Influence of the basement on the eruptive dynamics: the case of the Puig de la Banya del Boc volcano, Garrotxa Volcanic Field, NE Iberian Peninsula.

During monogenetic eruptions, external controlling parameters such as fracturing patterns, differences in the hydraulic properties and heterogeneities of the basement rocks play an important role in creating small edifices. This is reflected by changes in eruptive styles, deposits as well as the morphology of the volcanic cones.

The deposits of the Puig de la Banya del Boc (PBB), a monogenetic volcanic cone located in the Garrotxa Volcanic Field (GVF) are a good example of the complex basement-influenced eruptive behaviour.

The aim of this study is to determine the eruptive history and dynamics of the PBB volcano, by means of sedimentological, stratigraphic and lithostratigraphic analyses of its deposits. The PBB cone, located on a hard basement of Palaeozoic metamorphic rocks, was built during a single eruption and it shows a complex eruptive succession with phreatomagmatic, Strombolian, and effusive phases.

The succession of deposits of the PBB reveals the influence of the substrate, upon which the volcano forms, in this case the crystalline Paleozoic basement, and its hydrodynamic properties that controlled the way in which magma/water interactions occurred throughout the eruption

This work represents a further step towards improving the understanding of magma-water interaction in complex environments as the GVF.

This work was funded by the BECAS CHILE- ANID, PhD Scholarship Abroad, announcement 2022/Folio 72220257.