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

The depth conversion of seismic reflection records has been the subject of many papers, particularly where faults or other geologic features are present. The common‐depth‐point (CDP) stacked seismic sections with large spread lengths of the order of 2 km have resulted in different interpretation problems. Al‐Chalabi (1979) considered the effect on stacking velocities of subsurface inhomogeneities where different rays in the CDP gather do not penetrate the same type of earth column. He showed that small time delays of 10 msec produce steps in the hyperbolic offset distance‐time curve of the CDP gather and produce stacking velocity variations of the order of ten percent. Levin (1973) considered a time delay in only one ray of the CDP gather and its effect on both stacking velocity and the zero‐offset time [Formula: see text]. This paper models the effect of near‐surface faults on the zero‐offset time [Formula: see text] of deeper layers as determined by the CDP method. This is particularly important since the zero‐offset time is plotted on the processed final record.

REEVALUATING THE EVIDENCE FOR MIDDLE WOODLAND MAIZE FROM THE HOLDING SITE

American Antiquity ◽

10.1017/aaq.2016.2 ◽

2017 ◽

Vol 82 (1) ◽

pp. 140-150 ◽

Cited By ~ 18

Author(s):

Mary L. Simon

Keyword(s):

Mass Spectrometry ◽

Carbon Isotope ◽

Mississippi River ◽

The Other ◽

Geological Survey ◽

Crop Plant ◽

Middle Woodland ◽

American Bottom ◽

Three Samples ◽

Original Report

Maize fragments recovered from the Middle Woodland Holding site (11MS118) in the American Bottom have for several decades been recognized as the oldest directly dated maize east of the Mississippi River. A reevaluation of maize samples from this site indicates that finding was in error. Carbon isotope assessment (δ13C ratios) run on the original samples dated in 1994 indicated that they were not maize. Six additional samples originally identified as maize were submitted to the Illinois State Geological Survey for carbon ratio assessment and direct accelerated mass spectrometry dating. Three of the fragments, including one from the same feature dated previously, returned non-maize δ13C ratios. The other three samples were correctly identified as maize, but all returned post–A.D. 900 dates. These results invalidate the original report of Middle Woodland maize at Holding and support our ongoing reevaluations of maize histories in the American Bottom and western Illinois, which show that it was not an important cultivated crop plant in this part of the Midwest until about A.D. 900.

Processed and interpreted U.S. Geological Survey seismic reflection profile and vertical seismic profile, Carter County, Montana and Crook County, Wyoming

10.3133/oc115 ◽

1981 ◽

Keyword(s):

Seismic Reflection ◽

Seismic Profile ◽

Geological Survey ◽

Seismic Reflection Profile ◽

Vertical Seismic Profile ◽

Reflection Profile

Shallow High‐Resolution Shear‐Wave Seismic Reflection Acquisition Using a Land‐Streamer in the Mississippi River Floodplain: Potential for Engineering and Hydrogeologic Applications

10.4133/1.2927162 ◽

2002 ◽

Cited By ~ 1

Author(s):

André J. M. Pugin ◽

Timothy H. Larson ◽

Andrew C. Phillips

Keyword(s):

High Resolution ◽

Shear Wave ◽

Mississippi River ◽

Seismic Reflection ◽

River Floodplain

SEISMIC SURVEY IN THE REGION OF RECENT EARTHQUAKE ACTIVITY NEAR DENVER, COLORADO

Geophysics ◽

10.1190/1.1439985 ◽

1968 ◽

Vol 33 (6) ◽

pp. 915-925

Author(s):

Ben F. Rummerfield ◽

A. Peter Olson ◽

D. B. Hoover

Keyword(s):

Seismic Activity ◽

Seismic Reflection ◽

Geological Survey ◽

Seismic Survey ◽

Earthquake Activity ◽

Precambrian Basement ◽

Basement Complex

A seismic‐reflection survey was carried out near Denver, Colorado, for the U. S. Geological Survey, to determine if structures exist in the 12,000‐ft sedimentary section or in the Precambrian basement that might explain the recent earthquake activity. No major faults were revealed in the sedimentary section. Reflections from a steeply dipping horizon believed to be in the basement complex may be indicative of faulting; however, the magnitude cannot be ascertained, as reflection events cannot be correlated at these depths. The results of the survey suggest the possibility of monitoring and studying subsurface structural conditions and related parameters in regions of seismic activity and/or suspected zones of tectonic instability.