Eurasia Basin and Gakkel Ridge, Arctic Ocean: Crustal asymmetry, ultra-slow spreading and continental rifting revealed by new seismic data

Abstract

High Arctic new seismic data, collected by Russian Federation from 2011 to 2014, and additional geological and geophysical information, are used to interpret the basement and sedimentary structure of central and eastern Eurasia Basin, the Gakkel Ridge, and their transition into the Laptev Sea. We find that significant changes in basement topography occur in Nansen Basin at C20 (43.43 Ma) and in the Amundsen basins at C21 (45.7 Ma), and in both basins at C13 (33 Ma). A long seismic profile, that documents for the first time the structure of conjugate flanks and their margins in the central-eastern Eurasia Basin, confirms that oceanic accretion was asymmetric, with 10% less crust developed in the Amundsen Basin since continental break-up. In the eastern Amundsen Basin, we observe mid-ocean ridge uplift since C13 (33 Ma). We identify four distinct sedimentary packages in the Eurasia Basin: Early to Mid Eocene (c. 56 to 45.7 Ma), Mid Eocene to Early Oligocene (45.7 to 33.2 Ma), Early Oligocene to Early Miocene (33.2 to 19.7) and Early Miocene to Present (19.7 to 0 Ma); they are linked to the oceanic lithosphere age determined from magnetic data. The deepest part of the Gakkel Ridge (5215 m), situated close to the easternmost part of this mid ocean ridge, is imaged for the first time by seismic data that reveals volcanic constructions within the older axial ridges and on the flanks. Gakkel Ridge's asymmetric flanks with shallow, regularly-spaced, and rugged structure, typical to ultra-slow spreading ridges, imply periodicity of tectonic phases. The Khatanga-Lomonosov Fault between Lomonosov Ridge and the Laptev Sea region, is identified on few seismic profiles; kinematic models predict that it may have been active only for a maximum of 10 myr after continental break-up.

GlobSed: Updated Total Sediment Thickness in the World's Oceans

“…Our gridded oceanic crustal ages (Figure ) are based on an improved database of magnetic anomaly identifications that were modeled as described by Müller, Sdrolias, Gaina, and Roest () using the geomagnetic polarity timescale of Ogg (). The presented oceanic lithospheric age model builds on the Seton et al () global model and includes recent regional plate tectonic models of the African plate, Indian Ocean, NE Atlantic, and the Arctic (Gaina et al, , , , respectively, Nikishin et al, ) and a revised, more detailed global model for Eocene age oceanic lithosphere (Gaina & Jakob, ). The computation of age of oceanic lithosphere considers the formation of “normal” oceanic lithosphere through seafloor spreading.…”

“…Regions of the Arctic lacking seismic data were filled by the global CRUST1.0 (1°× 1°) sediment thickness Geochemistry, Geophysics, Geosystems grid of Laske et al (2013;Petrov et al, 2016). For the GlobSed compilation, the Arctic sediment thickness by Petrov et al (2016) has been further checked and modified according to recent seismic reflection data in the eastern Eurasia Basin (e.g., Nikishin et al, 2017) and in the Barents Sea.…”

Deposition History and Paleo‐Current Activity on the Southeastern Lomonosov Ridge and its Eurasian Flank Based on Seismic Data

“…Thus, a minimum age for a unit was inferred from the location where its top reflector onlaps the oceanic crust. The locations and timescale of the chrons were derived from studies of Gaina et al (2011), Chernykh and Krylov (2011), Nikishin et al (2018), and Ogg (2012). We matched our model to those of Franke (2013) and Weigelt et al (2014), and compared it to results of Jokat et al (1995), Chernykh & Krylov (2011), Nikishin et al (2017), and Castro et al (2018;Figures 2b and 4).…”

Ultraslow Spreading and Volcanism at the Eastern End of Gakkel Ridge, Arctic Ocean

“…A notable exception occurs between 81°10′N and 82°N latitude along 120°E longitude (Figure ). Here, on the easternmost part of the Gakkel Ridge, bathymetric data reveal a deep depression (maximum 5,310 m) almost devoid of sediments and thus referred to as the Gakkel Ridge Deep (GRD) (Figure ; Nikishin et al, ). Seismic reflection data (Nikishin et al, ; Piskarev & Elkina, ) confirm the near absence of sediment in the GRD.…”

“…It is still unknown whether this pattern of ridge segmentation continues at even slower spreading rates of ~6 mm/year along the remaining portion of the Gakkel Ridge toward the Laptev Sea, since the rift valley east of 70°E is filled by several‐kilometer‐thick sediments (Jokat & Micksch, ; Nikishin et al, ; Sekretov, ). East of 85°E, only a few high standing flanks of the rift valley are accessible to basement sampling.…”