Older orogenic systems
The Ossa Morena and South Portuguese Zones of the Variscan Belt of Iberia are interpreted to represent continental fragments that collided during the Variscan orogeny. Oblique northward subduction of an oceanic realm beneath the Ossa Morena Zone and subsequent collision induced thrusting and left-lateral transcurrent motion of crustal blocks and formation of a variety of ore deposits in both terranes. Most of the mineralization is related to dilational openings within thrusts and shear zones, extensional faults and pull-apart basins. A discontinuous diachronous vertical section from exhalative to deep mesozonal hydrothermal systems of Variscan age can be inferred. Volcanic-hosted massive sulphides are formed in third order pull-apart basins, but deeper related extensional structures are the loci for epithermal Hg, fluorite and Pb–Zn vein systems, Cu–Ni magmatic mineralization and iron-rich calcic skarns. Dilational regions along major shear zones also host mesozonal gold-bearing quartz veins. The overall Variscan mineralization pattern is inferred to be representative of an oblique collisional, (transpressional) geodynamic regime.
Figures & Tables
The Timing and Location of Major Ore Deposits in an Evolving Orogen
As an outcome of the European Science Foundation scientific programme, GEODE, on geodynamics and ore deposit evolution, this book examines the underlying geodynamic processes that lead to the formation of ore deposits in order to discover what controls the timing and location of major ore deposits in an evolving orogen.
A collection of 19 research papers examines various aspects of ore genesis in the context of the geodynamic processes occurring within an evolving orogen. Although the majority of papers relate to Europe, their findings have a global significance for metallogenesis.
The book will be of interest to all those involved in research or mineral exploration concerned with metallogenesis. In addition, ore deposits provide new evidence about magmatism associated with transient, rapid changes in plate motions and subduction processes in unusual tectonic settings, and are therefore of interest to those involved in both the magmatic and tectonic processes of orogenesis.