Lower crustal reflectivity modeled by rheological constraints on basaltic intrusions

Details

Serval ID
serval:BIB_77653A1F2A9F
Type
Article: article from journal or magazin.
Collection
Publications
Title
Lower crustal reflectivity modeled by rheological constraints on basaltic intrusions
Journal
Geology
Author(s)
Holliger K., Levander A.
ISSN-L
0091-7613
Publication state
Published
Issued date
1994
Peer-reviewed
Oui
Volume
22
Pages
367-370
Language
english
Abstract
Orogenic collapse, lithospheric extension, and associated basaltic
magmatism have affected many Phanerozoic regions. This has led to
the hypothesis that the high lower crustal reflectivity of these
areas originates from horizontal mafic dikes embedded in a more felsic
matrix. Tectonic extension, however, favors the intrusion of unreflective
vertical dikes. Stress distribution in an extending lithosphere varies
over several orders of magnitude, which explains the simultaneous
intrusion of vertical and horizontal dikes. Vertical dikes penetrate
rheologically strong zones and transform into horizontal dikes in
weak zones where stress conditions are quasi-isostatic and a subhorizontal
strain fabric is likely to exist. The seismic response of a corresponding
crustal model faithfully reproduces banded reflectivity patterns
typical of extended provinces. Because the loci of mechanical weakness
vary with temperature, composition, and fluid content, other common
reflectivity patterns can be explained similarly. This combination
of two prominent end-member models on the origin of lower crustal
reflections (i.e., ductile flow and mafic intrusions) is compatible
with pertinent features associated with postorogenic lithospheric
extension, such as high heat flow, bimodal volcanism, anatectic granites,
granulite-facies metamorphism, and uniform crustal thickness.
Keywords
CONTINENTAL-CRUST, UNITED-STATES, RANGE PROVINCE, SHEAR ZONES, BASIN, PLATEAU, STRESS, DIKES, MAGMA, ROCKS
Create date
25/11/2013 19:28
Last modification date
20/08/2019 15:34
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