HR: 0800h
AN: V11A-0364    [Abstracts]
TI: Dome Structures Above Sills and Saucer-Shaped Sills: Insights From Experimental Modeling
AU: Planke, S
EM: planke@vbpr.no
AF: Physics of Geological Processes, University of Oslo, Sem Selands vei 24, Oslo, NO-0316, Norway
AU: Planke, S
EM: planke@vbpr.no
AF: Volcanic Basin Petroleum Research, Gaustadalléen 21, Oslo, N-0349, Norway
AU: * Galland, O
EM: olivier.galland@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, Sem Selands vei 24, Oslo, NO-0316, Norway
AU: Malthe-Sørenssen, A
EM: malthe@fys.uio.no
AF: Physics of Geological Processes, University of Oslo, Sem Selands vei 24, Oslo, NO-0316, Norway
AB: Saucer-shaped magma and sand intrusions are common features in sedimentary basins. They result from fundamental processes for the emplacement of fluids in shallow sedimentary basins. Seismic data show that the overburden above saucer-shaped intrusions is usually deformed and exhibits a dome-like structure. The formation of such structures, and the associated deformation, are of primary importance in the evolution of petroleum systems. In this presentation, we report on experimental investigation of the deformation processes associated with the intrusion of saucer-shaped intrusions into sedimentary basins. The experimental setup consists of molten low-viscosity oil injected into fine-grained silica flour (see Galland et al., this session). It properly simulates the emplacement of saucer-shaped intrusions and the deformation of the country rock. During experiments, the surface of the model is digitalized through a structured light technique based on moiré projection principle. Such a tool provides topographic maps of the model and allows a periodic (every 1.5 s) monitoring of the model surface. When the model magma starts intruding, a symetrical dome rises above the inlet. As injection proceeds, the dome inflates and widens. Subsequently, the dome evolves to a plateau-like feature, with nearly flat surface and steep edges. The plateau keeps lifting up, but nearly stoppes widening. At the end of the experiments, the intruding liquid erupts at the edge of the plateau. The intrusion formed in the experiment is a typical saucer-shaped sill. The evolution of the deforming surface reflects the evolution of the intrusion. We infer that the first doming phase corresponds to the emplacement of a horizontal basal sill by open fracturing. The dome-to-plateau transition corresponds to a transition of the liquid emplacement mechanism from basal sill to inclined sheet. We suggest that the emplacement of the inclined sheets results from shear fracturing at the dome edge.
DE: 8020 Mechanics, theory, and modeling
DE: 8145 Physics of magma and magma bodies
DE: 8445 Experimental volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting