1887

Abstract

Integrated geophysical studies are carried out on St. Lawrence monastery's territory in Kaluga. The task of meals building basement's rests study in St. Lawrence monastery were considered. Magnetic, resistivity, GPR survey and metal detectors were used here. The main feature of the survey is a high amount of metal rubbish on territory (in particular in the uppermost layer). For example sheets of roofing iron at the total area about 20 sq. m were found here. Such strong source of noise could prevent not only magnetic prospecting, but also resistivity and georadar survey. Therefore geophysical studies of the area were conducted with preliminary searches of iron rubbish with metal detectors (TM-808, White's and ÑZ-7, Fisher) and its extraction. Magnetic prospecting Difficulties for magnetic survey were represented not only by metal rubbish, but also by high level of industrial noise, because the monastery is on Kaluga town territory. We used two proton magnetometers MMP-203, manufactured at St.-Petersburg enterprise «Geologorazvedka». To avoid the short period and high intensity variations (up to 50 nT) we used synchronous measurement's technology: the measurements on the area (13 x 20 m) and at base variational station were made simultaneously. The survey grid was 0.5 x 1 m. The survey accuracy consisted ± 5 nT (Fig. 1). The magnetic data interpretation was carried out with computer program DIPOLS-3 (K.M.Ermokhine), where field modeling is based on a dipole source method. Estimated anomalous magnetic field is presented at Fig.2. The model of the object producing such a field a field is presented at Fig. 3. Resistivity survey The survey territory was mapped by resistivity method with gradient array in two stages. At the first stage the current line was placed in S-N direction and measuring profiles were laid parallel to current line. Then the whole array was rotated on 90° (in E-W direction) and the survey was repeated. The area 18 x 25 m was mapped. The current line ÀÂ has length 50 - 60 ì, electric current value was 10 mA, frequency 4.88 Hz. Length of a measuring dipole was 0.5 m. The survey grid was 1 x 0.5 m. Resistivity instrument included the current generator (produced by ISR), and two measuring units ERA. The interpretation in accordance with the survey technology was carried out in two stages. At first stage the data for two different current line directions were analyzed separately, and then results for different polarizing fields' directions were united to receive a general map

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/content/papers/10.3997/2214-4609.201406370
1999-09-06
2020-04-09
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