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Crust and upper matle seismic structure, SKS anisotropy in upper mantle, and study of local and regional seismic activity associated with Ponta Grossa arch, PR


The Ponta Grossa Arch (PGA) is the largest and most intriguing geological feature of the Paraná Basin. It is a regional lithospheric arching associated with deep geological faults with crustal or lithospheric scale, which are related to one of the most important dike swarm in the Earth (Strugale 2002). In addition, the PGA was very important in erosive shaping of the Paraná Basin, and is currently regarded as one geological element to explain the accumulation of thick layers of salt in the offshore portion of Brazil and African countries, where there are oil reservoirs know as "pre-salt". Although the PGA has influenced the evolution of the Paraná Basin, the currently knowledge of its structure is limited by surface studies and a few estimates of its deep structure. The study area of this project lies between the Guapiara and Rio Piqueri lineaments, being cut by the Jacutinga fault. It will be studied with a 13-station regional seismograph network to determine the seismic velocity structure of the Paraná basin, crust and upper mantle by using shallow seismic refraction, P-wave receiver function of high and low frequencies, cross-correlation of natural seismic vibrations and surface wave dispersion of regional earthquakes. The seismic anisotropy in the upper mantle will be study with the splitting of SKS seismic phases from distant teleseismic events. The proximity of the seismograph stations (50 km) will enable the study of the regional seismic activity and identify possible local seismic swarms in the PGA. In cases of local activities we will be able to study the focal mechanisms to determine the directions of crustal tectonic stress in PGA region. The interpretation of all results will take into account other data sets of FAPESP Project No. 09/50493-8, such as gravity, magnetic and magnetotelluric soundings, allowing an integrated model for the structure of the crust and upper mantle in the study area. (AU)