Abstract
Here we present a high-resolution, continuous seismostratigraphic framework that for the first time, connects the over 1,000 km long western Svalbard-Barents Sea margin and covers the last ∼2.7 million years (Ma). By exploiting recent improvements in chronology, we establish a set of reliable age fix-points from available boreholes along the margin. We then use a large 2-D seismic database to extend this consistent chronology from the Yermak Plateau and offshore western Svalbard, southwards to the Bear Island Trough-Mouth Fan. Based on this new stratigraphic framework we divide the seismic stratigraphy along the continental margin into three seismic units, and 12 regionally correlated seismic reflections, each with an estimated age assignment. We demonstrate one potential application of this framework by reconstructing the Svalbard-Barents Sea Ice Sheet evolution from the intensification of the northern hemisphere glaciation at ∼2.7 Ma to the Weichselian glaciations. Through seismic facies distribution and sedimentation rate fluctuations along the margin we distinguish three phases of glacial development. The higher temporal resolution provided by this new framework, allows us to document a clear two-step onset to glacial intensification in the region during phase 1, between ∼2.7 and 1.5 Ma. The initial step, between ∼2.7 and 2.58 Ma shows glacial expansion across Svalbard. The first indication of shelf-edge glaciation is on the Sjubrebanken Trough-Mouth Fan, northwestern Barents Sea after ∼2.58 Ma; whilst the second step, between ∼1.95 and 1.78 Ma shows glacial advances beyond Svalbard to the northwestern Barents Sea. Phase 2 is characterized by variations in sedimentation rates and the seismic facies are indicative for a regional glacial intensification for the whole Barents Sea-Svalbard region with widespread shelf-edge glaciations recorded at around ∼1.5 Ma. During Phase 3, the western Barents Sea margin is characterized by a dramatic increase in sedimentation rates, inferring once again a regional glacial intensification. Our new stratigraphic framework allows for the first time differentiation of the sediments deposited on the slope during Early Saalian (∼0.4 and 0.2 Ma), Late Saalian (∼0.2 and 0.13 Ma), and Weichselian (<∼0.123 Ma) periods, providing new insights into the Barents Sea glaciations over the last ∼0.42 Ma.
Highlights
The western Svalbard-Barents Sea continental margin (Figure 1) is over 1,000 km long and is characterized by thick glacigenic sediments that have been deposited over the last ∼2.7 Ma
The seismic horizons ∼1.2, 1.78, 1.95, and ∼2.58 Ma are calibrated only by the Ocean Drilling Program (ODP) Sites on the Yermak Plateau, they are characterized by moderate- to high-amplitude seismic reflections, allowing them to be correlated along the whole margin
We utilize recent improvements in chronology to establish a set of reliable age fix-points from available boreholes along the margin, and with the use of a large dataset composed of both, conventional and recently acquired high-resolution 2D seismic data, we extend this consistent chronology from the Yermak Plateau and offshore western Svalbard, southwards to the Bear Island Trough-Mouth Fan (TMF)
Summary
The western Svalbard-Barents Sea continental margin (Figure 1) is over 1,000 km long and is characterized by thick glacigenic sediments that have been deposited over the last ∼2.7 Ma. These attempts have been hampered by inconsistent chronologies between the sparse boreholes along the margin and limited seismic surveys necessary to by-pass problematic areas and correlate between the available boreholes. This lack of a continuous chronostratigraphic framework has hindered attempts to provide a coherent reconstruction of paleoenvironmental variations along the entire western Svalbard-Barents Sea margin based on paleontological studies from the ODP sites on Yermak Plateau (ODP Site 910, 911, 912) and offshore west Svalbard (ODP 986). The interpretation of these proxies form the basis for the individual stratigraphic frameworks for each site (e.g., Cronin and Whatley, 1996; Hull et al, 1996; Matthiessen and Brenner, 1996; Spiegler, 1996; Eidvin and Nagy, 1999; Smelror, 1999; Grøsfjeld et al, 2014)
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