Structure of gold mineralization in the Arenigian of the Valongo area, Baixo Douro, Portugal [Caracterisation structurale des mineralisations auriferes de l'Arenigien dans la region de Valongo (Baixo Douro, Portugal)]

• Type: Other Publications
• Date: 1992

Authors

Combes, A (Author) Other; Cassard, D (Author) Other; Couto, H (Author) Other; Damiao, J (Author) Other; Ferraz, P (Author) Other; Urien, P (Author) Other

Other information

Authenticus ID: P-008-SAH

Abstract (EN): The main gold mineralization is contained within interbedded quartzite-schist of Arenigian age, overlain by a Llanvirnian schist sequence, in the normal limb of the large Valongo anticline. The Moirama and Banjas deposits belong to the vast family of mesothermal gold deposits hosted by weakly metamorphosed sandstones and mudstones. The mineralization occurs in two classic forms: (a) vein fillings associated with the initial movements of a conjugate strike-slip system; and (b) saddle reefs in the anticlinal hinges of the second-order folds on the Valongo anticline. The distribution and geometry of the orebodies are controlled by the combined influence of lithology and structure. These deposits have numerous features in common with the reference deposits for this type of mineralization characterized by emplacement during deformation and low-grade regional metamorphism (greenschist facies), with a short time interval between the ductile and the brittle deformation and a weak hydrothermal alteration of the host rock. -from English summary

Language: French

Type (Professor's evaluation): Scientific