymmetrical, i.e. This engine splutters at very low speeds: Isolated volcanoes, capable of vigorous eruptions . Only in the northernmost cases are some of these off-axial ridges non-linear. 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 ). Only in the northernmost cases are some of these off-axial ridges non-linear. A mid-ocean ridge demarcates the barrier between two tectonic plates and accordingly is termed a divergent plate boundary. Plio-Pleistocene boundary which is at ca. 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). B05408 MCADOO ET AL. The Pacific-Antarctic Ridge is the southern extension of the East Pacific Rise. This stress field is superimposed by a system related to rifting and latitudinal opening. In this thesis, I synthesize my research on the seismicity of ultraslow spreading ridges describing the overarching theme of 10 peer-reviewed publications. Deep convective cooling should form a thick low-resistivity layer (30 km) extending below the ridge. 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 ridges in water depths of 1000-2000 m and exhibits a well-developed rift valley between 2600 and 3400 m (Perry, 1986). side of Knipovich Ridge, 8 mm/yr (Ehlers and Jokat, 2009). 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 . Continuity from the Mohns Ridge rift valley into the rift valley of the Knipovich Ridge (Talwani and Eldholm, 1977) has been observed. the Knipovich Ridge respectively, have trapped fluids, formed gas hydrate and developed active seepage systems associated with exceptional chemosynthetic communities. Patterns (in . shown by grey 500, 1000, 2000, 3000 and 4000 m contours. The bathymetry is also A widely accepted tectonic model for the plate separation process in such slow-spreading ridges is shown in this slide. 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. The Oceanic crust is formed of rocks much newer than the . 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. spreading Knipovich Ridge. By Yuichi Nishimura. The normal thickness of the crust . It is classified as an ultra-slow spreading ridge (Dick et al., 1993). 3 km, which is normal for ultra slow spreading ridges. We demonstrate that the IMU event is linked to onset of uplift and massive shelf-progradation on the NE Greenland margin. comprises the high-Arctic portion of the North American-Eurasian (NOAM-EUR) 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. Preliminary analysis of the Knipovich Ridge segmentation: influence of focused magmatism and ridge obliquity on an ultraslow spreading system The around 500 km long transform free ridge is bound to the north by the Molloy transform fault. Figure 2a. 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. . a thick thermal boundary layer (lid) below the ridge axis that shuts off melt production down to 30 km or deeper. The Knipovich Ridge as it has been mentioned above, is drastically displaced eastward. 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 . 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). These ridges resemble unique archives for the evolution and . The basal age of . that one of the flanks of the axial rift valley The Arctic Mid-ocean Ridge system extends northward from the MAR and is the boundary between the Eurasian and North American Plates. 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. Its segmentation follows Bruvoll et al. The Knipovich ridge to the southwest of the Gakkel ridge is also isotopically distinct from . By Nilgun Okay. Rifting and spreading across the paleo-shear zone has led to the extremely oblique and asymmetric opening about the Knipovich Ridge. Accepted 2006 December 18. Therefore,changes inthe properties and dynamics of the Nordic seas impact not only the local climate and The Aegir Ridge and the ridge underlying the Iceland continental margin are all inactive mid-oceanic ridges. In total, 680 1-D . There, massive volcanoes form, like Logachev Seamount that we examine in detail in this project. The hydrographic sections agree with the SST field in Figure 1, which in combination with drifter observations substantiate this pathway as a topographically Bathymetric map of the northern part of the Norwegian-Greenland seas and the continental margins, showing the mineral Knipovich and Mohn Ridges.
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