PORRECA, M., CIFELLI, F., MATTEI, M., SORIANO, C., GIORDANO, G. (2011) - Magnetic fabric of the Miocene dikes and implications for magma flow propagation in subaqueous dome complex, Cabo de Gata (South East Spain). International Workshop on "Submarine and emergent volcanic arcs and associated volcano-sedimentary basins: facies models, petrology and volcano-tectonics”, Cabo de Gata, Almería, SE Spain, 2-7 Maio (Comunicação Oral).

The Miocene Cabo de Gata volcanic system comprises a 200 km² succession showing a wide variety of volcanic facies and eruptive styles, from subaqueous to subaerial and from effusive to explosive. The SW sector of this area (Cerro del Barronal-Cerro Canadilla) is characterized by the presence of subvertical dikes, intruding hyaloclastite deposits emplaced in submarine environment. The dikes trend mainly NNW-SSE and range in thickness between 10 and 50 m.

 

We have performed anisotropy of magnetic susceptibility (AMS) on four dikes. Three dikes have been sampled in the Cerro Barronal andesitic dome complex, whereas one dike has been sampled in Cerro Canadilla dacitic complex. The magnetic fabric data are generally well defined with a prevalence of oblate-triaxial shape of the AMS ellipsoids. The geometrical relationships between dikes and AMS axes suggest that two andesite dikes have subvertical upward magma propagation, whereas one dike has poor defined lateral magma propagation. The AMS results of the dacitic dike suggest well defined lateral magma propagation, with a source located to the NNW.

 

The geometrical and kinematics of the dikes provide information about the genetic relationships between dikes and hyaloclastite deposits. We propose that upward-flow propagation of the magma is controlled by high magma supply, following the main tectonic trend and intruded into poorly consolidated hyaloclastite deposits.