Aeromagnetic structural interpretation and evaluation of hydrocarbon and mineral prospects, Altiplano, Bolivia

Abstract

The results of an aeromagnetic survey over parts of the Altiplano, Bolivia are presented. The data were interpreter through a qualitative review of total magnetic intensity, seconc vertical derivative and Bouguer gravity data and a quantitative analysis of total magnetic intensity and horizontal gradient dati using Werner deconvolution profiles. Total magnetic intensity and Bouguer gravity data were also used in 2X-D model studies. The prominent directions of structural trends are northwestsoutheast, northeast-southwest and east-west. Several major grabens or depocenters have been mapped and accumulations of sediments exceed a thickness of seven to ten (7-10) kilometers. The interpretation outlined major features including: basement structural trends, major magnetic lineaments, faults, intrusives, extrusive zones, and magnetic intrasedimentary units. Mapped magnetic megalineaments are believed to be transition zones, which may represent major structural or lithologic changes within the basement. Several mapped features may be related to thrust and wrench related faults and structures which are favorable for hydrocarbon exploration targets in the Central and Southern Altiplano. 2%-D model studies used Bouguer gravity and total magnetic intensity data in the Salar de Coipasa rea to estimate the thickness of sediments. These studies reveal the existence of ten (10) kilometers of sedimentary section and rule out the possibility of a more than seventeen (17) kilometer thick section which was formulated earlier by geologic grounds. Several intrusive bodies have been mapped, some of which are associated with normal polarization and many others exhibit reverse polarization. As some of the intrusives are known to be associated with Sn-Ag mineralization, the locations of other intrusives form good targets for mineral prospects.