Holocene eolian activation as a proxy for broad-scale landscape change on the Gila River Indian Community, Arizona

Abstract

Eolian sediments are common within the middle Gila River Valley, southern Arizona, and reflect variability in eolian and fluvial processes during the late Holocene. This study focuses on deciphering the stratigraphic record of eolian deposition and associated luminescence dating of quartz extracts by single aliquot regeneration (SAR) protocols. Stratigraphic assessment coupled with luminescence ages indicates that there are four broad eolian depositional events at ca. 3145 ± 220 yr, 1950–1360 yr, 800 ± 100 yr, and 690–315 yr. This nascent chronology, correlated with regional archeological evidence and paleoclimate proxy datasets, leads to two general conclusions: (1) loess deposits, transverse-dune formation and sand-sheet deposition in the late Holocene are probably linked to flow variability of the Gila River, though the last two events are concordant with regional megadroughts; and (2) the stability of eolian landforms since the 19th century reflects the lack of eolian sediment supply during a period of fluvial incision, resulting in Entisol formation on dunes. The prime catalyst of eolian activity during the late Holocene is inferred to be sediment supply, driven by climate periodicity and variable flow within the Gila River catchment.

Interpretations and common challenges of aeolian records from North American dune fields

“…The adjacent Algodones Dunes exhibit periods of accumulation around 3.2 ka, as well as between 0.27e0.33 and 0.09e0.12 ka (Stokes et al, 1997). Crescentic dunes and sand sheets adjacent to the Gila River in Arizona provide evidence for depositional events at 3.15, 1.95e1.36, 0.8, and 0.7e0.31 ka (Wright et al, 2011).…”

“…There are four main areas of aeolian deposits in this region: 1) sand sheets and small dune fields in the Coachella Valley (Beheiry, 1967;Wasklewicz and Meek, 1995;Griffiths et al, 2002;Katra et al, 2009); 2) the active complex crescentic Algodones Dunes of southeastern California (Sweet et al, 1988;Derickson et al, 2008); 3) source-bordering dunes in the Gila River valley (Wright et al, 2011) and adjacent to the Colorado River (Parker dunes); and 4) the Gran Desierto sand sea of northern Mexico (Blount and Lancaster, 1990;Beveridge et al, 2006;Scheidt et al, 2011). The Colorado River has provided sediment for the Parker and Algodones dunes, and large parts of the Gran Desierto sand sea (Muhs et al, 1995Scheidt et al, 2011).…”

Eolian depositional phases during the past 50 ka and inferred climate variability for the Pampean Sand Sea, western Pampas, Argentina

“…A zero overdispersion percentage indicates high internal consistency in D e values with 95% of the D e values within 2s errors. Overdispersion values 20% are routinely assessed for small aliquots of quartz grains that are well solar reset, like eolian sands (e.g., Olley et al, 1998;Wright et al, 2011Meier et al, 2013 and this value is considered a conservative threshold metric for calculation of a D e value using the central age model (CAM) of Galbraith et al (1999). We consider overdispersion values >20% (at one sigma limits) to indicate post depositional mixing of grains, grains of various ages, partial solar resetting of grains or complex microdosimetry; the Finite Mixture Model (FMM) is an appropriate statistical treatment for such data (Galbraith and Green, 1990), and this model was used for quartz extracts that yielded overdispersion values of !25% (Table 2).…”

Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

“…We used single aliquot regeneration protocols (Murray and Wintle, 2003;Wintle and Murray, 2006) to estimate the apparent equivalent dose of the 250-150 μm quartz fractions in many tens of separate aliquots (Table 4; e.g., Wright et al, 2011;Brill et al, 2012;Prendergast et al, 2012). Very fine grains of sand from the upper 2 mm of sampled beds were selected for analysis because the uppermost grains are most likely to have been exposed to light following deposition.…”