Paleomagnetic reconnaissance of the grupo diábasico western andes (colombia)

Abstract

A paleomagnetic reconnaissance has been carried out on the Grupo Diabásico of the western Cordillera from the Colombian Andes, between El Tambo and El Penol, Departamento Nariño. The Grupo Diabásico wich is of Cretaceous age is thought to be of submarine origin and to have undergone a low grade metamorphism. The geometric mean of the natural remanent magnetization JNRM = 8.8 x 10-5 G. The low field magnetic susceptibility geometric mean X= 8.87 x 10-4G/Oe gives a Koenigsberger ratio of 0.28 indicating that the dominant magnetization is a induced one.Some pilot samples have been progressively demagnetized by alternating fields up to 600 O°. A viscous remanence test was applied to reject unstable sample. Despite the non ideal quality of the remanent magnetization a virtual geomagnetic pole has been calculated: pole latitude: 65° S; pole longitude: 186° E.

A paleomagnetic reconnaissance has been carried out on the Grupo Diabásico of the western Cordillera from the Colombian Andes, between El Tambo and El Penol, Departamento Nariño. The Grupo Diabásico wich is of Cretaceous age is thought to be of submarine origin and to have undergone a low grade metamorphism. The geometric mean of the natural remanent magnetization JNRM = 8.8 x 10-5 G. The low field magnetic susceptibility geometric mean X= 8.87 x 10-4G/Oe gives a Koenigsberger ratio of 0.28 indicating that the dominant magnetization is a induced one.Some pilot samples have been progressively demagnetized by alternating fields up to 600 O°. A viscous remanence test was applied to reject unstable sample. Despite the non ideal quality of the remanent magnetization a virtual geomagnetic pole has been calculated: pole latitude: 65° S; pole longitude: 186° E.