HR: 0830h
AN: P51B-0453    [PDF]
TI: Formation and Thermal Infrared Spectroscopy of Halite Crusts
AU: * Baldridge, A M
EM: alice@asu.edu
AF: Arizona State Univeristy, Department of Geological Sciences, Tempe, AZ 85287-6305 United States
AU: Christensen, P R
EM: philip.christensen@asu.edu
AF: Arizona State Univeristy, Department of Geological Sciences, Tempe, AZ 85287-6305 United States
AB: Efflorescent salt crusts form as groundwater evaporates from capillary updraw of brine through sediment. Salts precipitate at the surface, coating and cementing the upper few layers of sediment. If enough brine is present to completely saturate and pond on top of the surface, halite will precipitate at the surface of the brine and settle out as layers of crystalline salt on top of the sediment. In playa environments, salts such as sulfates, carbonates and halides, and forms such crusts. In remote sensing studies of such surfaces, it is important to understand how the presence of salt crusts affects the spectral features of the surrounding sediment. This is especially true when the crusts form from a non-absorbing salt such as halite. Halite has been observed to exhibit unusual spectral properties in the thermal infrared. Specifically, granular mixtures of minerals with halite produced spectra in which the spectral features inverted form reflectivity, shifted to shorter wavelengths and the spectral contrast increased near absorption bands. However, in crusted surfaces, in which the halite cements, coats or overlays the mineral grains, the presence of halite has a different affect on the spectra. This work will examine the precipitation of halite and the formation of salt crusts for several sediment and brine mixtures. Laboratory measurements of thermal emission spectra for the crusts will be compared to previous studies for particulate mixtures of halite with minerals and well as to natural surface crusts. Detailed knowledge of such surfaces will allow for their discrimination and identification in terrestrial playa settings as well as in paleo-environments on Mars.
DE: 3675 Sedimentary petrology
DE: 5464 Remote sensing
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting