[open quotes]Varve[close quotes] counting vs. tephrochronology and [sup 137]Cs and [sup 210]Pb dating: A comparative test at Skilak Lake, Alaska

Journal Article · Sun Nov 01 00:00:00 EST 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<1019:VCVTAC>2.3.CO;2· OSTI ID:6980461

Stihler, S D; Stone, D B; Beget, J E ^[1]

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1. Univ. of Alaska, Fairbanks, AK (United States)

The age of recently deposited sediments in Skilak Lake has previously been estimated only by counting [open quotes]varves[close quotes]. We measured the sedimentation rate of Skilak Lake using two radionuclides, [sup 137]Cs and [sup 210]Pb, and found it to be about an order of magnitude lower than previous estimates based on varve counts. We also identified several tephras through a combination of visual inspection, core X-radiographs, observation of variations of the magnetic susceptibility, intensity of magnetization of the unconsolidated sediments, and microprobe analyses of volcanic glass shards. Tephrochronologic dates using matches with the Katmai 1912 tephra and an Augustine tephra from 500-550 yr B.P. are in good agreement with the sedimentation rate estimates based on the radioisotope data, and indicate that the rhythmite layers at Skilak Lake are not annual varves. These new estimates of sedimentation rate reaffirm that care is needed in varve dating and require that earlier work on sunspot and climate changes thought to have been recorded in the Skilak Lake sediments be reevaluated. 16 refs., 6 figs., 1 tab.

• OSTI ID: 6980461
• Journal Information: Geology; (United States), Vol. 20:11; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ALASKA
SEDIMENTATION
CLIMATIC CHANGE
GLOBAL ASPECTS
SEDIMENTS
ISOTOPE DATING
SUNSPOTS
CESIUM 137
LEAD 210
AGE ESTIMATION
ALKALI METAL ISOTOPES
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CESIUM ISOTOPES
DEVELOPED COUNTRIES
EVEN-EVEN NUCLEI
HEAVY NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
LEAD ISOTOPES
NORTH AMERICA
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
SOLAR ACTIVITY
STARSPOTS
STELLAR ACTIVITY
USA
YEARS LIVING RADIOISOTOPES
540110*