Evolucìón petrogenética del magmatismo bàsico mesozoico en las Zonas Externas de las Cordilleras Béticas (S. España)

Abstract

Mesozoic basic magmatism from the External Zones of the Betic Cordilleras consisted of two magmatic events. The first one began at the end of the Triassic and the second developed during the Jurassic. Whole-rock geochemical characteristics and primary mineralogical compositions allow to define a tholeiitic affinity for the Triassic magmatism and a transitional to alkaline affinity for the Jurassic magmatism. Trace element ratios evidence an incompatible element enriched source ((La/Ce)n >1, La/Nb < 1.5) for both the Triassic and Jurassic magmatisms. Moreover, differences in other trace element ratios (Th/Nb, Th/Yb, Zr/Nb, Zr/Y, Ba/Zr, etc.) indicate a higher influence of a lithospheric component for the Triassic magmatism regarding to the Jurassic magmatism. This temporal evolution of the magmatism, Is related with the distensive events which affected the Sudiberic margin during the Mesozoic, in relation with the opening of the Central Atlantic ocean