Detalhes do Documento

Geochemistry of cassiterite and wolframite from tin and tungsten quartz veins i...

Data: 2008

Identificador Persistente: http://hdl.handle.net/10316/3927

Origem: Estudo Geral - Universidade de Coimbra

Assunto(s): Cassiterite; Columbite; Ixiolite; Wolframite; Portugal; Ore-forming fluids

Descrição
Cassiterite and wolframite compositions from Sn > W- and W > Sn-bearing quartz veins in Northern and Central Portugal are compared to provide evidence on fluid compositions. In Sn > W-bearing quartz veins, euhedral cassiterite shows sequences of alternating parallel darker and lighter zones. The darker zones are pleochroic, oscillatory zoned, exhibit exsolutions of columbite and ixiolite and are richer in Nb, Ta and Fe than the lighter zones which consist of nearly pure SnO2. Cassiterite from W > Sn-bearing quartz veins is usually zoned, with homogeneous and slightly pleochroic darker zones, which are chemically similar to lighter zones. Both zones have inclusions of rutile and rare ilmenite. The darker zones of cassiterite from the former veins are richer in Nb, Ta and Fe contents and poorer in Ti than the darker and lighter zones of cassiterite from the latter veins. This is attributed to differences in the composition of magmatic hydrothermal fluids. http://www.sciencedirect.com/science/article/B6V90-4PTMXMG-1/1/e922fe6d2d51481adff0c1b69e60236b

Tipo de Documento Artigo
Idioma Inglês