The A-type Mount Scott Granite Sheet: Importance of Crustal Magma Traps
The presence of rapakivi feldspar and of distinctive porphyritic texture of Mount Scott Granite indicates a period of crystallization prior to final emplacement beneath an extensive penecontemporaneous rhyolite volcanic pile provides pressure estimates which are interpreted as plumbing the depth of a temporary storage chamber at ~ 7-8 km. Based on magmastatic calculations, it is suggested that horizontal anisotropies become crustal magma traps where the magma driving pressure exceeds the lithostatic load when the anisotropy is encountered. During rifting, initial large influxes of magma may proceed passed crustal anisotropies but have the effect of increasing the relative magma driving pressure through reducing horizontal stress. Thus, magma driving pressure may eventually exceed the lithostatic load at the depth of the brittle-ductile transition thereby activating this crustal magma trap.
J. P. Hogan and M. C. Gilbert, "The A-type Mount Scott Granite Sheet: Importance of Crustal Magma Traps," Journal of Geophysical Research, vol. 100, no. B8, pp. 15779-15792, Wiley-Blackwell, Aug 1995.
The definitive version is available at http://dx.doi.org/10.1029/94JB03258
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Brittle/ductile Transition; Granite; Magma Ascent; Magma Trap; Petrogenesis
International Standard Serial Number (ISSN)
Article - Journal
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