Architecture of the Ainsa-1-Quarry Channel Complex, Spain
Published:January 01, 2008
Pau Arbués, Donatella Mellere, Oriol Falivene, Oscar Fernández, Josep Anton Muñoz, Mariano Marzo, Jordi M. de Gibert, 2008. "Architecture of the Ainsa-1-Quarry Channel Complex, Spain", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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The Ainsa turbidite system is part of the slope fill of the Ainsa basin. It was deposited in foredeep and wedge-top depozones. The base of the system is an angular unconformity; the top is a gradual facies change to a mudstone-dominated unit. Maximum thickness is 305 m (1000 ft) and preserved width and length are 8 km (4.9 mi) and 9 km (5.6 mi), respectively. Mean paleoflow is to the northwest, parallel to the main axis of the basin. The system consists of three cycles of channel complex development and abandonment. In the basal part of these cycles, there are one or two channel complexes that are nearly straight. The dimensions are greater than 1.5 km (0.9 mi wide), greater than 9 km (5.6 mi long), and up to 100 m (328 ft) thick. channel complexes are bounded laterally and above by thin beds that represent overbank and frontal-splay deposits, or by slump deposits with a dominant mudstone composition. Synchronous thrusting and folding caused the angular character of the basal unconformity, the marked thinning of the system towards the basin margins, the progressively rotated cycle boundaries, the frequent multilateral architecture of channel-complexes, and in some cases, channel-complex divergences around growing anticlines. The outcrop corresponds to a partial section of one of the two channel complexes in the lowermost cycle. Mean paleoflow is to the west-northwest (290°) and the outcrop trends 160°–340°. The base of the channel complex is not exposed. It is interpreted to be a few meters (>10 ft) below the stratigraphically lowest beds in the outcrop.
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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