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In 2013, two parallel ice cores (commonly referred to as the Denali Ice Cores) were drilled to bedrock on the summit plateau of Begguya, Alaska (62.93 N 151.083 W, 3912 m asl; also known as Mount Hunter). A robust chronology has been developed using a combination of techniques including annual layer counting, sulfate peaks (volcanics), radiocarbon dating and the 1963 atmospheric nuclear weapons testing horizon. Here, we employed tephrochronology practices to isolate and document the presence of the Lena Ash Layer and White River Ash east (WRAe) volcanic eruptions within the ice. We separated tephra from the meltwater and analyzed them using SEM-EDS and EPMA methodologies. The data are not immediately conclusive, and work is still ongoing to understand the findings.
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Denali Ice Core trace element laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data in basal ice, Begguya Plateau, Denali National Park, Alaska, 2025
A robust chronology has been developed for the Denali Ice Cores, Begguya, Alaska (62.93 N 151.083 W, 3912 m asl (meters above sea level); also known as Mount Hunter) using a combination of techniques including annual‑layer counting, volcanics, radiocarbon dating, and the 1963 atmospheric nuclear‑weapons‑testing horizon. Radiocarbon dating confirms that there is early Holocene ice preserved at the bottom of the Denali Ice Cores. To confirm this, researchers at the University of Maine have produced oxygen‑isotope records. Examining the data from the twin cores, we see replicate isotope profiles in the bottom 8 meters of ice, showing a sharp decrease of δ^18O (oxygen‑18 isotope ratio) of nearly 6 ‰ (permil) near the bottom. To investigate whether this decrease is a climate signal or an artifact of basal‑ice dynamics, we collected trace‑element data across the oxygen‑isotope decrease. Because the basal ice of the Denali Ice Cores contains too high a sediment load to be melted and analyzed with aqueous inductively coupled plasma mass spectrometry (ICP‑MS), we analyzed Na (sodium), Mg (magnesium), Cu (copper), Pb (lead), Al (aluminum), Ca (calcium), Fe (iron), and S (sulfur) in the basal ice (207.35 m to 208.76 m depth) using laser‑ablation inductively coupled plasma mass spectrometry (LA‑ICP‑MS). The data are still being analyzed and compared with data from other methods to determine the cause of the oxygen‑isotope‑signal decrease. Researchers seeking to use this dataset should proceed with caution, as there is some evidence of contamination in the Pb and Cu analyses.
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- Award ID(s):
- 2002483
- PAR ID:
- 10624931
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- Denali Ice Cores Begguya Alaska Ice cores paleoclimate laser ablation LA-ICP-MS cryo-LA-ICP-MS laser ablation inductively coupled plasma mass spectrometry trace element chemistry
- Format(s):
- Medium: X Other: text/xml
- Sponsoring Org:
- National Science Foundation
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{"Abstract":["Two parallel surface-to-bedrock ice cores (DEN-13A and DEN-13B) were drilled from the Begguya summit plateau in Denali National Park, Alaska (62.93 N 151.083 W, 3912 m asl; also known as Mount Hunter), during the summer of 2013. The summit of Begguya has a high accumulation rate and low melt rate, making it an ideal site to recover intact paleoclimate records. DEN-13A and DEN-13B, which reach depths of ~210 meters, respectively, cover at least 10,000 years (Fang et al., 2023). Shallow cores were drilled in the summers of 2019 (DEN-19A; 50 meters) and 2022 (DEN-22A; 20 meters) extend the paleoclimate record at this site through 2022. Together, these four ice cores are commonly referred to as the Denali Ice Core record or the Begguya summit plateau ice core record. A robust chronology has been developed using a combination of techniques including annual layer counting, sulfate peaks (volcanics), radiocarbon dating and the 1963 atmospheric nuclear weapons testing horizon (Fang et al., 2023). Here, we report aqueous ICP-MS elemental concentrations and Pb isotope ratio data for the top ~1,200 years (800 to 2022 CE) of the Begguya summit plateau ice core record."],"Other":["Fang, L., Jenk, T. M., Winski, D. A., Kreutz, K. J., Brooks, H. L., Erwin, E., Osterberg, E. C., Campbell, S. W., Wake, C. P., Schwikowski, M, (2023), "Early Holocene ice on the Begguya plateau (Mt. Hunter, Alaska) revealed by ice core 14 C age constraints." The Cryosphere, 17(9):4007-4020; Osterberg, E. C., Winski, D. A., Kreutz, K. J., Wake, C. P., Ferris, D. G., Campbell, S. W., Introne, D. S., Handley, M. J., Birkel, S. D., (2017), "The 1200 year composite ice core record of Aleutian Low intensification." Geophysical Research Letters, 44(14):7447-7454."]}more » « less
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