Compositional and Textural Analysis of Maar-Diatreme Volcanic Deposits at Hopi Buttes Volcanic Field (AZ) Using GigaPan and Thermal Infrared Imagery
Dr. Rachel Lee (SUNY Oswego)
Basaltic maar-diatreme volcanoes are produced when rising magma interacts with groundwater and produces a maar crater at the ground surface. This crater is underlain by a diatreme, a downward-tapering conical structure filled with a debris mixture of fragments of intruded magma, fractured host rock and clasts recycled through repeated discrete subsurface explosions. The debris is ejected by shallow explosions to form the classic tephra ring which surrounds many maar craters on the surface. These debris deposits are important as they can be used to help identify explosion depths, the source of material in maar tephra rings, and how energy is dissipated during a maar-diatreme eruption.
The bulk of the maar-diatreme deposits at the Hopi Buttes Volcanic Field (HBVF) in the Navajo Nation, Arizona, USA, represent classic diatremes with heterolithic clasts 10 mm to 10 m in size and are excellently-exposed near-vertical to vertical outcrops. However, detailed study of these deposits has been hindered by the limited physical accessibility of the best natural exposures, largely due to the elevation and verticality of the outcrops. Consequently, the formation processes and compositional/textural changes that result from subsurface explosions remains poorly constrained. Our ability to reconstruct the size, number and influence of these explosions is critical to our understanding of how maar-diatremes form.
A new approach for quantitatively characterizing maar-diatreme deposits, the Thermal Infrared (TIR) super-resolution technique, will be presented. This technique uses a combination of field-based TIR and visible wavelength imagery to improve the spatial and spectral resolution of the TIR image data. Overall, the technique will provide a simple and efficient method for collecting comprehensive textural and compositional information from diatreme deposits at HBVF, and will contribute to a better understanding of the formation processes of maar-diatreme deposits around the world.