Crustal thickness and magma storage beneath the Ecuadorian arc

The Northern Andes of Ecuador contain some the most active volcanic systems in and extend over a broad region from Western Cordillera to Subandean Zone. While it is known that arc straddles range basement compositions, accreted mafic oceanic terranes west silicic continental east, details crustal structure beneath unclear despite being critical for understanding magmatic tectonic processes this portion Andes. To gain insight into these processes, we create two 3D models upper mantle seismic properties throughout region. first highlights discontinuity using receiver functions, which allows recovery thickness Ecuadorian We observe ~50 65 km under high elevations, with thicker crust lower elevation compared higher Eastern Cordillera. This can largely be explained by density variations within are consistent observed at surface, implying depth. second model combines our functions Rayleigh wave dispersion data ambient noise measurements joint inversion construct 3-D shear velocity model. shows several mid-crustal (5–20 below sea-level) low zones volcanoes maximum ~14% melt. These likely represent long-term magma storage predominantly crystalline reservoirs, “mush zones”. Furthermore, depth inferred reservoirs centers (e.g., Chiles-Cerro Negro Tungurahua) agreement previous geobarometry geodetic modeling. Our results provide new observations possible other less-studied as well, further contributes mounting number indicating melt percentages mid-crust systems.