THE DETAILED GEOLOGICAL FIELD ANALYSIS AS A POWERFUL TOOL FOR DEPOSIT EVALUATION AND QUARRY DEVELOPMENT: CASE STUDIES FROM TUNISIA AND EGYPT

SERGIO MATTEOLI, GIUSEPPE NIRTA*, ELISA LIVI

Geofield srl, Via A. Volta 34/A, 56028-San Miniato, Italy

*Corresponding author: [email protected]

The detailed geological study is fundamental as a preparatory phase in order to assess the volume of the deposit and correctly address the future exploitation of a dimension stone quarry. In the same way, detailed geological and geo-mechanical analyses in already active quarries represent an essential tool to delineate deposit extensions, to drawn up the exploitation front direction, to locate new varieties and to define the geological situation and the possible features that impedes the correct exploitation of the material giving the hints to increase productivity.

Detailed geological-structural survey consists of ductile and fragile structural studies, stratigraphic and tectonic analyses. All the data coming from these studies are acquired with several technologies and allow to fully describe the geological setting of the quarry area through a geological model. The geological model must reproduce the three-dimensional geometry of a terrain portion giving the spatial relationships between lithologies, faults, bedding surfaces, etc. This techniques is crucial especially in the dimension stone quarrying for defining the discontinuities framework in the rock mass and for knowing which is the medium dimension of the blocks that could be exploited in a certain area. Moreover, using this kind of  study it is possible to optimize further detailed investigations such as drilling campaigns and geophysical surveys. Furthermore, using satellite imagery, aerial photographs and geological maps

The data collected on the field are transferred  in a computerised database and then elaborated through geo-spatial software and documented as maps (2D and 3D) and with geo-statistical diagrams. The definition of the geological model is the basis for any project concerning the interaction with the territory and quarry activities, and if properly built could guarantee the success in terms of production and economic savings.

Here we want to show the potentialities of the detailed geological field analysis through the case studies of three dimension stone quarries: two from Egypt and one from Tunisia. These areas represents there different geological situations and, as a consequence, three different ways to approach the construction of the geological model. As a main rule: the more complicated is the geological situation, the more detailed must be the description of the geological features.

As proved in this study, the transposition of the requirements of the geological study in quarrying activities results in a more correct excavation of the material with the proper technology and, in the short to medium term, in a lowering of the production costs and an increasing of the productivity.