Gas hydrate distributions in sediments of pockmarks from the Nigerian Margin - Results and interpretation from shallow drilling
|Author(s)||Wei Jiangong1, Pape Thomas1, Sultan Nabil2, Colliat Jean-Louis3, Himmler Tobias1, 2, Ruffine Livio2, de Prunele Alexis2, Dennielou Bernard2, Garziglia Sebastien2, Marsset Tania2, Peters Carl A.1, 5, Rabiu Abdulkarim4, Bohrmann Gerhard1|
|Affiliation(s)||1 : Univ Bremen, MARUM, D-28359 Bremen, Germany.
2 : IFREMER, Dept REM, Unite Geosci Marines, F-29280 Plouzane, France.
3 : TOTAL, Pau, France.
4 : Nigeria Inst Oceanog & Marine Res, Lagos, Nigeria.
5 : Macquarie Univ, Dept Earth & Planetary Sci, Sydney, NSW 2109, Australia.
|Source||Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2015-01 , Vol. 59 , P. 359-370|
|WOS© Times Cited||40|
|Keyword(s)||Gas hydrate, Pockmark, Chloride profile, Infrared thermal imaging, Fluid flow, Nigerian continental margin, MeBo drill rig|
|Abstract||A joint research expedition between the French IFREMER and the German MARUM was conducted in 2011 using the R/V Pourquoi pas? to study gas hydrate distributions in a pockmark field (1141 – 1199 meters below sea surface) at the continental margin of Nigeria. The sea floor drill rig MeBo of MARUM was used to recover sediments as deep as 56.74 meters below seafloor. The presence of gas hydrates in specific core sections was deduced from temperature anomalies recorded during continuous records of infrared thermal scanning and anomalies in pore water chloride concentrations. In situ sediment temperature measurements showed elevated geothermal gradients of up to 258 °C/km in the center of the so-called pockmark A which is up to 4.6 times higher than that in the background sediment (72 °C/km). The gas hydrate distribution and thermal regime in the pockmark are largely controlled by the intensity, periodicity and direction of fluid flow. The joint interaction between fluid flow, gas hydrate formation and dissolution, and the thermal regime governs pockmark formation and evolution on the Nigerian continental margin.|