Unprecedented U–Pb-Th SHRIMP and Lu–Hf isotopic data in zircon from Tandilia basement rocks, Argentina: new insights into Palaeoproterozoic and Neoproterozoic crustal reworking of the Río de la Plata craton
We present new geochronological zircon data from the Siempre Amigos Hill (SAH), a small but representative portion of Tandilia Terrane within the Río de la Plata Craton (RPC). U-Pb-Th SHRIMP data indicate a heterogeneous Palaeoproterozoic (Rhyacian) crust. A garnet-bearing granite (2165 ± 16 Ma) hos...
| Autores: | , , , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:dnet:digitalcsic_::ab6670d025b13e6b1c83e4c8bfe24c46 |
| Acesso em linha: | http://hdl.handle.net/10261/432016 |
| Access Level: | acceso abierto |
| Palavra-chave: | Brasiliano cycle Hf TDM model ages Isotopic signature Río de la Plata Craton Transamazonian-eburnean orogeny U-Pb-Th SHRIMP in zircons |
| Resumo: | We present new geochronological zircon data from the Siempre Amigos Hill (SAH), a small but representative portion of Tandilia Terrane within the Río de la Plata Craton (RPC). U-Pb-Th SHRIMP data indicate a heterogeneous Palaeoproterozoic (Rhyacian) crust. A garnet-bearing granite (2165 ± 16 Ma) hosts felsic (2108 ± 13.6 Ma) to intermediate gneiss protolith (2104 ± 8 Ma), andesite with a sanukitoid signature (2094 ± 47 Ma) and granulites or charnockites. Additionally, calc-alkaline granitoids (2092 ± 13 Ma) intruded, as a result of differentiation from an igneous mafic sanukitoid source. Localised low-temperature shear zones affected the sequence. Lu-Hf isotopic data for the post-orogenic stage (< 2.1 Ga) complement previous results, showing progressive negative Hf values. These isotopes suggest post-orogenic transtension. New Neoproterozoic ages (652 ±37 Ma, 618.4 ±11.2 Ma and 686 ±60 Ma) from granites, with low-to-very low zircon Th/U ratios, are presented as evidence of U-Th-Pb systems overprinting by Neoproterozoic (Cryogenian) thermal-hydrothermal events. Those Neoproterozoic ages are, within analytical uncertainty, equivalent to the 656 ± 19 Ma metamorphic age obtained for the Palaeoproterozoic granulite. These new Neoproterozoic ages, suggests a thermal perturbation linked either to the collision of the Nico Pérez Terrane against the passive margin of RPC, or the Neoproterozoic evolution of the Ventania System basement during the Brasiliano/ Pan-African orogeny. |
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