Dynamics of Igneous Plumbing Systems in Sedimentary Basins

Everybody is aware of volcanic eruptions, however, the mechanisms bringing magmas from the deep Earth interior to the surface through the so-called volcanic plumbing system remain unknown. For several decades, a dominant, widely established theory of magma propagation has been accepted by the volcanology community, and is now taken as granted. This theory assumes that magma propagate along simple fractures. Based on new outstanding geological observations and novel state-of-the-art physical models, we are now questioning the relevance of this theory. The fundamental scientific activity of the DIPS project consisted of ambitious and adventurous field expeditions in the Neuquén Basin, in the Northern Patagonian Andes of Argentina. There, the desert climate combined with the Andean reliefs offer spectacular exposures of ancient volcanic plumbing systems. We combined direct field observations and drone surveys to reconstruct the structures of entirely exposed volcanoes, where their interiors are nicely exposed. Thanks to new technologies, we are able to compute impressive 3-dimensional virtual models of the studied localities, which push forward our level of understanding. The limitation of field observations is that the studied systems are frozen, i.e. immobile. It is therefore challenging to feel how the observed systems evolved through time. To overcome this, we designed state-of-the-art laboratory and computer models that simulate the formation of volcano plumbing systems. For the first time, our models are able to reproduce the complex diversity of the natural features associated with volcanic plumbing systems observed in the field. Our models thus prove promising to bring our understanding of the dynamics of volcano plumbing systems to a new, unprecedented level.

- Scientific publications: the project activities lead to numerous scientific publications in international journals. Numerous other manuscripts are in preparation, in review or in revision. The impact in the scientific community will thus be tremendous. - New theory of magma emplacement: before the project, there were established theories for magma emplacement in Earth crust. The project activities questioned this theory and proposed a new one. This new theory lead to new collaborations with international volcanology experts in Iceland, among others, and to writing an invited manuscript. - Petroleum industry: the last decade of research has highlighted that volcanic plumbing systems potentially have tremendous impacts (negative or positive) on hydrocarbon systems. Through the project activities, we developed collaborations and partnerships with several oil companies, among others Equinor, YPF (national Argentinian oil company), Chevron, ROCH S.A. (small Argentinian company).

Volcanism represents fundamental forces contributing to heat and mass transfer through the Earth crust. Field and geophysical data in many sedimentary basins worldwide have shown that volcanism is linked with extensive sub-volcanic networks. These igneous plumbing systems (IPS) in sedimentary basins have tremendous implications on (1) the gas flux for the volcanic system feeding the climate system, (2) the maturation, circulation and trapping of hydrocarbons, (3) the location and violence of volcanic eruptions, and (4) the formation of massive ore deposits. Although IPS in sedimentary basins have been widely studied, first-order aspects of their emplacement dynamics are still not understood: (1) there is no unified mechanical model explaining and predicting the formation of the numerous igneous conduit shapes (e.g. dikes, sills, laccoliths, plugs, etc); (2) most existing models of magma emplacement only account for elastic host rocks, whereas geological observations show that substantial plastic and viscous deformation in the host rocks accommodates magma emplacement; (3) most models ignore the magma dynamics, whereas the role of magma viscosity is evident. In order to considerably expand our understanding of the dynamics of IPS in sedimentary basins, we propose a multidisciplinary project that (1) integrates quantitative fieldwork using state-of-the-art ground-based and aerial photogrammetric outcrop 3D modeling in an outstanding volcanic basin case study, (2) frontier quantitative laboratory experiments using the latest technical developments at UiO, (3) numerical modeling using Discrete Element Models (DEM) and (4) elasto-plastic theoretical modeling. This project has the ambition to develop a new generation of mechanical model of magma emplacement in sedimentary basins that realistically accounts for the complexity of geological systems.