New SHRIMP U-Pb data from the Famatina Complex: constraining Early–Mid Ordovician Famatinian magmatism in the Sierras Pampeanas, Argentina

Authors

  • J.A. DAHLQUIST CICTERRA-CONICET-UNCAv. Vélez Sarsfield 1611, Pabellón Geología, X5016CGA-Córdoba, Argentina.
  • R.J. PANKHURST British Geological SurveyKeyworth, Nottingham NG12 5GG, United Kingdom
  • C.W. RAPELA CIG-CONICET-UNLPCalle 1 Nº 644, 1900, La Plata, Argentina
  • C. GALINDO Departamento de Petrología y GeoquímicaUniversidad Complutense-Instituto de Geología Económica (CSIC), 28040 Madrid, Spain
  • P. ALASINO CRILAR-CONICETAnillaco Entre Ríos y Mendoza. 5301 Anillaco, La Rioja, Argentina
  • C.M. FANNING Research School of Earth SciencesThe Australian National University, Canberra, Australia
  • J. SAAVEDRA nstituto de Recursos Naturales y Agrobiología - CSIC-37071 Salamanca, España
  • E.G. BALDO CICTERRA-CONICET-UNCAv. Vélez Sarsfield 1611, Pabellón Geología, X5016CGA-Córdoba, Argentina

Keywords:

Famatina Complex, SHRIMP U-Pb data, Magmatism, Ensialic Basins

Abstract

New SHRIMP U-Pb zircon ages are reported for igneous and sedimentary rocks of the Famatina Complex, constraining the age of the magmatism and the ensialic basins. Together with whole-rock and isotope geochemistry for the igneous rocks from the complex, these ages indicate that the voluminous parental magmas of metaluminous composition were derived by partial melting of an older lithosphere without significant asthenospheric contribution. This magmatism was initiated in the Early Ordovician (481 Ma). During the Mid-Late Ordovician, the magmatism ceased (463 Ma), resulting in a short-lived (no more than ~20 Ma) and relatively narrow (~100–150 km) magmatic belt, in contrast to the long-lived cordilleran magmatism of the Andes. The exhumation rate of the Famatina Complex was considerably high and the erosional stripping and deposition of Ordovician sediments occurred soon after of the emplacement of the igneous source rocks during the Early to mid-Ordovician. During the upper Mid Ordovician the clastic contribution was mainly derived from plutonic rocks. Magmatism was completely extinguished in the Mid Ordovician and the sedimentary basins closed in the early Late Ordovician.

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Published

2009-04-28

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