Insights into combined radiogenic and stable strontium isotopes as tracers for weathering processes in subglacial environments

Stevenson, Emily; Aciego, S.; Chutcharavan, Peter M.; Parkinson, I. J.; Burton, Kevin W.; Blakowski, Molly A.; Arendt, Carli A.

doi:10.1016/j.chemgeo.2016.03.008

Cited by 45 publications

(27 citation statements)

References 59 publications

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“…Sr isotope measurements were carried out on a Thermo-Finnigan Triton Plus TIMS using the method outlined previously68. For natural runs, fractionation caused by mass-dependent evaporation during machine analysis was corrected for using 86 Sr/ 88 Sr=0.1194.…”

Section: Methodsmentioning

confidence: 99%

Dust outpaces bedrock in nutrient supply to montane forest ecosystems

et al. 2017

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Dust provides ecosystem-sustaining nutrients to landscapes underlain by intensively weathered soils. Here we show that dust may also be crucial in montane forest ecosystems, dominating nutrient budgets despite continuous replacement of depleted soils with fresh bedrock via erosion. Strontium and neodymium isotopes in modern dust show that Asian sources contribute 18–45% of dust deposition across our Sierra Nevada, California study sites. The remaining dust originates regionally from the nearby Central Valley. Measured dust fluxes are greater than or equal to modern erosional outputs from hillslopes to channels, and account for 10–20% of estimated millennial-average inputs of bedrock P. Our results demonstrate that exogenic dust can drive the evolution of nutrient budgets in montane ecosystems, with implications for predicting forest response to changes in climate and land use.

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Section: Methodsmentioning

confidence: 99%

Dust outpaces bedrock in nutrient supply to montane forest ecosystems

et al. 2017

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“…Sr and Nd isotopic compositions were measured on a Thermo Scientific Triton PLUS Thermal Ionization Mass Spectrometer (TIMS) following the same procedures employed by Blakowski et al (2016), Stevenson et al (2016), Clinger et al (2016) and Aarons et al (2016b). Sr measurements were normalized to 86 Sr/ 88 Sr = 0.1194 to correct for mass fractionation.…”

Section: Methodsmentioning

confidence: 99%

Geochemical characterization of critical dust source regions in the American West

Aarons

Blakowski

Aciego

et al. 2017

Geochimica et Cosmochimica Acta

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The generation, transport, and deposition of mineral dust are detectable in paleoclimate records from land, ocean, and ice, providing valuable insight into earth surface conditions and cycles on a range of timescales. Dust deposited in marine and terrestrial ecosystems can provide critical nutrients to nutrient-limited ecosystems, and variations in dust provenance can indicate changes in dust production, sources and transport pathways as a function of climate variability and land use change. Thus, temporal changes in locations of dust source areas and transport pathways have implications for understanding interactions between mineral dust, global climate, and biogeochemical cycles. This work characterizes dust from areas in the American West known for dust events and/or affected by increasing human settlement and livestock grazing during the last 150 years. Dust generation and uplift from these dust source areas depends on climate and land use practices, and the relative contribution of dust has likely changed since the expansion of industrialization and agriculture into the western United States. We present elemental and isotopic analysis of 28 potential dust source area samples analyzed using Thermal Ionization Mass Spectrometry (TIMS) for 87 Sr/ 86 Sr and 143 Nd/ 144 Nd composition and Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS) for 176 Hf/ 177 Hf composition, and ICPMS for major and trace element concentrations. We find significant variability in the Sr, Nd, and Hf isotope compositions of potential source areas of dust throughout western North America, ranging from 87 Sr/ 86 Sr = 0.703699 to 0.740236, e Nd = À26.6 to 2.4, and e Hf = À21.7 to À0.1. We also report differences in the trace metal and phosphorus concentrations in the geologic provinces sampled. This research provides an important resource for the geochemical tracing of dust sources and sinks in western North America, and will aid in modeling the biogeochemical impacts of increased dust generation and deposition caused by higher drought frequency and human activity.

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“…Large stable Sr isotopic variation has also been observed in biogenic and inorganic carbonates (Fietzke and Eisenhauer 2006;Ruggeberg et al 2008;Krabbenhoft et al 2010;Bohm et al 2012;Raddatz et al 2013;Stevenson et al 2014;Vollstaedt et al 2014), barite precipitation (Widanagamage et al 2014; and weathered residues (Halicz et al 2008;de Souza et al 2010;Krabbenhoft et al 2010;Wei et al 2013;Stevenson et al 2016), indicating the potential of using Sr isotopes as a tracer of continental weathering, marine Sr cycle, and paleoceanographic studies. In general, carbonates tend to have light Sr isotopic compositions relative to seawater, which has a homogenous δ 88 Sr of 0.387 ± 0.002‰ (2SE mean) (Shalev et al 2013).…”

Section: Stable Strontium Isotope Geochemistrymentioning

confidence: 99%