Location: Vienna, Austria
Web: http://meetings.copernicus.org/egu2012/
Includes the following sessions:
GMPV2.1/GD2.7/SM4.2/TS1.4: Geochemical, petrological and physical discontinuities in the lithospheric mantle: supporting evidence and hypotheses for their origin
Convenors: Igor Ashchepkov (igor.ashchepkov@igm.nsc.ru), Csaba Szabo (cszabo@elte.hu), Jeroen van Hunen (jeroen.van-hunen@durham.ac.uk)
Mantle discontinuities are the result of melt/fluid migration, mantle diapirism or subduction slab incorporation into subcratonic mantle. Recent results combine with great success geochemical, petrological, petrophysical and geophysical data to produce models of the evolution of the lithospheric mantle.
Key questions for studies of xenoliths in alkali basalts are: 1.Spatial and vertical metasomatic columns in permeable zones in subduction zones and plumes. 2. Determination of melt compositions using melt/fluid inclusions. 3. Pyroxenites and their parental melts. 4. Correlation of chemical and geophysical discontinuities.
Key questions for studies of xenoliths from the cratonic lithosphere are: 1. Characterisation and explanation of internal layering using petrological, geochemical and geophysical techniques . 2. growth mechanisms of the continental lithosphere and their evolution in time 3. types of mantle metasomatism and their relationship to tectonic setting 4. Mechanisms of melt migration through the lithosphere.
GMPV1.5/VPG4/GD6.2: Deep mantle mineralogy, geochemistry and geodynamics
Convenors: Michael Walter (m.j.walter@bristol.ac.uk), Reidar Tronnes (reidar.tronnes@ntnu.no)
The theme of this session is the composition, structure, dynamics and evolution of the mantle. We invite participation from a spectrum of disciplines, from seismic tomography, mineral physics, experimental petrology, geochemistry and numerical modeling to understand how the mantle functions and how it evolved to its current state. Some specific processes to be considered include the origin and evolution of large low shear velocity provinces (LLSVP), the interaction between plate tectonics and other modes of convection, the fate of subducted slabs, melting and the segregation of magma, recycling from the surface into the sources of mantle plumes, and the deep mantle volatile cycle.
GMPV5.1: Magma generation and differentiation: field, analytical, experimental and numerical investigation of magmatic and volcanic systems
Convenors: Valentin Troll (valentin.troll@geo.uu.se), Ralf Gertisser (r.gertisser@esci.keele.ac.uk), Carmela Freda (freda@ingv.it)
This session invites contributions targeting the generation and differentiation of magmas in the mantle and crust from field studies, petrology, geochemistry (major and trace elements and isotopes), experimental petrology and thermodynamic and geochemical modeling. Magma chemistry sampled in plutonic and volcanic rocks reflect combinations of processes operating in their sources (e.g. metasomatism by fluids and melts, asthenospheric-, lithospheric- and 'exotic' mantle components such as pyroxenites as well as crustal melting and anatexis) and during differentiation from mantle depths to shallow level magma reservoirs and volcanic extrusions/explosions (e.g. fractional crystallization, assimilation, mixing/mingling, replenishment of magma reservoirs and chambers). The fundamental question to be addressed by this session is how igneous systems operate in different tectonic settings and what are the principal controls on primary, parental and derivative magma compositions.
GMPV5.2: How magma chambers work: recent advances in the study of granitic, alkaline and mafic-ultramafic plutonic complexes
Convenors: Rais Latypov (rais.latypov@oulu.fi), Jacqueline Auwera (jvdauwera@ulg.ac.be), Tom Anderson (tom.anderson@geo.uio.no)
A key idea of the session is of bring together a diverse group of igneous petrologists to evaluate the current state-of-the-art in our understanding of processes of magma differentiation, crystallization and solidification in plutonic magma chambers of variable form and size (dykes, sills or large intrusions) and variable composition (granitic, alkaline and mafic-ultramafic). The fundamental aspects of magma chamber processes to be addressed by this session are as follows: the relative effects of in situ crystallization versus crystal settling in evolving magma chambers and the origin of layering; the role of thermal and compositional convection in magma differentiation; the effects of compaction and post-cumulus melt migration within the cumulate pile on compositional profiles of magmatic bodies; the formation of chilled margins and compositional reversals along the intrusive contacts of plutonic bodies; the interactions between resident melt in the chamber and inflowing magma during chamber replenishment events; the origin of different compositional profiles in dykes and sills. This session welcomes field, textural, mineralogical, geochemical, isotopic, experimental and numerical examination of plutonic intrusions that provide us with new ideas on how magma chambers operate and develop.
Keynote speakers: Grant Cawthorn (University of Witwatersrand), Liya Kogarko (Russian Academy of Sciences), Fernando Bea (University of Granada)
SSP4.8/GMPV6.4: Large Igneous Provinces (LIPs): effects on climate, oceanography and biotic evolution
Convenors: Darren Gröcke (d.r.grocke@durham.ac.uk), Jessica Whiteside (jessica_whiteside@brown.edu), P Olsen (polsen@ldeo.columbia.edu)
Increasing evidence links large igneous provinces, climate change, and extinction events throughout the Phanerozoic. This session addresses the possible links between these events, focusing on the geological mechanism and processes leading to environmental changes, like release of gases from magmas and from the sedimentary basins into which they intrude and through which they erupt. A main aim of the session is to merge proxy data and isotope studies with geological processes and extinction data and mechanisms. Papers are invited across the possible spectrum of investigations, which include petrology, isotope geochemistry, field measurements, biostratigraphy, geochronology, climate modeling, and geodynamics. The session encourages submissions particularly on the Siberian Traps and the end-Permian extinction, the Triassic-Jurassic boundary (CAMP) and Mesozoic oceanic anoxic events (Ontong Java and Caribbean), the KPg boundary (Deccan Traps) and the Cenozoic (North Atlantic).
GD4.1/GMPV6.16: Mid-ocean ridge processes: melting and melt extraction from a heterogeneous mantle
Convenors: Richard Katz (richard.katz@earth.ox.ac.uk), Andreas Stracke (andreas.stracke@erdw.ethz.ch), Johan Lissenberg (lissenbergcj@cf.ac.uk)
Mid-ocean ridges are our best window into the upper mantle because of their relatively well-understood dynamics and their broad and continuous sampling through extraction of partial melts. They therefore provide the context to address a persistent challenge: understanding the mechanism of sampling, as well as the nature, origin and consequences of chemical heterogeneity in the mantle. Especially relevant are questions such as: what is the "initial condition" of the MOR mantle source? How do heterogeneities melt? How is magma extracted and mixed? How is the chemical signature of the mantle source transposed to the erupted basalts? This interdisciplinary session welcomes all contributions to answering these and related questions.
GD2.4/GMPV6.17/SM2.12: Oceanic hotspot origin and dynamics
Convenors: George Helffrich (george.hellfrich@bristol.ac.uk), Gabi Laske (glaske@ucsd.edu), Yanick Ricard (ricard@ens-lyon.fr)
The development history of hotspots in oceanic environments differ depending on their geodynamic environments. Pacific hotspots, exemplified by Hawaii, develop from seamounts, emerge to volcanic islands, and then subside to a guyot stage. Atlantic hotspots develop to an emergent volcanic island yet resist subsidence and continue uplifting. This session aims to document these differences geologically and geophysically with the aim of understanding how different evolutionary histories arise geodynamically.
Keynote speakers: Ricardo Ramalho (University of Muenster), Neil Ribe (Université Pierre et Marie Curie)