Volcanic stratigraphy and mapping

Stratigraphic analysis and geological mapping in volcanic settings allow characterization of the geological and structural setting with a particular focus on the definition of the localization of source areas and eruptive vents, and provide features for the interpretation of the geological evolution and eruptive history of a volcano. The geological maps of volcanic areas set the basic knowledge for detailed volcanological and magmatic studies and for evaluation of volcanic hazards of active to recent volcanoes. The stratigraphic approach is generally based on the integrated use of Unconformity-Bounded Units (UBU), lithostratigraphic units and lithosomes for the purpose of describing the highly variable lithology of volcanic products with abruptly changing lateral and vertical lithofacies and rapid variations in chemical composition (even during a single eruption), their morphological features and origin from point-like or linear sources, and the episodic nature of eruptive activity which results in a rapid and frequently catastrophic supply of volcanic products interrupted by prolonged quiescence periods or volcanic collapses (calderas or lateral collapses). Particular care is given to the recognition and interpretation of the main stratigraphic discontinuities useful to define a framework of the volcano evolution as a result of constructional stages, represented by thick successions of primary volcanic products, and erosive stages, recorded in unconformities and the deposition of secondary reworked epiclastic products.