10.6084/m9.figshare.3453632.v1 Emanuele Roni Emanuele Roni David Scott Westerman David Scott Westerman Andrea Dini Andrea Dini Carl Stevenson Carl Stevenson Sergio Rocchi Sergio Rocchi Feeding and growth of a dyke–laccolith system (Elba Island, Italy) from AMS and mineral fabric data Geological Society of London 2016 flow paths laccolith layers results show Strong correlation AMS data feeder dykes field relationships magma displacement direction subhorizontal intrusions Elba Island flow pathways tabular particles magma flow aid interpretation mineral fabric data Dykes feed laccoliths coalescing pulses magma spread laterally felsic San Martino laccolith displays magma flow pathways influence AMS results sanidine megacrysts feeder dyke Geology 2016-06-21 11:34:09 Journal contribution https://geolsoc.figshare.com/articles/journal_contribution/Feeding_and_growth_of_a_dyke_laccolith_system_Elba_Island_Italy_from_AMS_and_mineral_fabric_data/3453632 <p>Dykes feed laccoliths and sills; however, the link between feeder and intrusion is rarely observed. The felsic San Martino laccolith displays a clear feeder–intrusion link, allowing reconstruction of the influence of the size and location of feeder dykes on magma flow during formation of subhorizontal intrusions. This work uses anisotropy of magnetic susceptibility (AMS) combined with mineral shape-preferred orientations of sanidine megacrysts to examine magma flow pathways through feeders into a laccolith. Strong correlation between AMS and K-feldspar datasets indicates that alteration affecting the paramagnetic mineralogy did not influence AMS results. The well-established field relationships between feeder and laccolith provided a robust ‘geo-logical’ model for flow pathways that we have used as a framework to aid interpretation of AMS data. The position and size of the main feeder dyke helped to predict the flow paths in the overlying laccolith. Our results show that magma spread laterally from the feeding system and built the laccolith layers with propagating and inflating divergent flow where tabular particles became aligned perpendicular to the magma displacement direction. The lack of internal discontinuities indicates that the magma was injected as a single pulse or a series of quickly coalescing pulses. </p>