Estudio estructural y geoquímico de las vetas del Dique, área Buena Esperanza, sudeste del Macizo del Deseado

GUIDO, D.; LOPEZ R.

Buenos Aires

Congreso; VI Congreso de Mineralogía y Metalogenia (MinMet); 2002

The Buena Esperanza area is an epithermal low sulfidation occurrence from the southeastern Deseado Massif. It is located in the south part of a NW-oriented horst (Leonardo?s Horst) and contains 18 quartz veins mainly hosted in La Golondrina Formation sandstones. 9 of these quartz veins belong to the Del Dique vein group and they have the most important precious metal anomalies. These veins, characterized by very poor outcrops and mainly consisting of floats (aligned fragments) of quartz veins, were mapped in detail and structural and geochemical studies were carried out in order to understand its behavior and predict the economical potential.Three directions (NNW, N5º and ENE) of fracturing and mineralization and its kinematic has been inferred from the detailed mapping. They are coincident with Buena Esperanza regional structure, in agreement with the extension produced during the opening of the South Atlantic Ocean by the end of Jurassic.Detailed geochemical studies allow to argue that fluid flow moved mainly from the edges (1 and 3 veins) to the Main Structure (2 and 9 veins), with three main concentrations zones (ore-shoots): the north, south and center of the Main Structure.The center and the edges of the Main Structure, specially in the fracture intersections, are highly prospective by concentration of low temperature (Au-Ag) metal precipitation. Also, potential to find Au-Ag bonanza mineralization in the Del Dique veins is inferred by the proximity with the La Golondrina and Bahía Laura volcanics unconformity and by the ore-shoot morphologies. The methodology proposed here could be applied to this type of ?float veins?, very common in Deseado Massif auroargentiferous province, were other type of studies (mineralogical and quartz textures) do not show important variations.