Onshore Structural and Stratigraphic Study of the Namibe Basin (Angola)

• Main Authors: Casciello, Emilio, Vergés, Jaume, Cruz, Israel, Baqués, Vinyet, Moragas, Mar, Sharp, Ian, Messager, G., Hunt, David, Freitag, Ulrike, Ferreira, Herrcinda, Machado, Vladamir
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Namibe Basin; Angola; Stratigraphy; Canada; South Atlantic Ocean
• Online Access: http://hdl.handle.net/10261/229789

AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016 The Namibe continental margin of Angola developed during the Cretaceous breakup of Pangea and the formation of the South Atlantic Ocean. Significant oil discoveries in the Brazilian Campos, Santos and Pelotas basins have attracted attention onto the under-explored regions of the `conjugate¿ African margin, including the Namibe Basin of Angola. Plate tectonic reconstructions suggest that these conjugate margins had similar histories, with deposition of reservoirs and source rocks in close proximity before sea-floor spreading separated the basins. The current focus of deep water exploration in the Kwanza and Namibe basins is similar to its Brazilian counterpart the sedimentary sequence beneath autochthonous Aptian-age salt. Along the Atlantic margin of Angola, in a strip extending about 100 km north of Namibe city, we analyzed the complete Mesozoic stratigraphic record exposed between the coastline and the Precambrian basement, focusing on re-incised Cretaceous paleovalleys. Here, field based structural study, RSM, sedimentological and diagenetic analyses allowed to unravel the tectono-sedimentary evolution and it's relation with the major magmatic and diagenetic stages. The on-land structural study highlighted two main tectonic processes, which were quantified and analyzed trough structural modelling. Firstly, is the large-scale ocean-wards tilt of the entire margin recorded by Pre-Salt deposits (Tumbalunda Fm.), and specifically documented by shallowperitidal carbonates of the lower Cangulo Fm that are presently tilted 10-15 grades westwards. This marginscale westward tilt can be related to tectonic hinge processes associated to a dramatic westward crustal thinning of the Namibe margin. Secondly, the chronology of 3 main sets of normal faults (~N-S; SW-NE, NWSE), determined through their interaction with the stratigraphy and well dated magmatic events. The ~N-S fault set exerted the strongest influence on the margin's evolution, ...