Preliminary model of regional Mesozoic groundwater flow and uranium deposition in the Colorado Plateau

Sanford, Richard F.

doi:10.1130/0091-7613(1982)10<348:pmormg>2.0.co;2

Cited by 20 publications

(7 citation statements)

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“…The dates obtained for secondary Pb-Pb isochrons and U-Pb ratios for the sandstone-hosted uraninite samples from Utah, Adair Mine, Big Indian Wash, and Happy Jack are within uncertainty of published mineralization ages for these deposits (Tables 1 and 3; Figure 6). These Colorado Plateau hosted uranium deposits are located within Permian and Triassic formations [50,54,66]. Samples from the Big Indian Wash U deposit, which is located within the Permian Cutler Formation, define a calculated secondary (2-point) Pb-Pb age of 333 ± 19 Ma and the combined three aliquots (bulk, pristine, altered) define a discordia line with a corroborating (given associated uncertainty) upper intercept age of 261 ± 75 Ma ( Figure S3).…”

Section: Resultsmentioning

confidence: 99%

“…Big Indian Wash is hosted below both the Moss Back and Shinarump member in the Cutler formation located Permian-Triassic unconformity and consists of alternating lenses of mudstone, calcareous siltstone, and arkosic sandstone [50]. It is proposed that there are two stages of uranium mineralization within the Colorado Plateau with the oldest being syngenetic with the Chinle Formation and secondary mineralization that occurred during the Late Jurassic [50,[52][53][54]. There are reported apparent ages for uranium ore associated with the Chinle formation based on their U/Pb ratios [52,53].…”

Section: Samples and Methodsmentioning

confidence: 99%

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Geochronology of Uraninite Revisited

Corcoran

Simonetti

2020

Minerals

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Identification of uraninite provenance for the purpose of nuclear forensics requires a multifaceted approach. Various geochemical signatures, such as chondrite normalized rare earth element patterns, help identify and limit the potential sources of uraninite based on the geological setting of the uranium ore mineralization. The inclusion of accurate age determinations to discriminate geochemical signatures for natural uranium ores may help to potentially restrict geographical areas for provenance consideration. Determining a robust age for uraninite formation is somewhat difficult, due to well known, inherent difficulties associated with open system behavior that involve either uranium and/or lead loss or gain. However, open system behavior should not perturb their Pb isotopic compositions to the same degree as Pb isotopes should not fractionate during alteration processes. Here, a suite of pristine and altered samples of uraninite was examined for their Pb isotope compositions, and these yielded geologically meaningful secondary Pb–Pb isochron ages. The degree of alteration within individual uraninite samples, which is extremely variable, does not appear to affect the calculated ages. The approach adopted here yields insightful age information, and hence, is of great value for source attribution in forensic analyses of raw nuclear materials.

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Section: Resultsmentioning

confidence: 99%

Section: Samples and Methodsmentioning

confidence: 99%

Geochronology of Uraninite Revisited

Corcoran

Simonetti

2020

Minerals

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“…As noted by Barton et al (2018a), paleofluids in the basin included meteoric, connate and magmatic water, potassium‐rich brines, CO 2 , H 2 S and hydrocarbons. These fluids interacted with one another and with host rocks to mobilise, transport and redistribute an assortment of metals (e.g., Cu, Fe, Mn, Mo, Pb, U, V) throughout the basin (e.g., Beitler et al, 2005; Chenoweth, 1996; Sanford, 1982; Thorson, 2018; Wigley et al, 2012). These metals are locally concentrated into economically significant deposits, most of which occur in Triassic to Lower Cretaceous sandstones (Barton et al, 2018b; Hahn & Thorson, 2005), along major fault zones (Breit & Meunier, 1990; Jacobs & Kerr, 1965; MacIntyre et al, 2005; Shawe, 2011), or along the margins of salt walls (Breit et al, 1990; Thorson, 2018).…”

