March 2015 | GeoPRISMS

Several sessions of interest to the GeoPRISMS Community will take place at the upcoming Goldschmidt Conference August 16-21, 2015 in Prague, Czech Republic.

Abstract submission and directions are available at: http://goldschmidt.info/2015/abstracts

(1) Session 16b: Integrated Geochronological and P-T Records of Tectonic Processes at Plate Margins

(2) Session 19a: Subduction zone fluids, metamorphism and the slab-mantle interface: The trench and forearc

(3) Session 19b: From the Slab, Through the Mantle Wedge: Processes and Transformations at the Sub-Arc and Beyond

(4) Session 19c: Cycling of Carbon, Sulfur, and Other Redox-Sensitive Elements at Convergent Margins

(5) Session 19d: Arc Volcanism: Petrogenesis, Ascent Dynamics, and Eruption Style Controls

(6) Session 19e: Drilling in Oceanic Arcs, the Birth Place of the Continental Crust and of Metallogenic Diversity at Oceanic Plate Boundaries

(7) Session 20c: Fluxed and Stretched – Making New Crust

(8) Session 21d: Volatile cycles and volatile-rich magmas in the deep Earth

(9) Session 21f: Chemical Geodynamics Through Time

See below for more details.

http://goldschmidt.info/2015/program/programViewThemes

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(1) Session 16b: Integrated Geochronological and P-T Records of Tectonic Processes at Plate Margins

Convenors: John C. Schumacher, Shah Wali Faryad, Thomas Zack

Keynote: Donna Whitney

This session focuses on understanding tectonic/geologic processes at plate margins through petrologic analysis that can include the use of geothermobarometry, thermochronology, geochronology, and/or the study of major- and trace- element zoning of metamorphic minerals. We look forward to contributions that apply these methods to further clarifying the details of plate-boundary processes.

(2) Session 19a: Subduction zone fluids, metamorphism and the slab-mantle interface: The trench and forearc

We are excited to announce session 19a at Goldschmidt 2015 in Prague. We invite you to contribute to the session.

This session focuses on geochemical, geophysical and petrologic studies that focus on the relatively shallow part of the subduction system, i.e., the slab, mantle wedge, and overriding lithosphere located between the trench and the volcanic arc, where the slab surface is located at depths of less than ~100 km. It is increasingly recognized that subduction materials are significantly processed in this region by metamorphism, metasomatism and mechanical mixing with vast implications for the physico-chemical state of subduction zones. We seek contributions from geochemistry, petrology, and geophysics, including experimental, modeling, and field studies that address the physical and chemical processes operating in the subduction system from the trench to a depth of ~100 km.

Keynote speaker: Matthias Konrad-Schmolke (University of Potsdam)

Convenors: Sarah Penniston-Dorland, Tatsuki Tsujimori, Horst Marschall

(3) Session 19b: From the Slab, Through the Mantle Wedge: Processes and Transformations at the Sub-Arc and Beyond

Convenors: Craig Manning, Tatsuhiko Kawamoto

Keynote: Sverjensky Dimitri

The subducting slab-mantle wedge system is one of Earth’s most important regions of chemical reaction and change. Fluids, melts, and rocks derived from subducting lithosphere interact with depleted mantle in a region of profound chemical and physical gradients. These interactions produce arc magmas and continental crust, mediate planetary-scale volatile cycling, and yield modified subducted lithosphere and mantle-wedge which possess chemical signals that may persist in the deep Earth for billions of years. We welcome all contributions on the processes and transformations from the sub-arc slab-mantle wedge region and beyond, through geologic time.

