Experimental evidence for high-temperature felsic melts formed during basaltic intrusion of the deep crust

Basaltic intrusion into the continental crust was simulated with melting experiments on layered charges of high-alumina olivine tholeiite (HAOT) and metapelite, at 11 kbar. Rapid diffusion of CaO and Na2O into the metapelite and H2O, K2O, SiO2, and Al2O3 into the basalt resulted in spectacular chang...

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Bibliographic Details
Published in:Geology (Boulder) 1997-05, Vol.25 (5), p.463-466
Main Authors: McCarthy, T. C, Patiño Douce, Alberto E
Format: Article
Language:English
Subjects:
acidic magmas
basaltic composition
basalts
continental crust
crust
crystal growth
experimental studies
Experiments
felsic composition
garnet group
Geology
geophysics
high pressure
high temperature
igneous and metamorphic rocks
igneous rocks
intrusions
lower crust
magmas
megacrysts
melting
melts
metamorphic rocks
metapelite
metasedimentary rocks
mineral properties
nesosilicates
olivine tholeiite
orthosilicates
P-T conditions
Petrology
pressure
silicates
simulation
temperature
volcanic rocks
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Summary:Basaltic intrusion into the continental crust was simulated with melting experiments on layered charges of high-alumina olivine tholeiite (HAOT) and metapelite, at 11 kbar. Rapid diffusion of CaO and Na2O into the metapelite and H2O, K2O, SiO2, and Al2O3 into the basalt resulted in spectacular changes in the phase assemblage. Garnet megacrysts crystallized profusely across the basalt layer, cumulate assemblages closely resembled rocks found in underplating localities, and glass compositions graded from dacite to rhyolite, even at temperatures as high as 1150°C. Silicic melts can be generated during interaction of basalt with metapelite, at temperatures well above the H2O-saturated granite minimum. Calculations based on these results and comparison with natural occurrences suggest that high-temperature felsic melts with >4 wt% H2O can form and segregate at rates of ∼1 cm/yr.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1997)025<0463:EEFHTF>2.3.CO;2