Scientific article

A genetic link between albitic magmas and IOCG mineralization in the Ossa Morena Zone (SW Iberia)

Publication date2021

A detailed geological and isotopic study of the Colmenar deposit (Ossa Morena Zone, SW Iberia) shows that the magnetite- rich mineralization formed by complex magmatic-hydrothermal processes related to the crystallization of water-rich albite- magnetite igneous rocks derived from the crystallization of unusual melts formed during anatexis in a high temperature-low pressure metamorphic regime. The most likely protolith includes a sequence of iron-rich chemical sediments, amphibolite and possible meta-evaporites of early Cambrian age. The albite-magnetite rock occurs as up to 20cm-thick dyke and breccia bodies and show complex immiscibility relationships with an albite-K-feldspar-quartz leucogranite. Iron-rich fluids exsolved during the crystallization of these melts are responsible of the formation of hydrothermal breccias and the widespread replacement of the hosting calc-silicate hornfels by a magnetite-ferroactinolite-albite assemblage along syn-mineralization shear zones. Geochronological data obtained for mineralization and related hydrothermal alteration points to a Variscan age (ca. 340Ma), interpreted also as the age of the high-grade metamorphism driving anatexis at the Valuengo Metamorphic Complex. Despite the low Cu and Au contents, this mineralization shares features with the IOCG systems, which in other districts show a spatial relationship with albite-rich rocks, evaporites and pre-existing iron mineralization. The observations presented from Colmenar support an alternative genetic model with prospective implications for the Ossa Morena Zone that can be extrapolated to other IOCG belts worldwide.

  • IOCG
  • Magnetite
  • Geochronology
  • Radiogenic isotope geochemistry
  • Albitite
Citation (ISO format)
CARRIEDO, Jorge et al. A genetic link between albitic magmas and IOCG mineralization in the Ossa Morena Zone (SW Iberia). In: Journal of Iberian Geology, 2021. doi: 10.1007/s41513-021-00162-3
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Article (Published version)
ISSN of the journal1886-7995

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