| Autor: |
Davison, Ian, Faull, Theodore, Greenhalgh, Jenny, O Beirne, Eoin, Steel, Ian |
| Zdroj: |
Geological Society, London, Special Publications; 2016, Vol. 431 Issue: 1 p235-248, 14p |
| Abstrakt: |
The Romanche Fracture Zone was originally a corridor of Aptian-age dextral transtensional rifting along the Equatorial Atlantic margins. Late Albian plate tectonic compression occurred due to a change in plate vectors, when the African and South American continents were still in contact across a 500 km-long section of the Romanche Fracture Zone. This dextral compression produced reactivation of the rift faults to produce asymmetric landward-vergent anticlines and thrusts that trend ENE to NE. Fold-axial planes dip seaward, parallel to the rift faults. Minor asymmetric anticlines were developed on the long seaward-dipping fold limbs and these have subvertical axial planes. The asymmetry of the minor folds is due to the southward stratal dip having been oblique to the horizontal maximum principal stress during the Albian inversion. The folds on the African margin were subsequently tightened by compression in Santonian and Oligo-Miocene times. Aptian-age ENE strike-slip faults were reactivated during the compression phases to produce broad positive flower structures up to 30 km wide that formed topographical ridges along the original strike-slip faults. The intervening and broader flat-bottomed synclines do not appear to be associated with rift faults.The folding and thrust faulting created seabed relief of 1–2 km at the end of the Albian; evidenced by the amount of subsequent erosion that removed the better-quality reservoirs in the upper Albian sequence from the major fold crests. Consequently, there has been a significant number of failed oil exploration wells drilled along the fold crests. The fold ridges would have diverted turbidite channels in the onlapping Cenomanian–Campanian sequence and these will be preferentially located on the landward side of the anticlinal crests. Late Cretaceous stratigraphic and structural traps located between the major anticlines have not yet been explored for hydrocarbons along the Romanche Fracture Zone margins. |
| Databáze: |
Supplemental Index |
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