An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories (original) (raw)
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Norwegian Journal of Geology
Kong Karls Land, easternmost in the Svalbard archipelago, displays a 300 m-thick Upper Triassic (Norian) to Lower Cretaceous (Aptian) succession. The islands are situated within a set of large-scale, NE-SW-trending folds. The sediments are poorly consolidated as a result of relatively shallow burial. Lower Cretaceous plateau lavas and sills cap the islands and have protected older strata from extensive Pliocene and Pleistocene erosion. Correlation between onland exposures and subsea seismic units shows that Kong Karls Land is a key reference area for the Late Triassic to Early Cretaceous development of the northern Barents Sea shelf, but also to the southwestern Barents Sea. The unique exposed succession can be correlated with nearby offshore data, enabling the recognition of key sequence stratigraphic surfaces which define major tectonic events. These enable subdivision of the succession into six tectonic megasequences (TMS 1 to TMS 6) of latest Permian to Early Cretaceous age. The TMS 1 is linked to denudation of the Uralian orogen and includes most of the northwestward prograding Triassic coastline in the northwestern Barents Sea and eastern part of Svalbard. The 200 m-thick estuarine to shoreface deposits of the Rhaetian to Pliensbachian TMS 2 in Kong Karls Land stands in contrast to the 5 to 20 m-thick condensed succession with numerous hiatuses in western Spitsbergen. This significant difference is suggested to be a response to an evolving foreland basin linked to the northern Barents Sea Basin and Novaya Zemlya Fold and Thrust Belt. The four youngest tectonic megasequences are represented by only thin remnants onshore and on the adjacent platform. Outcrop mapping and seismic profiles show high-amplitude weak folding in the Late Jurassic followed by Early Cretaceous reactivation, prior to deposition of the Helvetiafjellet Formation. The volcanism in Kong Karls Land is related to the High Arctic Large Igneous Province and opening of the Amerasian Basin, which resulted in uplift of the northern Barents Shelf and southwards tilting of the Svalbard Platform..
Activity Report The Paleontology Team Summer 2009, Svalbard
the Swe-Danes) Purpose of trip: to investigate and establish the stratigraphy of the exposed lower Palaeozoic sediments in Murchisonfjorden, Nordaustlandet. Background: The Lower Palaeozoic sediments exposed in Murchisonfjorden on Svalbard are practically unknown and -until now -have been referred to the Krossøya and Sparreneset units, respectively considered as Cambrian and Ordovician in age.
The inheritance of a Mesozoic landscape in western Scandinavia
Nature Communications
In-situ weathered bedrock, saprolite, is locally found in Scandinavia, where it is commonly thought to represent pre-Pleistocene weathering possibly associated with landscape formation. The age of weathering, however, remains loosely constrained, which has an impact on existing geological and landscape evolution models and morphotectonic correlations. Here we provide new geochronological evidence that some of the low-altitude basement landforms on-and offshore southwestern Scandinavia are a rejuvenated geomorphological relic from Mesozoic times. K-Ar dating of authigenic, syn-weathering illite from saprolitic remnants constrains original basement exposure in the Late Triassic (221.3 ± 7.0-206.2 ± 4.2 Ma) through deep weathering in a warm climate and subsequent partial mobilization of the saprolitic mantle into the overlying sediment cascade system. The data support the bulk geomorphological development of west Scandinavia coastal basement rocks during the Mesozoic and later, long-lasting relative tectonic stability. Pleistocene glaciations played an additional geomorphological role, selectively stripping the landscape from the Mesozoic overburden and carving glacial landforms down to Plio-Pleistocene times. Saprolite K-Ar dating offers unprecedented possibilities to study past weathering and landscape evolution processes.
Norwegian Journal of Geology
The Wilhelmøya Subgroup (Norian-Bathonian) is considered as the prime storage unit for locally produced CO 2 in Longyearbyen on the Arctic archipelago of Svalbard. We here present new drillcore and outcrop data and refined sedimentological and sequence-stratigraphic interpretations from western central Spitsbergen in and around the main potential CO 2-storage area. The Wilhelmøya Subgroup encompasses a relatively thin (15-24 m) siliciclastic succession of mudstones, sandstones and conglomerates and represents an unconventional potential reservoir unit due to its relatively poor reservoir properties, i.e., low-moderate porosity and low permeability. Thirteen sedimentary facies were identified in the succession and subsequently grouped into five facies associations, reflecting deposition in various marginal marine to partly sediment-starved, shallow shelf environments. Palynological analysis was performed to determine the age and aid in the correlation between outcrop and subsurface sections. The palynological data allow identification of three unconformity-bounded sequences (sequence 1-3). These sequences record intermittent deposition in the Early Norian, Early-Middle Toarcian, and Late Toarcian-Aalenian, interrupted by extended periods of erosion, bypass and/or non-deposition. The stratigraphically condensed development of the Wilhelmøya Subgroup in western central Spitsbergen is interpreted to be the result of very low subsidence rates coupled with a physiographic setting characterised by a very gentle depositional gradient. This facilitated rapid shoreline shifts in response to even relatively modest variations in relative sea level with considerable influence on the resulting depositional patterns. We present a revised depositional model for the regionally distinct Brentskardhaugen Bed at the top of the Wilhelmøya Subgroup involving condensation and partial reworking of a series of Upper Toarcian-Aalenian, high-frequency sequences. Coarse-grained extraformational fractions observed within conglomerates of the Wilhelmøya Subgroup are suggested to have been supplied from uplifted and exposed margins to the west (northern Greenland) and north (northern Svalbard).
Lower Cretaceous Mesoeucrocodylians from Scandinavia (Denmark and Sweden)
Cretaceous Research, 2009
The crocodyliform faunas of the lowermost Cretaceous Rabekke and Jydegård Formations on the Baltic island of Bornholm, Denmark, and the Annero Formation of Skåne, southernmost Sweden, are represented by isolated teeth, osteoderms, and vertebrae. The rich Berriasian assemblage of the Rabekke Formation includes at least three distinctive taxa: Bernissartia sp., Theriosuchus sp., and Goniopholis sp., an association that is also known from several other contemporaneous European vertebrate localities. In contrast to this fauna, the Jydegård and Annero Formations have yielded only rare mesoeucrocodylian remains, which are assigned to Theriosuchus sp. and an undetermined mesoeucrocodylian taxon, possibly Pholidosaurus. Geographically, the Scandinavian localities represent the easternmost and northernmost distribution of typical continental Jurassic-Cretaceous crocodyliform communities in Europe.