AVO Sample Information

StationID	Latitude	Longitude	Geologist	DateVisited	Age Info	Volcano	Eruption	Location Description	Text Description	Sample ID	Sample Type 1	Sample Type 2	Final Unit	Material	Coeff	SiO2	TiO2	Al2O3	FeOT	MnO	MgO	CaO	Na2O	K2O	P2O5	Total-majors	REF majors	METH majors	Fe2O3/Fe203T orig	FeO/FeOT orig	Volatiles csv	METH volatiles	Cs	Rb	Ba	Sr	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Y	Zr	Nb	Hf	Ta	Pb	Th	U	Sc	V	Cr	Fe	Co	Ni	Cu	Zn	Ga	Mo	As	Na	K	Ref trace1	METH trace1	Rb	Ba	Sr	La	Ce	Nd	Sm	Eu	Gd	Dy	Er	Yb	Lu	Y	Zr	Nb	Pb	Th	U	Sc	Ti	V	Cr	Ni	Cu	Zn	Ga	Ref trace2	METH trace2	Light csv	Halogen csv	other major csv	other lile csv	other ree csv	other hfse csv	other hpe csv	other tm csv	other misc csv
Jensen_2008_Chester_Bluff	65.38	-142.66997	Jensen, B. J. L.		< 780000 stratigraphy; 10291; Age based on magnetic polarity of the sediments.			Chester Bluff is located in Yukon Charley Rivers National Preserve (YCNP) in east-central Alaska, on the northwest bank of the Yukon River directly upstream from its confluence with the Charley River. It is a terrace comprising a series of individual bluffs dissected by gullies that extend laterally for about 3 km. The south-facing bluffs are dry and substantial excavation (>2m) is needed to reach frozen sediments. Chester Bluff can be broadly differentiated into four units. The base of the bluff is a bedrock terrace exposed up to ~10 m above river level, composed of argillite, part of the Cretaceous Biederman Formation. Deposited on the terrace are 8-10 m of paleo-Yukon River gravel, which are overlain by 5-10 m of sand and silt rhythmites with minor gravel and planar-bedded sand. Up to 40 m of silt, interpreted as loess and interbedded with multiple organic horizons and tephra beds, cap the sequence. Sites A through C were visited in the area and were found to host 19 distinct tephra beds. A near vertical slope at Site A prevented trench completion. Two trenches were excavated on either side of Site A to examine the lateral continuity of tephra beds. Site B was successfully logged from the top of the bluff to the upper-most sand unit associated with the flood deposits. Thick colluvium at Site C prevented completion of the trench at this site. No coordinates provided; location imprecisely georeferenced from Figure 1 in Jensen et al. (2008).	Present at Site A and Site B of Chester Bluff. Slaven's Roadhouse (SR) tephra, in contrast to Site B, is present 2m above the reworked PrH/MC tephra beds at Site A whereas SR tephra is below PrH/MC tephra at Site B. SR is heavily faulted, reworked and dipping steeply at Site A. Loess associated with the reworked SR is strongly mottled, Fe-stained, and includes small organic horizons that are reworked and overturned. Solifluction may have caused the mottling and overturning of the tephra beds or, alternatively, a faulted block of silt may have obscured the true stratigraphic position of the tephra beds. At Site B, SR is 2m above BP and is the lowest of six tephra beds, Tom King (TK), MC, PrH, Ben Creek (BC) and Yukon Tanana (YT), 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. SR is distinctly white, forming wispy pods up to 2mm thick and 3 cm long that are continuous across the trench. Glass morphology that contains bubble-walled and tri-cuspate shards, but also frothy inflated pumice. Contaminated with detrital material, making it difficult to determine phenocryst populations. The composition reported was calculated from analyses of six samples: UA1058, UA1073, UA1074, UA1215, UA1220, and UA1225.	Jensen_2008_Chester_Bluff_Slavens_Roadhouse_tephra	Tephra Fall	Cumulate		Glass		76.56	0.16	13.37	1.27	0.07	0.34	1.88	3.63	2.57			6162	EMP		1.27	Cl=0.16; H2O=5.82	EMP

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