AAPG Europe Regional Conference, Global Analogues of the Atlantic Margin

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Long-term dislocation and inversion of the Southermost segment of Western N. Atlantic margins north of Hispaniola.

Abstract

The N-S directed southernmost segment of Western N. Atlantic margins registered several tectonic episodes since Jurassic times. From rifting phases in Triassic times to the E-W opening stage of the equatorial ocean in E. Jurassic, the Atlantic margins were re-organized several times. Moreover, its southern edge appears to be bounded by the paleotransform fault zone which marks the limit of the N. and S. Atlantic Plates. This transform margin initiated during the Tethyan evolution connected, in Middle Jurassic Time, the proto Atlantic ocean with the Gulf of Mexico embayment. The location of induced paleofacies transition is not completely constrained during Mesozoic times, but may be approached by seismic interpretation, at least along flexural basin North of the N Hispaniola accretionary Prim, where series are not too much deformed. Four Mega tectonic cycles can be isolated, 1) E-W extension during Jurassic times , 2) NE rotating extension during the Cretaceous time, resulting from rifting and drifting phases co-eval with the opening of the Northern part of the South Atlantic ocean, 3) Late Cretaceous, paleo-Caribbean crust formation and 4) tectonic inversion and development of a tectonic accretionary prism North of Hispaniola, when transpressive regime was imposed by the oblique compression between Caribbean and N. American Plates . On this peculiar segment of the Atlantic Margin, the spectacular Bahamas carbonated plate-form developed and, as a precious marker, registered all the tectonic episodes of deformation. Extension processes initiated during Jurassic time and have been re-directed during Cretaceous time, resulting in normal and tear faults, rooted either on salt levels or intra- carbonated shale. The structural evolution of this Atlantic margin segment has been deconvoluated from the interpretation of some of the seismic lines acquired during Haiti-SIS oceanic survey in 2012 and 2013. These results outline the implication of the margin within the North Haitian accretionary Prims, as well as large inversion and dislocation of the Bahamas plate-form along-strike from West to east, since Eocene times in Cuba, and Middle Miocene North of Haiti. Tectonic heritage resulting from the initial N. Atlantic segmentation is discussed in terms of Present-day transform fault propagation and re-localization.