Location: Yokohama, Japan
Web: http://goldschmidt.info/2016/index
Includes the following sessions:
05d Large Igneous Provinces Through Time: Their Origin and Economic/Environmental Impacts
Convenors: Yigang Xu (yigang.xu@gig.ac.cn), Ian Campbell (ian.campbell@anu.edu.au), Richard Ernst (richard.ernst@ernstgeosciences.com), Christina Yan Wang (wangyan2002@graduate.hku.hk)
Large igneous provinces (LIPs) consist of enormous, rapid outpourings of magmas at the surface, and/or layered mafic and ultramafic intrusions within the crust that may host important mineral deposits. LIPs involve the transfer of large amounts of heat and mass from Earth’s interior to its surface, and this can have a profound impact of Earth evolution. LIP processes include the release variable amounts of greenhouse gases and/or toxic volatiles into the atmosphere that may cause harmful damage to the biosphere, which can lead to mass extinctions. Significant progress has been made with respect to our understanding of LIP genesis and evolution, but important questions remain. This session welcomes multidisciplinary contributions to our understanding of the nature and evolution of LIPs through time including, but not limited to, magmatic processes, the origin of associated mineral deposits, volatile speciation and emission budgets, and the environmental impact of LIPs, including mass extinctions. The aim of the session is to provide better insights into mantle-lithosphere-atmosphere-biosphere interactions.
09b Links between Large Igneous Province Events and Metallogeny
Convenors: Simon Jowitt (simon.jowitt@monash.edu), Richard Ernst (richard.ernst@ernstgeosciences.com)
Large Igneous Provinces (LIPs) have been genetically linked with a wide variety of differing types of mineralisation, including the genesis of magmatic, hydrothermal and sedimentary deposits. In many cases carbonatites and kimberlites and their associated ore deposits are also associated with LIPs. World-class mineralised provinces related to LIPs, include the Noril'sk-Talnakh deposits associated with the Siberian Trap LIP, the Olympic Dam IOCG deposit with the Gawler Craton LIP, and the Guinea bauxite deposits with weathering of rocks of the CAMP LIP. Increasing our understanding of the fundamental links between LIP magmatism and the post-magmatic processes that affect LIP rocks is vital to not only ensure success in future mineral exploration but also to understand the impact of these processes on the wider environment (e.g. the impact of potentially mineralised LIP-related hydrothermal vent complexes on the atmosphere), especially given the known links between LIPs and extinction events. The links between LIP events and metallogeny represent significant but under-investigated geochemical systems that are deserving of further research. As such, we invite submissions from researchers working on any aspect of LIP-related metallogenesis, including orthomagmatic systems, hydrothermal systems, ore deposits associated with carbonatites and kimberites, and the weathering of LIP rocks, as well as from the wider LIP community. The aim of this session is to further our knowledge of geochemical cycling associated with LIP events, and how this geochemical cycling has changed throughout the geological record.
04g Do Basalts Accurately Sample Mantle Source Rocks? The Role of Lithologic Heterogeneity in the Sub-Oceanic Upper Mantle during Melt Generation at Ridges and Hot Spots
Convenors: Lynne Elkins (lelkins@brynmawr.edu), John Lassiter (lassiter1@jsg.utexas.edu)
Mid-ocean ridge and ocean island basalts display considerable geochemical heterogeneity. However, the degree to which variations in the isotopic and trace-element compositions of mantle-derived basalts track changes in the major element compositions and lithology of mantle source rocks is uncertain. Recent studies have called on a role for preferential melting of pyroxenite in mixed pyroxenite/peridotite mantle sources to explain geochemical variations in oceanic basalts. Isotope signatures in abyssal peridotites may further suggest the presence of ancient refractory components that are under-sampled during melt generation. However, the importance and length scales of mantle major element heterogeneities remains unclear. This session aims to explore the role of lithologic heterogeneity in the mantle during melt generation, the extent to which the melting process may generate a biased sampling of mantle sources, and the impact of such bias on estimates of mantle composition. We invite submissions that explore the nature of melt production at ridges, hotspots, and ridge-hotspot interaction settings and how those processes impact differential sampling of mantle heterogeneities over a range of length scales. Studies examining the origins of petrologic and geochemical variations in mantle xenoliths and abyssal mantle rocks, the nature of elemental and isotopic compositions of oceanic basalts, results of empirical analysis, or geochemical modeling outcomes are all welcome.