Late Pliocene–early Pleistocene deep‐sea basin sedimentation at high‐latitudes: mega‐scale submarine slides of the north‐western Barents Sea margin prior to the shelf‐edge glaciations

Abstract

At high‐latitude continental margins, large‐scale submarine sliding has been an important process for deep‐sea sediment transfer during glacial and interglacial periods. Little is, however, known about the importance of this process prior to the arrival of the ice sheet on the continental shelf. Based on new two‐dimensional seismic data from the NW Barents Sea continental margin, this study documents the presence of thick and regionally extensive submarine slides formed between 2.7 and 2.1 Ma, before shelf‐edge glaciation. The largest submarine slide, located in the northern part of the Storfjorden Trough Mouth Fan (TMF), left a scar and is characterized by an at least 870‐m‐thick interval of chaotic to reflection‐free seismic facies interpreted as debrites. The full extent of this slide debrite 1 is yet unknown but it has a mapped areal distribution of at least 10.7 × 103 km2 and it involved >4.1 × 103 km3 of sediments. It remobilized a larger sediment volume than one of the largest exposed submarine slides in the world – the Storegga Slide in the Norwegian Sea. In the southern part of the Storfjorden TMF and along the Kveithola TMF, the seismic data reveal at least four large‐scale slide debrites, characterized by seismic facies similar to the slide debrite 1. Each of them is ca. 295‐m thick, covers an area of at least 7.04 × 103 km2 and involved 1.1 × 103 km3 of sediments. These five submarine slide debrites represent approximately one quarter of the total volume of sediments deposited during the time 2.7–1.5 Ma along the NW Barents Sea. The preconditioning factors for submarine sliding in this area probably included deposition at high sedimentation rate, some of which may have occurred in periods of low eustatic sea‐level. Intervals of weak contouritic sediments might also have contributed to the instability of part of the slope succession as these deposits are known from other parts of the Norwegian margin and elsewhere to have the potential to act as weak layers. Triggering was probably caused by seismicity associated with the nearby and active Knipovich spreading ridge and/or the old tectonic lineaments within the Spitsbergen Shear Zone. This seismicity is inferred to be the main influence of the large‐scale sliding in this area as this and previous studies have documented that sliding have occurred independently of climatic variations, i.e. both before and during the period of ice sheets repeatedly covering the continental shelf.

Late Cenozoic Erosion Estimates for the Northern Barents Sea: Quantifying Glacial Sediment Input to the Arctic Ocean

“…In terms of size (i.e., area affected), the Body A slide is smaller compared to the megaslide deposits from the southwestern margin of the Barents Sea (Hjelstuen et al, ; Figure ). The volume of sediments involved is comparable to the northwestern Barents Slide reaching a volume of 4,100 km 3 (Safronova et al, ). The Body A is approximately double the size of the Holocene Storegga Slide offshore mid‐Norway (Haflidason et al, ) but interestingly only less than half in terms of area affected.…”

“…Volume and area comparison for Body A with other submarine slides along the Norwegian continental margin. Note: a, Safronova et al (); b, Hjelstuen et al (); C, Elger et al (); d, Laberg and Vorren (); e, Osti et al (); f, Vanneste et al () and Winkelmann et al (); g, Haflidason et al (); h, Laberg et al (); i, Laberg et al ().…”

Sediment failures within the Peach Slide (Barra Fan, NE Atlantic Ocean) and relation to the history of the British-Irish Ice Sheet

“…There are similarities in the geological setting of the Barra Fan and the Barents Sea and Norwegian margins: shelf-edge ice, strong across-slope bottom current flow during interglacial periods, and a similar tectonic setting on the northwest European rifted margin (though the Barents Sea is tectonically more active with the Mohns and Knipovich ridges (Safronova et al, 2017)). There are also differences in setting, there was more ice located proximal to these more northern depo-centres (Hughes et al, 2016) and thicker accumulations of contourites were deposited during inter-glacial periods (Bryn et al, 2005b).…”

“…As a trough mouth fan, the sediment failures located within the Barra Fan are expected to share more similarities to other such failures, of which there are several on the Norwegian and Barents Sea margins (Vorren and Laberg, 1997). A large number of mass movement events have been documented on these fans, covering a time period from the late-Pliocene (Evans et al, 2005;Safronova et al, 2017) to the Holocene (Laberg et al, 2002a). Frequencies of failure events have increased since shelf-edge glaciation (Safronova et al, 2017;Solheim et al, 2005).…”

“…A large number of mass movement events have been documented on these fans, covering a time period from the late-Pliocene (Evans et al, 2005;Safronova et al, 2017) to the Holocene (Laberg et al, 2002a). Frequencies of failure events have increased since shelf-edge glaciation (Safronova et al, 2017;Solheim et al, 2005).…”