Structure of the Demerara passive-transform margin and associated sedimentary processes. Initial results from the IGUANES cruise
Published:January 01, 2016
L. Loncke, A. Maillard, C. Basile, W. R. Roest, G. Bayon, V. Gaullier, F. Pattier, M. Mercier de Lépinay, C. Grall, L. Droz, T. Marsset, P. Giresse, J. C. Caprais, C. Cathalot, D. Graindorge, A. Heuret, J. F. Lebrun, S. Bermell, B. Marcaillou, C. Sotin, B. Hebert, M. Patriat, M. A. Bassetti, C. Tallobre, R. Buscail, X. Durrieu de Madron, F. Bourrin, 2016. "Structure of the Demerara passive-transform margin and associated sedimentary processes. Initial results from the IGUANES cruise", Transform Margins: Development, Controls and Petroleum Systems, M. Nemčok, S. Rybár, S. T. Sinha, S. A. Hermeston, L. Ledvényiová
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The IGUANES cruise took place in May 2013 on the R/V L’Atalante along the Demerara passive transform margin off French Guiana and Surinam. Seismic, multibeam and chirp acquisitions were made. Piston cores were collected for pore geochemistry and sedimentology. A mooring was deployed on the sea-bottom for 10 months (temperature, salinity, turbidity and current measurements). This new dataset highlights the lateral variability of the 350 km-long Guiana–Surinam transform margin due to the presence of a releasing bend between two transform segments. The adjacent Demerara Plateau is affected by a 350 km-long giant slide complex. This complex initiated in Cretaceous times and was regularly reactivated until recent times. Since the Miocene, contourite processes seem to be active due to the onset of the North Atlantic Deep Water (NADW) bottom current. A main NADW water vein flows towards SE, eroding slide headscarps and allowing the deposition of contourite drifts. Numerous depressions looking like comet tails or comet scours record this flow. Some of those were interpreted before the cruise as active pockmarks. Pore geochemistry and core analysis do not show any evidence of present-day gas seepage.
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Transform Margins: Development, Controls and Petroleum Systems
This volume covers the linkage between new transform margin research and increasing transform margin exploration. It offers a critical set of predictive tools via an understanding of the mechanisms involved in the development of play concept elements at transform margins. It ties petroleum systems knowledge to the input coming from research focused on dynamic development, kinematic development, structural architecture and thermal regimes, together with their controlling factors. The volume does this by drawing from geophysical data (bathymetry, seismic, gravity and magnetic studies), structural geology, sedimentology, geochemistry, plate reconstruction and thermo-mechanical numerical modelling. It combines case studies (covering the Andaman Sea, Arctic, Coromandal, Guyana, Romanche, St. Paul and Suriname transform margins, the French Guyana hyper-oblique margin, the transtensional margin between the Caribbean and North American plates, and the Davie transform margin and its neighbour transform margins) with theoretical studies.