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

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.