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G. B. Tirey

Publications and source records attributed to G. B. Tirey.

2 recordsLinked to original sources
USGS1984

Common-depth-point seismic-reflection survey on the Mississippi River in the vicinity of Alton, Illinois

A high-resolution seismic-reflection survey was run on the Mississippi River using marine common-depth-point (CDP), digital, and multichannel techniques in an attempt to locate a possible fault that had been interpreted by others from magnetic and land seismic data to be in the vicinity of Lock and Dam No. 26. The geologic feature is commonly known in the literature as the Cap au Ores Fault or Cap au Ores Uplift. A second objective was to demonstrate that the marine seismic system could be used successfully for making relatively deep penetration seismic-reflection surveys on inland waterways with shallow water depths (less than 10 meters) and organic sediments on the waterway bottom. The survey was made by agreement between the U.S. Army Corps of Engineers (COE), St. Louis District, and the U.S. Geological Survey (USGS). The USGS used a specially equipped, trailerable, 38-ft aluminum boat for the work. The quality of the survey records can be classified as from fair to good. Seismic-reflection events could be interpreted in the upper 200 ms of data. Five reflecting horizons with little slope were recorded between Mississippi River Miles 195 and 210 without any evidence of faulting of the magnitude (50 to 100 m) suggested by the Shannon and Wilson report (1980). Minor faulting and buried channeling could be interpreted. This survey demonstrated the value and economy of obtaining deeper penetration seismic data on inland water using an offshore marine, CDP, digital, multichannel seismic-reflection system. On-going modifications in field procedure, equipment configuration, equipment, and data processing will further improve the results obtained with such equipment. Future marine-style surveys conducted with the newly available hydraulic waterguns (80-, 200-, and 400-in 3 ) would probably produce data that are a significant improvement over data obtained with the 15-in 3 pneumatic watergun and 40-in 3 airgun used during the 1980 survey.

Illinois, Missouri↗
USGS1984

U.S. Geological Survey common-depth-point seismic-reflection survey between Mississippi River miles 195 and 210 (R/V NEECHO cruise NE-80-3)

In December 1980, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (COE), conducted a seismic survey of the Mississippi River in the vicinity of Alton, Illinois, near St. Louis, Missouri (fig. 1). Seismic lines were run from the mouth of the Missouri River up the Mississippi River to a point approximately seven miles upriver from Lock and Dam No. 26 at Alton, Illinois (fig. 2a,b). Additional lines were run upriver from Lock and Dam No. 25 between the dam and River Mile 244, but these data are not reported because of mechanical problems with the larger sound-source equipment and inexact navigational control. The objective of the cooperative study was to utilize marine common-depth-point (CDP), digital, and multichannel techniques to locate a monoclinal flexure of the Cap au Gres Fault that earlier had been interpreted from land seismic data to be in the vicinity of Lock and Dam No 26 (Shannon and Wilson, 1980). A second objective was to demonstrate that the marine seismic system could be used for making relatively deep penetration seismic-reflection surveys on shallow (less than 10-m water depth) inland waterways that have organic sediment floors.

Illinois, Missouri↗