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Metadata
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ID
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T-51-70-BS
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Also Known As
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TT051
Cruise_51
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Abstract
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Chief Scientist: Joe Creager. Geological and Geophysical
data (sparker, airgun, pistoncore, VanVeengrab, gravitycore,
boxcore) of field activity T-51-70-BS in Chukchi Sea and
Bering Sea from 08/13/1970 to 09/16/1970
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Project/Theme
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Chukchi Sea - Bering Sea Continental Shelf
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Chief Scientist
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Joe Creager
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Activity Type
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Geological and Geophysical
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Platform
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Thomas G. Thompson
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Area of Operation
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Chukchi Sea and Bering Sea
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Location map
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Bounding Coordinates
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65.75000
160.25000 -155.25000
50.25000
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Dates
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08/13/1970 (JD 225) to 09/16/1970 (JD 259)
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Analog Materials
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No analog holdings.
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Index map
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Crew
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Joe Creager
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Chief Scientist, Univ of WA
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Mark Holmes
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Cruise Leader, Univ of WA
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F. T. Bean
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Master, Univ of WA
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D. Askren
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Scientific Watch, Univ of WA
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E. C. Baker
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Radio Operator, Univ of WA
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M. Crandall
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Scientific Watch, Univ of WA
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B. Farwell
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Scientific Watch, Univ of WA
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M. Jorgens
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Scientific Watch, Univ of WA
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H. J. Knebel
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Watch Chief, Univ of WA
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R. Lilly
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Scientific Watch, Univ of WA
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R. J. McCollom
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Scientific Watch, Univ of WA
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D. R. Morrison
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Bottom Sampling Supervisor, Univ of WA
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R. W. Roberts
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Watch Chief, Univ of WA
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N. Silverberg
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Watch Chief, Univ of WA
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R. W. Sternberg
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Current Measurements, Univ of WA
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R. Sylwester
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Electronics, Univ of WA
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J. Trimble
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Current Measurements, Univ of WA
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V. Walsh
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Scientific Watch, Univ of WA
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D. Williams
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Scientific Watch, Univ of WA
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Equipment Used
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sparker
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airgun
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pistoncore
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VanVeengrab
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gravitycore
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boxcore
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Purpose
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To provide the field collections
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necessary to interpret the stratigraphic history of the sediments
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deposited during a major marine transgression across a continental
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shelf-coastal plain complex. The area represents an excellent model
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for the study of transgressive sedimentary sequences because of its
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simplicity in sediment thickness, age, and marker horizons. The
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sediment, predicted to average no greater than 10 to 15 m, can be
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collected fully with presently available coring equipment where the
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sediment is soft, and yet it is thick enough to provide detail of
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sedimentologic events over the 20,000-year Holocene transgression.
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Because of the importance of the area covered by this cruise to the
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studies of the Bering Land Bridge and the migration of man to the
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New World, it is hoped that it will be of use in interpreting the
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paleotopography of the land bridge surface and the times of
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inundation. The Chukchi Sea portion of the cruise was made to
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delineate further the details of a marine "delta" discovered north of
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Bering Strait in 1957. The southern Bering Sea portion was made to
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complete the reconnaissance survey of the Alaskan side of the
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Bering Sea. Deep seismic reflection measurements were made to
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study the deep structure and two anchor stations were occupied for
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investigation of bottom currents and sediment transport.
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Information to be Derived
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stratigraphic, depth to basement
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Summary
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Shallow-penetrating continuous seismic profiling (using a 4.0-khz
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system, 150-joule sparker, and 1000- and 2000-joule air guns) was planned to
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permit continuous monitoring of the changing thickness of unconsolidated
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sediment. The air gun and sparker were used alternatively depending upon the
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depth to basement. Continuous reduction of the data permitted tentative location
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of buried Pleistocene drainage channels. A great deal of reduction and
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interpretation remains, however, because the upper 15 m of the sediments
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contained as many as six reflectors in some areas. Wherever the subbottom
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reflectors indicated a thickened section of unconsolidated sediment, the bottom
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was cored at least to the first major reflector and, where possible, through a
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number of reflectors. As was the case during past cruises, the suspected
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interfluves were covered by thinner sediment layers that were significantly more
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difficult to core. The area of the southern Bering Sea approximately delineated
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by the piston core locations is apparently covered by more recent coarser
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grained sands and silts, which make coring difficult to impossible and which
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reduce the amount of subbottom penetration of acoustic energy. The buried
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channels detected in the western and southern portions ofthe survey area were
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cored; the length of the piston core barrel was varied at each station until
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maximum penetration was attained. Additionally Van Veen grab samples were
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obtained and gravity cores were attempted at no greater than 56 km intervals
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along the cruise track in water less than 200 m deep in the southern Bering Sea.
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In order to delineate further the extent and nature of the marine "delta"
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evidently extending northward from Bering Straits and to add further information
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bearing on the problem of sediment transport from the Bering to Chukchi seas
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additional subbottom reflection profiles and piston cores were collected in the
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delta area and two anchored current measuring stations were occupied. In a
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cooperative study with Dr. David Scholl of the USGS, four subbottom profiling
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tracks were run across the continental slope south of the Pribilof Islands and
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samples were collected at three dredge stations. Approximately 9450 km of track
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were run, with 4.0 khz continuous seismic profiling system in operation from
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Station 1 to Dutch Harbor (8861 km). Approximately 4780 km of sparker profiles
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and 3627 km of air gun profiles were made. Seismic refraction measurements were
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made a seven locations, using sonobuoys and the sparker and air gun as sources.
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A total of 154 stations were occupied, with grab samples collected at all but
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three dredge stations. Dredge samples were collected at three stations, box
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cores at eight stations, and piston cores at 24 stations.
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Notes
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Cruise conducted by the University of Washington Department of
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Oceanography, Seattle, Washington. Information is from the "Preliminary Report
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RV Thomas G. Thompson Cruise 51" by J.S. Creager and D.A. McManus, M70-82,
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September 1970.
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Got Help?
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For T-51-70-BS, we would appreciate any information on -- analog materials, contract, days at sea, dive count, funding, information specialist, kms of navigation, national plan, NGDC Info, organization, owner, ports, project number, publications, scanned materials, seismic description, station count, station description, submersible, tabulated info.
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