Supplemental Material: Hydrogeochemical evolution of formation waters responsible for sandstone bleaching and ore mineralization in the Paradox Basin, Colorado Plateau, USA

Abstract

Table S1: (ST1). PHREEQC inverse mixing modeling for the Mississippian Leadville Ls brine (Solution 3) assumed to be evolved from a mixture of the meteoric water endmember (Solution 1) and evaporated paleo-seawater endmember (Solution 2); Table S2: (ST2). PHREEQC inverse mixing modeling for the salt anticline brine (Solution 3) assumed to be evolved from a mixture of the meteoric water endmember (Solution 1) and evaporated paleo-seawater endmember (Solution 2).

Krypton‐81 Dating Constrains Timing of Deep Groundwater Flow Activation

“…For example, the Leadville Ls brine contains ∼74% meteoric water and ∼26% EPS based on δD water values. This is somewhat consistent with PHREEQC inverse mixing model results using major ion chemistry indicating 96% meteoric water and 4% EPS in the Leadville Ls brine sample (Kim et al, 2022). Both results are in qualitative agreement with the high proportion of meteoric waters in the lower hydrostratigraphic unit, dilution of connate saline fluids, and regeneration of salinity via salt dissolution.…”

“…Detailed methods for sampling and analysis are described in Text S1 in Supporting Information S1. 81 Kr results were paired with previously published hydrochemical data (Kim et al, 2022), from corresponding water samples from the same wells (where available) or the same fields where the gas samples were collected (Table S2 in Supporting Information S1). The hydrochemical data were used to calculate the extent of meteoric recharge, salt dissolution, and mixing with remnant EPS-derived brines.…”

“…Hydrochemical data, including Na/Cl, Cl/Br, and δD water were compiled from previously published sources (Blondes et al, 2018;Hanshaw & Hill, 1969;Kim et al, 2022) to calculate the extent of meteoric recharge, salt dissolution, and mixing with remnant EPS-derived brines.…”

“…Kr, Na, Cl, Br, and δD water data is stored and publicly available on Hydroshare (at: https://doi.org/10.4211/ hs.d2a724a994b34fa3880ca21562912788). Hydrochemical data (Na, Cl, Br, and δD water ) are available through Hanshaw and Hill (1969), Spangler et al (1996), Blondes et al (2018), andKim et al (2022). 14 C data are available through Noyes et al (2021)…”

“…In addition to the salt dissolution-derived brines, EPS within the Paradox Fm, represented by a brine sample from the Cane Creek member ("Cane Creek brine"), is another major source of salinity in the formation waters of the Paradox Basin and has a distinct geochemical and isotopic signature with low Na/Cl (0.2), Na/Br (28), and Cl/ Br (156) molar ratios relative to modern seawater (0.85, 565, and 659, respectively) and the highest δ 18 O water and δD water values, plotting to the right of the Local Meteoric Water Line (Table S2 in Supporting Information S1; Kim et al, 2022). δD water values (Figures 2b and 2c; Table S2 in Supporting Information S1) show the variable amount of mixing between meteoric water recharge and remnant EPS for each formation water.…”