Assessing SPO techniques to constrain magma flow: Examples from sills of the Karoo Igneous Province, South Africa

Hoyer, L.; Watkeys, M. K.

doi:10.1016/j.tecto.2015.06.006

Cited by 4 publications

(1 citation statement)

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“…Such mineral alignment analyses have shown that the long axes of intrusive steps, bridge structures, and magma fingers, which are commonly super imposed onto the larger scale sheet intrusion morphology, correlate to the primary magma flow axis ( Fig. 4; e.g., Airoldi et al, 2012;Magee et al, 2012a;Schofield et al, 2012a;Hoyer and Watkeys, 2015). These flow indicators form because sheet intrusions typically do not initially intrude as continuous bodies of magma ( Fig.…”

Section: Constraining Magma Flow Patterns In Outcrop and Seismic Datamentioning

confidence: 98%

Lateral Magma Flow in Mafic Sill‐complexes

Magee

Muirhead

Karvelas

et al. 2016

Acta Geologica Sinica (Eng)

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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.

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Section: Constraining Magma Flow Patterns In Outcrop and Seismic Datamentioning

confidence: 98%