Modeling Intra-Caldera Resurgence Settings: Laboratory Experiments With Application to the Los Humeros Volcanic Complex (Mexico)

摘要

Scaled analogue models explored the role of different boundary conditions in intra-caldera resurgence processes. Models investigated the role of magma intrusion depth (ID) (Series 1), asymmetric and symmetric caldera collapse (Series 2), as well as the presence of existing discontinuities in the pre-volcanic substratum (Series 3) on the style of caldera resurgence. Experimental results indicate that different IDs resulted in different resurgence styles and structural patterns, which evolved from piston-like resurgence, for deeper intrusions, to intra-caldera resurgent domes for shallower intrusions. Asymmetric collapse was typically accompanied by a tilted roof block above the emptied analogue magma reservoir, while inherited faults influenced significantly the deformation pattern of piston-like resurgence. Experiments simulate many of the principal characteristics of calderas. We compare our modeling results primarily to the Los Potreros caldera nested within the Los Humeros Volcanic Complex, where the largest Mexico's Quaternary eruption occurred and which hosts an important geothermal field (eastern Trans-Mexican Volcanic Belt). A structural field survey was conducted to identify the kinematics of faults within the caldera and outside the volcanic edifice. The Los Potreros caldera shows a sub-orthogonal fault pattern strikingly similar to that of models deformed with shallow ID. We interpret this correlation as an evidence of similarity in dynamic processes, whereby modeling results would indicate a scaled ID of similar to 4.5 km. The Acoculco caldera complex, in Mexico, shows a fault pattern similar to the Los Potreros caldera, and geological information corroborates the attribution of renewed magmatic pressure to similar IDs.