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| Titel |
Venting of fluids around saucer-shaped sills |
| VerfasserIn |
Catherine Holley, Timothy Reston, Nick Schofield |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037470
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| Zusammenfassung |
| It has been proposed that the intrusion of sills into sedimentary basins can lead to the production of thermogenic methane, the release of which can contribute substantially to global warming and hence to mass extinctions associated with the emplacement of large-igneous provinces. To explore this possibility, we have investigated fluid escape structures associated with saucer-shaped sills emplaced in the Faroe-Shetland Basin, using industrial 3D seismic data. The 3D seismic reveal both a network of saucer-shaped sills beneath a marked subaerial unconformity, characterised by incised drainage systems, near the Paleocene-Eocene boundary. As a result, we interpret the age of sill emplacement as close to the Paleocene-Eocene boundary. Fluid escape structures can be identified on the 3D seismic as sub-vertical pipes where the strata have been disrupted and by the presence of bright reflections at the upper limit of the pipe. The pipes extend upwards from the edges of the sills, but do not terminate at the major incised unconformity, which might be expected if they transported thermogenic methane produced in the aureoles to the sills. Instead, the pipes terminate at different levels, mainly but not exclusively in the Eocene. We speculate that the pipes may have transported fluids released by sediment compaction at depth and diverted by the relatively impermeable sills, thus being concentrated at the edge of the sills. In effect, the sills may have acted as inverted umbrellas, with the pipes being the drips from the umbrella spokes. If confirmed, this result would question the importance of thermogenic methane generated by sill intrusion in the development of the Paleocene-Eocene Thermal Maximum and thus in climate change and mass extinctions linked to Large Igneous Provinces. |
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