CALDERAS REVISITED: VALLES CALDERA, NEW MEXICO

In the past few decades, the study of the formation of collapse calderas has seen significant advances through new field and petrological studies in addition to geophysical imaging and analog and theoretical models. Nevertheless, it has been recognized that any analysis of collapse caldera formation ideally should take a multidisciplinary approach. When each approach is used separately, they have their own advantages and disadvantages. To minimize the disadvantages, this study uses a multidisciplinary approach that include field, geochemical, geophysical, regional tectonics, local deformational history, magma and country rock properties, melt-structure interactions, interplay of structural discontinuities, and the geometry of the system to revisit the classic resurgent Valles caldera, NM, of Smith and Bailey (1968). The integration of data from these approaches set within the geodynamic context of the Rio Grande rift and Jemez Lineament suggests a scenario where crustal thinning allowed mantle melting along a fertile suture zone. This was followed by subsequent crustal melting and assimilation, and the development of a crustal-scale intrusive complex leading to the formation of the Jemez volcanic field (JVF). These processes lead to the thermomechanical evolution and hybridization of the crust and development of a high-level long-lived magmatic system that eventually failed, ultimately triggering massive eruptions from Valles caldera. Erupted products and their ordering both spatially and temporally permit reconstruction of the parent magma chamber and provide a snapshot of the development of the caldera and magma chamber during the eruption.