BOLETÍN DE LA SOCIEDAD GEOLÓGICA MEXICANA Vol 65, Núm. 3, 2013, P. 553-572 http://dx.doi.org/10.18268/BSGM2013v65n3a9

Reciclamiento sedimentario: Análisis composicional asociado a discordancias del noreste de México, un ejemplo del Triásico Superior al Cretácico Inferior

Yam Zul Ernesto Ocampo-Díaz^1,*, Igor Ishi Rubio-Cisneros²

¹Áreas de Ciencias de la Tierra, Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava No. 8, Zona Universitaria, San Luis Potosí, México, C.P., 78290.
² Petroleum GeoServices (PGS), Av. Paseo Tabasco 1406, 3° Piso, Torre Plaza Atenas, Tabasco 2000, Villahermosa, Tabasco, México, C.P. 86030.

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Abstract

The stratigraphic column of the Monterrey Trough in northeastern Mexico is represented by five Late Triassic to Early Cretaceous clastic sequences that show temporal relations defined by angular-erosive unconformities. This work analyses the composition of these sequences by means of sedimentary petrography, and compositional and recycling indices in order to comprehend the recycling-cannibalism process, the compositional variation between source-lands, and its relation to unconformities. The petrographic analysis, as well as the modal composition and the use of compositional indices (e.g., F, Lm, Qm) for the clastic sediments allows the establishment of three recycling periods or important source-rock addition using the QmFL diagram: 1) Upper Triassic (Qm70F10L20), medium-high grade metamorphic source rock erosion with an elevated Qm content suggesting a high rate of sediment transport; 2) Lower Jurassic (Qm40F22L38), a period with maximum rejuvenation of volcanic and metamorphic sources; and 3) Lower Cretaceous (Qm56F31Lt13), a period of short-lived exhumation for the source areas mainly characterized by granites or granodiorites, volcanic rocks and, to a lesser degree, low-grade metamorphic rocks.

The set of interpretations for compositional variations (QFL) and indices suggests the evolution of a recycling process, and allows proposing an empirical sedimentary recycling index (SeReIn). The SeReIn was applied and is described for three cases, demonstrating statistical sensitivity in changes related to sedimentary facies (e.g., high tide or storm deposits), grain size (e.g., tidal channels), and genetic implications in the unconformities within the stratigraphic column of the Monterrey Trough (intraformational cannibalism versus allocyclic controls).

Keywords: rejuvenation, compositional indices, recycling, Northeastern Mexico, sedimentary cannibalism, sedimentary petrography.