کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8913449 1640165 2018 41 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Coupled geophysical characterization of shallow fluvio-clastic sediments in Agwagune, southeastern Nigeria
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Coupled geophysical characterization of shallow fluvio-clastic sediments in Agwagune, southeastern Nigeria
چکیده انگلیسی
Geophysical investigation performed using electrical resistivity tomography (ERT), vertical electrical sounding (VES), seismic refraction (SRF) and ground penetrating radar (GPR) techniques were used to constrain and characterize shallow lithologic units in the Cross River bank (CRB) in southeastern Nigeria. Results show that the upper layer sediments comprise a 3-5-layered lithostratigraphic sequence with high clayey content. Around the Cross River bank (CRB), the top sediments consist of loose, silty and clayey sands with low resistivities (<150 Ωm) and low P-wave velocities (300-1000 m/s). These attenuating sediments have no reasonable continuity beyond the vicinity of the CRB. The low attenuating indurated silts/sands characterized by low resistivities (<25 Ωm) and high P-wave velocities (1000-2400 m/s) underlie the first layer around in the CRB. Localized microstructures (e.g., fractures) trending east-west, and saturated sand-filled channels truncate their lateral continuities. The lacustrine clays characterized by low resistivities (<15 Ωm) and high P-wave velocities (>2400 m/s) make up the third layer. The clayey sediments impede vertical percolation of groundwater forcing it to accumulate at the bottom of the second layer resulting in high static water levels of <3 m within the CRB and >5 m elsewhere. Hydraulic gradient in the Cross River bed (CRBD) and in the coastal groundwater drives groundwater flow into the CRBD through macropores. The sediments become unstable when these macropores become enlarged as more materials are continuously transmitted through them.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of African Earth Sciences - Volume 143, July 2018, Pages 67-78
نویسندگان
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