Mesozoic sediment dispersal patterns on the southwest Barents Shelf

During the Mesozoic, the Barents Shelf formed part of a large epicontinental seaway in which up to 8 km of predominantly clastic sediments were deposited. On the SW Barents Shelf, thick accumulations of sand were laid down in predominantly deltaic and shallow-marine environments. The sedimentary source region for these sands has traditionally been interpreted to be within the Caledonides and Fennoscandian Shield of northern Scandinavia. More recently, insights from wellbores and seismic surveys have revealed that a major deltaic system associated with the uplift of the Uralian Mountains may have spread northwest across the shelf and significantly affected sand dispersal patterns.

Utilising a range of provenance techniques, including petrographic data, heavy mineral abundance counts, mineral geochemistry and detrital zircon U-Pb geochronology in combination with sedimentology and analysis of published seismic interpretations, the lateral extent and evolution of these Triassic deltaic systems across the Barents shelf can be delineated. Two main sand types are recorded in samples recovered from offshore wells in the SW Barents Shelf. One sand type has a low abundance of chrome spinel and apatite, contains iron-rich garnets, metapelitic rutile and zircons that are predominantly Palaeo-Mesoproteorozoic in age. This sand type is thought to be proximally sourced from northern Scandinavia south of the Barents Shelf. The other sand type has abundant chrome spinel and apatite, metamafic rutiles, manganese-rich garnets and zircons that are mostly Late Palaeozoic in age. This sand type is thought to be sourced from more distal regions of the Uralides, southeast of the Barents Shelf.

Utilising these provenance results it is possible to differentiate between, and map the extent of, “Caledonide” and “Uralide” sourced dispersal systems in time and space on the SW Barents Shelf. The results have implications for our understanding of source area exhumation, sediment dispersal patterns and interactions, and the hydrocarbon prospectivity of the receiving basin.