Deglacial Hydroclimate of Midcontinental North America. Issue 2 (March 2015)

• Record Type: Journal Article
• Authors: Voelker, Steven L.; Stambaugh, Michael C.; Guyette, Richard P.; Feng, Xiahong; Grimley, David A.; Leavitt, Steven W.; Panyushkina, Irina; Grimm, Eric C.; Marsicek, Jeremiah P.; Shuman, Bryan; Brandon Curry, B.
• Is Part Of: Quaternary research. Volume 83:Issue 2(2015)
• Page Start: 336
• Page End: 344
• Publication Date: 2015-03
• Subjects: Relative humidity, -- Precipitation, -- Stable isotope, -- No-analog vegetation, -- Holocene, -- Younger Dryas, -- Bølling-Allerød, -- Glacial, -- Atmospheric circulation; Geology, Stratigraphic -- Quaternary -- Periodicals; Glacial epoch -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; Époque glaciaire -- Périodiques; Geology, Stratigraphic; Glacial epoch; Quaternary Geologic Period; Electronic journals; Periodicals; 551.79
• DOI: 10.1016/j.yqres.2015.01.001
• Languages: English
• ISSNs: 0033-5894

Abstract

Abstract : During the last deglaciation temperatures over midcontinental North America warmed dramatically through the Bølling-Allerød, underwent a cool period associated with the Younger-Dryas and then reverted to warmer, near modern temperatures during the early Holocene. However, paleo proxy records of the hydroclimate of this period have presented divergent evidence. We reconstruct summer relative humidity (RH) across the last deglacial period using a mechanistic model of cellulose and leaf water δ 18 O and δD combined with a pollen-based temperature proxy to interpret stable isotopes of sub-fossil wood. Midcontinental RH was similar to modern conditions during the Last Glacial Maximum, progressively increased during the Bølling-Allerød, peaked during the Younger-Dryas, and declined sharply during the early Holocene. This RH record suggests deglacial summers were cooler and characterized by greater advection of moisture-laden air-masses from the Gulf of Mexico and subsequent entrainment over the mid-continent by a high-pressure system over the Laurentide ice sheet. These patterns help explain the formation of dark-colored cumulic horizons in many Great Plains paleosol sequences and the development of no-analog vegetation types common to the Midwest during the last deglacial period. Likewise, reduced early Holocene RH and precipitation correspond with a diminished glacial high-pressure system during the latter stages of ice-sheet collapse.