Provenance of Cenozoic Siliciclastic Units in the Southern Gulf of Mexico by Heavy-Mineral Determinations and Geochemistry, and Detrital Zircon U-Pb Geochronology

摘要

We established provenance of Cenozoic sequences sampled in wells in the southern and southwestern Gulf of Mexico by heavy mineral analysis and LAICPMS detrital zircon U-Pb ages. The age spectra are dominated by Cenozoic ages. Other populations are of Cretaceous, Late Permian-Early Triassic, and Neo-Mesoproterozoic ages. Minor Jurassic, Devonian, and Ordovician ages are included. Paleoproterozoic-Archean ages are related to the Amazonian craton. Meso-Neoproterozoic ages(1 Ga)are ubiquitous in Mexico(Oaxaquia terrane)and are related to the Grenville orogen. Neoproterozoic ages (750-550 Ma)were possibly derived from sedimentary rocks on the Panafrican orogen. Cambrian-Ordovician ages(490-450 Ma)might relate to plutons of the Esperanza suite of the Acatlan complex. Carboniferous and Permian ages(350-290 Ma)were possibly derived from the western Gondwanan arc. Permian and Triassic ages(290-250 Ma)may represent the east Mexican arc. Late Triassic and Jurassic ages(210-170 Ma)suggest a derivation from the Nazas arc in north-central Mexico. Late Jurassic ages(160 Ma)may represent the Jurassic magmatism associated with an extensional regime. Cretaceous ages(145 Ma)might be derived from Early Cretaceous arc of Mexico. Cretaceous ages(135-90 Ma)were possibly derived from the Alisitos-Peninsular Ranges arc. Late Cretaceous-Early Palaeogene ages (90-55 Ma)suggest relations with Laramide magmatism and the Late Cretaceous volcanic province in southern Mexico. Paleogene-Neogene zircons(50 Ma and younger)are likely related to Cenozoic volcanic arcs in Mexico such as the Sierra Madre Occidental. Three earlier recognised ignimbrite flare-ups in the Eocene-Oligocene, early Oligocene, and early Miocene, match our detrital zircon populations. Furthermore, Miocene units contain kyanite-sillimanite possibly related to medium- to high-grade rocks such as the Acatlán complex or the Guatemalan Chuacús complex. We discuss the provenance based on geochemistry of the heavy minerals.