Petrography and provenance of the Grupo Morro Solar sandstones (upper Berriasian-Valanginian) of Lima (77°01’W, 12°10’S): Geodynamic and paleogeographic implications

Abstract

The sedimentary record of the continental margin of Lima, Peru (77°01’W, 12°10’S) plays a significant role in understanding the regional geology given its location along the westernmost part of a siliciclastic platform developed during the Early Cretaceous, prior to the Andean orogeny. In this contribution, the mineral composition of 20 samples of litho-quartzose sandstones and quartzose sandstones from the Salto del Fraile, La Herradura, and Marcavilca formations of the Morro Solar Group (Upper Berriasian-Valanginian) is examined by using the Gazzi-Dickinson method to shed light into sediment provenance. Results reveal that the sediments of the Morro Solar Group accumulated after the exhumation of a recycled orogen located in the Eastern Cordillera, which includes the Marañón Metamorphic Complex. This orogen is interpreted to be composed of sedimentary and volcanic rocks of Paleozoic and Triassic age. A minor provenance of metamorphic Precambrian rocks from the Amazon Craton is not totally discarded.