Abstract The study focuses on the offshore Guyana–Suriname–French Guiana region. It draws from seismic, well, gravimetric and magnetic data. They indicate that the continental break-up along the western margin of the Demerara Plateau took place during the Callovian–Oxfordian, associated with the Central Atlantic opening, and accommodated by normal faults. The continental break-up in the SE offshore Guyana accommodated by strike-slip faults was coeval. The continental break-up along the NE and eastern margins of the Demerara Plateau took place during the late Aptian–Albian, associated with the opening of the Equatorial Atlantic, and accommodated by dextral strike-slip and normal faults, respectively. Different spreading vectors of the Central and Equatorial Atlantic required development of the Accommodation Block during the late Aptian/Albian–Paleocene in their contact region, and in the region between the Central Atlantic and its southernmost portion represented by the Offshore Guyana Block, which were separated from each other by the opening Equatorial Atlantic. Its role was to accommodate for about 20° mismatch between the Central and Equatorial Atlantic spreading vectors, which has decreased from the late Aptian/Albian to Paleocene down to 0°. Differential movements between the Central and Equatorial Atlantic oceans were also accommodated by strike-slip faults of the Guyana continental margin, some active until the Paleocene.

Abstract The Granite Wash Mountains are located in west-central Arizona and are contiguous with the Harcuvar Mountains to the northeast and the Little Harquahala Mountains to the south. They are part of the Maria fold and thrust belt, a belt of large folds and major thrust faults that trends east-west through west-central Arizona and southeastern California (Reynolds and others, 1986; Spencer and Reynolds, 1990). In the Granite Wash Mountains, late Mesozoic deformation related to the Maria belt affected a diverse suite of rock units, including Proterozoic crystalline rocks, Paleozoic carbonate and quartzose clastic rocks, and Mesozoic sedimentary, volcanic, plutonic, and hypabyssal rocks. This deformation was mostly deep seated and produced an assortment of folds, cleavages, and both ductile and brittle shear zones. Several discrete episodes of deformation occurred, resulting in refolded folds, folded and refolded thrust faults, and complex repetition, attenuation, and truncation of stratigraphic sequences. Greenschist-facies metamorphism accompanied deformation and was most intense along the major thrusts. Deformation and metamorphism were followed by emplacement of two Late Cretaceous intrusions and numerous Cretaceous to mid-Tertiary dikes.