Section: Discussionmentioning

confidence: 99%

A two‐stage, fault‐controlled paleofluid system at the southern termination of the Gypsum Valley salt wall, Paradox Basin, Colorado, USA

et al. 2022

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This study combines field structural analysis with thin‐section petrography, U‐Pb dating, and strontium, carbon and oxygen isotopic analysis of calcite fracture fills to constrain the evolution of the 2‐5 km scale paleofluid system around the faulted, plunging fold nose comprising the southern termination of the Gypsum Valley salt wall in the Paradox Basin, U.S.A. Brittle deformation in this region began with the formation of a down‐to‐the‐northeast, counter‐regional fault and then progressed into jointing and faulting in a radial pattern, followed by jointing in a concentric pattern. Coupled with increases in fracture abundance toward the faults, multiple stages of mineralization suggest that the faults served as efficient and long‐lived conduits for vertical fluid migration. Although fracture cement textures and calcite colour are variable throughout the area, the distribution of these characteristics does not correlate with fracture orientation, relative age, stratigraphic or structural position. Irrespective of the type of calcite comprising the fracture cements, δ13C values average near −7‰ (VPDB), whereas δ18O values cluster into groups whose averages are roughly 6‰ apart, with the more negative grouping stratigraphically restricted to fracture cements in Jurassic rocks. The stratigraphic segregation of δ18O values suggests the paleofluid system contained two distinct paleofluids, a more recent one comprised of meteoric waters and an older one comprising brine that originated in Pennsylvanian strata. 87Sr/86Sr ratios in fracture‐filling calcite cements indicate that the older fluid underwent fluid‐rock interaction with Permian strata and that this evolved fluid migrated upwards along the faults until the Triassic or Jurassic. Thereafter, fluid migrating along the faults was more meteoric and appears to have migrated downward along the faults, where it interacted with Permian strata. Consistent U‐Pb dates from carbonates precipitated from the older fluid suggest this stage of the paleofluid system was active around 240 Ma. Local burial history models and published temperatures for fracture cements elsewhere in the basin suggest the younger stage of the paleofluid system occurred during the Latest Cretaceous to Oligocene. This study highlights the spatial and temporal complexity of fluid systems in the vicinity of salt structures and emphasises the need to interpret them through careful integration of high resolution stratigraphic and structural data in the context of evolving salt tectonics.

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“…U mining in the region largely focused on the Shinarump Conglomerate Member of the Chinle Formation (Chinle Fm. ), and the Salt Wash Member of Morrison Formation (Figure 1B) (Rosenzweig et al, 1954;Evensen, 1958;Sanford 1982). The Shinarump (occasionally Sinarump) Member is the stratigraphically lowest portion of the Chinle Fm.…”

Section: Introductionmentioning

confidence: 99%

Uranium in Waters of The Southern Colorado Plateau: Implications for the Navajo Nation

Webster¹,

Credo²,

Ingram³

et al. 2022

Preprint

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Uranium (U) has been observed to be enriched in the waters of the southern Colorado Plateau including waters of the Navajo Nation. The region has naturally occurring U in rocks and a history of mining which may exacerbate U concentrations in waters. Despite past research into the abundance of U in the waters of the Navajo Nation, a regional framework has not been established to understand where U is typically higher and lower. We examined data collected by multiple studies and organizations to establish where and why U is likely to be enriched in waters of the Navajo Nation. Our work shows that U concentrations are related to the presence of U-rich rock bodies, elevation, and the salinity of local aquifers. Additionally, we show that U concentrations in water sources downstream from abandoned U mines are higher than they are in water sources that are not downstream from mines. Our work provides a means for understanding the patterns of U concentration in waters of the Navajo Nation and can act as a guide for local water withdrawal, as well as remediation and mitigation efforts for regional water sources.

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Preliminary model of regional Mesozoic groundwater flow and uranium deposition in the Colorado Plateau

Cited by 20 publications

References 0 publications

Geochronology of Uraninite Revisited

Geochronology of Uraninite Revisited

A two‐stage, fault‐controlled paleofluid system at the southern termination of the Gypsum Valley salt wall, Paradox Basin, Colorado, USA

Uranium in Waters of The Southern Colorado Plateau: Implications for the Navajo Nation

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