The scope of this work is to show the observations of satellite GOCE in mapping geological units in a key area for mineral exploration, which is also a key location for understanding the formation of the America and Africa continents from the former western Gondwana. The observations of the satellite GOCE have allowed to achieve a qualitative leap ahead in today’s global gravity. The new global field has an improved resolution of 80 km with precision of 5 mGal; this resolution is sufficient to study crustal thickness variations and the upper crustal structure. Geological macrostructures generating density variations are mapped for the first time by a global satellite derived field in continental areas, which opens a new series of applications in geophysical exploration. The study area is located in and around the Congo craton, which is a part of Africa poorly covered in ground gravity surveys, so that GOCE data are essential there. The GOCE gravity field is reduced by the effect of topography, of the isostatic crustal thickness and by sediments, obtaining the field representative of the geologic lineaments. The foldbelts surrounding the Congo craton are identified well through the field, generating signals near to 50 mGal. Compared to the existing geologic map, along the Kibalien belt, a narrow belt with increased density is distinguished, about 125 km wide, and 800 km long, that must be representative of a major compressive or magmatic geologic event that generated these rocks. The distinction of separate geologic units characterized by density variation is useful for identifying the areas where focused future geophysical and geologic mapping will be effective in the exploration of new mineral resources.

A grip on geological units with GOCE

BRAITENBERG, CARLA
2014

Abstract

The scope of this work is to show the observations of satellite GOCE in mapping geological units in a key area for mineral exploration, which is also a key location for understanding the formation of the America and Africa continents from the former western Gondwana. The observations of the satellite GOCE have allowed to achieve a qualitative leap ahead in today’s global gravity. The new global field has an improved resolution of 80 km with precision of 5 mGal; this resolution is sufficient to study crustal thickness variations and the upper crustal structure. Geological macrostructures generating density variations are mapped for the first time by a global satellite derived field in continental areas, which opens a new series of applications in geophysical exploration. The study area is located in and around the Congo craton, which is a part of Africa poorly covered in ground gravity surveys, so that GOCE data are essential there. The GOCE gravity field is reduced by the effect of topography, of the isostatic crustal thickness and by sediments, obtaining the field representative of the geologic lineaments. The foldbelts surrounding the Congo craton are identified well through the field, generating signals near to 50 mGal. Compared to the existing geologic map, along the Kibalien belt, a narrow belt with increased density is distinguished, about 125 km wide, and 800 km long, that must be representative of a major compressive or magmatic geologic event that generated these rocks. The distinction of separate geologic units characterized by density variation is useful for identifying the areas where focused future geophysical and geologic mapping will be effective in the exploration of new mineral resources.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2829971
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