Boletín de la Sociedad Geológica Mexicana Volumen 76, núm. 1, A220224, 2024 http://dx.doi.org/10.18268/BSGM2024v76n1a220224

Sources of organic matter elucidated through Pyr-GC-MS, and relation to basin scale events in the Pimienta Formation (Central Mexico)

Fuentes de materia orgánica dilucidadas mediante Pir-CG-EM, y su relación con eventos a escala de cuenca en la Formación Pimienta (Centro de México)

María Colín-García¹, Antoni Camprubí¹, Fernando Núñez-Useche¹, Daniel Carrizo²,

Mayra León-Santiago³, Alexander Correa-Metrio⁴, Juan Josué Enciso-Cárdenas⁵,

Edith Fuentes-Guzmán^1,6

¹ Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Coyoacán, CDMX, Mexico.

² Centro de Astrobiología, INTA-CSIC, Instituto Nacional de Técnica Aeroespacial, Ctra. de Torrejón a Ajalvir, km 4, 28850 Torrejón de Ardoz, Madrid, Spain.

³ Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Coyoacán, CDMX, Mexico.

⁴ Centro de Geociencias, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, 76230 Querétaro, Qro., Mexico.

⁵ Centro de Investigación en Geociencias Aplicadas, Universidad Autónoma de Coahuila, Blvd. Simón Bolívar 303 A, Independencia, 26800 Nueva Rosita, Coah., Mexico.

⁶ Laboratorio Nacional de Geoquímica y Mineralogía (LANGEM), Ciudad Universitaria, 04510 Coyoacán, CDMX, Mexico.

* Corresponding author: (M. Colín-García) This email address is being protected from spambots. You need JavaScript enabled to view it.

How to cite this article:

Colín-García, M., Camprubí, A., Núñez-Useche, F., Carrizo, D., León-Santiago, M., Correa-Metrio, A., Enciso-Cárdenas, J.J., Fuentes-Guzmán, E., 2024, Sources of organic matter elucidated through Pyr-GC-MS, and relation to basin scale events in the Pimienta Formation (Central Mexico): Boletín de la Sociedad Geológica Mexicana, 76 (1), A220224. http://dx.doi.org/10.18268/BSGM2024v76n1a220224

Manuscript received: February 2, 2024; Corrected manuscript received: February 22, 2024; Manuscript accepted: February 24, 2024

ABSTRACT

The study of organic matter is essential for understanding the sedimentary and diagenetic processes that have occurred in a certain area. Sediments rich in organic matter with a vocation for producing hydrocarbons are of particular importance. Studies of organic matter in these environments help not only to determine their potential as hydrocarbon generators, but also contribute to the understanding of the processes that have occurred in the basin over time. In this study, the use of pyrolysis-gas chromatography-mass spectrometry (Pyr-GC-MS) is proposed to analyse the diversity of organic molecules contained in the sediments of the Pimienta Formation. This technique is versatile and, although destructive, allows rapid analysis of organic matter, in addition to the minimal quantities required for the study. Pyr-GC-MS allows functional groups to be determined; in this study 34 different moieties were identified. The use of this technique is perfectly complemented by Rock-Eval-pyrolysis and fluid inclusion studies, which allows greater detail of the origin of the molecules. The results of the Rock Eval Pyrolysis suggested that there were two types of kerogen: continental (Type III) and marine (Type II)]. Some samples contained organic matter of continental origin , while others contained organic matter of marine origin. Analysis of fluid inclusions suggested sedimentary-diagenetic and meteoric sources for fluids, as well as different types of interaction between them and the surrounding rocks.

The use of Pyr-GC-MS allowed us to determine that the organic matter in all samples is a mixture of continental and marine sources, although their proportions vary with depth in the Pimienta Formation. These results are consistent with the geological evolution in the area and indicate episodes of different organic contributions in the basin.

Keywords: Pyr-GC-MS, Pimienta Formation, organic content, fluid inclusions.