TY  - GEN
A1  - Bobos, Iuliu
A1  - Goncalves, Ana
A1  - Lima, Luis
A1  - Noronha, Fernando
A1  - Sudo, Masafumi
T1  - Micas Ar-40/Ar-39 dating of hydrothermal events related with the post-orogenic W (+/- Sn), (Cu, Mo) mineralization from Borralha, Northern Portugal
T2  - Life with Ore Deposits on Earth – 15th SGA Biennial Meeting 2019,
N2  - Secondary mica minerals collected from the Santa Helena (W- (Cu) mineralization) and Venise (W-Mo mineralization) endogenic breccia structures were Ar-40/Ar-39 dated. The muscovite Ar-40/Ar-39 data yielded 286.8 +/- 1.2 (+/- 1 sigma) Ma (samples 6Ha and 11Ha) which reflect the age of secondary muscovite formation probably from magmatic biotite or feldspar alteration. Sericite Ar-40/Ar-39 data yielded 280.9 +/- 1.2 (+/- 1 sigma) Ma to 279.0 +/- 1.1 (+/- 1 sigma) Ma (samples 6Hb and 11Hb) reflecting the age of greisen alteration (T similar to 300 degrees C) where the W- disseminated mineralization occurs. The muscovite 40Ar/39Ar data of 277.3 +/- 1.3 (+/- 1 sigma) Ma and 281.3 +/- 1.2 (+/- 1 sigma) Ma (samples 5 and 6) also reflect the age of muscovite (selvage) crystallized adjacent to molybdenite veins within the Venise breccia. Geochronological data obtained confirmed that the W mineralization at Santa Helena breccia is older than Mo-mineralization at Venise breccia. Also, the timing of hydrothermal circulation and the cooling history for the W-stage deposition was no longer than 7 Ma and 4 Ma for Mo-deposition.
Y1  - 2019
UR  - https://www.researchgate.net/publication/337901420_Micas_40_Ar_39_Ar_dating_of_hydrothermal_events_related_with_the_post-orogenic_W_Sn_Cu_Mo_mineralization_from_Borralha_Northern_Portugal
IS  - 1
SP  - 353
EP  - 356
PB  - SGA Soc Geology Applied mineral  depositis
CY  - Geneva
ER  -