Changes In The Characteristics of Basaltic Particles During Different Transport Processes

Abstract:

The physical and chemical characteristics of the grains in sedimentary deposits can provide valuable clues about transport processes, distance traveled, and provenance. A fundamental physical characteristic is particle shape, which is diagnostic of transport process as well as the distance traveled. For example, it is possible to distinguish the emplacement process of sediments based entirely on the shape of the quartz grains in the deposit [e.g., Folk, 1980]. Such basic sedimentological concepts have been applied to our interpretation of surface materials on the terrestrial planets [e.g. Cabrol et al., 2014]. However, what we know about the nature of sedimentary materials is based primarily on sediments that have weathered from felsic rocks—granite. This is true because felsic materials compose most of the landmass on the Earth. Yet, the surface of Mars is composed predominately of mafic materials—basalt—and sedimentary particles derived from basalt are much different than those derived from granite. Instead of quartz, feldspar, and heavy minerals commonly found in most terrestrial sedimentary deposits, basaltic sediments are typically composed of varying amounts of olivine, pyroxene, plagioclase, and vitric and lithic fragments. Both the persistence of basaltic particles and their specific gravities are different than particles derived from granite. These differences are important because they will affect the characteristics of basaltic sediment as it is transported by wind, water, and ice, and currently we have little to no understanding as to how basaltic sediment will weather as a function of the transport mechanism and distance.

We will present preliminary analyses of typical basaltic sediments that have been transported by a variety of geologic processes in Hawaii, including details about surface texture, componentry, and the influence different sedimentary processes may have on remote sensing data. The figure below shows examples of A) sediment transported by fluvial processes, B) sediment collected from the surface of a large climbing dune, and C) sediment collected from an end moraine located at the summit of Mauna Kea. The scale bar at the bottom is 500m.