Probing the Chilean subduction zone at mantle depths: Insights from Patagonian High-Pressure rocks

• Applicant: Professor Samuel Angiboust, Ph.D.
• Subject Area: Palaeontology
• Term: from 2014 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 266332247

Even though documented by numerous geophysical studies over the last 30 years, the Chilean subduction zone structure and dynamics at depths greater than 40 km remains poorly resolved. We herein propose to study the only high-pressure metamorphic terrane from the Chilean margin exhumed from blueschist-to-eclogite facies (40-50 km depth) on the Diego de Almagro Island (Patagonia, Chile), to highlight accretionary and fluid-rock interaction processes in the deep (40-50 km) Chilean subduction zone. The internal structure of the Island, which is apparently constituted by material from various origins and metamorphic histories, needs further characterization of its geological history. The field campaign will permit (i) to realize a widespread sampling and structural measurements throughout the Island (ii) to realize the first geological cross-section across the island and (iii) to perform detailed pressure-temperature-time-deformation paths for the various sub-units building up the island. The strength of our approach is to combine modern thermobarometric tools with in situ Ar-Ar geochronological constrains and Rb-Sr deformation ages. These results will be of importance to improve our vision of the lithological composition and structure of the Chilean subduction channel as well as of deformation processes rooted at the base of the seismogenic zone. The results will also shed light on subduction interface dynamics at Moho depths and will therefore be of importance of the geophysicists community.

• DFG Programme: Research Grants
• International Connection: Spain
• Cooperation Partners: Privatdozent Dr. Johannes Glodny; Thais Hyppolito; Professor Dr. Onno Oncken