Aspects of the attitude of mafic sheets in the Western Cordillera of Colombia

Abstract

Changes in the attitude of sheet-like bodies of mafic rocks ('diabase') are discussed in relation to changes in the attitude of the bedding of intercalated and otherwise associated sedimentary rocks. Examples are presented in photographs of outcrops along the main road between Buga and Buenaventura, W. Colombia. The mafic sheets of the Colombian Western Cordillera and their mode of emplacement are compared with the sheets of the Sheeted Intrusive Complex of Cyprus, with reference to the sheet swarms of Iceland. Horizontal emplacement of sheets, never questioned in the Western Cordillera of Colombia, is considered as an alternative to vertical emplacement of sheets, previously suggested for the Sheeted Intrusive Complex of Cyprus. The subject matter is thought to be of importance in the (geophysical) study of the framework of the ocean floors. Further field investigation of the volcanic-sedimentary complex of the Western Cordillera of Colombia should be encouraged.