(4) Session 19c: Cycling of Carbon, Sulfur, and Other Redox-Sensitive Elements at Convergent Margins

Convenors: Katy Evans, Glenn Gaetani, Weidong Sun

Keynote: Richard Arculus

Subduction of rocks that contain oxidized iron, carbon, and sulfur at convergent margins has the potential to introduce oxidation state heterogeneity into the Earth’s mantle. The oxidation state of the mantle exerts important controls on the melting process, melt chemistry, peridotite rheological properties, and the mobility of a wide range of elements, including those of economic interest, such as Cu and Au. Further, subduction cycling of carbon and sulfur affects climate via emission of C- and S-bearing gases at arcs. Contributions are invited from researchers interested in subduction cycling of redox-sensitive elements. The remit of the session extends from characterization of subduction inputs and outputs, to studies of the processes that lead to exchange of elements between reservoirs in the upper mantle. An interest in the economic aspects of the redistribution of redox sensitive elements is encouraged, as is the combination of one or more approaches that include petrology, experimental petrology, geochemistry, geophysics and thermodynamic modeling.

best regards, the convenors.

Katy Evans, Glenn Gaetani, and Weidong Sun

(5) Session 19d: Arc Volcanism: Petrogenesis, Ascent Dynamics, and Eruption Style Controls

Convenors: Georg Zellmer, Victoria Smith

Keynote: Marie Edmonds

Arc volcanism is characterized by an extreme range of eruption products, from small mafic lava flows to widespread felsic tephra deposits. What are the parameters that control this variety in magma composition, eruption style, and scale? We invite contributions that address any or all of these topics, using analytical, experimental, and/or computational approaches. We particularly welcome studies that put constraints on the role of volatiles; the timescales of magma evolution, ascent, and potential storage; and how subvolcanic processes lead up to volcanic eruption.

(6) Session 19e: Drilling in Oceanic Arcs, the Birth Place of the Continental Crust and of Metallogenic Diversity at Oceanic Plate Boundaries

Convenors: Yoshihiko Tamura, Cornel E. J. de Ronde, Mark Hannington, Jun-ichiro Ishibashi, Kaj Hoernle

Keynote: Simon Turner

Intuitively thick crust is necessary to produce andesitic magmas and continental crust if AFC (assimilation-fractional crystallization) plays an important role in the differentiation from mantle-derived (primary) basaltic magmas to andesites. However, seismic velocity images and andesite eruptions of the Izu-Bonin Mariana (IBM) oceanic arc suggests that juvenile components of continental crust may be produced in oceanic arcs. Andesitic crust is also produced in the Lau back-arc spreading systems at greater rates than in the volcanic arc itself with seismic crustal structure that mirrors some aspects of andesitic arcs. This has important implications for the metallogenic diversity of seafloor magmatic-hydrothermal systems in arc settings and their eventual inheritance by continental crust. Preliminary results from the three recent IODP Expeditions (Expeditions 350, 351 and 352) investigating the northern IBM subduction system during 2014 are welcome, as are new findings on the geodynamic and petrogenetic evolution of the Tonga-Kermadec system.

(7) Session 20c: Fluxed and Stretched – Making New Crust

Dear all –

we are organizing session 20c at Goldschmidt 2015 in Prague (August 16-21) entitled “Fluxed and Stretched – Making New Crust” (part of Theme 20: Mantle to Crust). The session covers crustal formation at mid-ocean ridges, continental rifts and arcs, and aims to examine the differences and commonalities between crust-forming processes in these different tectonic settings; the full session description is pasted below. We hope to see you there as contributors and/or in the audience.

Convenors: Susanne Straub, Johan Lissenberg, Philipp Brandl, Oliver Shorttle

Keynote: Mike Perfit

Invited Speakers: Tyrone Rooney (on Afar), Julian Pearce (on Izu Bonin – Mariana arc system)

Partial melts rise from the Earth’s upper mantle to form variably differentiated silicate crust in a range of settings, including mid-ocean ridges, arcs and continental rifts. The elemental and mass transfer associated with partial melting is a key process in the chemical differentiation of solid Earth with implications for climate evolution. The composition of the silicate crust, its thickness, structure and evolution differ strongly in various geotectonic settings, but the causes of this diversity remains poorly understood. Does the compositional difference between crust produced in the various tectonic settings reflect different primary melts, or the complex intra crustal differentiation? Does a singular primary melt type exist or do primary melts encompass a broader range? What portion of the primary melt finally erupts? What are the accumulation rates and how and at which rates do crustal structure, thickness and composition evolve through time?

