Holocene eolian sand deposition linked to climatic variability, Northern Great Plains, Canada

Abstract

The Bigstick and Seward Sand Hills are possibly two of the oldest dune fields within the late Wisconsin glaciated regions of the Northern Great Plains. As with most Northern Great Plains dune fields, source sediments are former proglacial outwash sands. Thus, Holocene dune construction is primarily related to spatial–temporal variations in surface cover and transport capacity, rather than renewed sediment input. However, eolian landscape reconstructions on the Northern Great Plains have been temporally constrained to recent periods of activity, as older episodes of deposition are typically reworked by younger events. In this study, sediment cores from shallow lacustrine basins and interdune areas provide an improved record of Holocene eolian sand deposition. Eolian sand accumulation in the interdunes and basins occurred between 150 and 270 years ago, 1.9 and 3.0 ka, 5.4 and 8.6 ka, and prior to ca. 10.8 ka. These episodes of sand accumulation were bracketed by lacustrine deposition and soil formation, which represented wetter conditions. Other than mid-Holocene dune activity, which may be related to peak warmth and aridity, most periods of eolian sand accumulation coincided with cooler but drier climatic events such as the Younger Dryas, late-Holocene cooling prior to the Medieval Climatic Anomaly, and the ‘Little Ice Age’. These depositional episodes are also spatially represented by other dune fields in the region, providing a broad-scale view of the connections between past climatic events and eolian landscape evolution on the Northern Great Plains.

Critical transitions in Chinese dunes during the past 12,000 years

“…However, caution is needed in relating stratigraphic evidence of dune state shifts to climate change, considering the range of climatic conditions under which this may occur at the local scale and the evidence of hysteresis in response at the regional scale. The results of this study, together with other evidence of the heterogeneous nature of dune records (28)(29)(30)(31), clearly imply that a small number of individual dune sections are not sufficient for regional climate and environmental reconstruction. A compilation of well-dated dune records with large spatial coverage and high temporal resolution presents a much clearer picture of dune field evolution, more useful for paleoclimate reconstruction, but also revealing more of the true complexity of dune field nonlinear dynamics (32).…”

“…However, it is also apparent that despite similar climatic forcing, dune strata and the timing and pattern of shifts in dune activity are quite varied and sometimes difficult to correlate among individual sites, even in the same dune field (24)(25)(26). This heterogeneity of dune records has also been recognized in many other dune fields globally (28)(29)(30)(31). Meanwhile, the increasingly large number of well-dated dune field records allows an integrated approach (32), providing a comprehensive picture of long-term dune field evolution and new insight on the past occurrence of bistability and hysteresis in response to environmental change.…”