Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/9499
AuthorsRooney, T. O.* 
Bastow, I. D.* 
Keir, D.* 
Mazzarini, F.* 
Movsesian, E.* 
Grosfils, E. B.* 
Zimbelman, J.* 
Ramsey, M. S.* 
Ayalew, D.* 
Yirgu, G.* 
TitleThe protracted development of focused magmatic intrusion during continental rifting
Issue Date2014
Series/Report no.6/33 (2014)
DOI10.1002/ 2013TC003514
URIhttp://hdl.handle.net/2122/9499
KeywordsPrecambrian lineaments control off-axis melt • Magmatic extension in Ethiopian rift is not ocean like • Magmatic belts at basins margins may not be seafloor spreading
Subject Classification04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics 
AbstractThe transition from mechanical thinning toward focused magmatic intrusion during continental rifting is poorly constrained; the tectonically active Main Ethiopian Rift (MER) provides an ideal study locale to address this issue. The presence of linear magmatic-tectonic belts in the relatively immature central MER may indicate that the transition from mechanical to magmatic rifting is more spatially distributed and temporally protracted than has previously been assumed. Here we examine lava geochemistry and vent distribution of a Pliocene-Quaternary linear magmatic chain along the western margin of the central MER—the Akaki Magmatic Zone. Our results show limited variability in parental magma that evolve in a complex polybaric fractionation system that has not changed significantly over the past 3 Ma. Our results suggest the following: (1) channeling of plume material and the localization of shear- or topography-induced porosity modulates melt intrusion into the continental lithosphere. (2) Pre-existing lithospheric structures may act as catalysts for intrusion of magmas into the lithospheric mantle. (3) The midcrustal to upper crustal strain regime dictates the surface orientation of volcanic vents. Therefore, although linear magmatic belts like those in the central MER may young progressively toward the rift axis and superficially resemble oceanic style magmatism, they actually represent prebreakup magmatism on continental crust. The oldest linear magmatic belts observed seismically and magnetically at the edge of the ocean basins thus may not, as is often assumed, actually mark the onset of seafloor spreading.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
tect20142.pdfMain Article10.73 MBAdobe PDFView/Open    Request a copy
Show full item record

Page view(s)

78
checked on Apr 23, 2017

Download(s)

20
checked on Apr 23, 2017

Google ScholarTM

Check

Altmetric