This session invites contributions that address all aspects of crustal formation at convergent and divergent plate boundaries and in intraplate settings. Case studies and conceptual approaches from all disciplines are welcome, including field studies, experimental petrology and geophysical approaches ranging from fluid dynamics to seismology. Studies that highlight differences and commonalities between the tectonic settings and those with a temporal perspective on crustal evolution are particularly encouraged.

(8) Session 21d: Volatile cycles and volatile-rich magmas in the deep Earth

Dear Colleagues,

We invite contributions to the following session at the 25th Goldschmidt Conference 2015 in Prague.

Keynote: Bernard Marty

Earth´s atmosphere and oceans likely formed by impact degassing during accretion followed by degassing of the mantle. In recent years, it has been increasingly recognized that extensive recycling of volatiles into the mantle also occurs, and that the mantle is still an important reservoir of volatiles today. However, the efficiency of recycling and degassing is poorly constrained; estimates of the present deep Earth volatile budget vary widely and the evolution of global volatile cycles with geologic time is poorly understood. The significance of various types of magmatism — silicate vs. carbonatite, plate boundary vs. intraplate, etc. — is debated. The possible role of the core in storing volatiles is hardly constrained. This session therefore invites contributions from experimental, observational, and modeling studies that may shed light on the deep cycles of hydrogen, carbon, nitrogen, noble gases, halogens and sulfur. We particularly encourage studies linking the behaviour of multiple volatile elements or their isotopes. Studies investigating the phase equilibria of volatile-bearing mantle assemblages and mantle-derived magmas and the effect of volatiles on the physical properties — viscosity, density, seismic velocity, conductivity, permeability, etc. — of the mantle and of melts are also welcome.

Cheers,

Jaime Barnes, Adrian Jones, Sujoy Mukhopadhyay, Mark Kendrick, Andrei Shiryaev, and Max Wilke

(9) Session 21f: Chemical Geodynamics Through Time

We would like to draw your attention to an interdisciplinary Goldschmidt session that seeks to understand the evolution of the Deep Earth through time.

Convenors: Matthew Jackson, Peter van Keken

Keynote: Janne Blichert-Toft (ENS Lyon, France)

Invited Speakers: Catherine Chauvel, Kaj Hoernle.

The Earth’s mantle is the largest reservoir in the Earth and it preserves an integrated record of the long-term geochemical and geodynamic evolution of the planet. Geochemical differentiation of the planet, from accretion to the present day, has modified the chemical composition of the Earth’s interior: subduction zone processes, continental crust extraction and injection of oceanic plates and sediments continuously change the mantle’s make-up. Mixing of chemical heterogeneity and the apparent long-term preservation of early Earth events require a fundamental understanding of the dynamic properties of the Earth and how these have changed over time. Geochemists are gaining new and more detailed insights into the geochemical make-up of the mantle and the early-Earth events, and subsequent geochemical processes that helped shape the current composition of the Earth, but geodynamics places fundamental constraints on possible models for the evolutionary path of the mantle. We encourage both geophysicists and geochemists to contribute to this session to build a dynamical understanding of the geochemistry of the mantle.

We look forward to seeing you in Prague!

Matt and Peter

Several sessions of interest to the GeoPRISMS Community will take place at the upcoming Goldschmidt Conference August 16-21, 2015 in Prague, Czech Republic.

The abstract submission and registration pages for Goldschmidt 2015 are now open. Abstract submission will remain open until April 2, 2015 at 23:59 (UTC) and early registration will end on June 16, 2015. Abstract submission and directions are available at: http://goldschmidt.info/2015/abstracts

(1) Session 19a: Subduction zone fluids, metamorphism and the slab-mantle interface: The trench and forearc

(2) Session 21f: Chemical Geodynamics Through Time