Anisotropía de la Susceptibilidad Magnética y direcciones de flujo en diques recientes. Complejos volcánicos de las Islas Corvo y Flores (Azores Occidentales, Placa Norteamericana)

Abstract

Different models of relation between flow and Anisotropy of Magnetic Susceptibility axis have been postulated. The main models link the magnetic foliation with the dyke wall, where the magnetic lineation is parallel to the flow direction or where the magnetic foliation develops an imbrications disposition respect the dyke wall. At a first approximation the main differences resides in the turbulence caused by the dyke walls during the flow. In this work is presented a systematic sampling along different Quaternary dykes (Western Azores) that show both models within the same dykes, differing in the position on it: imbrication models developed in the borders and magnetic lineation parallel to the flow direction in the center of the dyke. However, some dykes only show magnetic lineation parallel to the flow without any imbrication pattern. In these cases the magnetic parameters show the same trends, at different scale, between dykes with only one or two kind of fabrics. The magmatic flow direction, in some cases, can be better defined if the dyke is sampled just at the center of it, in contrast with the expected results in the borders which can be influenced by the local irregularities of the flow and the dyke wall