Roger D. Shew, 2008. "Deep-water Siliciclastic Outcrops from the Brushy Canyon and Cherry Canyon Formations, West Texas: Summary and Locations", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
Download citation file:
Slope to basin-floor-fan outcrops of the Brushy Canyon and cherry Canyon Formations are well exposed in West Texas (Figure 1) along the western edge of the Guadalupe and Delaware Mountains. The formations, which consist of sandstones, siltstones, and minor amounts of shales, were deposited during the Permian (Guadalupian) in an inland sea (Delaware basin) that was surrounded by a shallow-water carbonate ramp. The ramp later evolved into a reef-bounded shelf. The ramp is characterized by thick, cyclic, highstand carbonares and thin sandstones (deposited during sea level fall) of the San Andres and Grayberg Formations. The basin is dominated by thick, lowstand sandstones and siltstones of the Brushy Canyon and cherry Canyon Formations. The siliciclastics were deposited during a third-order lowstand cycle of approximately 2 m.y. The Brushy Canyon Formation has been divided into Lower, Middle, and Upper Members that correspond to fourth-order cycles, which are further subdivided into fifth-order cycles (Gardner and Borer, 2000). Fine-grained siltstones and minor shales with some organic matter are the highstand deposits separating the sandstone-rich lowstand deposits. Base-level fall resulted in 1) minor karstification and bypass on the ramp, 2) slumping, bypass, and then backfill on the slope, with mostly siltstones present between isolated canyons/channels, and 3) channelized and interchannel deposits near the toe of slope and upper fan that changed downdip to more mounded sheet deposits on the basin floor. It is evident that the slope was primarily a site of sediment bypass with only local sand accumulations, whereas the basin was the site of major deposition with some bypass in the channels. Lower to Upper Brushy Canyon slope progradation also led to a change from more distal to more proximal deposits vertically within the Brushy Canyon (Figure 2).
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