A loess–paleosol record of climate and glacial history over the past two glacial–interglacial cycles (~150 ka), southern Jackson Hole, Wyoming

Authors

Kenneth L. Pierce, U.S. Geological SurveyFollow
Daniel R. Muhs, U.S. Geological SurveyFollow
Maynard A. Fosberg, University of Idaho, Moscow
Shannon A. Mahan, US Geological Survey
Joseph G. Rosenbaum, US Geological Survey
Joseph M. Licciardi, University of New Hampshire, Durham
Milan J. Pavich, US Geological Survey

Date of this Version

2011

Citation

Quaternary Research 76 (2011) 119–141

doi:10.1016/j.yqres.2011.03.006

Comments

U.S. government work

Abstract

Loess accumulated on a Bull Lake outwash terrace of Marine Oxygen Isotope Stage 6 (MIS 6) age in southern Jackson Hole, Wyoming. The 9 m section displays eight intervals of loess deposition (Loess 1 to Loess 8, oldest), each followed by soil development. Our age-depth model is constrained by thermoluminescence, meteoric ¹⁰Be accumulation in soils, and cosmogenic ¹⁰Be surface exposure ages. We use particle size, geochemical, mineral-magnetic, and clay mineralogical data to interpret loess sources and pedogenesis. Deposition of MIS 6 loess was followed by a tripartite soil/thin loess complex (Soils 8, 7, and 6) apparently re!ecting the large climatic oscillations of MIS 5. Soil 8 (MIS 5e) shows the strongest development. Loess 5 accumulated during a glacial interval (~76–69 ka; MIS 4) followed by soil development under conditions wetter and probably colder than present. Deposition of thick Loess 3 (~43–51 ka, MIS 3) was followed by soil development comparable with that observed in Soil 1. Loess 1 (MIS 2) accumulated during the Pinedale glaciation and was followed by development of Soil 1 under a semiarid climate. This record of alternating loess deposition and soil development is compatible with the history of Yellowstone vegetation and the glacial !our record from the Sierra Nevada.