33rd International Geological Congress

Start Date: 
Wednesday, August 6, 2008
End Date: 
Thursday, August 14, 2008

Location: Oslo, Norway

Web: http://www.33igc.org/coco

Includes the following sessions:

Session MPI-04 Mafic dyke swarms: a global perspective

Convenors: R. Srivastava (rajeshgeolbhu@gmail.com), W. Bleeker (wbleeker@nrcan.gc.ca), R. Ernst (richard.ernst@ernstgeosciences.com)

Because of great depth and lateral extent, mafic dyke swarms provide the most complete record of short-lived, mantle-generated magmatic events through time and space. Our increasing ability to date mafic dyke rocks precisely has greatly enhanced their importance as high-resolution markers in time. Collectively, the record of mafic dyke swarms provides information on “the pulse of the Earth” - that is, the rhythm of mantle melting events through time, from minor rift-related events, to the largest known igneous events (LIPs) on the planet extruding millions of km3 of basaltic melt over short intervals of time (<1 my). Linked with precise ages, mafic dykes swarms become an unparalleled source of diverse and high-quality information: on tectonics and secular evolution, age and location of igneous centres, palaeostress directions, strain gradients, key palaeomagnetic poles, palaeo-intensities of the core dynamo, plume frequency, mantle sources, and much more. Successive short-lived dyke events define “bar codes” that identify a piece of crust and its original “nearest neighbours”. Thus they are the key to palaeogeographic reconstructions. “Bar coding” the geological record will allow, in principle, a full reconstruction of Earth’s palaeogeography, back to ca. 2.6 Ga. This session will bring together all those interested in these and other aspects of mafic dyke swarms.

Session MPI-05 Large Igneous Provinces: initiation, evolution and origin

Convenors: L. Vierect-Goette (Lothar.Viereck-Goette@uni-jena.de), S. Planke (planke@vbpr.no)

The events during initiation of some mafic Large Igneous Provinces (North Atlantic, Ferrar, and Karoo Igneous Province) were studied recently, with spectacular results and new (?) concepts. In all cases we see that early emplacement occurred as sills in a shallow crustal environment with abundant magma-wet sediment interaction and diatreme formation. However, this initial character may be due to the local geology of young unconsolidated sediments overlying crystalline basement. We can neither identify an initial phase of small volume magma emplacement, nor a regular early involvement of molten continental crust. In the Ferrar Province, we recognize that the magmas belong to the tholeiitic differentiation series with the early intrusive andesitic magmas being more evolved than the later plateau forming basaltic andesitic lavas. Which of these observations are of general relevance for LIP formation and are crucial pieces in the big puzzle? How are Silicic Large Igneous Provinces initiated, do they start with a mafic initial phase? We invite any geoscientist working on the topic of initiation of mafic or silicic LIP to present his/her new data from other LIPs on earth in order to gain a more precise understanding of the early processes during production, evolution and emplacement of such catastrophic volumes of magma.

Session MPE-02 Experimental petrology and the generation of plume magmas

Convenors: G. Sen (seng@fiu.edu), C. Hieronymus (christoph.hieronymus@geo.uu.se)

Mantle plumes are believed to be the underlying cause of hotspot volcanism. Wherever plumes originate, there is broad agreement that they sample a volume of the mantle that is distinct from the shallow source region of passively spreading mid-ocean ridges. The aim of petrology research of plume melting is to constrain the pressure and temperature conditions of melting and the source composition in order to improve our understanding of plumes and the evolution and dynamics of the mantle. The mantle is made up of various components, including remnant primordial mantle, depleted mantle formed as the residue of continental differentiation, subducted oceanic crust and lithosphere, and smaller volumes of sediments and continental lithosphere. Which of these reservoirs are present in the plumes, and to what degree are they represented in the melts? Do different plumes sample different reservoirs, or do the varying chemical signatures of plumes derive from differences in the melting dynamics? Are heterogeneities spread out randomly as blobs or filaments, are they stretched out as strings along the conduit, or are plumes radially or laterally zoned? Can the spatial and secular variability of plume lavas help determine the pattern of plume heterogeneity? We invite all contributions that apply petrology to melting at hotspots, but encourage a focus on the global perspective. We also welcome petrological evaluations of alternatives to the plume hypothesis.

Session MPV-03 Flood basalt volcanism and stratigraphy

Convenors: T. Thordarson (thor.thordarson@ed.ac.uk), D. Haldar (haldar2115@yahoo.co.uk)

Over the last two decades stratigraphic and volcanological research has revolutionised our views of LIP construction and the mechanisms of the eruption that are responsible for their formation. The purpose of this symposium is to bring together research that sheds light on shallow subsurface and surface processes involved in construction of flood basalt provinces of all ages as well as their potential climatic and environmental impacts. The symposium will focus on the following areas of research: upper crustal plumbing systems of LIPs; geochronology of flood basalt successions; volcanic, petrochemical and palaeomagnetic stratigraphy of LIPs; eruption styles, mechanisms and lava emplacement modes at LIPs; gas fluxes from flood basalt eruptions; potential climatic and environmental impacts of flood basalt eruptions and the link to mass extinctions.

Session EUR-08 North Atlantic Igneous Province stripped: origin, magmatic activity, crustal processes and plate kinematics

Convenors: M. Ganerød (morgan.ganerod@ngu.no), S. Rousse (sonia.rousse@ngu.no), W. Roest (walter.roest@ifremer.fr)

The North Atlantic Igneous Province (NAIP) which includes the UK, Ireland, the Faeroes, Greenland and the West Greenland-Baffin corridor is one of several well-known Large Igneous Provinces (LIP) temporally correlated with continental break-up. The NAIP likely owes its origin to the Iceland plume and broadly corresponds in time to the initiation of seafloor spreading in the NE Atlantic. It is also believed to have triggered global climate changes, with knock-on effects for the biosphere and sedimentary facies. In the last few decades, the Atlantic-Arctic margin has received much attention, partly as a result of hydrocarbon exploration, leading to a rapidly expanding, onshore and offshore geological and geophysical data set. This provides a unique setting to derive new insights into causal links between timing and style of magma emplacement, crustal processes, plume arrival, plate kinematics, uplift, subsidence and the evolution of sedimentary basins. In this session we aim to paint a more comprehensive picture of the NAIP, the complex thermal history of the North Atlantic region and its role in shaping the North Atlantic geology. We welcome contributions from all disciplines that will further and challenge our knowledge of the Mid-Cretaceous to present North Atlantic magmatism, its causes before, during and after continental break-up.

Oslo, Norway