Open AccessEvidence suggests slab melting in arc magmas
Author(s) -
Defant Marc J.,
Kepezhinskas Pavel
Publication year - 2001
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/01eo00038
Subject(s) - geology , andesites , eclogite , basalt , adakite , mantle wedge , subduction , geochemistry , slab , mantle (geology) , partial melting , island arc , crust , oceanic crust , petrology , andesite , volcanic rock , geophysics , seismology , volcano , tectonics
Most recent geology textbooks state that subduction‐related volcanism is due to the melting of the down‐going lithosphere. However, for the last 30 years, few in the field have seriously believed that the subducting slab is the source of arc basalts. The accepted hypothesis involves melting of the mantle wedge above the slab via hydrous fluids produced during the transition of the subducting basalt from amphibolite to eclogite. The parental basalts differentiate primarily through crystal fractionation, magma mixing, and differentiation at the Mohorovicic discontinuity into andesites and dacites as they ascend; the basalts are too dense to rise through the lower continental crust. This explains the relative abundance of differentiated rocks in arcs.