Petrography and whole-rock geochemistry of vaugnerites from NW Portugal (Central Iberian Zone)

• Type: Article in International Conference Proceedings Book
• Date: 2020

Authors

Oliveira, A (Author) Other; H. C. B. Martins (Author) FCUP; Noronha, F (Author) FCUP

Conference proceedings International

Title: International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM

Pages: 229-236

20th International Multidisciplinary Scientific Geoconference: Science and Technologies in Geology, Exploration and Mining, SGEM 2020

18 August 2020 through 24 August 2020

Indexing

Scopus - 0 Citations

Scientific classification

CORDIS: Natural sciences

FOS: Natural sciences

Other information

Authenticus ID: P-00T-CZ0

DOI: 10.5593/sgem2020/1.1/s01.029

Abstract (EN): In the portuguese section of the Central Iberian Zone, the Guimarães region hosts a wide diversity of plutonic variscan lithologies including biotite-rich granitoids and vaugnerites. Vaugnerite outcrops occur as small bodies, typically enclosed by the main regional granite (the coarse-grained, biotite-rich, porphyritic Guimarães and Santo Tirso monzogranite). Mafic enclaves of vaugnerites can also be identified in the host granite. The granitoids are peraluminous (ASI = 1.10 - 1.15), having crystallized from melts generated at deep crustal levels, and they derived from the partial melting of metaigneous rocks and/or metagreywackes with some minor mantle contamination. On the other hand, the vaugnerites are metaluminous (ASI = 0.79 - 0.85), they were generated from sources of higher temperature and with a more basic composition (i.e. mantle-derived), and their mineral assemblage presents biotite + plagioclase + orthopyroxene + clinopyroxene + hornblende ± allanite ± titanite ± zircon. Due to their low contents in K2O (3.50 - 3.68 wt%), these mafic rocks should be considered redwitzites or K-poor vaugnerites. Both petrographic analysis and whole-rock geochemistry point to the lack of a genetic relationship between vaugnerites and granitoids of the Guimarães region.

Language: English

Type (Professor's evaluation): Scientific