Paper No. 7
Presentation Time: 9:00 AM-6:00 PM

SEDIMENTOLOGY AND ICHNOLOGY OF THE TURONIAN-EARLY CAMPANIAN CARACOL FORMATION, SIERRA MADRE ORIENTAL, NORTHEASTERN MEXICO


PINZON-SOTELO, Marisol Polet, Posgrado en Ciencias Geológicas, Facultad de Ciencias de la Tierra, Universidad Autónoma de Nuevo León, Carretera a Cerro Prieto Km. 8, Ex-Hacienda de Guadalupe, Linares, N.L, 67700, Mexico and OCAMPO-DÍAZ, Yam Zul Ernesto, Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava No. 8, Zona Universitaria, San Luis Potosí, S.L.P, 78290, Mexico, poletpinzon@gmail.com

The sedimentology and ichnology of the Late Cretaceous Caracol Formation (Northeastern Mexico) have been used to divide this into two members: Tierras Blancas Member (Turonian) and Rancho Viejo Member (Early Campanian). The Caracol Formation consists of sandstone and shale sequence depposited within ancient deltaic shoreline enviroment associated with a hyperpicnal flows that produced submarine fan deposits. Tierras Blancas Member represent river and wave influenced/dominated delta front, mouth bar and prodelta sequences, showing thinning upward sequences, normal gradation, parallel and cross lamination, asymetric ripples, climbing ripples, hummocky and swaley cross stratification, with a absent to common bioturbation index (BI 0-4), characterized by Thallasinoides sp., Ophiomorpha sp., Palaeophycus sp., Chondrites sp. and Skolithos sp., traces. Rancho Viejo Member define mixed and depositional channels, overbank, cannel-lobe transition and lobe sequences, showing thickening and thinning upward sequences, normal gradation, parallel and cross laminaion, asymetric ripples, climbing ripples, convolute lamination and rip-up mud clasts, with a absent to abundant bioturbation index (BI 0-5), characterized by Zoophycus sp., Scoliccia stronzzi., Megagrapton submontanum., Palaeophycus tubularis., Cosmophorae sinuosa., Demograpton dertonensis., Helminthopsis abeli., Strobilorhaphe glandifer., y Protopaleodictyon spinela traces. The sedimentological and ichnological data obtained in this work contribute to improve the paleoenviromental and tectonic interpretation of the Late Cretaceous clastics successions in the Northeastern Mexico.