Deposited in the Alpine Zone of the Uinta Mountains USA Jeff Munroe Middlebury College USA Study Area Overview Design Results Summary Uinta Mountains The Uinta Mountains are located in the state of Utah in the western USA They are surrounded by arid lowland dust sources ID: 790223
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Slide1
Relative
Abundances of Regional vs. Far Traveled Mineral Dust Deposited in the Alpine Zone of the Uinta Mountains, USA
Jeff MunroeMiddlebury College, USA
Study Area
Overview
Design
Results
Summary
Slide2Uinta Mountains
The Uinta Mountains are located in the state of Utah in the western USA. They are surrounded by arid, lowland dust sources.
The highest elevations of the Uinta Mountains are a gently sloping periglacial upland that was not glaciated in the Pleistocene.Study AreaOverview
Design
Results
Summary
Slide3Dust is a Soil Parent Material
Dust is a Source of Base CationsDust is a pH Buffer
Dust Impacts Snow AlbedoDust
Regolith
Why is dust important here?
Study Area
Overview
Design
Results
Summary
Slide4NW wind
S wind
An active sampler was deployed at a location with a strongly bimodal wind regimeStudy AreaOverviewDesignResults
Summary
Slide5Hypothesis:
If dust is globally sourced, then NW and S samples will be similar.If local and regional sources of dust are important, then NW and S samples will be different.Study AreaOverview
DesignResultsSummary
Slide6Methods:
Grain Size AnalysisXRD mineralogyICP-MS geochemistryStudy AreaOverview
DesignResultsSummary
Slide7Uinta Mountains
Study Area
OverviewDesignResultsSummary
Possibledust source
Possibledust source
Slide850 km
The Uinta Mountains were extensively glaciated during the Pleistocene…Study AreaOverview
DesignResultsSummary
Slide9Munroe and
Laabs, 2009
…however the crest of the range was above the limit of Pleistocene glaciersReconstructed glaciersin blueStudy AreaOverview
Design
Results
Summary
Slide10The
ridgecrest is a gently sloping periglacial uplandWhat is the influence of mineral dustdeposition in this environment?Study AreaOverview
DesignResultsSummary
Slide11Dust is a Soil Parent Material
Dust is a Source of Base CationsDust is a pH Buffer
Dust Impacts Snow AlbedoDust
Regolith
Study Area
Overview
Design
Results
Summary
Slide12Research Question
:What is the relative importance of regional versus exotic mineral dust in the Uinta Mountains?
Remote AutomatedWeather Stationat 3700 m
Active
Dust
Sampler
Study Area
Overview
Design
Results
Summary
Slide1350 km
Active Dust Sampler
Study AreaOverview
Design
Results
Summary
Slide1412-year record
Wind regimeat this siteis strongly bimodalStudy AreaOverviewDesign
ResultsSummary
Slide15Hypothesis:
If dust is globally sourced, then NW and S samples will be similar.If local and regional sources of dust are important, then NW and S samples will be different.Study AreaOverview
DesignResultsSummary
Slide16Solar-powered fans pull air through filters to trap dust
One collector is oriented to NW, the other to the SSwindNWwind
Study AreaOverviewDesignResults
Summary
Slide17Wind-activated switch turns fans on and off
SwindNWwind
Study AreaOverviewDesignResults
Summary
Slide1830 Watts of solar power keeps the system running year-round
Study AreaOverviewDesign
ResultsSummary
Slide19Both fans run an average of 2-hr per day
*Malfunction during first winterlocked S fan in “on” position*Study Area
OverviewDesignResultsSummary
Slide20Wind from the S carries more dust than from the NW
Study AreaOverviewDesignResults
Summary
Slide21NW dust is coarser
Study AreaOverviewDesign
ResultsSummary
Slide22NW dust has more coarse silt and very fine sand
Study AreaOverview
DesignResultsSummary
Slide23NW and S dust have generally the same minerals detectable with XRD, although some NW samples contain
smectite or other expandable claysStudy AreaOverviewDesign
ResultsSummary
Slide24NW dust contains more feldspar
Study AreaOverviewDesign
ResultsSummary
Slide25On a seasonal basis, some elements are more abundant from the S or the NW
Study AreaOverview
DesignResultsSummary
Slide26Study Area
OverviewDesign
ResultsSummary
Slide27Enrichment of Li and Ba may reflect oil development to the south
Study AreaOverviewDesignResults
Summary
Slide28Enrichment of
Hf and Zr suggests source of zircon to the northStudy AreaOverviewDesign
ResultsSummary
Slide29Summary:
South wind delivers more dustS vs. NW mineralogy is similar but NW dust is coarserDirectional element enrichment varies seasonallyAnnual enrichments suggest that local sources are an important overprint on uniform, globally sourced dust.Study AreaOverview
DesignResultsSummary
Slide30T
hanks to…Emily Attwood, Sam O’Keefe, and Paul QuackenbushTony Desautels and Chris GoodrichNSF-EAR-1524476USFS-Ashley National ForestMiddlebury College