Missoula flood dynamics and magnitudes inferred from sedimentology of slack-water deposits on the Columbia Plateau, Washington

Smith, Gary A.

doi:10.1130/0016-7606(1993)105<0077:mfdami>2.3.co;2

Cited by 83 publications

(73 citation statements)

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“…In the late 1980s, these deposits began to be called by a variety of other informal names, including "slackwater facies" (Moody 1987;Lindsey et al 1992b;Connelly et al 1992a;Last et al 1989;Smith 1993), "silt-dominated facies" (Lindsey et al 1992a(Lindsey et al , 1994bConnelly et al 1992b), "silty facies" (Lindsey et al 1994a), and "rhythmite facies" (Baker et al 1991). Interbedded sand-and silt-dominated facies occur as sequences of rhythmic, graded beds that range from 0.1 to 1 m (0.3 to 3.3 ft) in thickness and are characterized by loose, horizontal-to ripple-laminated, grayish, coarse to medium sand, grading up into brownish, cohesive, fine sand to silt.…”

Section: Hanford Formationmentioning

confidence: 99%

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196 and RCRA Borehole 299-W11-39

Serne¹,

Bjornstad²,

Horton³

et al. 2004

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Executive SummaryThis report was revised in September 2008 to remove acid-extractable sodium data from Tables 4.8, 4.28, and 4.52. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in September 2004.The overall goal of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities at Hanford. To meet this goal, CH2M HILL Hanford Group, Inc. tasked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediments from within Waste Management Area (WMA) T-TX-TY. This report is the second of two reports written to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from boreholes C4104 and C4105 in the T Tank Farm, and from borehole 299-W-11-39 installed northeast of the T Tank Farm. Finally, the measurements on sediments from borehole C4104 are compared with a nearby borehole drilled in 1993, 299-W10-196, through the tank T-106 leak plume.Sediments from borehole 299-W-11-39 were considered to be background uncontaminated sediments against which to compare contaminated sediments for the T tank farm characterization effort. However, during characterization of the sediments from 299-W11-39, numerous indications were found that suggest some nearsurface contamination may have occurred in the past such that the water extract information for sediments from 299-W11-39 may not represent natural background conditions. Therefore, most of the comparisons of the contaminated T tank farm boreholes to natural background conditions used the sediment characterization information from background borehole 299-W10-27, just northeast of the TX Tank Farm.This report also presents our interpretation of the data in the context of sediment types, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the T Tank Farm. The information presented in this report supports the T-TX-TY Waste Management Area field investigation report (a) in preparation by CH2M HILL Hanford Group, Inc. Sediment samples from the boreholes were analyzed and characterized in the laboratory for the following parameters: moisture content, gamma-emitting radionuclides, one-to-one water extracts (which provide soil pH, electrical conductivity, cation, trace metal, radionuclide and anion data), total carbon and inorganic carbon content, and 8 M nitric acid extracts (which provide a measure of the total leachable sediment content of contaminants). Key radiocontaminants, technetium-99, actinides, fission products (including strontium-90, europium radioisotopes, ruthenium and molybdenum), cobalt-60, and uranium, along with other trace metals were determined in acid and water...

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Section: Hanford Formationmentioning

confidence: 99%

Characterization of Vadose Zone Sediments Below the T Tank Farm: Boreholes C4104, C4105, 299-W10-196 and RCRA Borehole 299-W11-39

Serne¹,

Bjornstad²,

Horton³

et al. 2004

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show abstract

“…Fans of this type are deposited where fl ood waters pass an obstruction, like the nearby bedrock ridge, and spread into a local hydraulic basin, like a tributary valley (Baker, 1973). Although we have not dug test pits in the slackwater basins because they are generally frozen (Reger and Solie, 2008), fi ne-grained slackwater deposits, including rhythmites, are typically deposited in these marginal backwater basins from the suspended loads carried by jökulhlaups (Waitt, 1980(Waitt, , 1984(Waitt, , 1985Smith, 1993;Baker and others, 2004).…”

Section: Evidence Of Multiple Paleofloodsmentioning

confidence: 99%

Surficial-geologic map, Delta Junction to Dot Lake, Alaska Highway corridor

D.N.¹

2008

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“…Sandy beds may be fine and grade upward into thin beds of sandy silt to silt (see Figures 4.9B and 4.1); graded beds such as these are sometimes referred to as "rhythmites." Each rhythmite may represent the deposition from a separate flood (Waitt 1980(Waitt , 1985Smith 1993), or perhaps surges from a single flood (Bjornstad 1980, Baker et al 1991. Most rhythmites go undetected in boreholes; however, because drill cuttings are generally collected at 5-ft intervals, the scale of the rhythmic bedding is much finer.…”

Section: Sand-dominated Sequence (H2 Unit)mentioning

confidence: 99%