Loading...
Publication
Geochemistry of granitic aplite-pegmatite veins and sills and their minerals from the Sabugal area, central Portugal
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 262.52 KB | Adobe PDF |
Advisor(s)
Abstract(s)
Granitic beryl-columbite-phosphate subtype aplite-pegmatite veins and sills from the Sabugal area intruded a biotite >
muscovite granite which is related to another two-mica granite. Variation diagrams of major and trace elements of whole rocks
show fractionation trends. REE patterns and δ18O of whole rocks, BaO and P2O5 contents of K-feldspar, anorthite and P2O5 contents
of plagioclase, major element and Li contents of muscovite and lithian muscovite support this series. Least squares analysis of major
elements indicate that the biotite > muscovite granite and aplite-pegmatite veins and sills are derived from the earlier two-mica
granite magma by fractional crystallization of quartz, plagioclase, K-feldspar, biotite and ilmenite. Modelling of trace elements
shows that magmatic fl uxes and fl uids controlled the Rb, Sr and Ba contents of aplite-pegmatites, probably also lithium micas (zinnwaldite,
polylithionite and rare lepidolite), cassiterite, columbite-tantalite, fl uorapatite and triplite. In aplite-pegmatites, lithian
muscovite replaces primary muscovite and late lithium micas replace lithian muscovite. Complexely zoned columbite crystals are
chemically characterized and attributed to disequilibrium conditions. Relations of granites and aplite-pegmatites and pegmatites
from other Portuguese and Spanish areas are compared. The granitic aplite-pegmatites from Sabugal are moderately fractionated
and the granitic complex type aplite-pegmatites from Gonçalo are the richest in Li and Sn, derived from a higher degree of fractional
crystallization and fl uxes and fl uids control the Ba and Rb behaviours and Li, Sn, F and Ta concentrations.
Description
Keywords
Geoquímica Aplitos Pegmatito granítico Feldspatos Micas Columbite Tantalite Fosfatos Região do Sabugal (Portugal) Portugal (Centro)
Citation
Neiva, Ana M. R.; Silva, Paulo B., Ramos, João M. F. - Geochemistry of granitic aplite-pegmatite veins and sills and their minerals from the Sabugal area, central Portugal. In: Neues Jahrbuch für Mineralogie Abhandlungen, vol. 189. n.1 (Feb. 2012), p. 49-74