Age-erosion constraints on an Early Pleistocene paleosol in Yukon, Canada, with profiles of 10Be and 26Al: Evidence for a significant loess cover effect on cosmogenic nuclide production rates

Evidence for early glaciation of southeastern Beringia

“…For more than a century of glaciological research, the investigated region has been assumed to be never glaciated (Table 1), in periglacial proximity to but nevertheless beyond the limits of late Miocene (Spurr 1897;Péwé 1975;Eyles and Eyles 1989;Lagoe et al 1993;Harris 1994;Rea and Snoeckx 1995;White et al 1997;Trop and Ridgway 2007;Bill et al 2018) and subsequent Cordilleran ice sheet (CIS) glaciations of late Pliocene and thereafter (Froese et al 2000;Duk-Rodkin et al 2004, 2010Hidy et al 2013Hidy et al , 2018.…”

“…No evidence exists to indicate that the investigated region was ever affected by a Laurentide or other continental ice sheet (Duk-Rodkin 1999). The supposedly earliest periglacial CIS was dated to 2.64 Ma and subsequently pushed back to 2.84 Ma (Hidy et al 2013(Hidy et al , 2018, and estimates for subsequent CIS glaciations advancing toward the investigated region exist (Table 1). Duk-Rodkin and Barendregt (2011) correlated glaciological findings in northwestern Canada, and Lagoe et al (1993) followed by Gulick et al (2003) did the same for Alaska.…”

“…However, the original proponent of this "unglaciated" interpretation could not be unequivocally identified. Moreover, even the most advanced aging methods have uncertainties (e.g., Hidy et al 2018), and 1913, 1914, 1917Prindle 1913;Cockfield 1921;Mertie 1930;Capps 1931;Péwé 1975;Hughes 1990;Carrara 2004;Roland et al 2004;Weber and Wilson 2012). The region continues to be described as never glaciated but "exposed and deeply weathered for at least 15 million years" (Smith et al 2004, p. 160).…”

“…Palynological and pedological investigations on the periphery of the investigated region indicate that Yukon experienced a relatively mild climate, similar to that of contemporary central British Columbia, until late Pliocene/early Pleistocene (Tarnocai and Smith 1989;Tarnocai and Schweger 1991;Askin and Spicer 1995). Based on permafrost dating, climate conducive to an ice age developed sometime between 2.9 and 2.6 Ma (Froese et al 2000(Froese et al , 2008Duk-Rodkin et al 1996;Berger et al 2008; Barendregt and Duk-Rodkin 2011; Duk-Rodkin and Headley et al 2012;Hidy et al 2013Hidy et al , 2018. At ϳ2.2 Ma, an ice sheet evidently extended as far south as Iowa (Harris 1994), and data of Jackson et al (2012) indicate that Yukon probably also experienced that stadial.…”

Fluvial dynamics and 14C‐10Be disequilibrium on the Bolivian Altiplano

“…The wide scatter in the concentrations reflects variability in nuclide inheritance, possibly due to a shift in the sediment supply source. Since depth-profile dating requires uniform inheritance, this variability disables computing a deposition age using the singlenuclide or dual-nuclide depth-profile models (Braucher et al, 2009;Hidy et al, 2010Hidy et al, , 2018. Similarly, combining 10 Be and 26 Al for burial isochron dating (Balco and Rovey, 2008) provides no age solution due to the high and variable inheritance concentrations and insufficient time to cause a measurable deviation in the 26 Al inventory.…”