1] The International Bathymetric Chart of the Arctic Ocean (IBCAO) released its first gridded bathymetric compilation in 1999. The IBCAO bathymetric portrayals have since supported a wide range of Arctic science activities, for example, by providing constraint for ocean circulation models and the means to define and formulate hypotheses about the geologic origin of Arctic undersea features. IBCAO Version 3.0 represents the largest improvement since 1999 taking advantage of new data sets collected by the circum-Arctic nations, opportunistic data collected from fishing vessels, data acquired from US Navy submarines and from research ships of various nations. Built using an improved gridding algorithm, this new grid is on a 500 meter spacing, revealing much greater details of the Arctic seafloor than IBCAO Version 1.0 (2.5 km) and Version 2.0 (2.0 km). The area covered by multibeam surveys has increased from $6% in Version 2.0 to $11% in Version 3.0.

The depositional history of the Storfjorden and Kveithola trough-mouth fans (TMFs) in the northwestern Barents\ud Sea has been investigatedwithin two coordinated Spanish and Italian projects in the framework of the International\ud Polar Year (IPY) Activity 367, NICE STREAMS. The investigation has been conducted using a multidisciplinary approach\ud to the study of sediment cores positioned on high-resolution multibeam bathymetry and TOPAS/CHIRP\ud sub-bottom profiles.\ud Core correlation and the age model were based on 27AMS 14C samples, rock magnetic parameters, lithofacies sequences,\ud and the presence of marker beds including two oxidized layers marking the post Last GlacialMaximum\ud (LGM) inception of deglaciation (OX-2) and the Younger Dryas cold climatic event (OX-1).\ud Sediment facies analysis allowed the distinction of a number of depositional processes whose onset appears\ud closely related to ice stream dynamics and oceanographic patterns in response to climate change. The glacigenic\ud diamictonwith lowwater content, high density, and high shear strength, deposited during glacial maxima, indicates\ud ice streams grounded at the shelf edge. Massive release of IRD occurred at the inception of deglaciation in\ud response to increased calving rates with possible outer ice streams lift off and collapse. The presence of a severalmeter-\ud thick sequence of interlaminated sediments deposited by subglacial outbursts of turbid meltwater\ud (plumites) indicates rapid ice streams' melting and retreat. Crudely-layered and heavily-bioturbated sediments\ud were deposited by contour currents under climatic/environmental conditions favorable to bioproductivity.\ud The extreme sedimentation rate of 3.4 cm a−1 calculated for the plumites from the upper-slope area indicates a\ud massive, nearly instantaneous (less than 150 years), terrigenous input corresponding to an outstanding meltwater\ud event.Wepropose these interlaminated sediments to represent the high-latitudemarine record ofMeltWater\ud Pulse 1a (MWP-1a). Different bathymetric and oceanographic conditions controlled locally the mode of glacial\ud retreat, resulting in different thickness of plumites on the upper continental slope of the Storfjorden and\ud Kveithola TMFs. It is possible that the southern part of Storfjorden TMF received additional sediments from the\ud deglaciation of the neighboring Kveithola ice stream

This study aims to present an overview of the seafloor morphology and shallow sedimentary structure of the Storfjorden and Kveithola Trough Mouth Fans (TMFs) on the northwestern Barents Sea continental margin. Data have been compiled from two International Polar Year (IPY) cruises (SVAIS, of the BIO Hespérides and EGLACOM of the R/V OGS-Explora) that yielded 15,340 km 2 of multi-beam bathymetry and 9,500 km of subbottom seismic profiles. In this area, the continental shelf edge defines three wide and subdued sedimentary lobes forming Storfjorden TMF, one single lobe on Kveithola TMF, and three inter-TMF areas on the continental slope. The two northernmost lobes of Storfjorden TMF (Lobes I and II) are composed by thick (up to 50 m) sequences of glacially derived debris flow deposits interbedded with thin a few metres de-glacial and interglacial deposits. A network of upper slope gullies incises these debris flow deposits as a consequence of subglacial meltwater release at or near the shelf break. Gullies evolve into channels whose morphologic evidence disappears midslope, leaving place to a subdued chevron-like morphological pattern inherited by the preceeding glacial maximum debris flow deposits. A drastic change occurs on the continental slope of Storfjorden TMF Lobe III and Kveithola TMF, where are several translational submarine landslides mostly originated in the upper slope, the majority of which detach at the contact between Middle Weishelian glacigenic debris flows and the overlying acoustically laminated plumites. Dendritic canyon systems only develop in inter-TMF areas. The data suggest that TMF continental slope progradation depends on short-lived episodes of extreme sedimentation during glacial maxima and during the early deglaciation phase, and that an important controlling factor is the mechanism of ice stream retreat from the continental shelf edge. We suggest that the two northern Storfjorden sub-ice streams were composed by thicker and perhaps faster ice progressively draining a distal and larger ice source mainly located on Svalbard. Conversely, the southernmost Storfjorden sub-ice stream and the Kveithola ice stream were fed by a local, smaller marinebased ice dome grounded on Spitsbergenbanken. The ice dome persisted after the LGM, maintaining a local ice drainage system close to the shelf edge whose sedimentary evidence can be found on the continental slope of the southern lobe of Storfjorden TMF and Kveithola TMF. The high degree of lateral variability in the style of sedimentation on TMF slopes suggests that ice stream dynamics may vary considerably within the same glacial trough, and that such variability affects the long-term development of the architecture of TMFs.

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