GMPV2.10/TS3.10Understanding granites – state of the art and ways ahead (co-organized)
|Convener: Patrizia Fiannacca | Co-Conveners: Vojtěch Janoušek , Jean-François Moyen , Carlos Villaseca|
Granites and their metamorphic equivalents make up a substantial part of the continental crust, underlining the fundamental role played by granitic magmatism in controlling continental crust growth and evolution. Nevertheless the origin of granitic magmas remains a highly controversial topic, because it involves a number of different interplaying parameters, reflecting contrasting geotectonic settings. These parameters include nature and composition of the magma sources, causes and conditions of the melting, processes of magma differentiation and post-magmatic modifications. In particular, mechanisms and timescales of granitic magma production, transport, emplacement and residence at mid–upper crustal levels are critical as they can, in turn, induce changes in the thermal regime and rheology of the continental crust. Granite magmatism thus plays a significant role in the tectono-metamorphic processes associated with formation and exhumation of orogenic belts; furthermore, it is tightly connected with impactful surficial processes such as silicic supereruptions. As a consequence of the variety of sources, processes and tectonic settings involved in the generation of granite melts, there is no consensus on the best way to classify this fundamental group of magmatic rocks. The most used geochemical and petrogenetic classification schemes (with the alphabetic one being dominant) are misleading or deceptive to many granitologists, but meaningful alternatives have never been proposed.
Many different techniques have been used to fruitfully investigate granites. Founding on field- and petrography-based work, they range from geochemical modeling, through melting/ crystallization experiments and thermodynamic modeling, combined with in situ geochronology and trace-element/isotope studies of accessory minerals.
This session is aimed to explore and discuss the state of the art, as well as the best possible approaches to advance our understanding of causes and consequences of granite magmatism in variable tectonic contexts.