The Upper Triassic Paralic Deposits of the De Geerdalen Formation on Hopen, Svalbard: An Analog to the Subsurface Snadd Formation in the SW Barents Sea
Tore Klausen
The De Geerdalen Formation of Hopen is time-equivalent to the upper part of the Snadd Formation of the Barents Sea, a formation that has received interest as a possible hydrocarbon reservoir in addition to having source rock potential. The De Geerdalen Formation on Hopen has previously only been superficially described in a regional context and has been suggested to be that of a tidally dominated, paralic coastal plain depositional system. Recent sedimentological investigations add to this understanding and explain subtle but important variability in sedimentary architecture pointing to different depositional processes. Tidal channel sandstone belts of equal size and geometry as fluvial channel sandstone belts reveal distinguishable and characteristic internal heterogeneities and structures that separate them form their fluvial counterparts. Lateral correlation along the island suggests that the channel sandstone belts are positioned at different stratigraphic levels with implications for palaeogeographic reconstructions. The scales of depositional architectures at Hopen Island are directly relatable to subsurface seismic
data in the Barents Sea, and through regionally correlatable maximum flooding surfaces these depositional features can be put in a stratigraphic context. Additionally some of the depositional features demonstrated at Hopen are also of comparable in size and geometry to plan-view sedimentary systems extracted from
seismic
attribute
mapping, and detailed sedimentological descriptions carried out for the present study explains these depositional features in more detail than that which can be resolved in subsurface data. The present study shows how the
seismic
scale depositional elements vary temporally and spatially on the island, and place them in context with the heterolithic deposits encasing them. Local palaeogeographic maps of the island show subtle changes in response to autogenic cyclicity before a regional maximum surface eventually caps the De Geerdalen Formation. Together these results provide a valuable backdrop for the investigation of time-equivalent upper Snadd Formation in the Barents Sea, an interval that contains reservoir rocks and proven gas discoveries. The link between outcrop and
seismic
data does not only help in understanding proven reservoirs, it aids in our understanding of the regional extent of this formation that is still under exploration. Keywords: Fluvial deposits, Upper Triassic, Svalbard, Barents Sea, outcrop analogue
AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013