%0 Journal Article
%A Galindo Francisco, María Del Carmen
%A Huertas Coronel, María José
%A Casquet Martín, César
%T Cronología Rb-Sr y K-Ar de diques de la Sierra de Guadarrama(Sistema Central Español)
%D 1994
%@ 0213-683X
%U https://hdl.handle.net/20.500.14352/56937
%X Two calcalkaline granite porphyries, an E-W and a N-S trending one, and three monzonitic dykesstriking 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 of314±31 Ma. Whole rock K-Ar ages of the monzonitic dykes are 245±7,i.e. Lower-Middle Triassic, fortwo of them, and 220±5 for the third. The first age rises doubts about the up-to-the-present allegedposteriority of the E-W dykes relative to the large granitic plutonism in the area. The second isgeologically reasonable within the limits of error only, as N-S dykes must be younger than the CabezaMediana pluton, which is 291 ±6 Ma old, and older than the hydrothermal episyenitic event dated at274±6 Ma. For the monzonitic dykes the age of 245±7 Ma is taken as representative of the injectionepisode, whilst the second age probably results from superimposed alteration. This alkaline episodecan be correlated with the opening of the Iberian trough.
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