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Christian Haug Eide
October 12, 2016 @ 12:00 pm - 1:00 pm
Tana – a very old river: Linking an Early Triassic delta to antecedent topography
The Fennoscandian Barents Sea Margin has been subject to little tectonic activity since the Carboniferous, and large portions have eluded significant Quaternary glacial erosion. Published fission track data indicate little denudation since the late Permian-Early Triassic. It may therefore be one of the most geologically stable margins on Earth, and it is therefore likely that catchments in the region could contain elements inherited from ancient catchments.
The catchment of the Tana River has long been interpreted to show features indicating that it was developed prior to present-day topography (Fig. 1A). A large delta-system that prograded from the present-day mouth of the Tana River during the Early Triassic, is visible in seismic data from the Finnmark Platform. In this study, we demonstrate that the present day Tana River Catchment shows several geomorphic evidence of having survived since the Earliest Triassic, that the studied Triassic delta was sourced from the present-day mouth of the Tana catchment, and that the post-Triassic modification of this catchment has been relatively small. We thus make the case that the present-day Tana catchment was formed close to the Permian-Triassic boundary.
This is important for explorationists because it demonstrates that reservoir properties in the Triassic of the Barents Sea are strongly influenced by catchment properties and sediment transport networks. Source-to-sink techniques can thus be instrumental in predicting extent and quality of subsurface reservoirs. Triassic strata in the Barents Sea generally show more favorable reservoir properties close to the Fennoscandian shield. This is because the majority of the basin fill was supplied through a vast fluvial system from the Uralian Orogen, and these sediments make up the bulk of the Triassic sedimentary package. Smaller catchments along the Fennoscandian margin supplied more mature shield-derived sediment to the basin margins only. Understanding these ancient catchments will help inform and constrain the amount of high-quality sand supplied from the shield to the basin through time.