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SAMPLE INFO : Jensen_2008_Chester_Bluff_Ben_Creek_tephra
Sample ID:Jensen_2008_Chester_Bluff_Ben_Creek_tephra
Station ID:Jensen_2008_Chester_Bluff
Sample Type 1:Tephra Fall
Text Description:
Only present at Site B of Chester Bluff. At Site B, Tom King (TK), MC, PrH, Ben Creek (BC) and Yukon Tanana (YT) are found within 2m of one another. SR, TK, MC and PrH are deposited within greyish brown loess 0.5 to 1m below a major organic unit that contains BC and YT. At the downstream end of the 6m lateral section the tephra beds are reworked and faulted downward. At the upstream end, the major organic unit above SR, TK, MC and PrH is deformed along its base, causing the tephra beds to be overturned and partially reworked into the base of the unit. A 6m wide trench was excavated to fully delineate the tephrostratigraphic relations of the six tephra beds. BC is within a distinct humified organic-rich bed. It forms creamy pink pods up to 6 cm long and 1 cm thick and is discontinuous over 2m. Richer in frothy pumice and have fewer bubble-walled and tri-cuspate shards. Rare phenocrysts (<20%) are dominated by ortho- and clino-pyroxenes, and very rarely contain green amphibole. Euhedral ortho-pyroxene grains dominate the phenocrysts in BC. They are likely hypersthene, identification based on petrologic characteristics, and most contain abundant melt inclusions. Contains brown glass. The composition reported was calculated from analyses of one sample: UA1235.

An extensive middle to late Pleistocene tephrochronologic record from east-central Alaska
Tephrochronology of middle to late Pleistocene loess in east-central Alaska


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