Abstract
Playas are ephemeral upland-embedded wetlands found in semiarid and arid regions worldwide. Lunettes are isolated dunes that form along the downwind margin of playas. The paleoclimatic and geomorphic history of High Plains playa-lunette systems (PLSs) are poorly understood. To address this, we characterize the stratigraphy of four PLSs in southwest Kansas, USA. Methods include: 1) collect soil-sediment cores from playa centers and windward slopes of lunettes; 2) describe cores using USDA techniques; 3) estimate age of stratigraphic units using radiocarbon (14C); and 4) reconstruct paleoenvironmental conditions using stable carbon isotopes (13C) and particle size analysis. Playa stratigraphy is relatively simple and consists of well-developed surface soils underlain by gleyed clays. Calibrated playa 14C ages range from 6,280-23,600 cal yr BP. Lunette stratigraphy is complex; buried soils and thick units of light-dark bands are common. Calibrated 14C ages for buried soils in lunettes range from 19,050-32,300 cal yr BP. Lunette 13C data are highly oscillatory. These data indicate a warm-dry period dominated with C4 plants preceded ~30 ka, and was followed by a cool-moist, C3 plant dominated period before returning to warm-dry conditions throughout much of the Holocene. Playa records extend from marine isotope stage (MIS) 3 (i.e., prior to the Last Glacial Maximum), and lunette records extend into MIS 3. Playa stratigraphy suggests they were dominated by alluvial-lacustrine processes during the late Pleistocene and early Holocene. Alternating light-dark bands in lunettes are hypothesized to represent incipient soils and aeolian sediment resulting from small-scale shifts in climate throughout much of the late Pleistocene and early Holocene, with geomorphic processes alternating between aeolian deposition and pedogenesis. Well-developed surface soils in playas and lunettes suggest stabilization and pedogenesis dominated the mid to late Holocene under a warming and drier climate. Thus, PLS development appears linked to both global-scale and regional climate processes.
Advisor
Mark Bowen
Committee Member
Phil Larson
Committee Member
Samantha Kaplan
Date of Degree
2022
Language
english
Document Type
Thesis
Degree
Master of Science (MS)
Program of Study
Geography
College
Social and Behavioral Sciences
Recommended Citation
Sims, Alyssa E. (2022). Reconstructing regional paleoenvironments and geomorphic history of High Plains playa-lunette systems [Master’s thesis, Minnesota State University, Mankato]. Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. https://cornerstone.lib.mnsu.edu/etds/1237/
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