by Torsten Dahm, Axel K. Schmitt, Shanaka L. de Silva, Yan Lavallée, Yan Lavallée

The Eifel region, Germany, hosts hundreds of distributed volcanoes of Quaternary age in an intracontinental setting and is renowned as the type locality of maar volcanism. Laacher See volcano in the eastern part of the region stands out as a sizable, dormant, but actively deforming and degassing system that represents the second youngest silicic-carbonatitic magmatic complex worldwide currently not erupting. Moreover, the Eifel boasts an extensive record of past research, easy access, and excellent infrastructure that uniquely permits implementation of cutting-edge scientific methods to study this type of distributed volcanism. Drilling in the Laacher See region has potential to enhance our knowledge on distributed volcanic fields, which are characterized by irregular eruptive recurrence over protracted durations of activity, and specific hazards resulting from high CO2 fluxes from the mantle to the surface Laacher See would be an ideal testbed to evaluate the physical and chemical properties of a shallow (~5?6 km depth at its top) intrusive silicic-carbonatitic complex formed by volatile-rich magmas and an associated hydrothermal system, both accessible to drilling. Only drilling can provide answers as to why the shallow hydrothermal system above a residual magma system after an eruption only 13,000 years ago is seemingly cold, although it is highly dynamic based on ongoing CO2 degassing, seismic activity, and exceptionally high rates of uplift on spatial scales of hundreds of kilometers. Moreover, silicic-carbonatitic magma systems are globally recognized as major hosts for critical metal deposits, which in case of Laacher See could be investigated in the making. With this proposal, we aim to harness enthusiasm for collaborative research to further develop and refine ideas on continental distributed volcanism, its geodynamic relevance, as well as hazard and resource potential in line with ICDP themes. We see high potential for a successful workshop that will gather further ideas on how to maximize the scientific gains from drilling into a magmatic-hydrothermal system of a dynamic yet dormant volcano. By reaching out to a broad and diverse international community, the workshop will sharpen scientific questions of global scope and relevance, and address opportunities and risks of drilling at particular sites and with potentially novel techniques.

• The overall objectives are to advance quantitative knowledge about distributed volcanic fields. Many aspects regarding the extent of these fields, their vent structures and the geometry of superficial dike swarms, as well as timing of eruptive activity, eruption recurrence and styles are poorly constrained. By focusing on the role of CO2, both in shallow hydrothermal systems and as a key player controlling physical and chemical properties of silicic magmas, we can improve our fundamental understanding of the processes involved in magmatic transport and storage. This fundamental knowledge will not only help to assess hazards from distributed volcanic fields, but will also be an important step towards volcano engineering and the potential use of geothermal energy and the extraction of critical elements such as rare earth elements or lithium. In addition, long-lived hydrothermal systems flushed by CO2 are natural labs to investigate physical, mineralogical, and chemical exchanges with the host rocks that are relevant for CO2-sequestration. Therefore, the Eifel drilling site will result in unprecedented basic science insights as well as provide analogues for real-world application such as geothermal energy, critical metals mining and CO2 sequestration.

Critical Metals, Distributed Volcanic Fields, Silicic-Carbonatitic Magma System, Volcanic Hazards

Latitude: 50.41279, Longitude: 7.27139