کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1044676 1484293 2007 21 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Evolution of Eureka Flat: A dust-producing engine of the Palouse loess, USA
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Evolution of Eureka Flat: A dust-producing engine of the Palouse loess, USA
چکیده انگلیسی

Sedimentologic, stratigraphic, and pedologic evidence demonstrates that Eureka Flat (EF), a narrow, 80-km-long deflation plain in south-central Washington, USA, is the source for the thick and widespread loess of the Palouse region. Located in the southern Columbia Plateau, EF has been a depocenter for abundant clay-to-sand-sized sediment derived from repeated glacial outburst floods that swept through the area during the Pleistocene. Prevailing SW winds that were funneled across EF remobilized flood sediment into sand dunes, sand sheets, and loess. An eolian sand sheet buried beneath 1.8 m of loess at the downwind end of EF attests to bioclimatically driven changes in the style of eolian deposition. The depositional transition from sand sheet to loess is characterized by a change from wind-rippled strata to structureless, bimodal sand and silt with insect burrows and rhizoliths, to unimodal sandy loess. Soil moisture and density of dust-trapping vegetation control where sand dunes and loess accumulate. Up to 4.5 m of post-LGM loess mantles the landscape adjacent to and downwind from EF. Some of the thickest loess deposits owe their origins to the sequestering of eolian sand particles by topographic traps such as the Touchet River and its tributary valleys. The removal of saltating sand from the eolian system promotes thick accumulation of loess downwind of topographic traps. Patterns of loess accumulation across the Columbia Plateau are identified on isopach maps of major pre- and post-LGM loess units and show that EF has been the major engine for the production of atmospheric dust and loess during both times.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary International - Volumes 162–163, March 2007, Pages 76–96
نویسندگان
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