Channel-fill Sandstones at San Clemente State Beach, California, USA
Mark chapin, Fred Keller, 2008. "Channel-fill Sandstones at San Clemente State Beach, California, USA", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
Download citation file:
Beach cliffs at San Clemente State Beach (Figure 1) provide excellent exposures of sandy turbidite channels of the Miocene Capistrano Formation. These outcrops have been a popular field trip destination since Walker (1975) described the general character of this channel system. The architecture and reservoir continuity of this section are dominated by deep scour surfaces, which step laterally from south to north and are filled mainly with sandy turbidite beds (Figure 2). The southern margin of the channel complex has incised silty slope mudstones of the Monterey Formation. No lateral overbank deposits are observed. The channel complex is interpreted to occupy a gorge eroded into a steep slope on the eastern edge of an active, strike-slip basin.
A bed-scale architecture section has been constructed for the San Clemente turbidite-channel complex and provides insight into depositional processes and reservoir performance issues. The architecture was traced onto a large-scale photo montage at the outcrop. Twelve measured sections and numerous local observations calibrate the lithology of the interpretation. The top of the channel system is covered by younger, gravelly terrace deposits, and the basal part of most of the channels is below the ground level. However, the lateral relationships of channel margins, channel drapes, and sand-dominated infill are spectacularly displayed.
The sandstone is very fine- to coarse-grained, with pebbles abundant at the north end. Most sandstone beds are classical turbidites with Bouma sequences, but at the north end, pebble-dominated beds become more common. Thick beds with granules and pebbles display coarse-tail grading, implying high-density turbidite deposition.
Figures & Tables
Atlas of Deep-Water Outcrops
Tor H. Nilsen, a red-haired Scandinavian who stood more than six feet tall, died October 9, 2005, at his San Carlos, California, home. This was after a valiant five-year fight with melanoma cancer. He was 63. His ashes were scattered at his family plot in Norway in 2006.
He was born in New York City on November 29, 1941, to Mollie Abrahamson and Nils Marius Nilsen of Mandal, Norway, and was the first of their children to be born in the United States. After graduating from Brooklyn Tech, he earned his B.S. in geology from City College of New York in 1962. While there, his prowess on the basketball court impressed a scout from the New York Knicks, but Tor went on to graduate school and earned his M.S. and Ph.D. degrees in geology from the University of Wisconsin at Madison in 1964 and 1967, respectively. His M.S. thesis was a study of Precambrian metasedimentary deposits in the Lake Superior area, and his Ph.D. thesis was a study of Devonian alluvial-fan deposits of the Old Red Sandstone in western Norway.
Dr. Nilsen’s principal expertise was in depositional systems analysis, stratigraphic analysis, and the relationships among tectonics, eustasy, and sedimentation. He began his industry career in 1967 as a research geologist with the Shell Development Company in Houston, Texas, and Ventura, California, where he worked on the tectonics and sedimentation of Tertiary shelf systems of coastal California. He subsequently spent two years with the U.S. Army Corps of Engineers as the Military