Source-to-sink Dynamics in the Early Cretaceous Boreal Basin; Progradational Lobes from a Missing Source

Abstract:

A coalescing array of fan lobes has been resolved in the central and western present-day Barents Sea from detailed seismic mapping of several progradational lobes above the Base Cretaceous Unconformity (BCU). The lobes developed over at least 200 000 km², and form thicknesses constrained to be between 200 and 500 metres. Multiple influx points into the basin are suggested by the variable lobe orientation and position on the Barents platform.

The sediment volumes were in part affected by bathymetric variation on the palaeo-seafloor, but this is considered a secondary variable in comparison to the push from sediment transport mechanisms. Sediments were routed into and along troughs, or around highs in places such as the Hoop Graben, Fingerdjupet Sub-basin, and the Fedynsky High, respectively, showing a natural response to local variation in basin floor topography. Highs that existed during this development represent source areas for small sediment lobes that interfinger with the larger-scale lobes, but are considered orders of magnitude smaller than the strata sourced from extrabasinal terrains.

The source areas for the mappable strata in the central and western Barents Sea area must have been landmasses with considerable vertical thickness and/or areal extent. Acknowledged sediment sources, such as the Lomonosov Ridge is insufficient as a single source for these sediment volumes, and warrants the inference of a land mass which is hitherto unknown, but has been termed “Crocker Land” by other workers. The sediment influx rate from the northeast can be estimated by age comparison between the most proximal and the most distal sediment lobe, which in turn has bearings on the hinterland erosion rate.

The increasingly understood High Arctic Large Igneous Province (HALIP) is linked to the uplifting of a source area to the northwest of present day sink areas in Svalbard and the Barents Sea. Expressed as a number of subsurface sill intrusions and scattered extrusives, the HALIP indicates a spike in magmatic activity around the Barremian, which can explain the expansion and emergence of a source for time equivalent strata in the Boreal Basin and neighboring areas.