Tectonic and sedimentary structures in the northern Chukchi region, Arctic Ocean

Abstract

[1] The interpretation of tectonic and sedimentary structures in the northern Chukchi region, Arctic Ocean, is important to enhance our understanding of the tectonic evolution of this region. Therefore, multichannel seismic lines as well as seismic wide-angle reflection and refraction data were acquired in the northern Chukchi region during the RV Polarstern ARK-XXIII/3 summer expedition in 2008. These data have been processed and interpreted for the three main geological provinces (Chukchi Plateau, Chukchi Abyssal Plain, and Mendeleev Ridge) to describe the sedimentary and basement structures of the northern Chukchi region. Furthermore, using the age control of five exploration wells drilled near the coast of Alaska in combination with additional seismic reflection lines located on the Chukchi Shelf, we were able to date sediment horizons within the research area. In total, six sediment horizons with ages between Barremian/Hauterivian and the Top Miocene were identified. Especially, the Top Oligocene horizon forms a pronounce unconformity on the Chukchi Plateau and on the Mendeleev Ridge flanks. The origin of this unconformity can be associated with the opening of the Fram Strait indicating a significant change in the Arctic Ocean current system.

Rift systems of the Russian Eastern Arctic shelf and Arctic deep water basins: link between geological history and geodynamics

“…All these conclusions are consistent with our conclusions. The main differences between the assumptions in [Hegewald, Jokat, 2013] and our conclusions concern the age and basement type of the basin. Hegewald and Jokat believe that the basement is of Jurassic age and looks more like an oceanic crust.…”

“…The following data and methods are taken as the basis for considering the seismic stratigraphy of the Arctic Ocean: (1) drilling data on the Lomonosov Ridge from the ACEX Project [Moran et al, 2006;Backman et al, 2008];(2) data on ages of linear magnetic anomalies of the Eurasian Basin [Glebovsky et al, 2006;; (3) data on the age of the sedimentary cover of the Chukchi Sea tied to wells Hegewald, Jokat, 2013;Nikishin et al, 2014]; data on the formation history of Mesozoic orogens in the Russian Far East and on islands of the East Siberian and Chukchi Seas; (4) data on ages of plateau basalts of the De Long Island and the Alpha-Mendeleev Ridge that are a part of the Alpha-Mendeleev LIP or HALIP [Drachev, Saunders, 2006;Grantz et al, 2011;Morozov et al, 2013;Brumley, 2014]. Earlier, we correlated the seismic stratigraphy of the Arctic Ocean with drilling data on the Lomonosov Ridge and with linear magnetic anomalies in the Eurasian Basin .…”

“…The Chukchi Abyssal Plain Basin was earlier characterized on the basis of seismic lines by the Alfred Wegener Institute [Hegewald, Jokat, 2013]. It was shown that the basement of the basin has a horst-graben structure with the north-south trends of grabens.…”

Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

“…The median values are calculated at 108 stations for which the number of velocity-depth samples is at least five, which ensures that the median statistic is not biased by possible outliers. This criterion corresponds to a minimum sedimentary thickness of about 1.5 km, and thereby excludes areas of the Northwind and Alpha-Mendeleev ridges where the succession is relatively thin and predominantly unlithified (Bruvoll et al 2012;Hegewald & Jokat 2013). The average of the median ratios for the 108 stations is 1.01, confirming that the regional reference model is a reasonably unbiased estimate of the overall sample set, but the 2-D spatial variation of the median ratios is strikingly nonrandom.…”

“…The prism thins to the north and west with increasing distance from the slope, and it is generally less than 1 km in thickness over the Northwind and Alpha-Mendeleev ridges (Bruvoll et al 2012;Hegewald & Jokat 2013). The sediment provenance is diverse, and it includes the Chukotka magmatic belt, the Brooks Range orogenic belt, the Ellesmerian orogenic belt, the Canadian craton, the Arctic Platform and volcanics associated with the Alpha Ridge (Houseknecht & Bird 2011).…”