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Theme 4

Ocean Ridge and Intraplate Volcanism: Deep Mantle Supply, Tectonic-magmatic Processes, and Ore Deposits through Time

Roberto Moretti, Napoli, Italy,
Philippe Sarda, Orsay, France,
Kenneth W. Sims, Wyoming,
Philip R. Kyle, New Mexico Tech.,

Co-hosted sessions

SESSIONS

4a. Melt generation and evolution at mid-ocean ridges

Co-convenors:
Leonid Danyushevsky (University of Tasmania) - L.Danutas.edu.au
Nobumichi Shimizu (Woods Hole Oceanographic Institution) - nshimizuwhoi.edu

This session is aimed at discussing a wide range of issues related to generation and evolution of MORB magmas. We encourage contributions on all aspects of MORB magmatism and intend to highlight a number of topics that thus far have received less attention than they deserve: the effects of ridge migration on magma generation beneath mid-ocean ridges; the importance of mid- and lower-crustal processes in controlling compositions of erupted magmas; spatial scales and magnitude of melt/rock interactions during magma ascent; the significance of volatiles in MORB magmas and their effect on MORB fractionation paths; the extent and importance of high-pressure fractionation during MORB magma evolution. We especially welcome contributions which combine geochemistry, geophysics and/or tectonics.

Keynote speaker:
Roger Buck (LDEO-Columbia University), buckldeo.columbia.edu

4b. The occurrence, genesis and evolution of alkaline magmas

Co-convenors:
Glenn A. Gaetani (Woods Hole Oceanographic Institution) - ggaetaniwhoi.edu
Philip R. Kyle (New Mexico Institute of Mining and Technology) - kylenmt.edu
Kenneth W W Sims (University of Wyoming) - ksims7uwyo.edu
Erin H. Writer (University of Wyoming) - ephilli8uwyo.edu

Alkaline volcanism occurs in oceanic and continental intraplate and rift settings and more rarely along convergent margins. In this session we will examine the similarities and differences in the occurrence, genesis and magmatic evolution of alkaline magmas from geochemical, petrologic and geophysical perspectives. We encourage contributions that involve a range of different approaches to understanding alkaline magmas including field studies, experiments, geochemical and isotopic measurements, and numerical modeling.

Keynote speaker:
Sébastien Pilet (University of Lausanne), sebastien.piletunil.ch

4c. Large volcanic plumbing systems and ore deposits at intraplate settings: from the mantle source to large volume eruptions and environmental effects

Co-convenors:
Massimo D’Antonio (Università degli Studi di Napoli) - masdantounina.it
James E. Mungall (University of Toronto) – mungallgeology.utoronto.ca
Ilya Bindeman (University of Oregon, Eugene, USA) – bindemanuoregon.edu

Relevant areas of volcanism on Earth are fed by large plumbing systems that generate large volume magmatism and volcanic eruptions that can profoundly affect climate. Large-scale melting events in the upper mantle at bottom of such systems and control the origin of major Ni-Cu-PGE deposits, depending on the contributing sources of parental magmas (e.g., depleted upper mantle, enriched OIB-type mantle or reactivated ancient subcratonic lithosphere). Moreover, volcanic-plutonic connections and architecture control the origin of large volume  magmas and may determine the mechanisms of large volume volcanic eruptions, hence their effects on climate. This session aims at bringing together experts working on such important topics around large volcanic plumbing systems with emphasis on  intraplate settings. We therefore invite contributions on the geochemical and isotopic characterization of magmatic processes, fluid transfer and fluxing at variable depth in the lithosphere, including issues related to the fertility of intraplate magmas parental to Ni-Cu-PGE deposits, and eruptive mechanisms of big-sized magma bodies. We also encourage contributions dealing with numerical modeling of caldera forming eruptions and influence of volcanic ash on the environments.

Keynote speakers:
Leonid Danyushevskyi (University of Tasmania), l.danutas.edu.au
Calvin Miller (Vanderbilt University), calvin.millervanderbilt.edu

4d. Stable isotope fractionation during magma generation and evolution

Co-convenors:
Julie Prytulak (Imperial College, London) - j.prytulakimperial.ac.uk
Jan Schuessler (GFZ Potsdam, Germany) - jan.schuesslergfz-potsdam.de

High temperature fractionation of stable isotopes can provide important constraints on magma generation and evolution - most intensively studied during the past decades for elements such as H, O, S, and C. Beside these, multiple stable isotope systems spanning the periodic table now present analytically resolvable variations (e.g., Li, Mg, Si, the transition metals, and heavy elements such as Tl, and U). These systems are poised to yield unique insight into processes such as melting, differentiation, diffusion, high T fluid flow, and oxidation-reduction. However, the dominant controls driving the variable extent of isotope fractionation remain poorly constrained. This session aims to bring together studies investigating natural samples, as well as experimental and theoretical studies on the effects of high temperature stable isotope fractionation (traditional and non-traditional isotope systems) during magmatic processes in the present and through geologic time.

Keynote speaker:
Helen Williams (Durham University, UK) - h.m.williams2durham.ac.uk

4e. Mid-ocean ridge processes: melting and melt extraction in a heterogeneous mantle.

Co-convenors:
Michael Bizimis (University of South Carolina) - mbizimisgeol.sc.edu
Andreas Stracke (Westfälische Wilhelms Universität, Münster) - stracke.andreasuni-muenster.de
Richard Katz (University of Oxford) - richard.katzearth.ox.ac.uk

The composition of mid ocean ridge basalts (MORB) and abyssal peridotites retain a time-integrated record of melting and melt extraction from a heterogeneous upper mantle. How are the different enriched and depleted components arranged in the mantle? What are their length scales and extent of heterogeneity? Under what conditions do they melt and how do the partial melts subsequently travel, react and modify the mantle lithosphere en route to the surface? These remain major, open questions of Mid-ocean Ridge processes. We invite contributions from field, petrological, geochemical geophysical and modeling studies that explore the above questions, especially from the perspective of the mantle sample.

