Aplicação do método potencial gravimétrico na investigação exploratória da bacia do Amazonas e solimões: estudo de caso

Abstract

The Amazon Basin is an elliptical and elongated 500,000 Km² intracontinental synechysis, nestled between the pre-Cambrian Guiana shields to the north and Brazilian to the south. It is bordered to the west by the Purus Arch, which separates it from the Solimões Basin and to the east by the Gurupá Arch that separates it from the Mesozoic Marajó Basin. Exploration in the Amazon Basin began in 1950 with gravity and seismic surveys along its main rivers. Unfortunately, the sheer extent and peculiarities of the region's exploration make basic geophysical surveys difficult. By 2000 nearly 180 exploratory wells had been drilled in the basin and approximately 70,000 km of 2D seismic had been surveyed. Commercial accumulations have not yet been discovered. A chain of gravitational highs of about 40 to 90 mGals cuts through the central part of the Amazon basin. Gravitational highs are bordered by gravitational lows of - 40 to ± 20 mGals. The observed model of a central chain of positive anomalies bordered by negative anomalies indicates intrusion into the crust by a higher density mantle material, caused by precambrian tectonic reactivation.