GPR Mapping of an aeolian siliceous sand deposit as a tool to define its structure and reserves in order to assess its economic potential

The aeolian siliceous sands that occur along the Portuguese northern littoral are interesting, either for the extension of their deposits, or for their potentialities as industrial minerals based on sands textural, mineralogical and chemical characteristics. Studies being carried out in the area of Mira-Vagos did consider the convenience to define shape, structure, volume and technological properties of the sand deposits. Also, the understanding of the geology and hydrogeology of this geological system were found to be of paramount importance to forsee eventual possibilities and limitations with regard to eventual urban, rural and industrial developments in the study area, the scientific and technical outputs of the studies being able to be extended to similar areas. Main goals of the present work are as follows: (1) to prospect and to evaluate aeolian sand reserves in the Mira -Vagos area; (2) to establish the geophysical model common to the aeolian sand deposits that occur along the littoral of the Aveiro lagoonar system, based on information provided by GPR exploration that includes relevant geological, stratigraphical, hydrogeological and structural features. The study area is located in the Aveiro lagoonar system, being part of a long and wide sandy strip that extends from Espinho-Nazaré, just interrupted by Cabo Mondego. Figure 1 shows a map with the location of the study area, included in the protected National Forest, as well as the GPR profiles and borehole sites. The background grid consists of sided squares of 1000 m, and the larger GPR profile is over 6000 m long in S-N direction. In the southwest corner of the map there is a short line that was used to develop the pulling technique and to establish the acquisition parameters (moving speed, signal receiver time, stack number, etc.) needed to carry out the GPR surveys.