Details

Autor(en) / Beteiligte

• Dahlquist, Juan A.
• Pankhurst, Robert J.
• Rapela, Carlos W.
• Basei, Miguel A. S.
• Alasino, Pablo H.
• Saavedra, Julio
• Baldo, Edgardo G.
• Murra, Juan A.
• da Costa Campos Neto, Mario

Titel

The Capilla del Monte pluton, Sierras de Córdoba, Argentina: the easternmost Early Carboniferous magmatism in the pre-Andean SW Gondwana margin

Ist Teil von

• International journal of earth sciences : Geologische Rundschau, 2016-07, Vol.105 (5), p.1287-1305

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• New geochronological, geochemical, and isotopic data are reported for the Capilla del Monte two-mica granite pluton in the northeastern Sierras de Córdoba. An Early Carboniferous age is established by a U–Pb zircon concordia (336 ± 3 Ma) and a Rb–Sr whole-rock isochron (337 ± 2 Ma). Zircon saturation geothermometry indicates relatively high temperatures (735–800 °C). The granites have high average SiO 2 (74.2 %), Na 2 O + K 2 O (7.8 %), and high field-strength elements, high K 2 O/Na 2 O (1.7) and FeO/MgO ratios (5.1), with low CaO content (0.71 %). REE patterns with marked negative Eu anomalies (Eu/Eu* 0.14–0.56) indicate crystal fractionation, dominantly of plagioclase and K-feldspar, from a peraluminous magma enriched in F. Isotope data ( 87 Sr/ 86 Sr initial  = 0.7086, ε Nd336  = −5.5 to −4.4 with T DM  = 1.5 Ga, zircon ε Hf336 +0.8 to −6.1; mean T DM  = 1.5 Ga) suggest a Mesoproterozoic continental source, albeit with some younger or more juvenile material indicated by the Hf data. The pluton is the easternmost member of a Carboniferous A-type magmatic suite which shows an increase in juvenile input toward the west in this part of the pre-Andean margin. The petrological and geochemical data strongly suggest a similar intraplate geodynamic setting to that of the nearby but much larger, Late Devonian, Achala batholith, although Hf isotope signatures of zircon suggest a more uniformly crustal origin for the latter. Further studies are required to understand whether these bodies represent two independent magmatic episodes or more continuous activity.