Shallow Subsurface Stratigraphy Inferred from the Use of Vertical Electrical Soundings (VES) Survey in Central Chihuahua, Mexico

作     者：Alejandro Villalobos-Aragón Vanessa V. Espejel-García Daphne Espejel-García Lucio Rivas-Lobera 

作者机构：Facultad de Ingeniería Universidad Autónoma de Chihuahua Chihuahua México 

出 版 物：《Open Journal of Geology》 (地质学期刊（英文）)

年 卷 期：2019年第9卷第1期

页      面：15-28页

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

主　　题：Geophysics Vertical Electric Soundings Geoelectrical Sections 

摘      要：Vertical Electrical Soundings (VES) provide fast and economical measurements used in geophysical exploration. VES were carried out in El Sauz-Encinillas (ESE) aquifer, in northern Mexico, to determine apparent resistivity and geoelectrical units’ thickness. Despite it being one of the three main aquifers feeding Chihuahua city, a lack of available geophysical data prevails in its northern portion. The main goal of this study was the determination of the geoelectrical units in the subsurface stratigraphy via electrical-resistivity soundings. The ESE’ aquifer is located within alluvial Quaternary sediments, with varying granulometry and reaching from a few meters to more than 600 meters of thickness at the center of the valley. Forty-five vertical electrical resistivity soundings (Schlumberger array, maximum AB/2 distance of 500 m) were performed throughout ESE aquifer’s northern portion. Field data were analyzed using software. Results illustrate a wide variability in resistivity values throughout the study area. Five geoelectrical units were identified: 1) a hardpan topsoil, with resistivity values ranging from 200 - 800 Ω-m;2) an alluvial material mixture (sand/silt) with resistivity values ranging from 25 to 100 Ω-m;3) playa lake-type material (clay/evaporites mixture) with resistivity values ranging from 0.2 to 15 Ω-m;4) a gravel/sand mixture with resistivity values from 100 to 300 Ω-m;and 5) a partly fractured rock or conglomeratic material with resistivity values ranging from 400 to 3500 Ω-m. The electrical resistivity data, therefore gives reasonably accurate results that can be used to understand the subsurface stratigraphy and basement configuration in groundwater exploration.