Location: Paris, France
Web: https://goldschmidt.info/2017/
Includes the following sessions:
03e: Large igneous provinces in the Precambrian and Phanerozoic and their environmental impacts
Convenors: Richard Ernst (richard.ernst@ernstgeosciences.com), Andrey Bekker (andrey.bekker@ucr.edu)
Rapidly accelerating research focused on environmental and climatic change in the Earth System is revealing many robust links with the timing of Large Igneous Provinces (LIPs). Some LIPs with the highest precision U-Pb ages are precisely matched to mass-extinction events. Many LIPs are implicated in a variety of kill and climate change scenarios, including global warming, global cooling (glaciations), anoxia events, acid rain, ocean acidification, toxic gas or metal release, deposition of iron formations, and stepwise oxygenation of the atmosphere. The environmental linkages are becoming particularly clear in the Phanerozoic record but equally extend to the Precambrian, which also has a robust LIP record (with events averaging every 20-30 myr at least through the Proterozoic). This session welcomes contributions that use the sedimentary record to characterize environmental changes that can be linked to LIPs, both in the Phanerozoic and Precambrian. From a complementary perspective, we welcome cutting-edge studies that further our understanding of LIPs generally in terms of temporal distributions, controls, magnitudes, environmental impacts, etc.
03f: Komatiites: witnesses to Earth's history
Convenor: Nicholas Arndt (nicholas.arndt@ujf-grenoble.fr)
Komatiites are a family of ultramafic volcanic/volcaniclastic or subvolcanic rocks that have crystallized from ultra-hot magmas containing between 18 and 31% MgO. Komatiites feature spinifex, a unique and arguably the most beautiful terrestrial rock texture known, comprising elongated skeletal crystals of olivine set in a glassy matrix. Due to high degrees of partial melting, the chemical composition of komatiites resembles that of mantle peridotite. Typical komatiite habitats are Archean greenstone belts; post-Archean komatiite occurrences are rare and usually characterized by lower MgO contents, an observation that has been taken as evidence for secular cooling of the mantle. Komatiites have been widely used to explore how Earth operated from very early on in its existence. They provide unique evidence pertinent to (i) Earth’s thermal history, (ii) the evolution of the oxidation state of the mantle, (iii) the timing of onset of inner core crystallization and mechanisms of core-mantle exchange, (iv) the history of planetary accretion and differentiation, and (v) mixing times of the mantle and evolution of mantle dynamics on Earth. Komatiites also host economically significant magmatic Ni-Cu-HSE ore deposits. This session invites abstracts dedicated to these and related topics across all disciplines of Earth Sciences.
05d: The geochemistry of hotspots and intraplate magmas: mantle sources, metasomatism, magmatic processes and xenolith cargoes
Convenors: Andrea Giuliani (andrea.giuliani@mq.edu.au), Matthew Jackson (jackson@geol.ucsb.edu)
Understanding the composition of the Earth’s interior away from convergent margins is fundamental to constrain the long-term lithosphere recycling as well as the survival of early-formed reservoirs in the modern mantle. Tracing the composition of the deep Earth, including the recycling of surface components, requires investigation of mantle-derived magmas and the xenoliths they entrain during ascent. Partial melting processes in intraplate settings generate a variety of magma compositions, which testifies to the heterogeneous nature of the Earth’s mantle and the complex processes affecting magmas during ascent and emplacement (melt differentiation, mixing, assimilation, degassing, etc). Therefore, the volcanic products observed at the surface commonly require complex – and often model-dependant – deconvolution of the contributions from these processes, to unravel the source signature. This session invites contributions that explore the geochemistry and petrology of hotspot lavas and mantle xenoliths at both oceanic and continental settings. We welcome studies which aim at providing insights into the lithological and geochemical (including stable and radiogenic isotope) composition of mantle sources that are sampled by, and the processes that operate on, intraplate volcanics. We particularly invite research that explores the geochemistry of bulk lavas, melt inclusions, single phases or xenoliths from intraplate volcanic settings including ocean island basalts (OIBs), petit spots, monogenetic basaltic fields, kimberlites and related rocks.
05f: Carbonatites, alkaline magmatism and associated mineral resources
Convenors: Lyderic France (lyde@crpg.cnrs-nancy.fr), Hannes Mattsson (hannes.mattsson@erdw.ethz.ch), Sam Broom-Fendley (s.l.broom-fendley@exeter.ac.uk), Wei Chen (wchencug@163.com)
This session is devoted to the understanding of the origin and evolution of carbonatites and alkaline magmatism in its widest sense, and to related mineral deposits. Contributions focused on the quantification of the igneous and hydrothermal parameters (P, T, X, Xvolatiles, fO2, partition coefficients) are encouraged. Research relying on elemental and isotopic geochemical, petrological, or experimental data connected to the geodynamic context are particularly welcome. Many of the elements of related deposits (e.g., REE, Sr, Nb, Ta, P) are considered as ‘critical metals’ by some governments. Although carbonatites and alkaline rocks are associated with the main REE-deposits on Earth, the origin and evolution of these magmatic/hydrothermal systems remain poorly constrained. This is partly due to their rare occurrence in active igneous systems, and to the lack of relation with geodynamic setting in most of the exhumed fossil systems. Nevertheless, through recent advances in igneous petrology, collaboration with exploration projects, and analytical developments, significant recent advances of our understanding of such systems have been achieved. This session offers an opportunity to discuss these new findings.
06e: Evolution of the continental crust and mantle lithosphere
Convenors: Roberta Rudnick (rudnick@geol.ucsb.edu), Nicholas Arndt nicholas.arndt@ujf-grenoble.fr), Sarah Brownlee (s.brownlee@eri.ucsb.edu)
This session invites contributions related to the composition and evolution of the continental crust and underlying mantle lithosphere. How and when did the continental crust and underlying lithospheric mantle form? Was growth continuous or episodic? Has the composition of the continental crust and mantle lithosphere changed over time? How different were Archean continents to those we have today and by what processes did they form? What is the relationship between the lithospheric mantle and overlying crust? We welcome contributions to the session from geochemists, petrologists, geophysicists and modelers.