COSTA, C. R. S.; COSTA, Cloves Rogério da Silva.
Résumé:
Storage and exploitation of groundwater
crystalline rocks face difficulties due to the complexities in the
hydrological properties of crystalline rocks such as rocks
metamorphic and magmatic. Usually the fractures in these rocks
provide the permeability and porosity necessary for them to be
make aquifers. But it is still quite costly and difficult to detect these
underground properties and the presence of water in these rocks. The goal
this work and to elucidate the nature of the fractures and the conditions that
govern the hydrodynamics in the crystalline rocks and try to figure out
occurrences of fractures and the areas favorable for the
groundwater storage. The research work involved a
25 km radius area with the central point of Campina
Big. In the field work, surveys were made on
location of rock outcrops, fracture azimuth measurements
and lithological description at each location. Field data were used
to prepare the fracture maps of each subarea, statistical analysis of the
fractures, and classification of fractures in relation to their spacing.
The tubular wells and other characteristics existing in the region were
placed in the fracture maps in order to observe the correlation
between wells and fractures.
The highest frequency and occurrence of fractures in the region
It is presented in azimuths ranging from N30W to N45E. Dives range from 30 ° to 90 °. The fractures were classified in relation to their
frequencies and occurrence and spacing, in classes of frequent local, frequent regional and regional fractures. Correlations were made between the
fractures and current failures in the region. In the areas of
shearings there is a tendency for occurrences of fractures very
frequent sites, micro-fracture beams and fragmented rock. THE
drainage formation and valleys in the study region are directly
related to fractures; wide valleys, with signs of water,
parallel to the intentional fractures or their intersections.
This research work showed that there are fractures
that serve as water conductors in rocks. O
water storage occurs where there is a large intersection
fractures with small spacing, as well as in the areas of
shear where rocks have a high concentration of
micro-fractures and rock fragmentation. Consequently the medium
acquires the characteristics of an aquifer.