ISSN:
0016-7835
Keywords:
Key words IBERIAN Peninsula
;
Variscan suture
;
Rb-Sr whole-rock isotopic data
;
Protolith ages
;
Orthogneisses
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract One of the main tectonic boundaries of the Variscan Belt in the Iberian Peninsula is the Ossa-Morena/Central Iberian contact. This contact is marked by a highly deformed unit (Central Unit) which recorded an initial high-pressure/high-temperature metamorphic evolution. Rb-Sr whole-rock isotopic data from three gneissic bodies cropping out in the Central Unit yield two Late Proterozoic ages (690±134 and 632±103 Ma) and an early Palaeozoic age (495±13 Ma), which we interpret as protolith ages. The two Late Proterozoic orthogneisses show initial 87Sr/86Sr ratios typical of mantle-derived materials or those with significant mantle participation (87Sr/86Sr〉0.709). These new radiometric data, together with ages previously published and the structural evolution of the Central Unit, lead to the conclusions that: (1) there are magmatic protoliths of Late Proterozoic and Early Palaeozoic ages; (2) the metamorphic evolution of this area, including the high-pressure event, belongs to the Variscan orogenic cycle; (3) the deformations observed affect the rocks of the entire Central Unit, accordingly they are post-Ordovician, i.e. Variscan; and (4) consequently, the Ossa-Morena/Central Iberian contact is interpreted here as a Variscan suture.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00260447
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