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Lateral magma flow in mafic sill complexes

Craig Magee, James D. Muirhead, Alex Karvelas, Simon P. Holford, Christopher A. L. Jackson, Ian D. Bastow, Nick Schofield, Carl T. E. Stevenson, Charlotte McLean, William McCarthy and Olga Shtukert
Lateral magma flow in mafic sill complexes
Geosphere (Boulder, CO) (June 2016) 12 (3): 809-841


The structure of upper crustal magma plumbing systems controls the distribution of volcanism and influences tectonic processes. However, delineating the structure and volume of plumbing systems is difficult because (1) active intrusion networks cannot be directly accessed; (2) field outcrops are commonly limited; and (3) geophysical data imaging the subsurface are restricted in areal extent and resolution. This has led to models involving the vertical transfer of magma via dikes, extending from a melt source to overlying reservoirs and eruption sites, being favored in the volcanic literature. However, while there is a wealth of evidence to support the occurrence of dike-dominated systems, we synthesize field- and seismic reflection-based observations and highlight that extensive lateral magma transport (as much as 4100 km) may occur within mafic sill complexes. Most of these mafic sill complexes occur in sedimentary basins (e.g., the Karoo Basin, South Africa), although some intrude crystalline continental crust (e.g., the Yilgarn craton, Australia), and consist of interconnected sills and inclined sheets. Sill complex emplacement is largely controlled by host-rock lithology and structure and the state of stress. We argue that plumbing systems need not be dominated by dikes and that magma can be transported within widespread sill complexes, promoting the development of volcanoes that do not overlie the melt source. However, the extent to which active volcanic systems and rifted margins are underlain by sill complexes remains poorly constrained, despite important implications for elucidating magmatic processes, melt volumes, and melt sources.

EISSN: 1553-040X
Serial Title: Geosphere (Boulder, CO)
Serial Volume: 12
Serial Issue: 3
Title: Lateral magma flow in mafic sill complexes
Affiliation: Imperial College London, Department of Earth Science and Engineering, London, United Kingdom
Pages: 809-841
Published: 201606
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 232
Accession Number: 2016-076727
Categories: Igneous and metamorphic petrologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 1 table, geol. sketch maps
Secondary Affiliation: University of Idaho, USA, United StatesSchlumberger Multiclient, GBR, United KingdomUniversity of Adelaide, AUS, AustraliaUniversity of Aberdeen, GBR, United KingdomUniversity of Birmingham, GBR, United KingdomUniversity of Glasgow, GBR, United KingdomUniversity of St Andrews, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201637
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