Neotectônica E Estruturação Dos Sistemas Hidrogeológicos Da Região De Castanhal / Pa

Abstract

The morphostructural and hydrogeological study conducted at Castanhal-PA in two different scales, 1:100,000 and 1:25,000, allowed the understanding of relationships between hydrogeological systems' geometrical elements and structural elements related to neotectonic events as a basis to determine, among other aspects, potential recharge areas of these systems. The morphostructural study, aided by geophysical data collected, showed that the area has a structural control related to a neotectonic pulse that triggered the reactivation of faults with NW-SE, NE-SW, EW and NS directions. This lead to anomalies and changes in drainage patterns and conditioned the establishment of units where flat-topped hills, pediplanized hills, and major river plains were produced. These faults may be compatible with a stress field that generated a geometric arrangement characterized by tectonic blocks and a destral kinematic configuration, where tensile fault were formed in NW-SE direction, setting up important conduits for the recharge of hydrogeological systems. The area studied is composed by three hydrological systems: Superior, Barreiras, and Pirabas, which present variable depth related to the vertical rupture of rock layers, promoted by neotectonic faults. These hydrological systems, considered confined (Pirabas) to semi-confined (Barreiras), have a recharge component from fault zones and fault trace of NW-SE direction. The recharge of free aquifers occurs through direct precipitation, from rain water at the Midwest and northeast of the studied area.