Stratigraphic Architecture and Evolution of a Meandering Slope Channel Complex, Capistrano Formation, San Clemente, California

Bouroullec, Renaud¹, David, R. Pyles², David, C. Jennette³, Mark Tomasso¹ (1) The University of Texas at Austin, Austin, TX (2) Colorado School of Mines, Golden, (3) Apache Corporation, Houston, TX

Slope channel complexes are important petroleum reservoirs in deep-water basins. Two Capistrano Formation exposures located at San Clemente State Beach, allow the detailed documentation of the lithofacies, architectural elements and stratigraphic evolution of a meandering slope channel complex. The upper Miocene-Pliocene Capistrano Formation is composed of deep-water clastic deposits incising into slope mudstones of the middle to upper Miocene Monterey Formation. Stratigraphic columns, paleocurrent, photomosaic and lidar data were collected to address the three-dimensional stratigraphy and evolution of the channel complex.

Each of the two exposures contains ten channels that constructed a single channel complex. The two exposures are laterally separated by 400 m of mudstone. The channel complexes cropping out are 25 m thick, 1260 m wide at the southern exposure and 560 m at the northern exposure. The channel facies and stratigraphic architecture are similar at both exposures. The channel stacking pattern shows lateral offset of the first eight channels, toward the north for the southern exposure and toward the south for the northern exposure, followed by vertical stacking of the last two channels for both exposures. The regional paleocurrent direction is to the northwest, but paleocurrent data for individual channels indicate an anticlockwise rotation of the paleo-flow within successive channels at the southern exposure and a clockwise rotation at the northern exposure. The lithofacies data, the channel stacking patterns and the paleocurrent data indicate that the same channel complex is meandering and crops out twice along the beach cliff.

The San Clemente channel complex is one of the rare outcrop examples of a meandering deep-water conduit. It teaches us valuable lessons concerning the sub-seismic scale heterogeneities within meandering slope channel reservoirs.