Structural Control on the Formation of Pb-Zn Deposits: An Example from the Pyrenean Axial Zone

Alexandre Cugerone (1) , Emilien Oliot (1) , Alain Chauvet (1) , Jordi Gavaldà Bordes , Angèle Laurent , Elisabeth Le Goff (2) , Benedicte Cenki-Tok (1)

1 Géosciences Montpellier
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

Pb-Zn deposits and specifically Sedimentary-Exhalative (SEDEX) deposits are frequently found in deformed and/or metamorphosed geological terranes. Ore bodies structure is generally difficult to observe and its relationships to the regional structural framework is often lacking. In the Pyrenean Axial Zone (PAZ), the main Pb-Zn mineralizations are commonly considered as Ordovician SEDEX deposits in the literature. New structural field analyzes focusing on the relations between mineralization and regional structures allowed us to classify these Pb-Zn mineralizations into three types: (I) Type 1 corresponds to minor disseminated mineralization, probably syngenetic and from an exhalative source. (II) Type 2a is a stratabound mineralization, epigenetic and synchronous to the Variscan D1 regional deformation event and (III) Type 2b is a vein mineralization, epigenetic and synchronous to the late Variscan D2 regional deformation event. Structural control appears to be a key parameter in concentrating Pb-Zn in the PAZ, as mineralizations occur associated to fold hinges, cleavage, and/or faults. Here we show that the main exploited type 2a and type 2b Pb-Zn mineralizations are intimately controlled by Variscan tectonics. This study demonstrates the predominant role of structural study for unraveling the formation of Pb-Zn deposits especially in deformed/metamorphosed terranes.

Domaines: Tectonique; Pétrographie; Minéralogie

Alexandre Cugerone, Emilien Oliot, Alain Chauvet, Jordi Gavaldà Bordes, Angèle Laurent, et al.. Structural Control on the Formation of Pb-Zn Deposits: An Example from the Pyrenean Axial Zone. Minerals, 2018, 8 (11), ⟨10.3390/min8110489⟩. ⟨hal-01918968⟩