27 research outputs found
Tourmaline occurrences within the Penamacor-Monsanto granitic pluton and host-rocks (Central Portugal): genetic implications of crystal-chemical and isotopic features
Viscous dissipation pattern in incompressible Newtonian simple shear zones: an analytical model
Large calcite and bulk-rock volume loss in metacarbonate xenoliths from the Qu,rigut massif (French Pyrenees)
Chemical mass transfer was quantified in a metacarbonate xenolith
enclosed within the granodiorite of the Qu,rigut massif (Pyrenees,
France). Mass balance calculations suggest a strong decrease of CaO, SrO
and CO(2) contents (up to -90%), correlated with a decrease of modal
calcite content as the contact is approached. Most other chemical
elements behave immobile during metasomatism. They are therefore
passively enriched. Only a small increase of SiO(2), Al(2)O(3) and
Fe(2)O(3) contents occurs in the immediate vicinity of the contact.
Hence, in this study, skarn formation is characterized by the lack of
large chemical element influx from the granitoid protolith. A large
decrease of the initial carbonate volume (up to -86%) resulted from a
combination of decarbonation reactions and loss of CaO and CO(2). The
resulting volume change has potentially important consequences for the
interpretation of stable isotope profiles: the isotope alteration could
have occured over greater distances than those observed today