The detrital record of Cretaceous to Pliocene sandstones across the NE South American margin

Abstract

The Cretaceous to Pliocene erosional history of the NE South American margin depicts the increasing influence of the uplifting Caribbean Mountain belt. Petrographic analyses of 59 Cretaceous to Late Pliocene sandstone samples derived from across the islands of Trinidad and Barbados, demonstrate systematic mineralogical changes whereby Early Cretaceous arkosic arenites gave way to mature quartz arenites by the Late Cretaceous and Caribbean Mountain-derived lithic-rich arenites during the Neogene. Changes in the framework compositions are accompanied by changes in textural attributes, with Caribbean Mountain detritus being notably finer grained than cratonic input. Silica cements predominate in quartzose sandstones and sericitic and clay cements within litharenites. The changing mineralogical compositions record the gradual deformation of the northern South American passive margin and initiation of the Andean–Caribbean Mountain foreland basin system, with incipient orogenic detritus evident from the latest Eocene and unambiguous orogenic input by the Late Oligocene. The preponderance of finer grain sizes within deltaic Pliocene sandstones records the later fill of an established foredeep with sediments sourced primarily from erosion of the Andean hinterland. These interpretations agree with heavy mineral compositional changes and the timing of uplift from geo- and thermo-chronological data across the margin. Supplementary material : Qualitative descriptions, sample coordinates and raw point counts are available at https://doi.org/10.6084/m9.figshare.c.3659381