Marine and Petroleum Geology 24 (2007) 540–563 Anatomy of a submarine channel–levee: An example from Upper Cretaceous slope sediments, Rosario Formation, Baja California, Mexico Ian A. Kane a,Ã , Benjamin C. Kneller b , Mason Dykstra c , Ahmed Kassem d , William D. McCaffrey a a School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK b Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, AB24 3UE, UK c Institute for Crustal Studies, University of California, Santa Barbara, CA 93106 1100, USA d BP Egypt, Cairo, Egypt Received 10 March 2006; received in revised form 10 November 2006; accepted 10 January 2007 Abstract To date, facies architecture models of submarine channel–levees have largely been derived from seismic data, isolated core data and limited field studies. We report field observations of an Upper Cretaceous submarine channel–levee complex within the Rosario Formation, Baja California, Mexico, which provide high-resolution data of lithofacies and ichnofacies distribution, and levee depositional thickness decay along transects perpendicular to the channel axis. Within the levee, both sandstone thickness and the overall proportion of sandstone decrease according to a power law away from the channel axis. Spatial variation in sedimentary structures away from the channel axis is predictable and provides an important link to the depositional flow regime. In channel-proximal locations, structureless sands, parallel lamination, overturned ripples, and ripple cross-lamination (including climbing ripple cross-lamination) are common; in channel-distal localities starved ripples are abundant. Sandstone bed thickness generally increases up stratigraphy within the levee succession, which is interpreted to indicate increasing turbidity current magnitude and/or contemporaneous channel floor aggradation reducing relative levee relief. However, in the most channel-proximal location sandstone bed thickness decreases with height; combined with evidence from both facies and palaeocurrent analysis this allows the position of the levee crest to be inferred. The thickest beds occur at higher levels with increasing distance from the channel axis, using this evidence we present a model for levee growth and migration of the crest. Quantitative analysis of ichnofacies distribution reveals that traces typical of the Cruziana and Skolithos ichnofacies are superimposed over the ‘normal’ background Nereites ichnofacies, forming a ‘bioturbation front’ which is indicative of proximity to the channel. By analogy with modern canyons and channels, the association of Cruziana and Skolithos ichnofacies with the channel may be attributed to oxygen and nutrient enrichment and possible turbidity current transport of organisms responsible for these ichnofacies. r 2007 Elsevier Ltd. All rights reserved. Keywords: Submarine channel–levees; Turbidity currents; Upper Cretaceous; Rosario Formation; Ichnofacies 1. Introduction Studies of modern submarine channel–levee systems provide information about depositional processes, channel and levee geometry and lateral facies relationships but provide little information on vertical stacking patterns and internal facies distribution. Ancient systems at outcrop may provide a better opportunity to study the facies and architecture of channel–levees but they commonly lack both three-dimensional control and an unambiguous context. Confident identification of deep-marine levee deposits in ancient strata is of particular significance in the subsurface in a petroleum geology context, where ARTICLE IN PRESS www.elsevier.com/locate/marpetgeo 0264-8172/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpetgeo.2007.01.003 Ã Corresponding author. Present address: Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401, USA. Fax: +44 113 343 5259. E-mail address: i.kane@earth.leeds.ac.uk (I.A. Kane).