Imagining the Deep Structure of a Mineralized Extensional Dome in the Variscan Central Iberian Zone (Spain) using Ambient Noise Seismic Data.

During the late stages of the Variscan orogeny, generalized gravitational collapse with coeval magmatism took place in the Central Iberian Zone, in Iberia. This event is getting the attention of the scientific community due to its likely role in the generation of strategic mineral resources (i.e. Sn, W, Nb, Ta, Sc, Au, Sb). In this regard, to study how the Variscan orogenic architecture controls the generation of mineral deposits the GOLDFINGER project was born. As part of the project, the Martinamor gneissic dome (Salamanca), which presents several mineral deposits, was covered by 31 short-period (2 Hz) 3-component seismic stations. Through applying techniques of ambient noise seismic interferometry, we have constructed a 3D S-wave velocity model of the extensional dome, allowing us to extend in depth the geometry of igneous rocks, their host rocks, and some of the structures. Among the most relevant results, we have identified the depth configuration of a granitic body outcropping discontinuously east of the study area, and whose upper boundary has been interpreted as the extensional dome detachment level. This structure may have provided a pathway for mineralizing fluids. This work demonstrates that the seismic noise interferometry technique has sufficient resolution to interpret medium-scale structures and to discern different lithologies with moderately contrasted physical properties.

Funding: grant PID2020-117332GB-C21 funded by MCIN/ AEI /10.13039/501100011033; EIT-Raw Materials project 17024 (SIT4ME: Seismic Imaging Techniques for Mineral Exploration); SA084P20 from the JCyL government, and TED2021-130440B-I00 funded by MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR.