LLNL/UC AMS facility and research program

Davis, J.C.; Proctor, I.D.; Southon, John; Caffee, Marc W.; Heikkinen, D.W.; Roberts, M.L.; Moore, Thomas L.; Turteltaub, Ken W; Nelson, D. E.; Loyd, D. H.; Vogel, John S.

doi:10.1016/0168-583x(90)90419-u

Cited by 159 publications

(88 citation statements)

References 3 publications

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“…Carbonate samples (~0.3 mg) were processed at the Lawrence Livermore National Laboratory Center for Accelerator Mass Spectrometry (LLNL-CAMS) (Davis et al 1990). Calcite powder was evacuated to below 20 mTorr in a 10-mL vacutainer and then reacted with 0.5 mL of phosphoric acid to generate CO 2 .…”

Section: Discussionmentioning

confidence: 99%

Intrashell Radiocarbon Variability in Marine Mollusks

Culleton¹,

Kennett

Ingram

et al. 2006

Radiocarbon

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We demonstrate variable radiocarbon content within 2 historic (AD 1936) and 2 prehistoric (about 8200 BP and 3500 BP) Mytilus californianus shells from the Santa Barbara Channel region, California, USA. Historic specimens from the mainland coast exhibit a greater range of intrashell variability (i.e. 180–240 14C yr) than archaeological specimens from Daisy Cave on San Miguel Island (i.e. 120 14C yr in both shells). δ13C and δ18O profiles are in general agreement with the up welling of deep ocean water depleted in 14C as a determinant of local marine reservoir correction (ΔR) in the San Miguel Island samples. Upwelling cycles are difficult to identify in the mainland specimens, where intrashell variations in 14C content may be a complex product of oceanic mixing and periodic seasonal inputs of 14C-depeleted terrestrial runoff. Though the mechanisms controlling ΔR at subannual to annual scales are not entirely clear, the fluctuations represent significant sources of random dating error in marine environments, particularly if a small section of shell is selected for accelerator mass spectrometry (AMS) dating. For maximum precision and accuracy in AMS dating of marine shells, we recommend that archaeologists, paleontologists, and 14C lab personnel average out these variations by sampling across multiple increments of growth.

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Section: Discussionmentioning

confidence: 99%

Intrashell Radiocarbon Variability in Marine Mollusks

Culleton¹,

Kennett

Ingram

et al. 2006

Radiocarbon

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“…Soils additionally underwent incubation for estimates of biomass abundances and C use efficiencies [9]. Radiocarbon abundance of bulk soils and density separates were measured by accelerator mass spectrometry at the NSF-Arizona AMS Laboratory at the University of Arizona (Tucson, AZ, USA) [40], the Centro Nacional de Aceleradores (Seville, Spain) [41], and the Center for AMS at Lawrence Livermore National Laboratory (Livermore, CA, USA) [42,43]. For each horizon, density/aggregate fractions and bulk soils from each site were composited for AMS analysis.…”

Section: Methodsmentioning

confidence: 99%

Variation in the Molecular Structure and Radiocarbon Abundance of Mineral-Associated Organic Matter across a Lithosequence of Forest Soils

et al. 2018

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Soil mineral assemblage influences the abundance and mean residence time of soil organic matter both directly, through sorption reactions, and indirectly, through influences on microbial communities. Though organo-mineral interactions are at the heart of soil organic matter cycling, current models mostly lack parameters describing specific mineral assemblages or phases, and treat the mineral-bound pool as a single homogenous entity with a uniform response to changes in climatic conditions. We used pyrolysis GC/MS in combination with stable isotopes and radiocarbon abundance to examine mineral-bound soil organic matter fractions from a lithosequence of forest soils. Results suggest that different mineral assemblages tend to be associated with soil organics of specific molecular composition, and that these unique suites of organo-mineral complexes differ in mean residence time. We propose that mineralogy influences the composition of the mineral-bound soil organic matter pool through the direct influence of mineral surface chemistry on organo-mineral bond type and strength in combination with the indirect influence of soil acidity on microbial community composition. The composition of the mineral-bound pool of soil organic matter is therefore partially dictated by a combination of compound availability and sorption affinity, with compound availability controlled in part by microbial community composition. Furthermore, results are suggestive of a preferential sorption of N-containing moieties in Fe-rich soils. These bonds appear to be highly stable and confer extended mean residence times.

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“…Be and Al were separated by anion and cation exchange ion chromatography in a chloride medium and purified by reprecipitation of the hydroxides. 10 Be and 26 Al accelerator mass spectrometry (AMS) measurements were carried out at the Lawrence Livermore National Laboratory AMS facility [Davis et al, 1990]. The observed ratios were normalized to ICN 10 Be and National Institute of Science and Technology 26 Al standards that were diluted by K. Nishiizumi (personal communication, 1995).…”

Section: Appendix B: Sampling and Cosmogenic Datingmentioning

confidence: 99%

Irregular earthquake cycle along the southern Tianshan front, Aksu area, China

et al. 2005

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[1] A long deformation record ($16.5 ka) showing nonsteady earthquake recurrence is established for the Aksu thrust (Tianshan, China) on the basis of cosmogenic 10 Be dating of faulted surfaces. Topographic leveling across the Aksu fault scarp indicates up to $10 m uplift across a moraine abandoned $16.5 ka and similar uplift of $6 m across two inset surfaces yielding ages of $12.5 and $5 ka. Successively smaller uplifts of terraces younger than 5 ka indicate that three or more major earthquakes occurred during this period. These data show that the Aksu thrust fault was quiet for at least 7500 years and active in the last $5000 years and probably in the interval 16.5-12.5 ka. The seismic cycle along the Aksu thrust fault over the last $16,500 years was thus strongly irregular showing long quiescence and clustering, which is a challenge for paleoseismology and hazard assessment. This irregularity also makes it more difficult to estimate long-term shortening rates. Nevertheless, we are able to constrain a minimum total shortening rate (>7 mm/yr) across the southern Tianshan front for the last 12,500 years that is about a third of the total geodetic rate for the western Tianshan ($20 mm/yr).

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LLNL/UC AMS facility and research program

Cited by 159 publications

References 3 publications

Intrashell Radiocarbon Variability in Marine Mollusks

Intrashell Radiocarbon Variability in Marine Mollusks

Variation in the Molecular Structure and Radiocarbon Abundance of Mineral-Associated Organic Matter across a Lithosequence of Forest Soils

Irregular earthquake cycle along the southern Tianshan front, Aksu area, China

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