Provenance analysis of the Matzitzi and Agua de Mezquite formations, southern Mexico: Different fluvial successions formed during late Paleozoic and post-Middle Jurassic time along the southernmost North America Pacific margin

• Published in: Journal of South American earth sciences 2021-01, Vol.105, p.102999, Article 102999
• Main Authors: Bedoya, Alejandra, Anaya-Guarneros, Jonathan A., Abdullin, Fanis, Martini, Michelangelo, Solari, Luigi
• Format: Article
• Language: English
• Subjects: Assembly of Pangea; Matzitzi formation; Permian; Sandstone provenance; Southern Mexico
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2020.102999

The Matzitzi Formation has been defined by previous authors as an uppermost Paleozoic fluvial succession that was developed during the final assembly of western equatorial Pangea. According to this interpretation, fluvial deposits of the Matzitzi Formation are an invaluable source of information for geologists aimed at reconstructing the tectonic processes that accompanied the consolidation of the most recent supercontinent on Earth. However, in this work we demonstrate that the Matzitzi Formation comprises fluvial successions with different age and provenance. We recognize at least two groups of different fluvial deposits. Group 1 is composed of fluvial deposits that show a main provenance from the Proterozoic and Paleozoic Oaxacan and Acatlán complexes, as well as minor detrital contributions from the Carboniferous–Permian East Mexico Arc. We keep the name Matzitzi Formation for fluvial deposits of group 1 because they comprise the outcrops on which this unit was originally defined and that contain the upper Paleozoic flora studied by previous authors. Group 2 is composed of post-177 Ma deposits that are derived from a more complex mix of sources, which comprises the Proterozoic Oaxacan Complex, the Carboniferous–Permian East Mexico Arc, the Lower–Middle Jurassic Nazas volcano-sedimentary province, and carbonate successions probably associated with the Late Jurassic–Early Cretaceous opening of the Gulf of Mexico. We assign these deposits to a new informal unit named the Agua de Mezquite formation. Our data indicate that fluvial deposits previously grouped into the Matzitzi Formation were emplaced by different fluvial systems that drained different catchment areas during different times. The differentiation between upper Paleozoic and post-177 Ma successions will permit a correct reconstruction of major changes in the fluvial drainage and, consequently, in the topographic configuration during the transition from the final assembly of Pangea to its breakup. •Informal stratigraphic redefinition of the Matzitzi Formation fluvial deposits.•Introduction of a new informal unit named Agua de Mezquite formation to designate post-177 Ma fluvial deposits.•The Matzitzi Formation, as it was originally defined, contains the stratigraphic record of different fluvial systems developed at different time and under different tectono-stratigraphic context.