LA-ICP-MS U Pb columbite ages and trace-element signature from rare-element granitic pegmatites of the Pampean Pegmatite Province, Argentina

Age and petrogenesis of the beryl-bearing granitic magmatism of the Velasco Pegmatite District, Pampeana Province, NW Argentina

“…Since this body has a similar composition and structure to the other beryl mineralized pegmatites of the Velasco district, the age obtained may be proposed for the whole district. The results are very close to the 'T 2 ages' (370-340 Ma) obtained by Galliski et al (2021) for post-orogenic pegmatites of the PPP with lithium-cesium-tantalum (LCT), niobium-yttrium-fluorine (NYF) or mixed NYF-LCT signatures. According to these authors, these post-orogenic pegmatites show chemical and geochronological features compatible with the A-type parental monzogranites, a similar framework defined for the Early Carboniferous intrusive rocks of the Velasco mountain range.…”

“…Furthermore, the author introduces the designation of 'orogenic pegmatitic fields or districts' for those developed during the Lower Paleozoic, but mainly during Early and Middle Ordovician age -Famatinian orogenic cycle -and 'post-orogenic pegmatitic fields or districts' to those genetically related to parental granites of Upper Devonian/Lower Carboniferous age -generically called ' Achalian' magmatic event. Recently, Galliski et al (2021) determined columbite U/Pb ages from several pegmatites of the PPP. The obtained ages define two clear periods: one between 490 and 440 Ma (T 1 ), corresponding to 75% of the LCT Rare-Elements pegmatites formed during the Famatinian orogeny, and the other between 370 and 340 Ma (T 2 ), comprising post-orogenic LCT and NYF (or mixed) pegmatitic signatures.…”

The Li-Bearing Pegmatites from the Pampean Pegmatite Province, Argentina: Metallogenesis and Resources

“…Two K-Ar muscovite ages give values of 564 ± 25 Ma for Santa Elena and 545 ± 15 Ma for Tres Tetas pegmatites [14]. The recently obtained Laser Ablation-Inductively Coupled Plasma-Mass Spectrosmetry (LA-ICP-MS) columbite ages give values between 529.9 ± 11.5 and 485.2 ± 7.5 Ma [40]. The pegmatites were only mined in the last century by CGM and bismuth, producing about 10 and 5 t of ore concentrates, with grades over 40% Ta 2 O 5 and 50% Bi, respectively.…”

“…Two K-Ar muscovite ages for Ipizca II and Santa Gertrudis presented values of 445 ± 17 and 709 ± 34 Ma [42]. A LA-ICP-MS columbite age for the beryl-type San Isidro pegmatite located in the same group gave an average value of 486 ± 5.9 Ma [40].…”

“…In one individual pegmatite, the spodumene can be evenly distributed along the dikes (Cabeza de Novillo) or concentrated in a specific portion (e.g., the southern part of Las Cuevas). Ages of these pegmatites are variable; old K-Ar data on muscovite give values between 536 ± 27 to 413 ± 7 Ma [42] and recent LA-ICP-MS columbite data of CGM range from 512.6 ± 10.6 to 454.6 ± 4.2 Ma [40]. Most of the pegmatites were worked in quarries by open pit cuts, except some with small subsurface works (Géminis, Las Cuevas, Cabeza de Novillo), and the spodumene was manually concentrated.…”