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

Abstract

The Bonneville Salt Flats form a saline pan in western Utah, USA. This modern saline pan has a unique history of land-speed racing and potash mining. Multi-decadal measurements record decreasing evaporite volume and extent, spurring multiple environmental studies. The goal of this work is to describe saline pan evaporite morphologies within the context of environmental measurements. Environmental data include field observations, groundwater and dust trap samples, precipitation, albedo, time-lapse photography, groundwater level, and temperature measurements of air, groundwater and the shallow evaporite crust. Petrographic data include thick sections, evaporite slabs and sediments, and X-ray computed tomography of evaporites. Diverse halite morphologies are formed at the surface, vadose and phreatic zones. The presence and preservation of these morphologies are influenced by spatially heterogenous natural and anthropogenic processes, including daily to seasonal changes in brine salinity, mineral saturation states, and water level within and across saline pan stages. In addition to hydrological balances delineated by the saline pan stages of flooding, evapoconcentration and desiccation, changes in vertical brine movement, temperature and surficial sedimentary structures influence evaporite morphologies. These results are transferable to the interpretation of altered evaporites and enhancing saline pan depositional models.

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

“…Four primary sediment cores (SOL, SC1, and colocated cores WS1 and WS2; Table 1) were collected from BSF with a "vibracore" system (Lanesky et al, 1979) in 2017 and 2019 (Table 1). Samples from core D35 (described in Bowen et al, 2018b) and from crust sample D45 (Bernau and Bowen, 2021) were also studied (Fig. 1B).…”

“…(C) Cross section A-A ′ of saline pan sediments. (B and C) Adapted from Bernau and Bowen (2021). Bernau et al, 2023; Fig.…”

“…saline depositional environment where halite crystallized in situ from surface water and was later altered by dissolution and secondary halite growth (Bernau and Bowen, 2021). Subunit Ic is more extensive and thicker than subunit Id.…”

“…BSF is valued for potash production and recreation, including vehicular land-speed racing (Bowen et al, 2018a). Researchers have extensively studied the hydrology and salt crust dynamics of BSF over the past century (e.g., Nolan, 1927;Turk, 1973;Lines, 1979;Mason and Kipp, 1998;Bowen et al, 2017Bowen et al, , 2018bBernau and Bowen, 2021). However, BSF's depositional history has poor temporal constraints, and the conditions that led to saline pan formation at BSF are poorly understood.…”

Metabolic Potential of Microbial Communities in the Hypersaline Sediments of the Bonneville Salt Flats

“…Despite the sterile surface appearance of BSF, the shallow subsurface hosts remarkably robust microbial communities. These are visible as colorful pigments just below the top layer of the halite crust, and signs of life are observed within and upon the evaporite sediments with microscopy ( 9 ). However, the role of the microbial ecosystem within the geochemical and mineralogical evolution of the salt flats is generally unknown.…”