Sourcebook of locations of geophysical surveys in tunnels and horizontal holes, including results of seismic refraction surveys, Rainier Mesa, Aqueduct Mesa, and Area 16, Nevada Test Site

1983 ◽  
Author(s):  
R.D. Carroll ◽  
J.E. Kibler
Geophysics ◽  
1962 ◽  
Vol 27 (5) ◽  
pp. 599-610 ◽  
Author(s):  
John W. Allingham ◽  
Isidore Zietz

A granitic stock at Oak Spring, Nevada, was selected in 1960 by the Atomic Energy Commission as a possible site to study the seismic effect of a deep nuclear shot contained in a large volume of rock. Geophysical surveys were conducted to determine the general configuration of the stock, particularly the thickness. The stock intrudes a sequence of carbonate and siliceous sedimentary rocks of Paleozoic age, which are overlain by Tertiary pyroclastic rocks consisting of tuff, welded tuff, and breccia. A three‐dimensional analysis of a detailed aeromagnetic survey indicates that the stock has a shape similar to a truncated cone, the diameter of which increases from about one mile at the surface to at least 6 miles near sea level, 5,000 feet beneath the surface. The stock, therefore, is much larger than indicated by the area of [Formula: see text] square miles exposed at the surface. In addition, computations show that the intrusion has a thickness of at least 13,000 ft. Much of the ambiguity of interpretation was removed from the analysis because susceptibility measurements of cores from recent drilling and remanent magnetization data from surface samples were available. Interpretation of a gravity profile over the stock gives the probable thickness of the overlying alluvial fill and buried tuff, but does not delineate the intrusive from the Paleozoic rocks.


2020 ◽  
Vol 25 (3) ◽  
pp. 415-423
Author(s):  
Ahmed Lachhab ◽  
El Mehdi Benyassine ◽  
Mohamed Rouai ◽  
Abdelilah Dekayir ◽  
Jean C. Parisot ◽  
...  

The tailings of Zeida's abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and very low-frequency electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.


1959 ◽  
Author(s):  
W.H. Diment ◽  
R.E. Wilcox ◽  
G.V. Keller ◽  
E. Dobrovolny ◽  
F.C. Kracek ◽  
...  
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