Geophysical contribution for the study of the Granitic Batholit Santa Helena, southwest of the Amazonian Craton

The Santa Helena batholith is subject of many controversies concerning its geographical extension, lithological constitution,geochemical characterization and geotectonic setting. This paper aims to contribute for a better understanding ofthis intrusion using geophysical data (gammaspectrometric and aeromagnetic). These data were obtained through surveyscontracted by the Geological Survey of Brazil (CPRM) flown over the study region. Given the compositional variety of therocks, we analyzed the susceptibility contrast (magnetometry) and distribution of radioelements (K, Th and U, measuredby gammaspectrometry) in the batholith. The resulting geophysical signature is different when comparing the northern andsouthern parts of the body, suggesting the presence of two distinct suites. The boundary between these two suites coincideswith the location of an approximately N75°W oriented fault system that extends through the batholith.