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Age of oceanic plates at subduction and volatile recycling
Author(s) -
Abbott Dallas,
Lyle Mitchell
Publication year - 1984
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl011i010p00951
Subject(s) - geology , subduction , asthenosphere , lithosphere , trench , oceanic crust , slab , plate tectonics , convergent boundary , geochemistry , seismology , geophysics , tectonics , layer (electronics) , chemistry , organic chemistry
The age of the subducting plate as it enters the trench controls the maximum depth of volatile transport by the downgoing plate. As the slab descends and heats up, decarbonation and dehydration reactions cause alteration minerals and sediments to release volatiles. Our calculations show that subducting oceanic plates <11 m.y. old in oceanic arcs and <34 m.y. old in continental arcs heat up so rapidly that no H 2 O or CO 2 can return to the asthenosphere. Instead, these volatiles rise into the over‐riding lithospheric plate. CO 2 and H 2 O are released differently during subduction. A thickly‐sedimented plate subducting beneath an oceanic arc will return H 2 O to the asthenosphere only if the subducting plate is older than 11 m.y. and CO 2 only if it is older than 25 m.y. If Archaean oceanic lithosphere had a maximum age of 30‐50 m.y. and an average age of 10‐18 m.y., then the amount of volatile recycling to the asthenosphere could have been much lower than at present, despite a greater total consumption rate.