Polygonal mounds in the Barents Sea reveal sustained organic productivity towards the P–T boundary

Abstract

Three-dimensional (3D) seismic-reflection data from the Barents Sea show geometric similarities between Permian coolwater mounds and older carbonate build-ups. In detail, the Samson Dome area records the development of polygonal mounds in Upper Permian strata; at the same time, a gradual drowning event took place in the Barents Sea. The presence of these polygonal mounds is interpreted to reflect: (i) shallower conditions around the Samson Dome than in other parts of the Barents Sea; and (ii) earlier drowning of Upper Permian mounds towards the west and northwest into the Ottar Basin. Based on the recognition of mounds~20 m below the Permian-Triassic stratigraphic boundary, this paper proposes for the first time that shallow areas of the Barents Sea, such as the Samson Dome, witnessed sustained organic productivity until the onset of the P-T extinction event.

New style of honeycomb structures revealed on 3D seismic data indicate widespread diagenesis offshore Great South Basin, New Zealand

“…These mounds developed in a quiet, relatively deep water setting, which suggests there maybe parallels with the HS structures. The carbonate mounds depicted in Alves (2016) appears in a unit ~150 m thick as undulations affecting continuous reflections, with relief up to about 50 ms TWT and an average wavelength of ~250 m. In time-slices the morphology of the mounds compared with HS structures is more irregular, often elongate to elliptical, and less regularly packed. The carbonate mounds in vertical seismic section do not exhibit the diversity of structures (e.g.…”

“…As described in the Geological Setting section the deposits in which the HS are found are deeper water marls, that do not show evidence for surface exposure. Alves (2016) discusses the development of Upper Permian carbonate mounds in the Barents sea that exhibit polygonal forms. These mounds developed in a quiet, relatively deep water setting, which suggests there maybe parallels with the HS structures.…”

Strike‐Slip Tectonics in the SW Barents Sea During North Atlantic Rifting (Swaen Graben, Northern Norway)

“…Their ages were established based on the regional geology. Horizon H1 is a component of the Ørn to Isbjørn Formations, that is, the top of the regional carbonate platform and buildups in the Barents Sea (Alves, ; Glørstad‐Clark et al, ; Larssen et al, ). The regional stratigraphic correlations that were published in Mattos et al () suggested that H2 and H3 represent the tops of the Early Triassic Havert and Klappmyss Formations.…”

Distribution and growth styles of isolated carbonate platforms as a function of fault propagation

“…Isolated carbonate platforms (ICPs) are of great interest to petroleum exploration due to their reservoir potential. Some of the best examples of such potential are recorded in the South China Sea (Neuhaus et al, 2004;Ding et al, 2014;Hutchison, 2014), Kazakhstan (Collins et al, 2006;Kenter et al, 2008;Collins et al, 2016), the Middle East (Alsharhan, 1987), the Brazilian Coast (Buarque et al, 2017), the Barents Sea (Blendinger et al, 1997;Elvebakk et al, 2002;Nordaunet-Olsen, 2015;Alves, 2016), amongst others. It is estimated that reserves of about 50 billion barrels of oil equivalent are accumulated within these structures around the world (Burgess et al, 2013) including fields such as the Luconia Province and the Malampaya Field in the South China Sea (Neuhaus et al, 2004;Zampetti et al, 2004;Rankey et al, 2019), the Karachaganak gas-condensate-oil field and the Tengiz field in the Pre-Caspian Basin, Kazakhastan (Elliott et al, 1998;Collins et al, 2006;Borromeo et al, 2010;Katz et al, 2010).…”