Linking an Early Triassic delta to antecedent topography: source-to-sink study of the southwestern Barents Sea margin

Abstract

Present-day catchments adjacent to sedimentary basins may preserve geomorphic elements that have been active through long intervals of time. Relicts of ancient catchments in present-day landscapes may be investigated using mass-balance models andcan give important information about upland landscape evolution and reservoir distribution in adjacent basins. However, such methods are in their infancy and are often difficult to apply in deep-time settings due to later landscape modification.The southern Barents Sea margin of N Norway and NW Russia is ideal for investigating source-to-sink models, because it has been subject to minor tectonic activity since the Carboniferous, and large parts have eluded significant Quaternary glacial erosion. A zone close to the present-day coast has likely acted as the boundary between basin and catchments since the Carboniferous. Around the Permian-Triassic transition, a large delta system started to prograde from the same area as the present-day largest river in the area, the Tana River, which has long been interpreted to show features indicating that it was developed prior to present-day topography. We performed a source-to-sink study of this ancient system in order to investigate potential linkages between present-day geomorphology and ancient deposits.We investigated the sediment load of the ancient delta using well, core, twodimensional and three-dimensional seismic data, and digital elevation models to investigate the geomorphology of the onshore catchment and surrounding areas. Our results imply that the present-day

Mud‐rich delta‐scale compound clinoforms in the Triassic shelf of northern Pangea (Havert Formation, south‐western Barents Sea)

“…The regressivetransgressive sequences were picked using maximum flooding surfaces (MFS) and maximum regressive surfaces (MRS; Galloway, 1989;Zhang et al, 2016;Gomez-Veroiza & Steel, 2017), so that the transgressive half-cycle is developed from the MRS up to the MFS, and the regressive half-cycle from the MFS to the MRS. (Gradstein et al, 2012) Lithostrat. (Mørk et al, 1999;Vigran et al, 2014) Lithology (Eide et al, 2017;Henriksen et al, 2011b) Marginal SW, NW…”

“…During this time, the Barents shelf was infilled by shelf margin clinoforms (300 to 500 m thick) formed by repeated transits of prograding deltaic and coastal systems from the east and south-east (Uralian belt), south (Finnmark and Baltic Shield; H1 system) and west (Greenland) in Svalbard (Mørk et al, 1982;Wignall et al, 1998;Glørstad-Clark et al, 2010;Henriksen et al, 2011a;Klausen et al, 2015;Eide et al, 2017). In other words, several clastic wedges infilled the basin, separated by basin-wide transgression events, and created a very thick succession (>2500 m thick).…”

“…Veevers, 1990;Crowell, 1999;Veizer et al, 2000); a dramatic mass extinction (e.g. Wignall & Hallam, 1992;Erwin, 1994;Twitchett & Wignall, 1996;Hochuli et al, 2017); anoxia and stratified water column in the world's oceans (Isozaki, 1997;Bond & Wignall, 2010); emplacement of the Siberian Traps (Burgess et al, 2017); a lithological change (Mørk et al, 1982;Wignall et al, 1998;Vigran et al, 2014;Eide et al, 2017) from coolwater carbonates and spiculites (Tempelfjorden Group) to siliciclastic deposits (Sassendalen and Kapp Toscana groups).…”

Clinoform development and topset evolution in a mud‐rich delta – the Middle Triassic Kobbe Formation, Norwegian Barents Sea

“…Where reservoir-scale sandstone deposits are encountered they are usually of poorer quality than the sandstone of the Goliat Field (Tsikalas et al, 2017). This is primarily due to how the more fine-grained, immature and mud-rich nature of sediments are sourced from the south-east (Bergan & Knarud, 1993;Mørk, 1999;Eide et al, 2017).…”

“…The best reservoir properties are instead found along the southern margin of the basin (i.e. the Goliat Field) and are attributed to a more mature provenance area in the Norwegian Caledonides to the south (Bergan & Knarud, 1993;Mørk, 1999;Ryseth, 2014;Fleming et al, 2016;Eide et al, 2017). How far the southerly derived sedimentary systems extend into the basin and how the depositional system has evolved in response to variations in autogenic and allogenic forcing factors is not known, but the reservoir properties of the Kobbe Formation are likely to be governed by the influx and extent of mature sediment from the south in combination with reservoir preserving factors in more central parts of the basin which counter the effects of burial that varied across the basin (Baig et al, 2016).…”