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Journal of Geophysical Research, 1962-06, Vol.67 (6), p.2529-2536
Ort / Verlag
Blackwell Publishing Ltd
Erscheinungsjahr
1962
Link zum Volltext
Beschreibungen/Notizen
Coring operations in the bottom of Lake Superior were undertaken during the summer of 1961. The motor vessel Submarex, 173‐foot converted Navy P.C., was used on contract from the Global Marine Exploration Company of Los Angeles, California. The ship was equipped with an over‐the‐side rotary drilling rig capable of drilling in a maximum water depth of 1300 feet. A modified piston coring technique was developed whereby continuous soft lacustrine material could be cored. The wire line normally used to suspend a piston coring device was replaced by rigid drill pipe. The technique permitted the taking of a 28‐foot core from any part of the upper 50 to 60 feet of soft sediments. Other modifications permitted using the inner core barrel techniques for punch coring in the deeper sediments of campact clay and glacial till. After complete penetration of the uncemented sediments, bedrock was cored by ordinary rotary techniques. All drilling sites were in water 500 feet or deeper. Six locations in the central and western Lake Superior basin were drilled. Two went to bedrock through 116 and 147 feet of lacustrine and glacial deposits, and at one location in 938 feet of water near the Minnesota shore, the bottom was penetrated 686 feet without striking bedrock.