Magma transport pathways in large igneous provinces: Lessons from combining field observations and seismic reflection data

Abstract

Large Igneous Province (LIP) formation involves the generation, intrusion, and extrusion of significant volumes (typically > 1 Mkm3) of mainly mafic magma and is commonly associated with episodes of mantle plume activity and major plate reconfiguration. Within LIPs, magma transport through Earth’s crust over significant vertical (up to tens of kilometres) and lateral (up to thousands of kilometres) distances is facilitated by dyke swarms and sill-complexes. Unravelling how these dyke swarms and sill-complexes develop is critical to: (i) evaluating the spatial and temporal distribution of contemporaneous volcanism and hydrothermal venting, which can drive climate change; (ii) determining melt source regions and volume estimates, which shed light on the mantle processes driving LIP formation; and (iii) assessing the location and form of associated economic ore deposits. Here, we review how seismic reflection data can be used to study the structure and emplacement of sill-complexes and dyke swarms. We particularly show that seismic reflection data can reveal: (i) the connectivity of and magma flow pathways within extensive sill-complexes; (ii) how sill-complexes are spatially accommodated; (iii) changes in the vertical structure of dyke swarms; and (iv) how dyke-induced normal faults and pit chain craters can be used to locate sub-vertical dykes offshore.