Estructuras elípticas en el plutón de la Sierra del Francésestudio de su geometría e hipótesis sobre su origen convectivo

Resum

Direct evidences of magmatic convective flow in granitic plutons are scarce. The possible complex history of magma cooling in plutons can delete partially or completely this registration. We describe a complex elliptical structure in a porphyritic monzogranite and the granitic fabric around this. We distinguish three zones based on the study of their morphology and internal structures (cross-cutting layering, curved schlierens, lobulated mafic-leucocratic laminaes). We propose a model of vertical flow pipes with motion of magma generation point. Three possible convective pulses build the elliptical structure. This model is similar those proposed in the literature for snail and ladder dike structures. Fabric defined by K-feldspars megacrysts in the immediately surrounding monzogranite is basically linear to 355-010°