Application of GPR to ornamental rock quarry

Abstract

This paper presents a geophysical survey, which is being carried out with the use of the Ground Penetrating Radar (GPR) in an ornamental rock quarry located at Santo Antonio de Padua area, northwest of Rio de Janeiro State, Brazil. The quarry is settled in a milonitic rock belt. It is exploited the "olho de pombo" rock, which is in commercial demand, in Brazil and abroad. The purpose of the investigation is to test the applicability of the GPR technique in order to determine the thickness of the sterile material, and the fractures within the rock massif from where the rock blocks are taken. However it will be discussed the results of two radargrams obtained on the rock without altered cap rock The study is developed with the partnership of the Centro de Tecnologia (Mineral Technology Center - CETEM), which has a great experience in deals with ornamental rock research. The acquired data were processed with the use of the software GRADIX® (version 1 . 1 1 — Interpex) in order to enhance the anomalies and the stratigraphy it was generated originated sections, with average depth of 20 meters. In the surveys it was utilized 100 MHz frequency antennae. It is intended to build a work methodology for the local mining operator in order to contribute to reduce the environmental impact problems, which in general occur within this kind of activity. It was possible to identify the fractures and also the weathering cover thickness. Presently, the requirements of govemmental institutions, the environmental impact caused by ornamental rock mining, occupy increasing distinction within mineral exploiting industry. The survey presented higer quality results.