Depositional paleoenvironments of the Lower Permian (upper Cisuralian) carbonate succession of Paso Hondo Formation in Chiapas State, southeastern Mexico

• Published in: Journal of South American earth sciences 2017-11, Vol.79, p.254-263
• Main Authors: Torres-Martínez, Miguel A., Barragán, Ricardo, Sour-Tovar, Francisco, González-Mora, Sergio
• Format: Article
• Language: English
• Subjects: Chiapas; Lower Permian; Mexico; Paleoenvironment; Paso Hondo Formation; Transgression event
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2017.08.018

The Paso Hondo Formation outcrops around of the Chicomuselo region, Chiapas State, Mexico. It is a Permian lithostratigraphic unit mainly composed of massive limestone which has been dated for the Artinskian-Kungurian (late Cisuralian). A microfacies analysis carried out on the carbonate rocks of a stratigraphic section, allowed for the first time the recognition of the depositional conditions that prevailed in the Chicomuselo region at the end of the Cisuralian. The facies associations studied allowed identifying different marine paleoenvironments related with a homoclinal carbonate ramp. The presence of anhydrite nodules, a mud-dominated carbonate production in euphotic zone (precursor of mudstones and packstones) and the presence of a diverse fauna mainly composed of photic-independent biota (mollusks, bryozoans, brachiopods and crinoids), indicate that the studied section was deposited in a relatively uniform low angle ramp. Thus, facies of different environments of inner ramp were detected, including those of a lagoon close to a peritidal area, with periodical restricted or open circulation, and open waters deposits influenced by the storm zone. In addition, mid-ramp facies were also observed. Facies associations of the basal levels on the studied section were mainly correlated with lagoonal shallow marine environments, being ostracods, calcispheres and peloids the dominant allochems. In contrast, there is a shift upwards to facies of open waters and mid-ramp environments, characterized by abundant skeletal grains of bryozoans, brachiopods and crinoids. The paleoenvironments recorded through the stratigraphic section were related with specific bathymetries, having a general tend towards the sea level rise. This record coincides with the global transgression event occurred during the Early Permian which have also been described for coeval localities of Texas and New Mexico in the United States and western Venezuela. •It recognizes paleoenvironments from shallow inner ramp to mid-ramp.•Environments of shallow lagoon, open waters and mid-ramp were identify.•The paleoenvironments are associated with a low angle homoclinal ramp.•It observes a tendency towards a rise in the sea level during the late Cisuralian.•Bathymetric changes were associated with the Early Permian transgressive event.