RT Journal Article
T1 Heterogeneous metasomatism in cumulate xenoliths from theSpanish Central System: implications for percolative fractionalcrystallization of lamprophyric melts
A1 Orejana García, David
A1 Villaseca González, Carlos
AB The alkaline lamprophyres and diabases from the Spanish Central System carry aheterogeneous suite of xenoliths including a group of highly altered ultramafic pyroxenites thatcontain Cr–Mg-rich high-T hydrous minerals (Ti-phlogopite and pargasitic to kaersutitic amphibole),indicative of modal metasomatism. The trace element mineral compositions of these xenolithsshow three patterns: type A xenoliths, with light rare earth element enriched clinopyroxeneswith high field strength element (HFSE) negative anomalies; type B xenoliths, with clinopyroxenesand amphiboles with high incompatible trace element contents (large ion lithophile elements(LILE), HFSE and REE); type C xenoliths, with relatively REE- and HFSE-poor clinopyroxenesand amphiboles. These metasomatic signatures suggest the involvement of three different metasomaticagents: carbonate, silicate and hydrous fluids or melts, respectively. These agents couldhave been derived from the progressive differentiation of a CO2–H2O-rich highly alkaline magma,genetically related to the Late Permian alkaline magmatism. Because of the original sub-alkalinenature of the pyroxenite xenoliths, theymight have been formed originally as pyroxene-rich cumulatesassociated with underplated Hercynian calc-alkaline basic magmas. Metasomatism as a result ofthe infiltration of alkalinemagmaswithin these cumulatesmight explain the relatively high radiogenicNd composition of the altered ultramafic xenoliths.
PB Geological Society of London
SN 0305-8719
YR 2008
FD 2008
LK https://hdl.handle.net/20.500.14352/49601
UL https://hdl.handle.net/20.500.14352/49601
LA eng
DS Docta Complutense
RD 22 abr 2025