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SAMPLE INFO : Jensen_2008_Chester_Bluff_Yukon_Tanana_tephra
Sample ID:Jensen_2008_Chester_Bluff_Yukon_Tanana_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. A single isolated white pod of the YT tephra, 1.5 cm thick and 3 cm long, was found 20 cm above BC in a thick fibrous organic bed. Appears to have a low percentage of phenocrysts. Its glass morphology is predominantly chunky glass shards and pumice, with rare frothy pumice. Glass is commonly brown and rich in microcrysts. Phenocrysts are dominated by ortho-pyroxene, green amphibole is present but rare.

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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Page modified: August 1, 2017 15:29
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