Siliciclastic provenance of the Cenozoic stratigraphic succession in the southern Gulf of Mexico: Insights from U-Pb detrital zircon geochronology and heavy minerals analysis

Abstract

This work presents new geochronological and mineralogical data to investigate the provenance of sediments accumulated in deep-water environments in the southern and southwestern regions of the Gulf of Mexico during the Cenozoic. We integrated U-Pb geochronology with heavy and light minerals data to better understand the provenance of the Paleocene–Miocene strata and the evolution of the sediment source terranes. The analyzed samples came from drill cuttings of sandy levels in five exploration wells offshore in the Gulf of Mexico: Puskon-1, Aktum-1, Kunah-1, Kabilil-1, and Chuktah-201. The material contained abundant barite, a component of the drilling mud. Consequently, a semiquantitative approach to discriminate mineral phases and to quantify concentrations was used. Overall, we recognized 10 zircon populations that range from Proterozoic to Cenozoic ages. Proterozoic ages show a prominent peak at ca. 1.0 Ga and a minor peak at ca. 1.8 Ga. The Neoproterozoic to Cambrian population displays a broad distribution with a peak at ca. 600 Ma. Ordovician–Silurian zircons exhibit minor peaks at ca. 460 and 445 Ma. Devonian and Carboniferous zircons are very scarce in our data set. Permian–Triassic zircons are abundant, and they show a prominent peak at ca. 255 Ma and a minor one at ca. 228 Ma. Jurassic zircons are not common and display several minor peaks at ca. 185, 170, and 155 Ma. The Early Cretaceous population displays a noticeable peak at ca. 120 Ma. Late Cretaceous–Paleocene zircons exhibit several peaks at ca. 92, 82, 72, and 65 Ma. Cenozoic zircons also display several prominent peaks at ca. 40, 35, 25, and 18 Ma. Zircons of Proterozoic to Early Cretaceous ages are interpreted to be derived from the Mesozoic sedimentary cover of basement blocks in southern and eastern Mexico terranes due to their rounded to subrounded morphology. Late Cretaceous and Cenozoic zircons are the most abundant populations in the analyzed samples. These zircon populations exhibit euhedral and subhedral morphology indicating derivation from primary sources in the magmatic arcs. This has important implications in assessing the reservoir quality, since the sediments were directly delivered from the magmatic arc into the deep-water environments. Our results allow us to conclude that the sedimentary provenance of the southwestern and southern strata in the Gulf of Mexico was not associated with Laurentian terranes, as has been proposed for Late Cretaceous–Paleogene strata of northern Mexico and the northern Gulf of Mexico, such as the world-class Wilcox-type hydrocarbon reservoirs. We propose that the provenance of the analyzed strata was related to the tectono-magmatic evolution of the southern Mexico terranes during the Cenozoic; therefore, large NW-SE dispersal systems that eroded Laurentian terranes in the southern United States did not deliver sediments into the southern sectors of the Gulf of Mexico, probably constrained by the Tamaulipas Arch and the Gulf Stream.