Discussion of: Ortega-Flores et al. (2018) Provenance analysis of Oligocene sandstone from the Cerro Pelon area, southern Gulf of Mexico.https://doi.org/10.1080/00206814.2018.1476922

摘要

We discuss the 2018 publication that reports petrographic, heavy mineral data, mineral chemistry, and zircon geochronology for Oligocene sandstones in the Cerro Pelon area in southern Mexico Sureste basin. As the title of their paper says, the goal of their study is to establish the source (s) of the voluminous Cenozoic section in this region, reaching several kilometres in thickness and important as a petroleum system. These authors conclude that Oligocene sandstones of La Laja Formation were mostly sourced from eclogite- to greens-chist-facies metasedimentary, metaigneous, and ultramafic rocks of the Guatemala suture complex. Minor contributions from the Chiapas Massif Complex, exposed directly to the south ~60 km of the Cerro Pelon area, were also suggested by the authors. They thus conclude that the Palaeogene stratigraphic record in southeastern Mexico was mostly controlled by the development of the Caribbean-North America plate boundary rather than by orogenic processes at the Pacific margin of North America. Presently, we do not agree with the conclusions of Ortega Flores and colleagues who studied the Cerro Pelon section, thus some discussion is required. Serpentinite bearing Nanchital Conglomerate is well exposed in the Cerro Pelon area, and high- to low-grade metamorphic rocks experienced an uplift in the vicinity of the Cerro Pelon area at the time of deposition of the La Laja Formation. We believe the data are better explained by multiple local sources in southern and eastern Oaxaca as well as sources to the south and southwest, which include the Cenozoic coastal batholith, the Grenvillean/Guichicovi basement complexes, the Chiapas Massif, the Mazatlan schist and other units in the Cuicateco Belt, as well as the Mesozoic cover of these areas (Todos Santos Formation, Cretaceous carbonate rocks, and Paleogene strata such as the Soyalo and Bosque Formations).