Goldschmidt Conference 2008

There are several sessions of interest to InterRidge at the upcoming Goldschmidt Conference to be held in Vancouver, Canada, 13-18 July 2008(http://www.goldschmidt2008.org/).
Abstract deadline: March 1st.

Session 6a: Ridges and Geochemical Mapping of the Mantle
Session 10e: Mechanisms and time scales of crustal assimilation
Session 15c: Hydrothermal systems in ultramafic rocks
Session 15e: Quantifying the chemical exchange between the oceanic lithosphere and oceans

Session 6a: Ridges and Geochemical Mapping of the Mantle
Conveners: David Graham, Emily Klein
This session will highlight the use of state-of-the-art chemical and isotopic measurements in rocks from mid-ocean ridge environments to investigate the length scales and origins of geochemical variability in the sub-ridge mantle. Pertinent topics include, but are not restricted to, multple isotopic tracer studies (Pb, Sr, Nd, Hf, Os, noble gases), major and trace element geochemistry, similarities and differences in the geochemical signatures of basalt, gabbro and peridotite, U-series measurements, melt inclusion studies, and modeling of melt generation, mantle flow and heterogeneity in the upper mantle beneath ocean ridges.

Session 10e: Mechanisms and time scales of crustal assimilation
Conveners: David W. Peate & Michael Rowe (University of Iowa), Wendy Bohrson (Central Washington University)
Exciting progress has been made recently in documenting the nature of interactions between mantle-derived mafic magmas and the overlying crust (continental and oceanic). Key advances have included development of quantitative models of assimilation, improved micro-analytical methods that allow measurement of elemental and isotopic variations within single crystals and melt inclusions, and new approaches for documenting assimilation time scales. For this symposium, we solicit submissions that illuminate the mechanisms and time scales of crustal assimilation through integrated geochemical and petrological studies. Contributions from the macro- to micro-scale are encouraged, including detailed stratigraphic studies that provide insight into the evolution of melt-crust interaction, quantitative elemental and isotopic modelling, in situ studies of crystals and melt inclusions, diffusion modelling, and kinetics of mineral dissolution. Examples from continental and oceanic settings are welcome.
Keynote speaker will be: John Wolff (Washington State University).

Session 15c: Hydrothermal systems in ultramafic rocks
Conveners: Wolfgang Bach, Dionysis Foustoukos
Interactions between aqueous solutions and ultramafic rocks take place in a range of geotectonic settings, from ophiolites to rifted continental margins to subduction zones to mid-ocean ridges. Despite pronounced differences in pH and ionic composition, the interacting fluids invariably develop high concentrations of hydrogen and methane, and those compounds serve as energy source supporting chemosynthesis-based ecosystems. Recent progress in defining the reactions that set hydrothermal fluid chemistry is paralleled by new insights into the microbial utilization of ultramafic rock-derived energy sources. This session invites contributions pertaining to any of these issues. Papers reporting on field, experimental, theoretical, molecular, isotopic, and microscopic approaches that further our understanding of mechanisms and rates of the geochemical and biogeochemical reactions involved are particularly welcome.

Session 15e: Quantifying the chemical exchange between the oceanic lithosphere and oceans
Conveners: Laurence Coogan, Kathy Gillis
Understanding the extent and timing of chemical exchange between the oceanic lithosphere and oceans is important if we are to quantitatively understand a broad range of processes from element fluxes in subduction zones through to using present and past seawater compositions to interpret chemical weathering rates and paleo-climate. Exchange occurs throughout the lifetime of a plate from high-temperature ridge crest hydrothermal activity through lower temperature circulation on the ridge flanks, to enhanced circulation around subduction zones. Hydrothermal exchange is also enhanced around both active and extinct seamounts. Contributions that focus on any of these areas using the compositions of either fluids or rocks, or that use models, to try to constrain chemical fluxes are welcome.