Architecture of Lateral-accretion Deposits in Two Stacked, Deep-water, Sinuous Channel Fills: Relationship Between Coarse Channel-fill and Adjacent Inner-bend Levee Deposits, Isaac Channel 2, Castle Creek South, Windermere Supergroup, British Columbia, Canada
Published:January 01, 2008
R. W. C. Arnott, 2008. "Architecture of Lateral-accretion Deposits in Two Stacked, Deep-water, Sinuous Channel Fills: Relationship Between Coarse Channel-fill and Adjacent Inner-bend Levee Deposits, Isaac Channel 2, Castle Creek South, Windermere Supergroup, British Columbia, Canada", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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The outcrop consists of the inner-bend deposits of two sharp-based, laterally accreting sinuous channels (C1, C2) that are oriented perpendicular and moderately oblique to the outcrop, respectively. Many important channel attributes can be measured because of the perpendicular orientation of C1. Lateral-accretion deposits, although well developed in both channel fills, are inclined at 7–12° to the channel base in C1, and based on geometry, are of the order of 120–140 m (394–460 ft) long. Lateral-accretion deposits show negligible change in grain size along their length or stratigraphically upward (although beds generally thin upward. They consist of subparallel but inclined, decimeter (0.3 ft)-thick beds composed of very coarse-grained sandstone to granule conglomerate grading upward to medium-grained sandstone. Near the updip terminus of each lateral accretion layer, strata are ungraded and distinctively poorly sorted. In addition, traction sedimentary structures, mostly dune cross-stratification, occur in the upper half, or more commonly, upper third of the lateral accretion deposit.
Mudstone (silty slate) is generally absent in all channel fills. Where present, it occurs typically as isolated patches of intraclast breccia in the lower third of the channel fill. These clasts were probably derived from erosion of local mudstone layers, and, as a consequence, coarser grained beds amalgamate in the lower part of the channel fill. At the top of the channel fills, mudstone intertongues with typically very coarse-grained sandstone that thins and pinches out, commonly abruptly, into mudstone. The mudstone interval consists of thinly bedded, single-set-thick, fine-grained sandstone Tc turbidites interstratified with silty mudstone
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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