Gradientes Térmicos Crustais Das Bacias Sedimentares Na Região Amazônica

Results of a regional scale analysis of geothermal gradients are presented for the area covered by sedimentary basins in the Amazon region. The data sets employed in the present work are composed of results of geothermal investigations carried out in 185 localities situated in the sedimentary basins of Acre, Solimoes, Amazon, Marajo and Barreirinhas, as well as those obtained over 719 localities in neighboring countries. The mean geothermal gradient values in the study area are found to fall in the range of 21,13 ± 3,48 oC/km to 31,04 ± 2,07 oC/km. However, geothermal gradient values greater than 40 oC/km have also been encountered in the basins of Solimoes and Amazon. In the Amazon and Marajo basins the mean gradient values are lower, in the range of 15 to 20 oC/km. Regional scale mapping have identified the existence of an east – west trending major geothermal belt between the southwestern part of the Acre basin and western part of the Solimoes basin. This area is considered as having considerable potential for relatively higher values of thermal maturation levels of hydrocarbons in the sedimentary strata. The high geothermal gradients are also likely to provide favorable conditions for occurrence of geothermal resources located in the upper parts of the basement rocks.