Developing a lateral topographic density model for Brazil

Abstract

Topographic density distribution models are used in many geodetic and geophysical problems. Due to the difficulty in developing a high-resolution three-dimensional density model, many studies are focusing on the development of lateral density models and, despite the existence of global models, it is understood that these are less detailed and need to be improved to be used in regional and local studies. In this context, this research develops a distribution model of the lateral density of topographic masses for Brazil (LTD_Brazil, with 30 arc-seconds grid spacing), associated with their uncertainties, considering more detailed information from geological maps and apparent density values of rock types. The model results indicated an average density of 2459 kg/m³, ranging from 1625 to 3400 kg/m³, with standard deviations ranging from 8 to 351 kg/m³. This average density value has great influence of large Phanerozoic sedimentary basins (Amazonas/Solimões/Acre, Alto Tapajós, Parecis, Parnaíba and Paraná basins) located in Brazil. Furthermore, comparing the LTD_Brazil with a global model (UNB_TopoDensT), it was possible to suggest that the differences (ranging from −500 to 600 kg/m3), more significant in metamorphic and igneous rocks regions, are associated with greater detail of the lithological units used and accuracy of the model.