Keynote speaker:
Henry J. Dick (Woods Hole Oceanographic Institute), hdickwhoi.edu

4f. Roles of lithospheric, depleted, and enriched mantle sources in the genesis of large Ni-Cu-PGE deposits.

(co-hosted by Themes 4 and 9)

Co-convenors:
James E. Mungall (University of Toronto) – mungallgeology.utoronto.ca
Edward M. Ripley (Indiana University-Bloomington) - ripleyindiana.edu

SESSION MERGED with 4c

4g. Geochronology and geochemistry of large igneous provinces

(co-hosted by Themes 4 and 5)

Co-convenors:
Paul Sylvester (Memorial University, Newfoundland, Canada) - psylvestermun.ca
Richard Ernst (Ernst Geosciences) - Richard.ErnstErnstGeosciences.com
Mike Hamilton (University of Toronto) -mahamiltongeology.utoronto.ca
Wouter Bleeker (Geological Survey of Canada-Ottawa) - Wouter.BleekerNRCan-RNCan.gc.ca

Large igneous provinces (LIPs) are the result of large volume magmatic events emplaced over short time scales, found through all of the geologic record. Recent advances in U-Pb geochronology of baddeleyite by TIMS, SIMS and LA-ICPMS have allowed many more mafic LIP events to be dated precisely. The new ages are used for correlations between LIP units on now dispersed terrane fragments, providing constraints on reconstructions of supercontinents. Precise age data also allow geochemical comparisons between different LIP events, leading to a better understanding of variations in their mantle sources and melting processes. This session aims to highlight the analytical developments of U-Pb geochronology of baddeleyite and the application of high-precision age data for LIPs to paleo-continental reconstructions, mantle geochemistry, mantle dynamics and plumes, the intrusive and extrusive architecture of LIPs, global environmental catastrophes and biological mass extinctions, and the genesis and distribution of ore deposits and hydrocarbons within LIP systems.

Keynote speaker:
Kevin Chamberlain (University of Wyoming), kchamberuwyo.edu
Jean H.J. Bedard (Geological Survey of Canada-Québec) - JeanH.BedardRNCan-NRCan.gc.ca

4h. Geochemical and isotopic insights into large volume silicic eruptions and supereruptions

(co-hosted by Themes 4, 5 and 6)

Co-convenors:
Ilya Bindeman (University of Oregon, Eugene, USA) - bindemanuoregon.edu
Erwan Martin (Université Pierre et Marie Curie, Paris, France) - erwan.martinupmc.fr

SESSION MERGED with 4c

4i. Mass transfer processes at the mantle-seawater interface

(co-hosted by Themes 4 and 6)

Co-convenors:
Dionysis Foustoukos (Carnegie Institution of Washington) - dfoustoukosciw.edu
Michael Bizimis (University of South Carolina) - mbizimisgeol.sc.edu

Mantle – seawater exchange in peridotite-hosted hydrothermal systems has important implications for the evolution of Earth’s crust, hydrosphere and the underlying subsurface biosphere. Hydrothermal circulation within the peridotitic mantle may act both as a source and sink for REE, metals and volatiles (e.g. H₂, hydrocarbons) affecting the chemical composition of the oceanic column, the habitability of near-seafloor hydrothermal environments, as well as the transfer of chemical components from the surface back into the mantle through subduction zone processes. In this session, we invite contributions from field, experimental and theoretical studies that address any aspects of the serpentinization processes and mass transfer mechanisms at the mantle seawater interface, including mantle dehydration during subduction.

Keynote speaker:
Tom McCollom (University of Colorado at Boulder), mccollomlasp.colorado.edu

4j. New views of mantle heterogeneity from oceanic basalts

Co-convenors: Aaron Pietruszka (San Diego State University) - apietruszkageology.sdsu.edu
Dominique Weis (University of British Columbia) - dweiseos.ubc.ca

The chemical and isotopic diversity of young basalts from oceanic islands, seamounts and plateaus record evidence of the compositional heterogeneity of the Earth’s mantle. The goal of this session is to highlight recent studies on the nature and origin of mantle heterogeneity at all length scales and over a range of depths. We welcome contributions that use elemental and/or isotopic measurements of oceanic basalts (and their minerals and melt inclusions) and/or geochemical modeling to see through the filter of the melting process to the underlying compositional heterogeneity of the mantle. Integrated contributions, with geophysical and/or geodynamical perspectives, are also encouraged.

Keynote speakers:
Cinzia Farnetani (Institut de Physique du Globe de Paris), cinziaipgp.jussieu.fr
Kaj Hoernle (IFM-GEOMAR), khoernleifm-geomar.de
Edward M Stolper (California Institute of Technology), emscaltech.edu

Co-hosted sessions:

Please note that for abstract submission purposes, the following sessions and their respective descriptions appear in their primary Theme assignments (numbers in red or before the title).

3g.- Melts, glasses and magmas

Co-convenors: Daniel Neuville/IPGP, Cristina de Campos/Munich, Akio Suzuki/Tokyo and Kelly Russell/UBC
(co-hosted by Themes 3,4 and 6)

6a.- Earth’s deep carbon cycle

Co-convenors: Eric Hauri/Carnegie and Juske Horita/Texas Tech
(co-hosted by Themes 6, 3 and 4)

6e.- From crystallization to exsolution: the origin and fate of magmatic volatiles and the magmatic-hydrothermal transition in ore-forming systems.

(co-hosted by Themes 4 and 6)

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