Changes in Paleosol Morphology and Geochemistry Associated with Mid-Paleozoic Afforestation and Decline in Atmospheric pCO2

9418183莫拉 拟议的研究调查的古土壤和成土碳酸盐形态和地球化学保存在志留纪-泥盆纪时期，一个时期的快速演变和多样化的陆地生态系统的变化。 陆地植物的进化导致植物的体积越来越大，生根能力越来越深，陆地表面的植树造林越来越广泛。 维管陆生植物的发展和丰富度的增加可能导致了风化速率的增加，并使大气pCO 2从中古生代的非常高的水平下降到石炭-二叠纪的近现今水平。 拟议的研究将评估造林，增加风化剖面，也有助于在成土碳酸盐的稳定同位素组成的变化的假设。 拟议的研究将强调从十个地层单位（主要是红层）暴露在露头在美国和海洋加拿大阿巴拉契亚山脉的志留纪-泥盆纪古土壤的形态和地球化学分析。 详细的宏观和微观形态表征的古土壤，估计古土壤厚度，质量平衡评价土壤主要和微量元素地球化学和稳定同位素分析的成壤碳酸盐相将结合现有的古生物学信息，为这些单位的特点“土壤学签名”的植被的土地表面的维管植物。 结果将允许在此期间的深刻变化，使用Cerling的土壤碳酸盐古压力计的大气pCO 2的详细评估。 研究结果将有助于我们了解古土壤和成壤碳酸盐沉积的分布和保存及其作为古环境和古气候监测的有用性（或局限性）。 这些结果与预测地球岩石圈和生物圈对大气pCO 2显著变化的响应的模型有关。

9418183 Mora The proposed research investigates changes in paleosol and pedogenic carbonate morphology and geochemistry preserved during the Siluro-Devonian time period, a period of rapid evolution and diversification of terrestrial ecosystems. Land plant evolution led to progressively more robust plant size and deeper rooting capabilities and more widespread afforestation of the land surface. The development and increasing abundance of vascular land plants may have contributed to increased weathering rates and draw down of atmospheric pCO2 from very high levels in the middle Paleozoic to near-present day levels in the Permo-Carboniferous. The proposed research will evaluate the hypothesis that afforestation, increased weathering profiles and also contributed to changes in the stable isotope composition of pedogenic carbonate. The proposed study will emphasize morphological and geochemical analysis of Siluro-Devonian paleosols from ten stratigraphic units (chiefly red-beds) exposed in outcrop in the U.S. and maritime Canada Appalachians. Detailed macro- and micromorphological characterization of the paleosols, estimation of paleosol thickness, mass balance evaluation of soil major and trace element geochemistry and stable isotopic analyses of pedogenic carbonates phases will be combined with existing paleontological information for these units to characterize the "pedological signature" of afforestation of the land surface by vascular plants. The results will permit a detailed evaluation of atmospheric pCO2 during this period of profound change using Cerling's soil carbonate paleobarometer. The results will contribute to our understanding of the distribution and preservation of paleosols and pedogenic carbonate deposits and their usefulness (or limitations) as monitors of paleoenvironments and paleoclimate. The results are relevant to models which predict the response of the Earth's lithosphere and biosphere to significant changes in atmospheric pCO2.