Publication: Melts and Residua Geochemistry in a Low-To-Mid Crustal Section (Central Spain)
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Publication Date
2001
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Elsevier Sciences Ltd.
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Abstract
Granulite terranes from Central Spain are
Hercynian anatectic areas of mid-crustal levels (P-T
conditions: 750-800 ° C and 4-6 kb), The granulite xenolith
suite of the same sector comes from the lower crust as
deduced from their P-T estimates (850-950 ° C and 8-11 kb).
Chemical differences between granulites from terranes and
those from xenoliths are less marked in Central Spain than
in other places as this xenolith suite lack mafic lithologies.
Granulitic xenoliths show U and Rb depletion, and
occasionally a subtle enrichment in Ba, Fe, Mg, Ti, (V) and
HREE. Contents in Zr, Th, Y, and REE in both granulite
types might be explained as a consequence of the minor
role of accessory phases in controlling the geochemistry of
the residual rocks in the lower crust. Migmatitic
leucosomes and other felsic anatectic melts show the same
trend of Rb and K enrichment and Fe, Mg, Ti, Cr, Ni, V
and Th, Y, Zr, Nb, REE impoverishment (compared to
protoliths) than granitic plutons. Although plutonic granites
show higher Ca (Na), Fe and Mg contents a genetic link
with anatectic melts is suggested. Isotopic differences (Sr,
O) between granitic plutons and anatectic melts might be a
reflection of their derivation from a different crustal level in
an isotopically stratified crust.