Norwegian Journal of Geology: Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data

Sten-Andreas Grundvåg1, Mads Engholm Jelby2, Kasia Kamila Śliwińska3, Henrik Nøhr-Hansen3, Tore Aadland4, Sara Elvelund Sandvik5, Ingrid Tennvassås1, Thea Engen1 and Snorre Olaussen6 have an article accepted with minor corrections in the Norwegian Journal of Geology. The article is titled “Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data”.

1UiT The Arctic University of Norway, 2Natural History Museum of Denmark, Univ. Copenhagen, 3Geological Survey of Denmark and Greenland, 4University of Bergen, 5Lundin Norway AS, 6University Centre in Svalbard.

The uncorrected proof can be downloaded from the ARCEx intranet.

Abstract: 

The stratigraphic and genetic relationship between the Rurikfjellet (open marine), Helvetiafjellet (paralic) and Carolinefjellet (open marine) formations of the Lower Cretaceous succession (LCS) in Svalbard is evaluated by combining sedimentological outcrop studies with well log and core data across Nordenskiöld Land, central Spitsbergen. Sedimentological characteristics and stratigraphic units are mapped within a refined dinocyst biostratigraphic framework, enabling relatively well-constrained palaeogeographic reconstructions. The Valanginian – lowermost Barremian Rurikfjellet Formation consists of a lower shale-dominated unit of offshore origin which grades upwards into storm-reworked lower shoreface sandstones displaying hummocky cross-stratification. Local occurrences of prodeltaic successions and thick successions of gravity flow deposits containing coal-bearing slump blocks of delta plain origin in some wells, reveal a late Hauterivian progradational pulse which has previously not been recorded in Svalbard. The lower Barremian – lower Aptian Helvetiafjellet Formation consists of fluvial braidplain and paralic deposits which rest unconformably on the Rurikfjellet Formation across the entire study area, reflecting regional uplift and wide-spread subaerial exposure prior to the onset of paralic deposition. The Helvetiafjellet Formation exhibits increased marine influence upwards, and in the investigated cores, the uppermost part of the unit consists of wave-reworked mouth bar deposits which are truncated by a transgressive conglomerate lag containing iron ooids. An up to 10 m thick regionally extensive organic-rich (TOC up to 2.1 wt %) shale unit of early Aptian age marks the base of the overlying Carolinefjellet Formation. The shale accumulated during a regional flooding event which drowned and eventually transformed the Helvetiafjellet Formation coastal plain into a shallow shelf. The organic facies of the shale unit (Type II-III kerogen) and a high Pr/Ph ratio (>2), in combination with abundant long-chained n-alkanes, suggest that the unit was deposited in a suboxic paralic marine environment strongly influenced by input of terrestrial organic matter.

Reference: 

Grundvåg, S.A.; Jelby, M.E.; Śliwińska, K.K.; Nøhr-Hansen, H.; Aadland, T.; Sandvik, S.E.; Tennvassås, I.; Engen, T.; Olaussen, S. (accepted): Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data. Accepted with minor corrections in Norwegian Journal of Geology. [intranet]


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