DEPOSITIONAL ARCHITECTURE OF A MAAR-PITTED PLAYA - SEDIMENTATION IN THE HOPI BUTTES VOLCANIC FIELD, NORTHEASTERN ARIZONA, USA

Primary and reworked tephra in the Mio-Pliocene Bidahochi Formation of northeastern Arizona was produced by, and partly preserved in, maar volcanoes and related hydrovolcanic structures. The temporal and geometric relationships among lithofacies of the Bidahochi Formation illustrate the dynamic interplay between volcanism and sedimentation in an essentially "closed" sedimentary system. Maar volcanism in the low-relief, basinal, environments of the Bidahochi appears to have resulted in little net aggradation, both because the total amount of magma erupted was relatively modest, and because the large maar volcano craters produced areas of lowered base level within the basin that formed sediment "sinks" for much of the newly erupted tephra. The volcanically "eroded" maar craters commonly contain deposits of lakes, multiple stream channels, and eolian dunes. They formed an integral part of the basin's overall depositional environment and affected sedimentation in the playa lake stream systems beyond the vents, both during and following the major eruptive period. © 1990.