TY - JOUR
T1 - The Variegated (VT) tephra
T2 - A new regional marker for middle to late Marine Isotope Stage 5 across Yukon and Alaska
AU - Jensen, Britta J. L.
AU - Preece, Shari J.
AU - Lamothe, Michel
AU - Pearce, Nick J. G.
AU - Froese, Duane G.
AU - Westgate, John A.
AU - Schaefer, Janet
AU - Begét, Jim
PY - 2011/12/20
Y1 - 2011/12/20
N2 - The Variegated (VT) tephra, likely sourced from the eastern Aleutian arc, has a geographic distribution that places it amongst the most widespread tephra beds in eastern Beringia. First identified in the Fairbanks area of interior Alaska, it has been identified at eight additional sites ranging from Togiak Bay in southwestern Alaska, to the Klondike area of west-central Yukon. Correlation of these occurrences is established through the equivalence of glass major and trace-element geochemistry, Fe-Ti oxide geochemistry, stratigraphy, and independent age data. In Yukon and Alaska, VT tephra has a minimum bulk tephra volume estimate of ∼32 km3. Previous age estimates for VT tephra have varied, ranging from a glass fission-track age of 125 ± 30 ka to a weighted mean thermoluminescence (TL) age of 77.8 ± 4.1 ka from bracketing ages on loess. A new infrared stimulated luminescence (IRSL) age of 106 ± 10 ka, paleoenvironmental data, and several TL and IRSL ages from Togiak Bay suggest that the time of deposition is more likely between these previous age estimates: post-marine isotope stage (MIS) 5e but underlying a prominent soil likely associated with MIS 5c, placing it within late MIS 5d.
AB - The Variegated (VT) tephra, likely sourced from the eastern Aleutian arc, has a geographic distribution that places it amongst the most widespread tephra beds in eastern Beringia. First identified in the Fairbanks area of interior Alaska, it has been identified at eight additional sites ranging from Togiak Bay in southwestern Alaska, to the Klondike area of west-central Yukon. Correlation of these occurrences is established through the equivalence of glass major and trace-element geochemistry, Fe-Ti oxide geochemistry, stratigraphy, and independent age data. In Yukon and Alaska, VT tephra has a minimum bulk tephra volume estimate of ∼32 km3. Previous age estimates for VT tephra have varied, ranging from a glass fission-track age of 125 ± 30 ka to a weighted mean thermoluminescence (TL) age of 77.8 ± 4.1 ka from bracketing ages on loess. A new infrared stimulated luminescence (IRSL) age of 106 ± 10 ka, paleoenvironmental data, and several TL and IRSL ages from Togiak Bay suggest that the time of deposition is more likely between these previous age estimates: post-marine isotope stage (MIS) 5e but underlying a prominent soil likely associated with MIS 5c, placing it within late MIS 5d.
UR - http://hdl.handle.net/2160/8648
U2 - 10.1016/j.quaint.2011.06.028
DO - 10.1016/j.quaint.2011.06.028
M3 - Article
SN - 1040-6182
VL - 246
SP - 312
EP - 323
JO - Quaternary International
JF - Quaternary International
IS - 1-2
ER -
