A ∼33,000 year record of environmental change from Arolik Lake, Ahklun Mountains, Alaska, USA

Darrell S. Kaufman, Feng Sheng Hu, Jason P. Briner, Al Werner, Bruce P. Finney, Irene Gregory-Eaves

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

A continuous record of lacustrine sedimentation capturing the entire full-glacial period was obtained from Arolik Lake in the Ahklun Mountains, southwestern Alaska. Fluctuations in magnetic susceptibility (MS), grain size, organic-matter (OM) content, C/N ratios, δ13C, and biogenic silica (BSi) record marked environmental changes within the lake and its watershed during the last ∼33 cal ka. Age control is provided by 31 14C ages on plant macrofossils in four cores between 5.2 and 8.6 m long. Major stratigraphic units are traceable throughout the lake subbottom in acoustical profiles, and provisional ages are derived for six prominent tephra beds, which are correlated among the cores. During the interstadial interval between ∼33 and 30 cal ka, OM and BSi contents are relatively high with values similar to those of the Pleistocene-Holocene transition, suggesting a similar level of aquatic productivity. During the glacial interval that followed (∼30-15 cal ka), OM and BSi decrease in parallel with declining summer insolation. OM and BSi values remain relatively uniform compared with the higher variability before and after this interval, and they show no major shifts that might correlate with climate fluctuations evidenced by the local moraine record, nor with other global climate changes. The glacial interval includes a clay-rich unit with a depauperate diatom assemblage that records the meltwater spillover of an ice-dammed lake. The meltwater pulse, and therefore the maximum extent of ice attained by a major outlet glacier of the Ahklun Mountain ice cap, lasted from ∼24 to 22 cal ka. The Pleistocene-Holocene transition (∼15-11 cal ka) exhibits the most prominent shifts in OM and BSi, but rapid and dramatic fluctuations in OM and BSi continue throughout the Holocene, indicating pronounced paleoenvironmental changes.

Original languageEnglish (US)
Pages (from-to)343-361
Number of pages19
JournalJournal of Paleolimnology
Volume30
Issue number4
DOIs
StatePublished - Nov 2003

Keywords

  • Ahklun Mountains
  • Alaska
  • Lake core
  • Paleoenvironment
  • Quaternary

ASJC Scopus subject areas

  • Aquatic Science
  • Earth-Surface Processes

Fingerprint Dive into the research topics of 'A ∼33,000 year record of environmental change from Arolik Lake, Ahklun Mountains, Alaska, USA'. Together they form a unique fingerprint.

  • Cite this