San Felipe and Caracol tuffaceous sandstones, NE Mexico – Late Cretaceous continental arc petrogenetic link: Petrographic, geochemical, and geochronological evidence Article uri icon

abstract

  • Sedimentological and provenance (petrography, whole-rock geochemistry, zircon geochemistry, and ages documented by other authors) analysis carried out in San Felipe Formation and provenance (petrography and zircon geochemistry) analysis established for this unit and the Caracol Formation have allowed inferring the depositional environment for the San Felipe Formation, source area composition, and a possible relationship with the Laramide continental arc system during the Late Cretaceous in Northeast Mexico for both units. San Felipe Formation is constituted by two facies that are characterized by (a) intercalations of shales, tuffaceous sandstones that have Bouma sequence-like structures, ash tuffs and lapilli that develop supercritical and critical flow regime structures (e.g., low-angle parallel lamination), and (b) limestones with mudstone, wackestone, and packstone texture, that show Cruziana and Zoophycos ichnofacies. These features can be interpreted as a mixed ramp system in open sea conditions developed in the foredeep, forebulge, and back-bulge depozones. The San Felipe tuffaceous sandstones are lithic-feldspatho-quartzose to feldspatho-lithic-quartzose rocks (Q54F22L24; n = 13; mean value), rich in microlithic and lathwork tuffaceous volcanic fragments (Lvf40LvMic Lvlt15LvTob45; felsitic volcanic grains-microlithic volcanic fragments lathwork lithic fragment-tuffaceous fragments), with abundant volcanic glass. Tuffaceous sandstones from the Caracol Formation, a facial variant of the San Felipe unit, are lithic feldspatho-quartzose to feldspatho-lithic-quartzose rocks (Q46F26L28; n = 12; mean value) rich in felsitic (Lvf79LvMic Lvlt4LvTob17) and plutonic lithics with subordinate metamorphic fragments and abundant volcanic glass. A predominance of felsitic tuffaceous volcanic lithics and plutonic fragments with low weathering degree (CIA = 41 ± 7; PIA = 38 ± 9) in the San Felipe volcaniclastic strata and magmatic zircons with chemistry linked mostly from continental arcs (log of U/Yb and Nb/Yb ratios) in both formations suggest that the volcaniclastic rocks of the San Felipe and the Caracol Formations have an origin related to the Cretaceous-Eocene Mexican Magmatic Arc. After a relatively fast transport, the volcanic tuffs were deposited in the foredeep, forebulge, and back-bulge depocenters distributed in Northeast Mexico. © 2022 Elsevier Ltd
  • Sedimentological and provenance (petrography, whole-rock geochemistry, zircon geochemistry, and ages documented by other authors) analysis carried out in San Felipe Formation and provenance (petrography and zircon geochemistry) analysis established for this unit and the Caracol Formation have allowed inferring the depositional environment for the San Felipe Formation, source area composition, and a possible relationship with the Laramide continental arc system during the Late Cretaceous in Northeast Mexico for both units. San Felipe Formation is constituted by two facies that are characterized by (a) intercalations of shales, tuffaceous sandstones that have Bouma sequence-like structures, ash tuffs and lapilli that develop supercritical and critical flow regime structures (e.g., low-angle parallel lamination), and (b) limestones with mudstone, wackestone, and packstone texture, that show Cruziana and Zoophycos ichnofacies. These features can be interpreted as a mixed ramp system in open sea conditions developed in the foredeep, forebulge, and back-bulge depozones. The San Felipe tuffaceous sandstones are lithic-feldspatho-quartzose to feldspatho-lithic-quartzose rocks (Q54F22L24; n = 13; mean value), rich in microlithic and lathwork tuffaceous volcanic fragments (Lvf40LvMic %2b Lvlt15LvTob45; felsitic volcanic grains-microlithic volcanic fragments %2b lathwork lithic fragment-tuffaceous fragments), with abundant volcanic glass. Tuffaceous sandstones from the Caracol Formation, a facial variant of the San Felipe unit, are lithic feldspatho-quartzose to feldspatho-lithic-quartzose rocks (Q46F26L28; n = 12; mean value) rich in felsitic (Lvf79LvMic %2b Lvlt4LvTob17) and plutonic lithics with subordinate metamorphic fragments and abundant volcanic glass. A predominance of felsitic tuffaceous volcanic lithics and plutonic fragments with low weathering degree (CIA = 41 ± 7; PIA = 38 ± 9) in the San Felipe volcaniclastic strata and magmatic zircons with chemistry linked mostly from continental arcs (log of U/Yb and Nb/Yb ratios) in both formations suggest that the volcaniclastic rocks of the San Felipe and the Caracol Formations have an origin related to the Cretaceous-Eocene Mexican Magmatic Arc. After a relatively fast transport, the volcanic tuffs were deposited in the foredeep, forebulge, and back-bulge depocenters distributed in Northeast Mexico. © 2022 Elsevier Ltd

publication date

  • 2022-01-01