channel-levee Complexes of the Fossil Bluff Group, Antarctica
Peter J. Butterworth, David I. M. Macdonald, 2008. "channel-levee Complexes of the Fossil Bluff Group, Antarctica", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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During the Mesozoic, the present-day Antarctic Peninsula was the site of an active volcanic arc related to the eastwards subduc-tion of proto-Pacific oceanic crust. Alexander Island is the largest of the many islands that lie on the western (forearc) side of the Antarctic Peninsula. The island is comprised of a greenschist facies, accretionary prism complex (LeMay Group), unconformably overlain and faulted against the forearc sedimentary deposits of the Fossil Bluff Group.
The Fossil Bluff Group ranges in age from Middle Jurassic to latest Early Cretaceous and has a stratigraphic thickness of 7 km (4.4 mi). Aalonian-Tithonian clastic units are derived from the accretionary complex, recording the transition from trench-slope to forearc basin sedimentation. The upper formations represent a large-scale, shallowing-upwards cycle of Kimmeridgian to Albian age, with a volcanic arc provenance.
The Himalia Ridge Formation is a 2.2 km (1.4 mi)-thick sequence of Late Jurassic to Early Cretaceous conglomerates, immature arkosic sandstones, and mudstones, derived from an andesitic volcanic arc, and deposited in a north-south elongate forearc basin. At the type locality (Himalia Ridge on Ganymede Heights), the formation was deposited as a series of migrating, conglomerate-filled, innet-fan channels and associated overbank-crevasse-splay sheet sands, thin-bedded levees, and interchannel mudstones flanking the basin matgin.
The basin was inverted within a strike-slip regime in the middle Cretaceous, and the sttata deformed into a broad monocline with associated thrusting. At Himalia Ridge, the formation is exposed as a continuous section dipping southeast at about 30°. The upper part of the formation is repeated
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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