Characteristics of Volcanic Rock Series from the Bikou Group and New Idea of Geological Mapping in the Mian-Lue-Ning Triangle Area, Shaanxi

The volcanic rock series of the Middle-late Proterozoic Bikou Group is developed in the Mian-Lue-Ning triangle area, Shaanxi Province, which has a complete magmatic eruption sequence of acid-mafic volcanic, containing rhyolite, basalt, pyroclastics and andesite. The volcanic rock series is made of multiple volcanic rhythms with strong deformation, developing with penetrative replacement, foliation plastic flow and ductile shear. This rock series have obvious characteristics of "partial order, total disorder and large variable". Through several years practice of geological mapping in this area, a new idea for geological mapping method for the deformation volcanic rock series has been proposed on the basis of the volcanic cycle-metrical division, the recognition of volcanic lithology, volcanic series deformation and tectonic style. After using the new method of "volcanic lithology, lithofacies and tectonic deformation style", a good result in Mian-Lue-Ning regional geological mapping has been obtained. The new volcanic mapping method will be great significance to reshape the tectonic deformation mechanism and summary metallogenic regularities of the Bikou Group volcanic rock series in the Mian-Lue-Ning triangle area.