Collaborative Research: Illuminating the characteristics, causes, and paleoclimatic importance of the Mid-Cenozoic Loess in the Western USA

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Loess deposits consist of fine-grained, windblown sediments and contain critical information about continental aridification processes that are key to understanding biotic evolution and climate change. This project integrates field data collected from loess deposited ~37-30 million years ago in Wyoming, Nebraska and Montana, laboratory analyses, and paleoclimate simulations to understand the nature, causes, and paleoclimatic importance of these loess deposits. The research will advance STEM diversity by supporting a two-day GEOCAMP for historically underrepresented high-school students from east Texas. In addition, this project will promote further development of the high-resolution Community Earth System Model to be used to better understand ancient climate changes. This project will include field sedimentological observation and lab analyses of bulk sediment and quartz grain-size, quartz surface morphology, detrital and high-precision zircon U-Pb geochronology to study the ancient loess deposits in Wyoming, Nebraska and Montana, USA. These proxy data will constrain the extent, timing, pattern and characteristics of the loess; and determine sediment provenance and sediment recycling mechanisms. These proxy data will be integrated with a coupled atmosphere-land model to simulate changes of regional climate and vegetation induced by topography changes, global climate cooling, glaciation and shoreline regression to understand the cause and climate significance of the loess. In additional to gaining fundamental understanding of the loess deposits, the project will shed light on 1) the influence of climate change on biotic evolution at the Eocene-Oligocene transition (~34 million years ago); 2) the validity of different models of surface uplift in the western USA; and 3) the potential positive climate feedback of enhanced mineral dust emissions on global cooling at the transition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.