Overview of Mixed Braided- and Leveed-channel Turbidites, West Crocker Fan System, Northwest Borneo
Published:January 01, 2008
Paul D. Crevello, Howard D. Johnson, Felix Tongkul, Martin R. Wells, 2008. "Overview of Mixed Braided- and Leveed-channel Turbidites, West Crocker Fan System, Northwest Borneo", Atlas of Deep-Water Outcrops, Tor H. Nilsen, Roger D. Shew, Gary S. Steffens, Joseph R. J. Studlick
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The West Crocker Formation is a major, basin-floor, submarine-fan complex that was deposited in an accretionary foredeep basin during the Oligocene to early Miocene (20–37 Ma) in the South china Sea and adjacent onshore Borneo (Figure 1). This sandstone-dominated succession is several kilometers thick (2.0 m), but may be up to 10 km (6.2 mi). It is more than 25,000 km2 (9652 mi2) in extent, and is exposed across a large part of the coastal ranges of Sabah, east Malaysia (Figures 2, 3). In terms of its size and extent, the West Crocker deep-water turbidite system, which forms part of the Crocker-Rajang fold belt, is comparable to other world-class modern and ancient turbidite systems. However, it is relatively poorly known (Stauffer, 1976; Tongkul, 1987; Crevello, 2002). This study focuses on the nature of the sedimentary facies and high-frequency depositional sequences. It is based on inland outcrops (quarries and road sections) in the vicinity of Kota Kinabalu (Figure 3), where the West Crocker Formation occurs as a series of steeply dipping, north-northeast- to south-southwest-trending, thrust-bounded outcrops. Although thrust faults typically define the bases and tops of the individual outcrop segments, the vertical sections that have been logged for this study are extensive (-150–300 m [492–984 ft] long) and contain only minor internal faulting. Hence, the latter has negligible impact on the interpretation of the stratigraphic elements. The outcrops are aligned along regional strike for -100 km (-62 mi), from north to south,
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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