AKA: 69ANC
Other ID: TT042
Status: Completed
Organization(s):
Funding Program(s):
Principal Investigator(s): Mark Holmes
Affiliate Investigator(s): Joe Creager
Information Specialist(s):
Data Type(s): Sampling: Geology, Seismics: Air Gun / Water Gun, Seismics: Sparker
Scientific Purpose/Goals: To provide the field collections necessary to interpret the stratigraphic history of the sediments deposited during a major marine transgression across a continental shelf-coastal plain complex. The area represents an excellent model for the study of transgressive sedimentary sequences because of its simplicity in sediment thickness, age, and marker horizons. The sediment, predicted to average no greater than 10 to 15 m, can be collected fully with presently available coring equipment where the sediment is soft, and yet it is thick enough to provide detail of sedimentologic events over the 20,000-year Holocene transgression. Because of the importance of the area covered by this cruise to the studies of the Bering Land Bridge and the migration of man to the New World, it is hoped that it will be of use in interpreting the paleotopography of the land bridge surface and the times of inundation.
Vehicle(s):
Start Port/Location:
End Port/Location:
Start Date: 1969-08-19
End Date: 1969-09-12
Equipment Used: gravitycore, Shipekgrab, vanveengrab, Sparker, sparker, airgun, airgunarcer
Information to be Derived: stratigraphic
Summary of Activity and Data Gathered: Physical data holdings Shallow-penetrating continuous seismic profiling (using a 3.5-khz system, 150-joule sparker, and 1000- and 2000-joule air guns) and precision echo sounding were planned to permit continuous monitoring of the changing thickness of unconsolidated sediment. The 3.5-khz system was never successfully operated because of malfunctioning of the equipment as supplied by the manufacturer. The air gun was operated over about half of the total track, and the 150-joule sparker was operated almost continuously. The precision echo-sounding system was operated continuously. Continuous reduction of the data permitted tentative location of buried Pleistocene drainage channels. A great deal of reduction and interpretation remains, however, because the upper 15 m of the sediments contained as many as six reflectors in some areas. Wherever the subbottom reflectors indicated a thickened section of unconsolidated sediment, the bottom was cored at least to the first major reflector and, where possible, through a number of reflectors. As was the case during past cruises, the suspected interfluves were covered by thinner sediment layers that were significantly more difficult to core. The area east of 172 degrees W was apparently covered by more recent coarser grained sands and silts, which make coring difficult and which reduce the amount of subbottom penetration of acoustic energy. The buried channels detected in the western part of the survey area were cored; the length of the piston core barrel was varied at each station until maximum penetration was attained. Additionally Van Veen or Shipek grab samples and gravity cores were obtained at no greater than 56-km intervals along the cruise track. Transmissometer measurements of suspended sediments were made along the leg between Nunivak and Northeast Cape, St. Lawrence Island. One 20-foot piston core assembly and one transmissometer were lost. Approximately 7200 km of track were run, with the precision echo sounder continously in use. Approximately 4700 km of sparker profiles and 2200 km of air-gun profiles were made.158 stations were occupied, with grab samples collected at all stations and gravity cores collected at 92 stations. Piston cores were collected at 44 stations.
Staff:
Affiliate Staff:
Notes: ID created on August 15, 2018.
Staff from Infobank:
Joe Creager Chief Scientist, Univ of WA
Mark Holmes Cruise Leader, Univ of WA
E. Baker Radio Operator, Univ of WA
S. Barnes Scientific Watch and Photographer, Univ of WA
K. Duff Scientific Watch, Univ of WA
R.J. Echols Coring Watch and Recorder, Univ of WA
J. Kummer Scientific Watch, Univ of WA
D.R. Morrison Coring Supervisor, Univ of WA
R. Nishimori Scientific Watch, Univ of WA
R.W. Roberts Watch Chief, Univ of WA
N. Silverberg Watch Chief, Univ of WA
C.S. Smyth Scientific Watch and Computer Operator, Univ of WA
J. Svensson Scientific Watch, Univ of WA
Dick Sylwester Electronic Technician, Univ of WA
N. Varney Scientific Watch, Univ of WA
K. Von Bock Watch Chief, Univ of WA
V. Walsh Scientific Watch, Univ of WA
Cruise conducted by the University of Washington
Department of Oceanography, Seattle, Washington. Information is
from the "Preliminary Report RV Thomas G. Thompson Cruise 42" by
J.S. Creager and D.A. McManus, M69-80, September 1969
Location:
Chukchi Sea-Bering Sea continental shelf, between St. Matthew and St., Bering Sea Island and Alaska, Bering Sea
Boundaries | |||
---|---|---|---|
North: 62.23059902 | South: 51.06003745 | West: 170.27347862 | East: -157.56506305 |
Platform(s):
Thomas G Thompson |
Survey Equipment | Survey Info | Data Type(s) | Data Collected |
---|---|---|---|
gravitycore | --- | Geology | |
Shipekgrab | --- | Geology | sample_locations (data on FAD) |
vanveengrab | --- | Geology | |
Sparker | --- | Sparker | |
sparker | --- | Sparker | |
airgun | --- | Air Gun / Water Gun | |
airgunarcer | --- | Air Gun / Water Gun |