Goldschmidt 2015

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Start Date: 
Sunday, August 16, 2015
End Date: 
Friday, August 21, 2015

Location: Prague, Czech Republic


Includes the following sessions:

16e: Silicic Magmas: Connecting Plutonic and Volcanic Systems

Convenors: Carol Frost (, Peter Bowden (

This session will investigate the processes by which silicic magma systems produce felsic intrusions and volcanic rocks. Contributions are welcomed on silicic rocks of varying geochemical composition emplaced in a variety of tectonic settings. Questions include whether eruptive products have intrusive equivalents, and the relationship of petrogenesis to tectonic setting of magmatism.

16h: Mantle-Derived Intraplate Magmas and their Xenoliths: Source-Forming Processes, Impact on Lithosphere Stability, and Other Geodynamic Implications

Convenors: Sebastian Tappe (, Tyrone Rooney (, Andrea Giuliani (

Mantle melting processes that occur away from subduction zones and mid-oceanic ridges are an important though often overlooked process by which both oceanic and continental lithosphere can grow and stabilize, or even weaken. In contrast to other tectonic settings, the intraplate environment produces an enormous range of primitive magma types with diverse isotopic compositions. The compositional diversity is commonly explained by variable thickness and enrichment style/history of the affected lithospheric plates. However, whether the lithospheric mantle is actively involved in melt generation, and to what extent, remains a controversial subject. It also remains poorly understood whether some intraplate magmatic provinces are sourced from deep-rooted thermochemical plumes or simply derived from convecting upper mantle materials by decompression melting. Equally, differences in COH-volatile speciation, as a function of mantle oxidation state, may have profound effects on melting and phase relations in both peridotitic and eclogitic sources. We welcome contributions - based on observation, experimentation, and modeling - that investigate the generation and evolution of primitive magmas in intraplate settings. This can include studies on the processes and products associated with melt/fluid-facilitated overprinting of mantle lithosphere, such as metasomatism including megacryst- and diamond-formation. We also encourage discussion of plume-lithosphere interaction, as well as of the potential links between volatile mobility in Earth’s mantle and processes that lead to lithosphere destruction and continental break-up. We particularly invite research that exploits modern analytical tools at the micro-scale or smaller to address large-scale phenomena observed within intraplate magmatic provinces and their plumbing systems.

18c: Making Intermediate Magmas: From the Archean to the Present

Convenors: Kristoffer Szilas (, Peter Kelemen (

Intermediate magmatic rocks, particularly “calc-alkaline” andesites, dacites and plutonic rocks, closely resemble the composition of continental crust. They are complex and can form by many different processes including: fractional crystallization, magma mixing, mantle assimilation, crustal assimilation, and – for the crust - mechanical juxtaposition of mafic and felsic rocks. Although intermediate magmas can potentially form in any tectonic setting, they are usually found in subduction-related volcanic arcs. Indeed, calc-alkaline andesites and dacites are found almost exclusively in arcs, leading to the hypothesis that the formation of continental crust occurs in the subduction zone environment. In any case, the petrogenesis of intermediate magmatic rocks may help shed light on the details of the processes that led to the formation of the continents. We invite contributions to this session that concern intermediate magmas in the broadest sense, including presentation of field-based studies, geochemical analyses, thermodynamic modeling, or experimental work, that can lead to new insights on formation of intermediate magmas throughout Earth history.

22a: The Record and Influence of Impacts and Volcanism on the Early Earth

Convenors: Alexandra Davatzes (alix@temple.ed), Gary Byerly (, Fabrice Gaillard (, Steven Goderis (

Surface conditions on the early Earth were influenced by external delivery of material through meteor impacts as well as emissions from the interior via volcanic activity. Both of these processes cause significant and sudden environmental disturbances to the atmosphere, hydrosphere, and to life. Recent work has begun to re-evaluate the impact flux to the early Earth: was there a Late Heavy Bombardment, a continual and rapid decline of impact rate in the Hadean, or a continual delivery of large bolides to the surface throughout the Precambrian? How have impacts throughout the Archean and Proterozoic created transient or permanent shifts in climate or biology? Was the Archean Earth continuously producing large igneous provinces or was subduction and the associated volcanic activities already operating? What is seen in the geological record that would allow us to better understand the evolution of the nature, style and impact of volcanism on early Earth? And finally how does the hydrothermal or surficial alteration of volcanic rocks produce biologically favorable or adverse conditions? We invite contributions using observations from the geological record, experimental data, and models that explore the rate(s) and effects of these events to the earliest history of our planet. This session also includes observations and models from the Moon, Mars, and asteroids/meteorites that inform our models for early Earth’s evolution.

Prague, Czech Republic