Late Quaternary eolian and alluvial response to paleoclimate, Canyonlands, southeastern Utah

Abstract

In upland areas of Canyonlands National Park, Utah, thin deposits and paleosols show late Quaternary episodes of eolian sedimentation, pedogenesis, and climate change. Interpretation of the stratigraphy and optically stimulated luminescence ages of eolian and nearby alluvial deposits, their pollen, and intercalated paleosols yields the following history: (1) Eolian deposition at ca. 46 ka, followed by several episodes of alluviation from some time before ca. 40 ka until after 16 ka (calibrated). (2) Eolian deposition from ca. 17 ka to 12 ka, interrupted by periods of pedogenesis, coinciding with late Pleistocene alluviation as local climate became warmer and wetter. (3) A wetter period from 12 to 8.5 ka corresponding to the peak of summer monsoon influence, during which soils formed relatively quickly by infiltration of eolian silt and clay, and trees and grasses were more abundant. (4) A drier period between ca. 8.5 and 6 ka during which sheetwash deposits accumulated and more desertlike vegetation was dominant; some dunes were reactivated at ca. 8 ka. (5) Episodic eolian and fluvial deposition during a wetter, cooler period that began at ca. 6 ka and ended by ca. 3?2 ka, followed by a shift to drier modern conditions; localized mobilization of dune sand has persisted to the present. These interpretations are similar to those of studies at the Chaco dune field, New Mexico, and the Tusayan dune field, Arizona, and are consistent with paleoclimate interpretations of pollen and packrat middens in the region. A period of rapid deposition and infiltration of eolian dust derived from distant igneous source terranes occurred between ca. 12 and 8 ka. Before ca. 17 ka, and apparently back to at least 45 ka, paleosols contain little or no such infiltrated dust. After ca. 8 ka, either the supply of dust was reduced or the more arid climate inhibited translocation of dust into the soils.Peer reviewe

Lithologic controls on regolith weathering and mass flux in forested ecosystems of the southwestern USA

“…1). Soils forming on the Colorado Plateau are known to have a long history of dust accumulation (Reheis et al, 2005;Reynolds et al, 2006), and both the dolostone and basalt soils exhibited evidence of substantial eolian deposition. The dolostone soil also contained mafic cinder material, deposited during the formation of local cinder cones.…”

Rock varnish microlamination dating of late Quaternary geomorphic features in the drylands of western USA

“…First, they are basic and ubiquitous landforms in desert landscapes that deserve intensive scientific scrutiny (e.g., Blake, 1904;Blackwelder, 1931;Williams, 1958;Bull, 1964Bull, , 1977Malde, 1964;Denny, 1965;Melton, 1965;Hunt and Mabey, 1966;Denny, 1967;Hooke, 1967Hooke, , 1968Cooke, 1970;McFadden et al, 1987;Prokopovich, 1987;Dorn, 1988;Harvey, 1990Harvey, , 1992Whitney and Harrington, 1993;Wells et al, 1995;Friend et al, 2000;Quade, 2001;Anderson et al, 2002;Wood et al, 2005;Valentine and Harrington, 2006). Secondly, the geomorphic processes responsible for formation and evolution of these landforms may hold a key to our understanding of past environments, especially climate changes in the world's deserts (e.g., Lustig, 1965;Wells et al, 1987;Bull, 1991;Throckmorton and Reheis, 1993;Whitney and Harrington, 1993;Dorn, 1994;McFadden et al, 1998;Harvey et al, 1999;Harvey, 2002a;Hanson, 2005;Reheis et al, 2005). However, radiometric dating of these geomorphic features has always been difficult.…”

Age of Barrier Canyon-style rock art constrained by cross-cutting relations and luminescence dating techniques

“…The T2 deposit dates to the latest Pleistocene-early Holocene transition, which in this area was a time of highly variable climate, vegetation disturbance, and later, an enhanced onset of the Southwest Monsoon (38,39). Middle Holocene incision along the drainage may be driven by the monsoon but also corresponds to a long-recognized episode of aridity (38)(39)(40). Finally, paleoflood deposits of the T1 coincide with the late Holocene increase in frontal-derived winter moisture (41) and more variable climate with episodes of drought, flooding, and arroyo cutting.…”