AVO Logo
Site Map | FAQ |
Alaska Volcano Observatory
 
You are here: Home > Samples > UA1124

SAMPLE INFO : UA1124
Sample ID:UA1124
Station ID:Palisades_Site_B
Latitude:65.09
Longitude:-153.25997
Datum:NAD83
Sample Type 1:Tephra Fall
Text Description:
Tephra occurs ~25 m above river level and is 3.5 m below woody, organic-rich silt and peat that host abundant and exceptionally well-preserved large stumps and logs. The tephra is up to 10 cm thick and has sharp upper and lower contacts with the surrounding grey silt, which is massive and contains rare rootlets as well as local orange mottling and thin wavy organic laminae. The tephra bed is not uniformly tabular; locally it is offset by cm-scale faults, or appears as stretched pods or lenses. At least two frost cracks, including one ~12 cm long, incorporate wisps of tephra and small angular blocks of silt. The tephra and the wood/peat horizon are separated by massive and faintly laminated grey silt.

References:
Permafrost response to last interglacial warming: field evidence from non-glaciated Yukon and Alaska
A late-Middle Pleistocene (Marine Isotope Stage 6) vegetated surface buried by Old Crow tephra at the Palisades, interior Alaska
The Palisades is a key reference site for the middle Pleistocene of eastern Beringia: new evidence from paleomagnetics and regional tephrostratigraphy
A catalogue of late Cenozoic tephra beds in the Klondike Goldfields and adjacent areas, Yukon Territory

GEOCHEM DATA
StationIDLatitudeLongitudeGeologistDateVisitedAge InfoVolcanoEruptionLocation DescriptionText DescriptionSample IDSample Type 1Sample Type 2Final UnitMaterialCoeffSiO2TiO2Al2O3FeOTMnOMgOCaONa2OK2OP2O5Total-majorsREF majorsMETH majorsFe2O3/Fe203T origFeO/FeOT origVolatiles csvMETH volatilesCsRbBaSrLaCePrNdSmEuGdTbDyHoErTmYbLuYZrNbHfTaPbThUScVCrFeCoNiCuZnGaMoAsNaKRef trace1METH trace1RbBaSrLaCeNdSmEuGdDyErYbLuYZrNbPbThUScTiVCrNiCuZnGaRef trace2METH trace2Light csvHalogen csvother major csvother lile csvother ree csvother hfse csvother hpe csvother tm csvother misc csv
Palisades_Site_B65.09-153.25997Froese, D. G.0000-00-00 124000 ± 10000 known unit; 10271; Age is approximate. Revised glass fission-track age with re-calibration; four Old Crow Tephra sample glass fission-track ages (UT1434, UT613, UT501, UT613).North-facing river-cut exposures on the Yukon River in Alaska about 70 km downstream of the village of Tanana. Site B at Palisades East is a series of shallow gullies emanating from the edge of a retrogressive thaw slump. Active slumping in 2005 exposed frozen sediments near Old Crow tephra, but most of the upper exposure was covered in 2007. The section is dominated by massive to weakly laminated silt, with rare beds of organic-rich silt and peat. Several tephra beds are present in the lower ~15 m of the exposure, but here we focus on the interval between 24 and 30 m above river level. Location imprecisely georeferenced from Figure 1 of Reyes et al. (2010).Tephra occurs ~25 m above river level and is 3.5 m below woody, organic-rich silt and peat that host abundant and exceptionally well-preserved large stumps and logs. The tephra is up to 10 cm thick and has sharp upper and lower contacts with the surrounding grey silt, which is massive and contains rare rootlets as well as local orange mottling and thin wavy organic laminae. The tephra bed is not uniformly tabular; locally it is offset by cm-scale faults, or appears as stretched pods or lenses. At least two frost cracks, including one ~12 cm long, incorporate wisps of tephra and small angular blocks of silt. The tephra and the wood/peat horizon are separated by massive and faintly laminated grey silt.UA1124Tephra FallCumulateGlass 75.32 0.3 13.02 1.77 0.06 0.29 1.49 3.82 3.63 8023EMP1.77Cl=0.27; H2O=3.64EMP 4.34 102 989 139 25.2 53.8 6 24.4 5.79 0.94 5.13 0.96 5.55 1.34 3.62 0.56 3.74 0.58 35.1 252 7.49 9.88 4.42 6.02 10271ICPMS
Palisades_Site_B65.09-153.25997Froese, D. G.0000-00-00 124000 ± 10000 known unit; 10271; Age is approximate. Revised glass fission-track age with re-calibration; four Old Crow Tephra sample glass fission-track ages (UT1434, UT613, UT501, UT613).North-facing river-cut exposures on the Yukon River in Alaska about 70 km downstream of the village of Tanana. Site B at Palisades East is a series of shallow gullies emanating from the edge of a retrogressive thaw slump. Active slumping in 2005 exposed frozen sediments near Old Crow tephra, but most of the upper exposure was covered in 2007. The section is dominated by massive to weakly laminated silt, with rare beds of organic-rich silt and peat. Several tephra beds are present in the lower ~15 m of the exposure, but here we focus on the interval between 24 and 30 m above river level. Location imprecisely georeferenced from Figure 1 of Reyes et al. (2010).Tephra occurs ~25 m above river level and is 3.5 m below woody, organic-rich silt and peat that host abundant and exceptionally well-preserved large stumps and logs. The tephra is up to 10 cm thick and has sharp upper and lower contacts with the surrounding grey silt, which is massive and contains rare rootlets as well as local orange mottling and thin wavy organic laminae. The tephra bed is not uniformly tabular; locally it is offset by cm-scale faults, or appears as stretched pods or lenses. At least two frost cracks, including one ~12 cm long, incorporate wisps of tephra and small angular blocks of silt. The tephra and the wood/peat horizon are separated by massive and faintly laminated grey silt.UA1124Tephra FallCumulateGlass 75.32 0.3 13.05 1.77 0.06 0.29 1.49 3.82 3.63 8083EMP1.77Cl=0.27; H2O=3.64EMP

SAMPLE LOCATION

Contact AVO Privacy Accessibility Information Quality FOIA
URL: avo.alaska.edu/samples/sample_info.php
Page modified: August 1, 2017 15:29
Contact Information: AVO Web Team

twitter @alaska_avo
facebook alaska.avo
email Receive volcano updates by email: USGS VNS

This website is supported by the U.S. Geological Survey under Cooperative Agreement Grant G22AC00137

Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey.