Paper No. 13-2
Presentation Time: 2:35 PM-2:55 PM
METALLOGENESIS AND TRANSPRESSION: THE OSSA-MORENA ZONE (SW IBERIA) CASE STUDY
GUMIEL, Pablo, Dirección de Recursos Minerales y Geoambiente, Instituto Geológico y Minero de España, Ríos Rosas 23, Madrid, 28003, Spain, p.gumiel@igme.es and QUESADA, Cecilio, Dirección de Geología y Geofísica, Instituto Geológico y Minero de España, Ríos Rosas 23, Madrid, 28003, Spain

Transpressional deformation regimes characterize the tectonic evolution of the Ossa-Morena Zone during the collisional Variscan orogeny. This is due to the impingement of a promontory in NW Gondwana onto Laurussia. Development of lithospheric scale strike-slip structures greatly enhanced magma ascent and emplacement and hydrothermal circulation, thus providing unique conditions for generation of various types of ore-forming processes and deposits. A selection of these includes:

Antimony (i.e. the San Antonio mine, the largest antimony deposit in the Iberian Peninsula) and gold mineralizations are spatially and genetically related to the Badajoz-Córdoba shear zone (BCSZ), which is a major left-lateral shear zone (suture) separating the Central Iberian and Ossa Morena zones, and is one of the sinistral transpressional belts in which deformation was accommodated as a result of highly oblique convergent process of continental collision. The gold concentrations are located following the antithetic NW-trending faults connected to the main shear zone.

Variscan to late-Variscan mineralizations are characteristic of an active continental margin setting with mineral deposits related to early plutonism (i.e. Fe- skarns at Burguillos) and to late collisional granitoids (i.e. Pb-Zn-Ag-Va veins at Santa Marta granodiorites) and the Ni-Co-Bi-Ag-U, Pb-Zn-Cu-F-Ba, Sb-As-Zn-W, Cu-Zn-Pb-F-Ba late-Variscan veins (i.e. Pedroches, Azuaga, and Cerro Muriano in the Córdoba province).

W-Sn-Bi-Mo-(Au) porphyry-Sn-greisen deposits are in close relationship with highly evolved epizonal leucogranites.

During the final extensional (transtensional) period, along regional fracture zones convective cells of hydrothermal circulation produced epithermal deposits (Hg-Ba-Pb-Sb).

Finally, the geometry of the host-structures induced by continued left-lateral transpression was important in focusing mineral precipitation in specific fractures/shear zones (targets) and may play a major role in the future exploration of the whole area.

Cordilleran Section - 99th Annual (April 1–3, 2003)
General Information for this Meeting
Session No. 13
Modern and Ancient Orogens II
Hotel NH Krystal: Jalisco C
2:15 PM-5:15 PM, Tuesday, April 1, 2003
 

© Copyright 2003 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.