EAR-PF: A Deep Critical Zone Observatory: Towards understanding the relationships of denudation and weathering through time and space

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Dr. Brendon Quirk has been awarded an NSF EAR Postdoctoral Fellowship to study the relationship of global climate conditions and the breakdown of rocks using lake sediments. The work will be conducted at Purdue University under the mentorship of Dr. Darryl Granger. Understanding how rocks break down (weather) and how the resulting material is transported (erosion) throughout geologic history is critical for understanding how Earth’s climate has evolved. Specifically, the breakdown of rock through chemical reactions may help to stabilize global climate and produce a habitable Earth. This work will use lake sediments to understand how different climate conditions affect rates of weathering and erosion of rock and soil across Earth’s surface. The anticipated results will be useful for evaluating specific models of weathering and erosion in geologic history and may shed light on potential natural feedbacks between erosion, weathering, and climate. The project includes outreach and mentoring programs for first-generation college students to conduct research. The development of accessible laboratory techniques designed to reduce barriers to conducting research into global climate is another activity supported by this research. Understanding variations in denudation (the sum of physical and chemical weathering fluxes) of Earth’s surface through time and space remains one of most pressing problems in the earth sciences. Chemical weathering of silicate minerals is thought to be one of the main processes which regulate the global carbon cycle. Thus, denudation may act to stabilize global climate over geologic timescales and may be an important factor in earth’s habitability. However, high-resolution records of terrestrial denudation and weathering for the Quaternary period are rare and questions remain if and how erosion and weathering might interact to regulate and stabilize the chemical weathering flux across interglacial-glacial timescales. The work proposed here seeks to address these outstanding questions by quantifying paleo-denudation and weathering rates spanning several glacial-interglacial cycles. This project will use well established methods to quantify paleo-denudation (in situ cosmogenic Be-10) and weathering intensities (chemical depletion fractions) in lacustrine sediment archives as well as calibrate promising new methods (Be-10(meteoric)/Be-9) to quantify each from fine grained, quartz-poor, lake sediments.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.