An official website of the United States government
The Denali Ice Cores were collected from the summit of Begguya (Mt. Hunter), Denali National Park, Alaska in the summer of 2013. Sampling permits were granted by Denali National Park for the drilling and removal of the ice cores. Here, we use the Tescan II at the University of Maine to examine tephra particles recovered from the ice cores.
more »
« less
University of Maine EMPA Tephrochronology Method for the Denali Ice Cores
The Denali Ice Cores were collected from the summit of Begguya (Mt. Hunter), Denali National Park, Alaska in the summer of 2013. Sampling permits were granted by Denali National Park for the drilling and removal of the ice cores. Here, we use the Cameca SX100 at the University of Maine to examine tephra particles recovered from the ice cores.
more »
« less
- Award ID(s):
- 2002483
- PAR ID:
- 10616971
- Publisher / Repository:
- Interdisciplinary Earth Data Alliance (IEDA)
- Date Published:
- Subject(s) / Keyword(s):
- Regional (Continents, Oceans) Tephrochronology, volcanoes, tephra, glass, volcanic eruptions, ice, ice cores, glaciers, paleoclimate, EPMA, electron probe microanalysis, methodology
- Format(s):
- Medium: X Other: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
- Location:
- Alaska, Denali National Park, Begguya, Mount Hunter, Denali Ice Cores; (East Bound Longitude:-151.09; North Bound Latitude:62.93; South Bound Latitude:62.93; West Bound Longitude:-151.09)
- Right(s):
- Creative Commons Attribution 4.0 International [CC-BY-4.0]
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
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.more » « less
-
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.more » « less
-
Abstract. Investigating North Pacific climate variability during warmintervals prior to the Common Era can improve our understanding of thebehavior of ocean–atmosphere teleconnections between low latitudes and theArctic under future warming scenarios. However, most of the existing icecore records from the Alaskan and Yukon region only allow access to climateinformation covering the last few centuries. Here we present asurface-to-bedrock age scale for a 210 m long ice core recovered in 2013from the summit plateau of Begguya (Mt. Hunter; Denali National Park,Central Alaska). Combining dating by annual layer counting with absolutedates from micro-radiocarbon dating, a continuous chronology for the entireice core archive was established using an ice flow model. Calibrated14C ages from the deepest section (209.1 m, 7.7 to 9.0 ka cal BP)indicate that basal ice on Begguya is at least of early Holocene origin. Aseries of samples from a shallower depth interval (199.8 to 206.6 m) weredated with near-uniform 14C ages (3 to 5 ka cal BP). Our resultssuggest this may be related to an increase in annual net snow accumulationrates over this period following the Northern Hemisphere Holocene ClimateOptimum (around 8 to 5 kyr BP). With absolute dates constraining thetimescale for the last >8 kyr BP, this paleo-archive will allowfuture investigations of Holocene climate and the regional evolution ofspatial and temporal changes in atmospheric circulation and hydroclimate inthe North Pacific.more » « less
-
Hopkins, Jack (Ed.)Abstract Carrion represents an important resource for carnivores. Examining competition for carrion in a risk–reward framework allows for a better understanding of how predator guilds compete for and benefit from carrion. We used trail camera data to compare wintertime carrion use and vigilance behavior of four carnivores in Denali National Park and Preserve. We found that carrion use was dominated by wolves (Canis lupus) and wolverines (Gulo gulo), followed by red foxes (Vulpes vulpes) and coyotes (Canis latrans). Wolves and wolverines were twice as likely to visit a carcass as foxes and coyotes, and their visits were longer and more numerous. Our results suggest scavenging animals reduced their risk exposure primarily by reducing their use of carrion, with some evidence of increased vigilance at busy sites. We found that carrion use and behavior at carcass sites were influenced by the mortality type of the carcass, the age of the carcass, and the long-term intensity of wolf use in the area. Our results also suggest that wolves are the “top scavenger,” and indicate that intraguild competition for carrion strongly affects which species benefit from carrion, with larger and more aggressive species dominating.more » « less
