AVO Logo
Site Map | FAQ |
Alaska Volcano Observatory
 
You are here: Home > Samples > Jensen_Palisades_East_PAL_tephra_average-Pop.1

SAMPLE INFO : Jensen_Palisades_East_PAL_tephra_average-Pop.1
Sample ID:Jensen_Palisades_East_PAL_tephra_average-Pop.1
Station ID:Jensen_Palisades_East
Latitude:65.1
Longitude:-153.19997
Datum:NAD83
Sample Type 1:Tephra Fall
Text Description:
The composition reported here is the average of analyses of six samples: UA1199, UA1200, UA1201, UA1305, UA1306, and UA1307. Strikingly pink tephra that is one of the most prominent tephra beds found at the Palisades. Collected at all logged sites across Palisades East, except Site F, and as two opportunistically collected samples while tracing the tephra laterally across the exposure. It was generally found below a peat, although organic-rich silt and peat deposits were also found below it at several sites (Fig.2; Jensen and others, 2013). Site D1, which contains a primary bed of PAL complete with root casts and laminations, appears to be the least disturbed measured section (Fig. 4A; Jensen and others, 2013). There, PAL is overlain by a 1 m thick peat bed, while organic-rich silt with large woody macrofossils is present w2 m below the tephra (Figs. 2 and 4B; Jensen and others, 2013). Primary beds of PAL are 2-5 cm thick, but locally the bed is reworked to thicknesses of 10-20 cm. Glass morphology is diverse, and includes tricuspate and bubble-walled shards, and blocky to frothy pumice.

References:
The Palisades is a key reference site for the middle Pleistocene of eastern Beringia: new evidence from paleomagnetics and regional tephrostratigraphy

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
Jensen_Palisades_East65.1-153.19997Jensen, B. J. L. The Palisades are on the south bank of the Yukon River in Nowitna National Wildlife Refuge, ~70 km downstream of Tanana village. Palisades East forms a heavily gullied, cliff-like exposure that is generally ~40-45 m in height, but ranges from ~25 m high at Site E to ~55-60 m high at Site D. It is difficult to access safely, with many near-vertical exposures and overhanging blocks of frozen sediment that frequently break free into the Yukon River. Location imprecisely georeferenced from Figure 1 in Jensen et al. (2013). Multiple sections were mapped and sampled across Palisades East: Site B1, B2, IB4, F, D1, and D2. See Jensen et al. (2013).The composition reported here is the average of analyses of six samples: UA1199, UA1200, UA1201, UA1305, UA1306, and UA1307. Strikingly pink tephra that is one of the most prominent tephra beds found at the Palisades. Collected at all logged sites across Palisades East, except Site F, and as two opportunistically collected samples while tracing the tephra laterally across the exposure. It was generally found below a peat, although organic-rich silt and peat deposits were also found below it at several sites (Fig.2; Jensen and others, 2013). Site D1, which contains a primary bed of PAL complete with root casts and laminations, appears to be the least disturbed measured section (Fig. 4A; Jensen and others, 2013). There, PAL is overlain by a 1 m thick peat bed, while organic-rich silt with large woody macrofossils is present w2 m below the tephra (Figs. 2 and 4B; Jensen and others, 2013). Primary beds of PAL are 2-5 cm thick, but locally the bed is reworked to thicknesses of 10-20 cm. Glass morphology is diverse, and includes tricuspate and bubble-walled shards, and blocky to frothy pumice.Jensen_Palisades_East_PAL_tephra_average-Pop.1Tephra FallCumulateGlass 73.48 0.33 13.48 2.16 0.05 0.32 1.56 3.85 4.21 9361EMP2.16Cl=0.56; H2O=4.51EMP

SAMPLE LOCATION

Contact AVO Privacy Accessibility Information Quality FOIA
URL: www.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.