RESULTS OF MAGNETIC SURVEY INVESTIGATIONS IN THE FLOODPLAIN AREAS OF THE YELLOW AND BLACK RIVERS IN THE LORI REGION OF ARMENIA
A. A. Tamrazyan, R. K. Gasparyan, A. H. Avdalyan, M. V. Ohanyan
Nazarov Institute of Geophysics and Engineering Seismology of the National Academy of Sciences of the Republic of Armenia, Gyumri, Armenia
Keywords: magnetic survey, anomalous magnetic field, ultrabasic rocks, hydrothermal alteration, tectonic faults, Lori Region.
Abstract
The results of magnetic survey investigations conducted in the floodplain areas of the Yellow and Black rivers in the Lori Region of Armenia (northern part of the Republic of Armenia) are presented. Based on field observations, digital and graphical maps of the anomalous magnetic field (∆Ta) and its three-dimensional model were constructed. Analysis of the anomalous magnetic field structure made it possible to identify a number of positive and negative anomalous zones associated with geological formations differing in magnetic properties. It has been shown that the positive anomalies are caused by the presence of ultrabasic rocks (peridotites, pyroxenites) exposed along the left bank of the Yellow River and the right bank of the Black River. An extensive negative anomaly zone has been identified and interpreted as a reflection of a tectonic fault zone and the adjacent thick area of hydrothermally altered rocks. Comparison with the data on the physical properties of rocks confirmed the high contrast of magnetic characteristics between the ultrabasic and ore-hosting rocks.
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