Assessing Weathering as a Function of Climate in Proximal Alluvial Sediments

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Assessing Weathering as a Function of Climate in Proximal Alluvial SedimentsbyGerilyn Sorghan, Megan Elwood-Madden, EAR-1225162, University of OklahomaABSTRACTInferring a glacial influence from sedimentary facies is elusive, especially in the absence of ice-contact indicators (e.g., striated clasts). Illustrating this, inferences of glaciation on the basis of sedimentary facies have ignited controversies for sediments and sedimentary rocks from the murky depths of the Archean through the comparable light of the Pleistocene. Traditional chemical weathering indices are also ambiguous, particularly in discerning glacial/proglacial alluvial deposits from those formed in hot-arid systems. However, integrating chemical, mineralogical, and textural observations of alluvial sediments formed in temperature-precipitation extremes could provide valuable indicators of climate for sedimentary studies, particularly in distinguishing glacial from non-glacial systems. PIs propose to test the hypothesis that bulk chemistry, texture, and mineralogy, and solute fluxes of granitoid-sourced alluvial sediments show systematic and robust variations between glacial and non-glacial systems owing to differences in reactive surface area, temperature, and aqueous conditions. Accordingly, the objective of the proposed research is to quantify natural variation of chemical and physical weathering in granitoid-sourced proximal alluvial sediments in end-member glacial and non-glacial systems when other, "non-climatic" factors (e.g., provenance, drainage basin area and relief, sample grain size, sediment facies) are controlled. The ultimate goal is to establish a quantitative matrix of chemical and textural metrics to differentiate sediments formed in contrasting climates.