Deep-water Channel Margin Architecture, Cerro Toro Formation, Cerro Mocha, chile
Stephen M. Hubbard, Brian W. Romans, Stephan A. Graham, 2008. "Deep-water Channel Margin Architecture, Cerro Toro Formation, Cerro Mocha, chile", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
Download citation file:
Conglomeratic deep-water deposits of the Cerro Toro Formation are exposed for more than 100 km (62 mi) along a north–south trending outcrop belt in the Ultima Esperanza District of southern chile. The deposits accumulated within a broad channel belt (4–5 km [2.5–3.1 mi] wide) that occupied the axis of the Magallanes basin during the Late Cretaceous (Campanian). The elongate depocenter represented the foredeep to the fold-thrust belt presently exposed in the stucturally complex Patagonian Andes to the west of the study area. The Andes were actively uplifting during deposition of the Cerro Toro Formation, and have been interpreted to represent the source of the coarse-grained channel fill. Outcrops of the Cerro Toro Formation have long been studied as architectural analogs to hydrocarbon reservoirs, although the outcrop at Cerro Mocho that is the focus of this paper has not been documented before. The exceptional, seismic-scale exposure of the western channel margin at Cerro Mocho is an ideal place to document the relationship between conglomeratic channel fill and fine-grained, out-of-channel deposits. Structures associated with Andean tectonics are present in the study area but do not significantly hinder sedimentologic and stratigraphic interpretations.
The channel margin at Cerro Mocho is complex, shaped by both constructional and erosional processes. Total relief of the margin is almost 300 m (984 ft) over a lateral distance of 1 km (0.6 mi). Deposition of predominantly sand and gravel in the channel axis was influenced by erosive gravity flows and traction processes (driven by overlying turbidity currents). Beds near
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