THE VITAL STATISTICS OF A CONTINENTAL MONOGENETIC VOLCANIC FIELD: THE FINAL DATA FOR SPRINGERVILLE FIELD, IN EAST-CENTRAL ARIZONA

The recent efforts in 2010 and 2011 resulted in completion of the mapping of the Springerville Volcanic Field (SVF), a 3000 km² field, located in east-central Arizona. These rocks comprise arguably one of the best-characterized monogenetic volcanic fields in the world. The organizational framework of magmatic mapping focuses on the delineating distinct magmatic units, each representing a volcanic product erupted at a moment in time. Data from the 515 units in the SVF has now been compiled to comprehensively characterize the field as well as provide information for comparison. The need for this is becoming more acute, given that many continental volcanic fields, including those within close proximity to large population centers such as Mexico City or the Eifel fields of Germany, are currently active, but have recurrence rates that are too long to study in real time. Predictions of future eruptions are dependent on studies of past eruptions, such as in the SVF, where the lifespan of a continental volcanic field is documented from start to finish. Increasingly detailed basaltic volcanism is being mapped on other terrestrial-like planets. This planetary work, with image resolution now as high as 25 cm, can now be profitably compared to results from a well-studied terrestrial analog.

The 515 flows of the SVF are classified in one of thirteen distinct lithologic classes. The area percentages were determined for each lithologic type as a proxy for volume and olivine basalts were found to be the most prevalent. Similar percentages were deduced for the area of each of ten geochemical classes and the most abundant was determined to be tholeiites, although 310 km² were not classified geochemically. A distinct geochemical trend occurs through time, from tholeiitic basalts to increasingly evolved alkalic products. A total of 56 units are classified as composite units that likely contain more than one flow but cannot be further subdivided. We suggest that although it cannot be compared to maps of eruptive products made from observations of real time eruptions (e.g. Pu’u O’o, Hawaii), magmatic mapping in the SVF has proven to be successful in obtaining details that can serve as a unique framework and example for comparison to other continental and planetary volcanic fields, and as a template for compiling data for similar volcanic occurrences.