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

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 o...

Full description

Saved in:
Bibliographic Details
Published in:Journal of Iberian geology 2021-05, Vol.47 (1-2), p.85-119
Main Authors: Carriedo, Jorge, Tornos, Fernando, Chiaradia, Massimo, Galindo, Carmen
Format: Article
Language:English
Subjects:
Cambrian
Chemical sediments
Crystallization
Earth and Environmental Science
Earth Sciences
Geology
High temperature
Igneous rocks
Immiscibility
Iron
Isotopes
Metamorphism
Mineralization
Research Paper
Structural Geology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:1698-6180
1886-7995
DOI:10.1007/s41513-021-00162-3