THE PROPOSED EVOLUTION OF SHALLOW-SOURCED METHANE MUD VOLCANO GEOMORPHOLOGY: LAKE POWELL, HITE UTAH

Mud volcanoes are typically viewed as large-scale, dome-shaped landforms in deep ocean settings. At Hite, Utah shallow-sourced mud volcanoes are developing on the modern delta plain as the Colorado River enters Lake Powell. These features are seen on a much smaller scale and with forms different from the expected mud volcano shape. Examining the various forms and speculating on sedimentary processes has presented a complex evolution of mud volcanoes that has not been documented from either modern or ancient mud volcanoes. This proposed evolution adds to the understanding of the geomorphic variability of short-lived mud volcanoes from initial activity to dormancy that have gone unrecognized in both modern and ancient settings.

These mud volcanoes display various stages of landform evolution, beginning as positive features then collapsing to caldera-like forms. The initial form is an upward-arching phase, breaching the water surface and then leading to typical mud volcano formation. The positive form actively erupts sans, mud, and gas, up to 95% methane, from single or multiple clustered vents. After a period of eruption, the landform undergoes collapse and the positive form inverts to a negative, caldera-like form that can then be either active or dormant. Active, collapsed forms can expel gas or potentially resurge to create another dome mud volcano housed in the caldera. A mud volcano can become dormant at any of the geomorphic stages described if the conduit fills with sediment and gas pressure drops.

These documented modern geomorphic changes in mud volcanoes illustrate the growth history of shallow-sourced, fluid escape features, from initial landform through dormancy that can potentially recognized in the rock record.