Rola obrazowania elektrooporowego w uszczegółowieniu skomplikowanej budowy geologicznej wzgórza Morasko w Poznaniu
Abstract
Geoelectrical imaging of complex geological structures of the Morasko Hill in Poznań.
A b s t r a c t. The paper focuses on the problem of developing reliable geological models based on point data from boreholes and two-dimensional results of geophysical surveys with application of electrical resistivity tomography (ERT). The study area was the Morasko Hill in Poznań (Poland), located within frontal moraines overlying Pliocene clays with a top surface strongly deformed glaciotectonically. Due to the presence of these deformations, the study area shows a complex geological structure. Analysis of archival boreholes indicates that the top surface of the Pliocene clays is extremely variable, hampering unequivocal determination of geological boundaries. ERT measurements were used to recognize the detailed geological structure of the area. Next, additional boreholes and CPTU soundings were made in selected localities characterized by anomalies in the distribution of electrical resistivity values. Following the drillings and soundings, and the results of the geophysical survey were reinterpreted. Such complex methodology of field work, including geophysical and geological surveys, has allowed us to present a reliable geological model of the area, in which the ERT results coincide with the drilling results. In practice, the preparation of an appropriate geological model, particularly in the vicinity of escarpments and slopes, is indispensable for designers of construction objects in the selection of foundations and analysis of slope stability.
A b s t r a c t. The paper focuses on the problem of developing reliable geological models based on point data from boreholes and two-dimensional results of geophysical surveys with application of electrical resistivity tomography (ERT). The study area was the Morasko Hill in Poznań (Poland), located within frontal moraines overlying Pliocene clays with a top surface strongly deformed glaciotectonically. Due to the presence of these deformations, the study area shows a complex geological structure. Analysis of archival boreholes indicates that the top surface of the Pliocene clays is extremely variable, hampering unequivocal determination of geological boundaries. ERT measurements were used to recognize the detailed geological structure of the area. Next, additional boreholes and CPTU soundings were made in selected localities characterized by anomalies in the distribution of electrical resistivity values. Following the drillings and soundings, and the results of the geophysical survey were reinterpreted. Such complex methodology of field work, including geophysical and geological surveys, has allowed us to present a reliable geological model of the area, in which the ERT results coincide with the drilling results. In practice, the preparation of an appropriate geological model, particularly in the vicinity of escarpments and slopes, is indispensable for designers of construction objects in the selection of foundations and analysis of slope stability.