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| Titel |
Mud volcano formation within the Western slope of the Nile Cone sourced from pre-salt layers |
| VerfasserIn |
Christopher Kirkham, Joseph Cartwright, Christian Hermanrud, Christopher Jebsen |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106077
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| Publikation (Nr.) |
 EGU/EGU2015-5730.pdf |
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| Zusammenfassung |
| Mud volcanos are prevalent in a variety of settings, particularly in those where rapid
sedimentation, thrust loading or horizontal tectonic stresses are observed. Here we describe
from a three-dimensional (3D) seismic survey located on the Western slope of the Nile
Cone, a suite of mud volcanoes emplaced throughout the post-salt Pliocene-Recent
succession. These mud volcanoes are highly variable in scale, some among the largest
ever described. Extrusive volumes range from 100 km3. Evaporites
are widely considered a world class seal which has given rise to the discovery of
numerous pre-salt hydrocarbon accumulations. Pre-salt depletion features, contrasts in
p-wave velocity and salt welding due to mud remobilisation, are all indicative of a
pre-Messinian (sub-salt) primary mud source, predominantly Tortonian in age.
This implies large scale mud remobilisation through the thick Messinian evaporite
succession.
It is our interpretation that the formation of mud volcanoes within this region is intimately
related to the basinal hydrodynamics, which include undercompaction and subsequent fluid
retention, local sea level variation and overpressure generation. These mechanisms are
controlled by key events in the geological history of the basin such as the Messinian Salinity
Crisis (MSC) and the Zanclean flood. We argue that the formation of these mud
volcanoes is a direct response to overpressure generated primarily through rapid
loading of pre-salt sediments during the MSC and catastrophic re-flooding during its
immediate aftermath. Ultimately the location at which they form is associated with
deeper features such as underlying faults and potential hydrocarbon plays. It is
feasible that similar basin-scale remobilisation and overpressure could be expected
for other salt basins world-wide that have undergone similar priming processes. |
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