Cyclic variations of uranium concentrations and oxygen isotopes in tufa from the middle Miocene Barstow Formation, Mojave Desert, California

Becker, Mona Louise; Cole, Jennifer; Rasbury, E. Troy; Pedone, Vicki A.; Montañez, Isabel P.; Hanson, Gilbert N.

doi:10.1130/0091-7613(2001)029<0139:cvouca>2.0.co;2

Cited by 20 publications

(20 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The densely laminated calcite is composed of layers of bladed calcite terminated by microcrystalline calcite (cf. Becker et al ., 2001) and appears to be an early precipitate (e.g. Figs 5A and 6A).…”

Section: Tufa Mound Depositsmentioning

confidence: 99%

“…The bladed calcite in the densely laminated cement is often dully orange luminescent (Fig. 7C and F), similar to the sample described by Becker et al . (2001).…”

Section: Tufa Mound Depositsmentioning

confidence: 99%

“…8), suggesting the flow of a later, reducing fluid through the mounds. This later cement contains almost no U (Becker et al ., 2001). Phosphor imaging also shows the densely laminated calcite to be more enriched in U (Figs 5 and 6A and B), even though samples that are almost completely spongy in morphology can have significant U enrichments (Fig.…”

Section: Tufa Mound Depositsmentioning

confidence: 99%

“…Tufa deposits of the middle Miocene Barstow Formation have significant U enrichments, and U has been shown to occur in cyclic repetitions of low to high U concentrations (Becker et al ., 2001). This and other analogous tufa calcites have also yielded precise U‐Pb ages (Cole, 2003).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Petrographic and trace element analysis of uranium‐rich tufa calcite, middle Miocene Barstow Formation, California, USA

et al. 2004

Self Cite

View full text Add to dashboard Cite

An integrated petrographic and spectroscopic (X‐ray diffraction, phosphor imaging and synchrotron X‐ray absorption spectroscopy) study of tufas from the Miocene Barstow Formation, California, relates sample morphology, mineralogy and geochemical composition. The tufas, composed mainly of calcite that formed at the interface between an ancient alkaline lake and ground or spring waters, have textures similar to those of microbially mediated terrestrial stromatolites and travertines. The tufas have elevated concentrations of a number of trace elements including Mn, Fe, Sr and U. Synchrotron X‐ray fluorescence analyses show that U concentrations can exceed 500 p.p.m. X‐ray absorption spectroscopy indicates that the U in these samples is incorporated as U(IV). It is suggested here that alkaline lake waters had a high U/Ca ratio and tufa calcite formed where groundwater or (possibly epithermal) springs brought in Ca and trace elements such as Sr. The rapid, and possibly microbially mediated, precipitation of calcite allowed for incorporation of high concentrations of trace metals as either structural substitutes or extremely fine‐scale inclusions.

show abstract

Section: Tufa Mound Depositsmentioning

confidence: 99%

“…The bladed calcite in the densely laminated cement is often dully orange luminescent (Fig. 7C and F), similar to the sample described by Becker et al . (2001).…”

Section: Tufa Mound Depositsmentioning

confidence: 99%

Section: Tufa Mound Depositsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Petrographic and trace element analysis of uranium‐rich tufa calcite, middle Miocene Barstow Formation, California, USA

et al. 2004

Self Cite

View full text Add to dashboard Cite

show abstract

“…One well-known example is the Lower Permian Karniowice travertine of Poland, where a rich fossil fl ora and fauna has been uncovered (Szulc and Cwizewicz, 1989). There is evidence that tufas date back to at least the Tertiary within the Barkly karst area of Queensland, Australia (Carthew et al, 2003b), and they have also been recorded in the Eocene Chadron Formation in South Dakota (Evans, 1999), the middle Miocene Barstow Formation in the Mojave Desert of California, USA (Becker et al, 2001), and in the Miocene Ries crater basin in Germany (Pache et al, 2001). …”

Section: Distribution Field Occurrence and Geomorphological Relationsmentioning

confidence: 99%