100,000-year-long terrestrial record of millennial-scale linkage between eastern North American mid-latitude paleovegetation shifts and Greenland ice-core oxygen isotope trends

Abstract

We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+ yr interval (~ 115–15 ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermally dependent forest assemblages, ranging between two endmembers: subtropical oak-tupelo-bald cypress-gum forest and high boreal spruce-pine forest. Sedimentary textural evidence indicates fluvial, paludal, and loess deposition, and paleosol formation, representing sequential freshwater to subaerial environments in which this record was deposited. Its total age"depth model, based on radiocarbon and optically stimulated luminescence ages, ranges from terrestrial oxygen isotope stages (OIS) 6 to 1. The particular core sub-interval presented here is correlative in trend and timing to that portion of the oxygen isotope sequence common among several Greenland ice cores: interstades GI2 to GI24 (≈ OIS2–5 d). This site thus provides the first evidence for an essentially complete series of "Dansgaard"Oeschger" climate events in the MAR. These data reveal that the ~ 100,000 yr preceding the Late Glacial and Holocene in the MAR of North America were characterized by frequently and dynamically changing climate states, and by vegetation shifts that closely tracked the Greenland paleoclimate sequence.

Synthesis on Quaternary aeolian research in the unglaciated eastern United States

“…19 and 20), and Dansgaard-Oeschger events (Dansgaard et al, 1993) prior to the LGM. This pattern of variability is similar to that reported by Litwin et al (2013) for the MACP record (Fig. 20f).…”

“…The 55À50 ka cooling agrees with the midcontinent speleothem data (Harmon et al, 1978b;Dorale et al, 1998;Fig. 20d, this paper) and the LMV loess record (Markewich et al, 2011b), and appears comparable to the cooling from interstades GI 17 to just before GI 14, as documented in the Hybla Valley pollen record (Litwin et al, 2013;Fig. 20f, this paper).…”

“…19 and 20). These dune-forming intervals are temporally consistent with periods of cooler forest assemblages occurring further north in the MACP (Litwin et al, 2013;Fig. 20f in this article).…”

“…Dansgaard-Oeschger events (DO) are unlabeled, but have a 1:1 relation to the interstades (per Svensson et al, 2006). (f) Percent Quercus (oak) for the pollen record in the Hybla Valley core, VA. Green line at the $40% threshold for oak represents the average modern % value of oak for Hybla Valley (i.e., modern baseline) (Litwin et al, , 2013. Oxygen isotope stage (OIS) boundary placements generally conform to those proposed by Martinson et al (1987), inclusive of the more recent boundary refinements suggested by Thompson and Goldstein (2006) and Litwin et al (2013).…”

“…(f) Percent Quercus (oak) for the pollen record in the Hybla Valley core, VA. Green line at the $40% threshold for oak represents the average modern % value of oak for Hybla Valley (i.e., modern baseline) (Litwin et al, , 2013. Oxygen isotope stage (OIS) boundary placements generally conform to those proposed by Martinson et al (1987), inclusive of the more recent boundary refinements suggested by Thompson and Goldstein (2006) and Litwin et al (2013). References for the timing and duration of the Bølling-Allerød (BA) is per Weaver et al (2003); the Younger Dryas (YD) is per Carlson (2010), and the LGM is per Clark et al (2009).…”