From provenance to precipitation: controls on fertility of crustal-derived magmas
Mountain building causes changes in topography, erosion rates, and atmospheric circulation patterns. Mountain building also causes changes at depth in crustal thickness, mineralogy of rocks and occurrence of fluids. As the crust thickens, rocks undergo higher pressures and temperatures leading to dehydration and melting. These fluids (melts and aqueous) are of interest to mineral deposits because they efficiently migrate through the crust and selectively scavenge specific elements. Crustal magmas, in particular, significantly differ from other types of magmas in that they can gather elements that are either too large or too highly charged to fit in common minerals (incompatible elements). One of these incompatible elements is tungsten.
Tungsten deposits are typically related to reduced magmatism in orogenic to post-orogenic settings. However, while reduced magmatism and crustal extension are widespread, over ninety percent of tungsten is produced in only three countries worldwide. In this talk I will discuss crustal magmatism in orogenic to post-orogenic settings, the factors that have been proposed as potential regional controls on tungsten mineralization and what are the likely controls on the local distribution of tungsten.