Levantamento Gravimétrico do Complexo de Barro Alto, GO - Resultados preliminares

Abstract

A gravity survey was carried out at the region of the Goianésia-Barro Alto Mafic-Ultramafic Complex. Using the Brazilian Fundamental Gravity Network as reference, 75 new stations were occupied and a preliminary Bouguer map of the area was constructed. The area between Goianésia and Corumbá de Goiás (Araxá Group) is characterized by relatively constant Bouguer anomalies of -110 to -120 mgal. A sharp gradient of 4 mgal/km coincides with the S and SE limits of the mafic-ultramafic complex and is in agreement with the interpretation that the mafic-ultramafic rocks were obducted over the Goiás Basal Complex to the SE. The increase of Bouguer anomalies to about -55 mgal over the mafic-ultramafic body leads 1o an estimate of its thickness at about 5 km. Another small gradient south of the Goianésia-Corumbá de Goiás area is not inconsistent with previous suggestion that the limits of the Paramirim craton follow an approximate E-W direction from Anápolis. A spectacular gravimetric low of -140 mgal was found east of the maficultramafic complex over rocks of the Bambuí Group which may indicate a basement tectonic depression.