The Application of Ichnology to Facies Characterization of a Channel-Levee System in the Late Cretaceous Rosario Formation, Baja California, Mexico
Sedimentology and ichnology of the Late Cretaceous Canyon San Fernando channel system (Rosario Formation, Baja California) have been used to generate an ichnofabric model that may be applied to enhance facies characterization and improve palaeoenvironmental interpretations of subsurface hydrocarbon reservoirs. The Canyon San Fernando system consists of conglomerate-dominated channel axes, with individual thalwegs that may be bound by small confined levees. Laterally away from the channel axis the system consists of overbank/terrace environments composed of isolated conglomerate bodies within heterolithic turbidite sediments, and a major channel-bounding levee composed of sandstone and siltstone turbidites. This sedimentological and ichnological model is based upon a composite lateral transect of facies from channel-proximal to channel-distal depositional settings. Ichnofabric data provide high resolution palaeoenvironmental information. Five ichnofabric associations are recognised: 1) The Ophiomorpha ichnofabric association characterizes the innermost channel terrace settings; 2) the Scolicia ichnofabric association is typical of outer terrace and inner levee palaeoenvironments; 3) the Nereites ichnofabric association dominates the channel-bounding levee; 4) an Ilmenichnus ichnofabric is characteristic of bypass surfaces at the base of submarine channels; and 5) a phycosiphoniform ichnofabric association occurs across almost all studied depositional environments. The distribution of ichnofabrics provide a framework for comparison with other turbidite channel systems in the field, as well as in core. Ichnofabric analysis has the potential to be applied to the study of other slope and basin floor depositional settings, and in subsurface investigation of turbidite facies in hydrocarbon reservoirs.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California