USING A FLOW EQUATION TO EXPLAIN ROCK GLACIER DEFORMATION: A NEW APPROACH

Rock glaciers serve as transport mechanisms and storage sinks for mass (i.e., debris, clasts, muds, ice, etc.) in numerous alpine critical zones. The critical zone, defined by the NSF in 2007, is the zone that extends from the top of the canopy to the bottom of the aquifer. In alpine regions, above treeline, the top of the critical zone extends from the boundary layer between the atmosphere and the surface of Earth rather than the top of the canopy; processes drive all interactions in the critical zone. The formation of rock glaciers has been the focus of studies for the past one hundred plus years, and these studies have ranged from descriptive, through mapping and monitoring movement to modeling of surface deformation and movement mechanics. The structure of most rock glaciers can be categorized as a three-tiered system with a top layer of rock fragments with an open matrix, covering a ice-cemented and void-filled zone or ice core that overlies bedrock or rock deposited and overridden by the top layers. Although many studies have attempted to answer the question as to how rock glaciers operate, no completely adequate explanation exists. Study of these layers can provide important information regarding the type and style of mechanisms of deformation of a rock glacier. Thus, understanding the spatial and temporal deformation patterns are a vital step in understanding the relationship between movement, process mechanics, and the form and mass preserved in the geologic record. A three-dimensional numerical model using a continuum mechanics’ approach has been developed. The model uses the general equation expressing the conservation of mass, momentum, and energy: ρ(Dv/Dt) = div T + ρg. We assume that flow of a rock glacier is incompressible (div v = 0). This approach allows explanation of the internal temporal and spatial patterns of deformation, movement and mixing of a rock glacier using a 3D perspective.