Assessing Weathering as a Function of Climate in Proximal Alluvial Sediments

[摘要]从沉积相中考虑冰川的影响是难以捉摸的，特别是在缺乏冰接触指标（如条纹碎屑）的情况下。为了说明这一点，在沉积相的基础上对冰川作用的推断引发了对太古宙阴暗深处的沉积物和沉积岩的争论，通过更新世的可比光。传统的化学风化指标也很模糊，特别是在区分冰川/前冰川冲积矿床与热干旱系统形成的冲积矿床时。然而，综合在极端温度-降水条件下形成的冲积沉积物的化学、矿物学和结构观测，可以为沉积研究提供有价值的气候指标，特别是在区分冰川系统和非冰川系统方面。pi提议测试花岗岩源冲积沉积物的总体化学、结构、矿物学和溶质通量在冰川和非冰川系统之间由于反应表面积、温度和水条件的差异而表现出系统和强大的变化的假设。因此，本研究的目的是在控制其他“非气候”因素（如物源、流域面积和地形、样品粒度、沉积相）的情况下，量化冰川期和非冰川期末端花岗岩源近端冲积沉积物化学和物理风化的自然变化。最终目标是建立化学和质地指标的定量矩阵，以区分在不同气候条件下形成的沉积物。

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.