Emplacement mechanisms and magma flow in sheet intrusions in sedmentary basins

Extensive magmatic sill and dike complexes are commonly present in sedimentary basins, e.g., the Vøring and Møre basins offshore mid-Norway and the Karoo basin in South Africa.The intrusive processes and deposits may have major impacts on the basin develo pment, petroleum geology, and groundwater circulation in such basins. However, the intrusive processes are not very well understood. The proposed multi-disciplinary project will combine detailed fieldwork in the Karoo basin with Anisotropy of Magnetic Susceptibility (AMS), palaeomagnetic, and geochemical analyses as well as analogue and numerical modeling. This integrated approach will enable us to reconstruct magma flow geometries within the igneous bodies, to indentify and isolate the parameters that control the initiation and growth of the intrusive complex, and to develop a dynamic model for the magma emplacement. We will in particular investigate (1) why sills commonly have a saucer-shaped geometry, and (2) how very long (100's of km) dikes are emplaced, in particular if the emplacement is dominantly lateral or vertical flow. The dike data will further be used to test the mantle plume hypothesis for the break-up of Gondwana.