Effects of glaciations on sedimentary basins

Fjeldskaar, Willy; Amantov, Aleksey

doi:10.1016/j.jog.2017.10.005

Cited by 43 publications

(38 citation statements)

References 27 publications

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“…Driven by buoyancy forces and pressure gradients, gas migration along faults, fractures, and inclined bedding planes is a common mechanism of relatively fast methane transfer through unlithified sediments (Cartwright, ; Chand et al, ; Sun et al, ; Vadakkepuliyambatta et al, ). Tectonic and glacial‐isostatic events may reactivate fractures and faults imposing a temporal variability on spatially heterogeneous fluid flow (Andreassen et al, ; Fjeldskaar & Amantov, ; Wallmann et al, ).…”

Section: Introductionmentioning

confidence: 99%

Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

Waage

Portnov

Serov

et al. 2019

Geochem Geophys Geosyst

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In 2014, the discovery of seafloor mounds leaking methane gas into the water column in the northwestern Barents Sea became the first to document the existence of nonpermafrost-related gas hydrate pingos (GHPs) on the Eurasian Arctic shelf. The discovered site is given attention because the gas hydrates occur close to the upper limit of the gas hydrate stability, thus may be vulnerable to climatic forcing. In addition, this site lies on the regional Hornsund Fault Zone marking a transition between the oceanic and continental crust. The Hornsund Fault Zone is known to coincide with an extensive seafloor gas seepage area; however, until now lack of seismic data prevented connecting deep structural elements to shallow seepages. Here we use high-resolution P-Cable 3-D seismic data to study the subsurface architecture of GHPs and underlying glacial and preglacial deposits. The data show gas hydrates, authigenic carbonates, and free gas within the GHPs on top of gas chimneys piercing a thin section of low-permeability glacial sediments. The chimneys connect to faults within the underlying tilted and folded fluid and gas-hydrate-bearing sedimentary rocks. Correlation of our data with regional 2-D seismic surveys shows a spatial connection between the shallow subsurface fluid flow system and the deep-seated regional fault zone. We suggest that fault-controlled Paleocene hydrocarbon reservoirs inject methane into the low-permeability glacial deposits and near-seabed sediments, forming the GHPs. This conceptual model explains the existence of climatesensitive gas hydrate inventories and extensive seabed methane release observed along the Svalbard-Barents Sea margin.Plain Language Summary Gas hydrates (concentrated hydrocarbon gases in cages of ice) are stable within high pressure and low temperature. At boundary conditions, minor increases in ocean temperature may trigger gas hydrate decay and the possibility that gas hydrates may dissociate due to future warming causes particular awareness. We present observations of a hydrate system expressed as ≤450-m wide and ≤10-m high gas hydrate pingos (seabed mounds bearing gas hydrates). The geological conditions controlling the formation of these shallow gas hydrate accumulations have not been previously investigated. Along a~700-km region that coincides with a regional fault system, the Hornsund Fault Zone, more than 1,200 seeps releasing gas from the seafloor have been observed. Linkage of this fault zone to the methane hotspots has been hypothesized but never supported by empirical data. Combining new and published data, we postulate the major preconditions for GHP development: geologically constrained focused release of methane from 55-65 million-year-old rocks, modern gas hydrate stability conditions, and a drape of muddy bottom sediments favorable for heaving due to hydrate growth. We observe a clear relationship between this methane system and the regional fault system, which potentially demonstrates a typical scenario of fault-controlled methane migration across the Svalba...

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Section: Introductionmentioning

confidence: 99%

Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

Waage

Portnov

Serov

et al. 2019

Geochem Geophys Geosyst

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“…4c). In addition, continued present-day isostatic rebound of the Norwegian mainland as a response to the Plio-Pleistocene glaciations may also be critical factors for hydrocarbon retention in traps in this region (Stoddart et al 2015;Fjeldskaar & Amantov 2018). Outcrop analogues to Lofoten are found on the Vesterålen archipelago, as well as on the island of Andøya (Fig.…”

Section: The General Characteristics Of Each Basement Play and Onshormentioning

confidence: 99%

Fractured basement play development on the UK and Norwegian rifted margins

Trice¹,

Hiorth²,

Holdsworth³

2019

Geological Society, London, Special Publications

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Fractured crystalline basement reservoirs (basement) on the UK Continental Shelf (UKCS) and the Norwegian Continental Shelf (NCS) have been underexplored. Over the last 12 years, Hurricane Energy has deliberately set out to explore basement potential by exploring and appraising the Rona Ridge, West of Shetland; and the Rona Ridge Lancaster Field is now being progressed towards being the first UK basement field development. The Norwegian basement play is also recognized as a potentially material resource through serendipitous oil discoveries, with the 16/1-15 well, drilled in 2011, being the first successful full-scale basement test on the NCS. Building on this success, the 2018 Rolvsnes appraisal well (16/1-28 S) has demonstrated the significant basement potential of the extensive Utsira High and confirmed the materiality of a Norwegian basement play. The Rona Ridge and Utsira basement discoveries are used as a comparison with two other, yet to be evaluated, prospective basement plays on the NCS, with the objective of establishing technical subject areas where future UKCS and NCS collaboration would aid in accelerating understanding of the UKCS-NCS basement play.

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“…We follow the work of [36]; their LGM extent model is shown in Figure 1. [36]) and maximum thickness model for the Last Glacial Maximum (LGM), from [3]. The production licenses (from www.npd.no) in the Norwegian continental shelf are shown by grey polygons.…”

Section: Ice Thicknessmentioning

confidence: 99%

“…The Earth's response to deglaciation shows that the lithosphere acts as an elastic shell overlying a viscous mantle. If a load is applied to the elastic lithosphere, part of the applied load will be [36]) and maximum thickness model for the Last Glacial Maximum (LGM), from [3]. The production licenses (from www.npd.no) in the Norwegian continental shelf are shown by grey polygons.…”

Section: Glacial Isostasy and Tilting Of Reservoirsmentioning

confidence: 99%

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Tilting and Flexural Stresses in Basins Due to Glaciations—An Example from the Barents Sea

2019

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Many of the Earth’s sedimentary basins are affected by glaciations. Repeated glaciations over millions of years may have had a significant effect on the physical conditions in sedimentary basins and on basin structuring. This paper presents some of the major effects that ice sheets might have on sedimentary basins, and includes examples of quantifications of their significance. Among the most important effects are movements of the solid Earth caused by glacial loading and unloading, and the related flexural stresses. The driving factor of these movements is isostasy. Most of the production licenses on the Norwegian Continental Shelf are located inside the margin of the former Last Glacial Maximum (LGM) ice sheet. Isostatic modeling shows that sedimentary basins near the former ice margin can be tilted as much as 3 m/km which might significantly alter pathways of hydrocarbon migration. In an example from the SW Barents Sea we show that flexural stresses related to the isostatic uplift after LGM deglaciation can produce stress changes large enough to result in increased fracture-related permeability in the sedimentary basin, and lead to potential spillage of hydrocarbons out of potential reservoirs. The results demonstrate that future basin modeling should consider including the loading effect of glaciations when dealing with petroleum potential in former glaciated areas.

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Effects of glaciations on sedimentary basins

Cited by 43 publications

References 27 publications

Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

Fractured basement play development on the UK and Norwegian rifted margins

Tilting and Flexural Stresses in Basins Due to Glaciations—An Example from the Barents Sea

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