GROUNDWATER TYPES AND STRUCTURAL CONDITIONING STUDY OF THE GUARANI AGUIFER SISTEM IN THE WESTERN OF PARANÁ STATE (BRAZIL)

Abstract

The hydrochemical typology and the tectonic structures that affect the Guarani Aquifer System (GAS) and Serra Geral Aquifer System (SGAS) in in the western part of Paraná Sedimentary Basin, in Paraná State (Brazil), are discussed in this work. The SAG is placed 600 m under the Mesozoic basalt and other volcanic-related rock layers. The aquifer waters are sulfated and chlorinated, with a total dissolved solids ratio higher than 1.000 mg L^-1 with a particular predominance of sodium ions in relation to calcium as well as magnesium. Even though SASG drills may reach less than 180 m into the basaltic rock layers, this aquifer system show similar hydrochemical and physicochemical characteristics with to SAG waters including temperatures above 30ºC. Although the SAG waters are currently being used for tourism purposes, when appropriately mixed with proper amount of surface waters it can be used as drinking water supply. The high density of geologic faults in the region, mainly in the SE-NW direction, acts as GAS discharge zones and eventually, recharging upwards the SGAS. The GAS hydrogeological framework can be represented by a series of compartments which are resultant from the geologic faults and intrusions of dolerite dykes. The recharge process is not completely understood for this part of the GAS, due to its structural complexity. Isotopic analysis from water samples collected in the study area result that the GAS water age are over 20,000 years.