TY - GEN
T1 - Fluid-escape features due to silica diagenesis in the Faeroe-Shetland Basin
AU - Goulty, N. R.
AU - Davies, R. J.
PY - 2008
Y1 - 2008
N2 - Conversion of opal-Ato opal-CT in biosiliceous sediment during burial expels water expulsion by porosity reduction and dehydration. This release of water occurs over large tracts of sedimentary basins within discrete diagenetic reaction zones at burial depths in the range 200 800 m. Seismic data from the Faeroe-Shetland Basin provide evidence for a variety of fluid conduits which terminate upwards in roughly circular erosional depressions at an Early Pliocene unconformity, interpreted as the contemporaneous seabed. These features are indicative of water expulsion and focused fluid flow emanating from the opal-A to opal-CT reaction zone. The sediment immediately below the reaction zone contains, on average, ∼30% opal-CT by weight. The estimated volumetric rate of water expulsion per unit surface area during the Quaternary has averaged ∼6 m3 My-1 per square meter, which is greater than the vertical flux of water at the same depth from compaction of the deeper basin fill, and amounts to a volumetric rate of ∼120 km3 My-1 across the whole basin. In late Miocene times, the calculated rate of water expulsion was around six times greater, which explains why the fluid-escape features terminate at the Early Pliocene unconformity.
AB - Conversion of opal-Ato opal-CT in biosiliceous sediment during burial expels water expulsion by porosity reduction and dehydration. This release of water occurs over large tracts of sedimentary basins within discrete diagenetic reaction zones at burial depths in the range 200 800 m. Seismic data from the Faeroe-Shetland Basin provide evidence for a variety of fluid conduits which terminate upwards in roughly circular erosional depressions at an Early Pliocene unconformity, interpreted as the contemporaneous seabed. These features are indicative of water expulsion and focused fluid flow emanating from the opal-A to opal-CT reaction zone. The sediment immediately below the reaction zone contains, on average, ∼30% opal-CT by weight. The estimated volumetric rate of water expulsion per unit surface area during the Quaternary has averaged ∼6 m3 My-1 per square meter, which is greater than the vertical flux of water at the same depth from compaction of the deeper basin fill, and amounts to a volumetric rate of ∼120 km3 My-1 across the whole basin. In late Miocene times, the calculated rate of water expulsion was around six times greater, which explains why the fluid-escape features terminate at the Early Pliocene unconformity.
UR - http://www.scopus.com/inward/record.url?scp=70449561039&partnerID=8YFLogxK
M3 - Conference proceedings published in a book
AN - SCOPUS:70449561039
SN - 9781605604749
T3 - 70th European Association of Geoscientists and Engineers Conference and Exhibition 2008: Leveraging Technology. Incorporating SPE EUROPEC 2008
SP - 59
EP - 63
BT - Society of Petroleum Engineers - 70th European Association of Geoscientists and Engineers Conference and Exhibition - Incorporating SPE EUROPEC 2008
PB - Society of Petroleum Engineers
T2 - 70th European Association of Geoscientists and Engineers Conference and Exhibition - Incorporating SPE EUROPEC 2008
Y2 - 9 June 2008 through 12 June 2008
ER -