Structure mapping on enhanced landsat images of Southern Brazil: Tectonic control of mineralization and speculations on metallogeny

Terry W. Offield; E.A. Abbott; A. R Gillespie; S.O. Loguercio

doi:10.1190/1.1440720

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Structure mapping on enhanced landsat images of Southern Brazil: Tectonic control of mineralization and speculations on metallogeny

Terry W. Offield·E.A. Abbott·A. R Gillespie·S.O. Loguercio

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Abstract

Computer enhancement, particularly contrast-stretching, reveals a previously unnoticed east-west structural zone across a Landsat image of the southern Brazilian Precambrian shield. In this zone occur the only known economic or near-economic deposits of gold, tin, and copper. Such deposits are typically localized by small east-west structural elements. Non-economic copper occurrences elsewhere in the region appear to be related to major northeast- and northwest-trending lineaments mapped on Landsat images. Mineral exploration should be primarily directed at the main east-west lineament, but two other possible east-west zones might be worthwhile targets also. The major east-west lineament projects through a break in the continental shelf, across the Atlantic along a large transoceanic fracture zone and into the African continent along a mapped tectonic trend that goes through an area that produces copper, gold, and tin. Global geophysical data suggest that the mapped east-west trend in South America is a surface reflection of structures that developed in the tectosphere in Precambrian time and that have persisted until the present. © 1977 Society of Exploration Geophysicists.

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Source-reported bounding extent: -33.76838° to 5.24449° latitude; -73.98724° to -34.72999° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Terry W. Offield, E.A. Abbott, A. R Gillespie, S.O. Loguercio. 1977. Structure mapping on enhanced landsat images of Southern Brazil: Tectonic control of mineralization and speculations on metallogeny. https://doi.org/10.1190/1.1440720

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