Abstract

EGUILUZ Y DE ANTUNANO, Samuel et al. Stratigraphy of the Sierra Madre Group in Chiapas and its hypothetical petroleum potential. Bol. Soc. Geol. Mex [online]. 2023, vol.75, n.3, e301023.  Epub May 28, 2024. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2023v75n3a301023.

The Sierra Madre Group of Chiapas has informalities in its stratigraphic nomenclature that have been transmitted through geological literature. This work describes the characteristics of three lithostratigraphic successions that make the tripartite division of the Sierra Madre Group understandable. A particular lithology, which here is defined as the El Chango succession, separates the Cantelhá and Cintalapa successions to integrate this group. Additionally, the El Chango succession makes it possible to do an appropriate mapping and its correlation allows interpreting the regional distribution of sedimentary facies that these successions. Epifluorescence of rocks from the El Chango succession (Cenomanian) exhibits organic compounds. Pyrolysis data indicate ⁓0.22% of total organic carbon in carbonate rock, its equivalent reflectance is 0.7 and 1.0, which places the rock in the generation window of metagenic oil and gas, S2 values less than 0.2 mg HC/g make the low hydrocarbon expulsion potential questionable, so additional analyzes are required. The porosity impregnated with asphalt in rocks of the Sierra Madre Group suggests the existence of reservoir rock, regionally covered by pelitic rocks as a seal, and the changes in facies and deformation indicate the existence of potential traps. The data from this work proposes to explore a hypothetical oil play in this region.

Keywords : Cenomanian; play; sedimentary facies; pyrolysis.