Discrete fracture network characterization using multiple, high-resolution borehole methods in a crystalline rock aquifer in tropical Sao Paulo city, Brazil

The geological scenario of thick weathering materials over a fresh bedrock is characteristic of tropical climate regions. The application of the Discrete Fracture Network (DFN) methodology relying on multiple, high resolution measurements methods on continuous cores and/or boreholes in such geological conditions, particularly in a contaminated area, is unprecedent. A total of 977 structures were described, between rock cores, geophysical profiling and outcrops, with emphasis on brittle structures due to their importance for groundwater flow. Five fracture sets were characterized, related to lithology. The correlation of these fracture sets with large structures from regional studies indicated the representativeness of this detailed survey. Finally, it is expected that the model presented here can be applied in the management of other contaminated areas of similar geological contexts, particularly in Brazil, where the discussions regarding contaminated fractured aquifers are still quite recent. (AU)