An integrated geophysical and geological 3D model to characterize the feeder system of La Joya Honda and La Joyuela maars complex in central Mexico

Abstract

La Joya Honda maar is recognized as one of the largest maar craters of the world (∼1200 m x 930 m), and La Joyuela maar, with axes of ∼1160 m x ∼790 m, is located in San Luis Potosí, México. Geophysical characterization using terrestrial magnetometry, aeromagnetic data, satellital gravimetry, and petrographic analysis of rock samples were interpreted jointly to improve the knowledge of both maars, their structural root geometry, and dimension maar-diatreme volcanoes. Magnetic and gravimetric analysis of both maars exhibit high magnetic anomaly values (≥400 nT) related to low gravimetric signatures (-5.2 to 1.5 mGal) and show characteristic geophysical maar behavior, complemented by positive anomalies (0.137 nT/m and 0.019 mGal/m, respectively) in the Analytic Signal result. Additionally, associated with the diverse tectonic and faulting events that the area has been subjected to, lineaments analysis and rose diagrams were used to determine structural tendencies, indicating the regional stress field (NNW trending) related to local fault orientations (E-W, NE-SW), which might be expected for the formation of maars with a comparable fracturing disposition at a depth between La Joya Honda and La Joyuela maars. This investigation shows the first magnetic inversion model in the zone, identified two vertical conduits susceptibility isosurface (2.53x10-4 SI) with an exceeded depth of -12 km below both volcanic structures, where regional analysis of lineaments and Werner solutions determine weak cortical structures. Furthermore, the petrological evidence (xenoliths) supports the geophysical model, which helps to understand regional factors that make the ideal environmental conditions for maar formation. Our new results contribute to the knowledge of the feeder system of the maars complex found in La Joya Honda and La Joyuela maars, demonstrate that the combination of different regional structural and local trends controls the magmatic evolution producing preferential paths for magma ascent.