Location: Congress Centre, Davos, Switzerland
Web: http://www.goldschmidt2009.org/index
Includes the following sessions:
Session 03b: Origin of Hotspots and Flood Basalts
Convenors: Nick Arndt (nicholas.arndt@ujf-grenoble.fr), Cinzia Farnetarni
The aim of this session is to provide a coherent view of thermal and thermochemical instabilities in the deep mantle and their evolution during mantle upwelling, and the petrological and tectonic processes that result in the formation and emplacement of magmas in oceanic islands and continental intraplate settings. Understanding these processes requires contributions from petrologists, geochemists, tectonicians and geophysicists. We invite contributions discussing the dynamics of the source regions of plumes and their mineralogical and chemical compositions, the melting processes and their control on magma compositions, the extent to which melting anomalies reflect excess fertility in the mantle rather than excess mantle temperatures, and finally, the interaction between magma and wall rocks during passage to the surface.
Session 04d: Magma Generation and Evolution and Global Tectonis – A Symposium in Honour of Peter J Wyllie for his Life-Long Contributions to Understanding How the Earth Works by means of Experimental Petrology
Convenors: Yaoling Niu (yaoling.niu@durham.ac.uk), Marjorie Wilson (m.wilson@earth.leeds.ac.uk), Ed Stolper (ems@expet.gps.caltech.edu), Hans Keppler (hans.keppler@uni-bayreuth.de)
Magma generation and evolution are the most effective mechanisms that have led to chemical differentiation of the earth through its history. Our current understanding of magmatism owes much to experimental petrology, including the more than 300 original research contributions by Peter Wyllie and his co-authors. Peter correctly recognized in early days the significance of volatiles in magma genesis in all geological environments. Remarkably, when the plate tectonics theory was still in its infancy, Peter effectively brought that theory to classrooms through his book "The Dynamic Earth", which lucidly explains why volcanoes occur where they do. This symposium honors Peter's contributions and brings together scientists from many parts of the world to discuss their new research on magma generation and evolution. Topics include observations, experimental petrology, igneous geochemistry, and modelling with emphasis on the use of petrology and geochemistry as a means to understanding the working of our planet.
Session 05b: What is the Evidence for Geochemical and Mass Transfer between Mantle and Crust and Back?
Convenors: Mihai Ducea (ducea@geo.arizona.edu), Julian Pearce (pearceja@cf.ac.uk)
Crustal growth can be represented as a box model in which material is transferred in both directions between mantle and crustal reservoirs. Understanding the rates and mechanisms of mass transfer between these reservoirs, and their changes with time, is a minimum requirement for developing a quantitative model of crustal growth. This session focuses on the evidence for these rates and mechanisms. In terms of crustal inputs, we are particularly interested in evidence for the magnitudes and compositions of crustal additions through mantle plume and volcanic arc activity. In terms of outputs, we are particularly interested in geochemical and geophysical evidence for crustal delamination and for the return of crustal materials to the deep mantle via subduction zones. We also encourage contributors to address some of the controversies in crustal growth, which might include the following. What is the role of adakitic and boninitic magmas in crustal growth? Which contributed more to crustal growth: – plumes or subduction? If crustal growth is episodic, what caused the episodicity? How and when does continental crust delaminate and what is the fate of delamination products? What do OIBs tell us about crust-to-mantle transfer and its evolution with time? What fraction of subducted crustal material is returned to the mantle? We look forward to a lively discussion of these and other issues.
Session 10e: Large-Scale Tectonic Controls on Fertility of Magmatic Suites for Ore Genesis
Convenors: Jim Mungall (mungall@geology.utoronto.ca), Steve Barnes (steve.barnes@csiro.au)
This session will focus on the petrogenetic processes that dictate the potential for a magma to become the progenitor of an ore deposit, rather than on the ore deposits themselves. All deposit types - whether magmatic or hydrothermal in origin - whose main fluxes of economic elements are derived from magmas constitute suitable topics. Examples include the conditions required to generate U-rich S-type granites in collisional zones, the origins of the magma parental to the numerous deposit types found in the Bushveld complex, or the optimal conditions for the formation of Au-rich magmas in volcanic arcs.