Sediment provenance signal of the Northern Andes during the Oligocene-Pliocene: Insights from the detrital record of the forearc and intra-arc basins, northwestern Colombian margin

Abstract

The Cenozoic uplift and relief history of the Colombian Andes controlled the evolution of drainage systems and the filling history of sedimentary basins. The understanding of the associated polyphasic orogenic history has been reconstructed from the history of hinterland and foreland basins in eastern Colombia. In contrast, the tectonostratigraphic record of the forearc and intra-arc basins is less known, despite their potential to record both the exhumation and magmatic history of the orogen and the lesser-known history of the Central and Western cordilleras. A review of the regional stratigraphy together with provenance constraints from sandstone petrography, and U-Pb zircon geochronology a (n = 2738 new and 2456 published data) of the Oligocene-Pliocene successions in the Caribbean and Pacific forearc basins and the Amagá and Cauca intra-arc basins (NW Colombia) is used to infer the topographic evolution of the Central and Western cordilleras, as well as the distribution of depositional environments and ancient drainage systems. The results indicate that the Oligocene-Lower Miocene sandstones of the intra-arc and Caribbean forearc basins document the uplift of both the Central and Western cordilleras, as seen by the quartz-rich character with fragments associated to the Pre-Cenozoic sources, while sandstones of the Pacific forearc segment show a lithic character with volcanic fragments derived from the Cretaceous and Eocene-Oligocene sources of the proto-Western Cordillera. After the Lower-Middle Miocene, sandstones are more immature including sources derived from the cordilleran basement and volcanic fragments from the upper Oligocene-Middle Miocene magmatic arc located exclusively in the Western Cordillera. The Upper Miocene-Pliocene sandstones in general exhibit a lithic character with fragments derived from upper Oligocene-Middle Miocene and Middle Miocene-Pliocene magmatic rocks located in the Western Cordillera and intra-arc region. When the provenance record between basins is compared, changes in topographic continuity are seen through time, with some marine passages connecting the Pacific forearc with the Cauca intra-arc basin during the Oligocene-Miocene, followed by the formation of a continuous cordilleran system after the Middle Miocene that interrupts marine passages. The integrated detrital zircon signature from the different basins show that within a regional perspective, Miocene-Pliocene magmatism was continuous along the northwestern South American margin.