CENOZOIC DEPOSITION IN THE NANSEN BASIN, A FIRST-ORDER ESTIMATE BASEDON PRESENT-DAY BATHYMETRY

Considering the age of the underlying oceanic crust, the Eurasia Basin is anomalously shallow, especially the southern Nansen sub-Basin. Par ticularly large bathymetric anomalies are found outside major erosiona l troughs on the Barents Sea Shelf, indicating sediment infill from th e adjacent shelf as a major cause of the shallowing. To obtain a first order estimate of the sediment isopachs in the Eurasia Basin, the sta ndard age-depth curve for oceanic crust in the North-Atlantic was used as a reference to define a bathymetric anomaly which was then inverte d, assuming local isostatic equilibrium. The isopachs reveal a huge de lta outside the St. Anna and Voronin troughs. Conservatively estimated this ''twin delta'' covers approximate to 75,000 km(2) and has a maxi mum sediment thickness approximate to 7 km. Similar, but smaller, delt as are found both east and west of this delta. The deltas in the Nanse n Basin appear analogous to the Bjornoyrenna and Storfjordrenna deltas , which are located off major submarine troughs in the Western Barents Sea and are comparable to the St. Anna/Voronin Delta in size. The lat ter deltas contains huge amounts of young, glacigenic sediments, and t his is also likely to be the case for the deltas in the Nansen Basin. The huge sediment accumulations off the northeastern Parents Sea, the anomalously large depth of the Barents Shelf, and its trough dominated morphology, suggest that extensive erosion similar to that documented in the Western Barents Sea (0.5-1.5 lan) affected the entire Barents Shelf.