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Cronología Rb-Sr y K-Ar de diques de la Sierra de Guadarrama (Sistema Central Español)

Galindo Francisco, Mª del Carmen and Huertas Coronel, María José and Casquet, César (1994) Cronología Rb-Sr y K-Ar de diques de la Sierra de Guadarrama (Sistema Central Español). Geogaceta, 16 . pp. 23-26. ISSN 0213-683X

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Abstract

Two calcalkaline granite porphyries, an E-W and a N-S trending one, and three monzonitic dykes
striking NE-SW, have been dated. For the first dyke a whole rock Rb-Sr isochrone age of 296±3 Ma, i.e.
Upper Carboniferous, is obtained. However, the second dyke pro vides only a regression age of
314±31 Ma. Whole rock K-Ar ages of the monzonitic dykes are 245±7,i.e. Lower-Middle Triassic, for
two of them, and 220±5 for the third. The first age rises doubts about the up-to-the-present alleged
posteriority of the E-W dykes relative to the large granitic plutonism in the area. The second is
geologically reasonable within the limits of error only, as N-S dykes must be younger than the Cabeza
Mediana pluton, which is 291 ±6 Ma old, and older than the hydrothermal episyenitic event dated at
274±6 Ma. For the monzonitic dykes the age of 245±7 Ma is taken as representative of the injection
episode, whilst the second age probably results from superimposed alteration. This alkaline episode
can be correlated with the opening of the Iberian trough.

Item Type:Article
Uncontrolled Keywords:Geocronología Rb-Sr, Geocronología K-Ar, Diques, Sierra de Guadarrama, Sistema Central Español.
Subjects:Sciences > Geology > Petrology
ID Code:11552
Deposited On:16 Nov 2010 11:47
Last Modified:16 Nov 2010 11:47

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