Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4698739 | Chemical Geology | 2014 | 18 Pages |
Abstract
87Sr/86Sr ratios are correlated with δ18O values only during the Laney Member, when both are readily explained by a common forcing mechanism (drainage capture). Modeling of Sr isotope compositions and concentrations indicates a short residence time for Sr (~ 103-104 years or less) in both balance-overfilled and underfilled phases of the Green River Formation lacustrine system. This in turn suggests that paleo-lacustrine sediments in most lakes can preserve Sr isotope records with high-resolution (~ 102 years) timescales. Rates of Sr sequestration in carbonate are shown to have a strong influence on lacustrine Sr concentration, and high Sr concentrations of lacustrine carbonate consistent with high salinity are observed in the underfilled Wilkins Peak Member and the balance-filled Tipton and lower Laney Members. In the Laney Member, 87Sr/86Sr mass-balance modeling results provide additional support for previous interpretations that the introduction of a large drainage system produced an isotopic shift across the lower LaClede/upper LaClede boundary. Major drainage reorganization is not required to drive high variability in 87Sr/86Sr ratios, however. Modeling shows that variability in 87Sr/86Sr ratios of ~ 0.004 observed in the Wilkins Peak Member can be explained by change in the characteristics of intrabasinal water sources during highstand vs. lowstand conditions.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Amalia C. Doebbert, Clark M. Johnson, Alan R. Carroll, Brian L. Beard, Jeffrey T. Pietras, Meredith Rhodes Carson, Brooke Norsted, L. Ashley Throckmorton,