Revistes Catalanes amb Accés Obert (RACO)

Estructura y mecanismos intrusivos de los lamprófidos de Sa Planassa - Punta d'Es Mut (Costa Brava, Cordillera Litoral Catalana): su interés didáctico

Domingo Gimeno Torrente

Resum


The lamprophyric outcrops of Aiguablava location have been didactically used over half a century without a detailed study of their igneous textural and fabric characteristics. This paper shows that the lamprophyres, and specially the cretaceous camptonite sill show a number of structures and textures that allow us to understand their intrusive mechanisms. The work describes the cooling and vesiculation processes. It includes evidence referred to lateral forced intrusion (flow banding accumulation of phenocrysts, removing and uplift of large host rock xenolits from the bottom of the sill) that shows that the well-known evidence of gravity-related accumulation of mafic phenocrysts at the bottom of the camptonitic sill has been largelly overemphasized. The study includes an analysis of the didactic resources of this outcrop. The conclusion is that its main interest is related with the study of intrusive mechanisms of the dikes (only available through the study of their inner structures). A sequence of didactic activities of field work that can be developed with the students is suggested.

Key words: Leucogranite, Lamprophyric dikes, Spessartite, Camptonite, Sill, Intrusive mechanisms, Cooling, Vesiculation, Magmatic flow, Gravity-related accumulation, Didactic activities, Catalonia, Spain.

Text complet: PDF