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CURIE SURFACE OF THE GOIÁS CENTRAL REGION The study area is located in the central region of the State of Goiás, between 14° and 16° South and 48° and 51° West and is a part of the Tocantins Structural Province. Several geophysical surveys were performed in the region starting in the 70's, with the Brazil-Canada Geophysical Project (PGBC) when a regional aeromagnetic survey took place. Magnetic interpretation of prismatic models allows the evaluation of depths where rocks lose their magnetization, the Curie depth. A group of depths defines a Curie surface. Depth were evaluated for 13984 locations in the studied area. The Curie surface indicates shallow areas with characteristic linear pattern referred as 'Curie crests', and deep regions representing the magnetic basement for the crust. The surface was compared with geological map and Bouguer map and with the distribution of gold occurrences in the study area. Many of the Curie crests coincide with ancient structural elements containing hydrothermal mineralizations. The Pirineus Megainflection and the Niquelândia Inflection are remarkable features. Parallelism and coincidence with greenstone belts and volcano-sedimentary sequences are clear. The relation with gravity map indicates an ancient suture. Four episodes are suggested to explain the origin of Curie structures: 1) Collision episode, responsible for the geosuture formation; 2) Late erogenic extentional episode, responsible for granitoid and shear zone mineralizations; 3) Sul-Atlantian episode, related with Gondwanaland disruption, and 4) Recent episode, related to E-W regional stresses as the result of South-American plate tectonic. The relationship between gold mineralizations with Curie crests suggest that the former may be a good guide for prospecting in the region.

CHARACTERIZATION OF THE ARCHEAN ORTOGNAISSE COMPLEXES OF GOIÁS BY AIRBORNE GAMMA-RAY SPECTROMETRY The Archean terranes of Goiás, Central Brazil, consist of 5 greenstone belts, and four complexes and one block of orthogneisses. The lithologic similarity among the complexes, inspite of their diferent ages, contribute significantly for their delimitation and interna subdivision during geologic maping. These dificulties may be eliminated by means of quantitatively interpreted aeroradiometric data.