S47: Links between radioactive isotopes and diffusion modelling to constrain the timescales of magmatic processes

Conveners:	Fidel Costa RodrÌguez	(fcosta@ija.csic.es)
	Mark Reagan	(mark-reagan@uiowa.edu)
Keynote:	Ken Sims	(Woods Hole Oceanographic Institution)

In the last 10 to 15 years, there have been major advances in our understanding of igneous processes because we have been able to determine the time scales of magmatic processes with an unprecedented level of precision, age range, and spatial resolution. These include measurements of the timing of magmatic events using short-lived radioactive isotopic clocks (e.g., U-Th series disequilibria) and in situ age determinations of single crystals or even individual parts of very young materials (< 1 Ma). Kinetic modelling techniques have also increasingly constrained the time scales of igneous processes, which in many cases are of durations accessible only to the shortest-lived isotope clocks. This session welcomes presentations that constrain the rates of igneous processes using any of these methods and aims to find a common ground for applications. Possible topics of discussion include: (1) the rates of evolution of silicic volcanic and plutonic systems, (2) magma generation, transport and storage time scales at subduction zones and ocean islands, (3) temporal evolution of radioactive isotopes at long lived versus currently active volcanoes.

Note that contributions related to/ mid-ocean ridges/ should be sent to Symposium S48: "Rates of heat and mass transport through mid-ocean ridges", which is complementary to this symposium.

S48: Rates of heat and mass transport through mid-ocean ridges

Conveners:	Laurence Coogan	(lacoogan@uvic.ca)
	Craig Lundstrom	(lundstro@uiuc.edu)
Keynote:	James A. Van Orman	(Close Western Reserve University, USA)

The processes of heat and mass transport operating at mid-ocean ridges, from mantle melting through to seafloor ecosystems, are intricately linked. However, the rates of processes in different parts of this system are poorly constrained. This session will focus on quantifying the rates of magmatic and hydrothermal processes at mid-ocean ridges addressing questions such as: What are the rates of mantle upwelling and melt ascent beneath ridges? How episodic is melt supply to the lithosphere? How rapidly do magmas crystallise and differentiate? How quickly does the surrounding crust cool? When and where do different hydrothermal reactions occur in the sub-seafloor? And, how quickly do hydrothermal systems respond to changes in the underlying system? This symposium will be a forum for discussing a wide range in temporal constraints on MOR processes. We welcome abstracts presenting both physical and chemical constraints on the rates of processes at mid-ocean ridges including numerical modeling, geophysical observation, experimental studies and geochemical analyses of fluid and rock samples.

Note that contributions related to timescales of continental magmatic systems should be sent to Symposium S47: "Links between radioactive isotopes and diffusion modelling to constrain the times scales of magmatic processes", which is complementary to this symposium.

S49: High-grade metamorphism: Duration and rates

Conveners:	Daniela Rubatto	(Daniela.Rubatto@anu.edu.au)
	Kurt Stüwe	(kurt.stuewe@uni-graz.at)
	Ethan Baxter	(efb@bu.edu)
Keynote:	Martin Hand	(Adelaide, Australia)

Understanding high-grade metamorphism is fundamental for the comprehension of the dynamics of orogenic processes. Whereas the relationship between pressure and temperature is reasonably well understood, constraints on the temporal rates and duration of metamorphic processes remain limited. Speakers in this session are invited to discuss new advances in documenting time-dependent metamorphic processes by presenting results obtained from isotopes, geochronology, textural/structural criteria and other geospeedometry tools.

In addition, durations and rates of low temperature processes will be covered in:
S69: Geochemical constraints on the topographic evolution of Cenozoic orogens
S70: In-situ cosmogenic nuclides: Advances in methodology and applications
S82: Timescales and rates of climate change

The following symposia listed under Themes 11 and 12 are also relevant for Theme 8. Details of Symposium 69 and Symposium 70 are given in Theme 11 and details of Symposium 82 are given in Theme 12.

S69: Geochemical constraints on the topographic evolution of Cenozoic orogens

Conveners:	Andreas Mulch	(mulch@geowi.uni-hannover.de)
	Todd Ehlers	(tehlers@umich.edu)
Keynote:	P.C. Chamberlain	(Stanford)

S70: In-situ cosmogenic nuclides: Advances in methodology and applications

Conveners:	Tibor Dunai	(Tibor.Dunai@ed.ac.uk)
	Fred Phillips	(phillips@nmt.edu)
Keynote:	John Stone	(Seattle)

S82: Timescales and rates of climate change

Conveners:	G. Winckler	(Winckler@ldeo.columbia.edu)
	S. Mukhopadhyay	(sujoy@eps.harvard.edu)
	A. Immenhauser	(adrian.immenhauser@rub.de)