Mapping mineralogy in evaporite basins through time using multispectral Landsat data: Examples from the Bonneville basin, Utah, USA

Abstract

The Bonneville basin, located in north-western Utah, is a vast evaporite basin which is home to the world-renowned Bonneville Salt Flats international speedway and is a highly valued landscape undergoing rapid change and anthropogenic influence.Air quality, snowpack, the local hydrological system, and state tourism are all impacted by the nature of the surface sediments exposed in the Bonneville basin. Mapping the Bonneville basin over time with remote sensing methods provides insight into the dynamics and impacts of the changing surface landscape. Utilizing the Landsat-5 Thematic Mapper (TM) and Landsat-8 Operational Land Imager (OLI) sensors, a set of band math indices are empirically established to map the predominant halite, gypsum, and carbonates mineralogical zones of the Bonneville basin. Spectral comparisons of representative samples from the study area and imagederived spectra indicate the halite of the Bonneville basin is wet and that gypsum deposits are slightly mixed with halite. The established indices are assessed in four ways, all of which support the ability of the indices to accentuate the associated mineralogical endmembers. Two study areas within the Bonneville basin are investigated temporally from 1986, 1995, 2005, and 2016 and show changing patterns in mineral distribution that align with surface processes active through these timescales. These indices provide a resource for mapping mineralogy though time in evaporite basins globally with diverse applications for questions about land use and environmental change.

Depositional and early diagenetic characteristics of modern saline pan deposits at the Bonneville Salt Flats, Utah, USA

“…A drainage divide separates the Newfoundland Basin and Bonneville Salt Flat watersheds. Surface mineralogy consists of halite, gypsum, carbonate muds and mixed alluvium (autumn 2016 satellite imagery; Nolan, 1927; Wold & Waddell, 1994; Bowen et al., 2017; Radwin & Bowen, 2021). (B) Overview of Bonneville Salt Flats setting, thickness and sample locations (after Bowen et al., 2018b).…”

“…1A). The Bonneville Salt Flats is the only naturally occurring saline pan with a persistent halite crust within the Great Salt Lake Desert (Nolan, 1927; Wold & Waddell, 1994; Radwin & Bowen, 2021). The BSF is bounded by the Silver Island Mountains’ alluvial fan to the west/north‐west, lacustrine mudflat to the east, and a potash mine and major interstate highway to the south.…”

Lateral and temporal constraints on the depositional history of the Bonneville Salt Flats, Utah, USA

“…Modern observations indicate GSLD dune systems are mobile, with eastward movement (>1 km in some areas) occurring in the Knolls dune field from 1953 to 1972 (Fitzgerald, 2019). Remote sensing also detected the northeast movement of GSLD gypsum dunes between 1986 and 2016, suggesting winds coming from the direction of BSF (Radwin and Bowen, 2021). However, our measurements of gypsum 87 Sr/ 86 Sr ratios from GSLD gypsum dune sand to the east and southeast of BSF indicate that the impact of BSF gypsum, if present, is negligible on GSLD gypsum dunes.…”

Evolution of Great Salt Lake’s Exposed Lakebed (1984-2023)

“…Gypsum deposits are found precipitating from springs found within the Great Salt Lake system, but much of the gypsum within the system is likely redistributed rather than actively precipitating, as the Great Salt Lake chemistry is calcium limited and now an MgSO 4 system (Hardie and Eugster, 1970;Jagniecki and others, 2021). To map these three sediment type classes, each satellite image is processed to mask out other landcover, leaving only surficial sediments, and then each sediment type is differentiated using multispectral indices adapted from work in the Bonneville basin mapping similar surface types (Radwin and Bowen, 2021). To map the extent of water and vegetation, which is used to isolate surficial sediments, the Normalized Difference Water Index (NDWI) and Normalized Difference Vegetation Index (NDVI) are utilized (McFeeters, 1996;Gandhi and others, 2015;Huang and others, 2021).…”

“…The results will help to understand the evolution of exposed sediments, halite crust formation, changes in vegetation, and the relationships between land-use, climate, and increasing sediment area. This work builds off of recent remote sensing studies in the Bonneville basin which utilized Landsat 5 TM and 8 OLI multispectral imagery to map halite, gypsum, and carbonate-muds (lacustrine detritus; Bowen et al, 2017;Radwin & Bowen, 2021).…”