Middle and Upper Devonian Black Shales: Testing the Productivity-Anoxia Feedback and Land Plant-Weathering Rate Hypotheses

中、上泥盆统黑色页岩thomas Algeo（美国辛辛那提大学）、Ariel Anbar（美国亚利桑那州立大学）、Robert Creaser（加拿大阿尔伯塔大学）、Peter Sauer（美国印第安纳大学）和Lorenz Schwark（德国科伦坡大学）验证生产力-缺氧反馈和陆地植物-风化速率假设泥盆纪中晚期以海洋和陆地生物的深刻变化（包括“frasian / famenian大灭绝”）、风化过程和土壤发育为特征。全球气候和外源C-S循环。关于重大撞击的不确定证据和记录海洋营养循环长期变化的大量数据支持基于海洋学和/或风化速率控制的内在过程。基于这种机制的两个重要假设是生产力-缺氧反馈（Ingall et al., 1993）和陆地-植物风化率（Algeo et al., 1995, 2001）模型。这些模型设想了泥盆纪浅海的类似环境条件（富营养化地表水、初级生产力提高和底栖动物氧气消耗），但它们的控制方式不同，但并非相互排斥。生产力-缺氧反馈模型考虑了水柱内营养物质微生物循环的增强，以及低级反硝化作用、季节性水柱翻转和初级生产力的氮限制，而陆地植物-风化速率模型考虑了由于陆地植物的扩散和土壤作用的加强而导致的风化源营养物质通量的增加。石油公司建议在关键层位（相当于北美的Kellwasser和Hangenberg事件）中测试这些模型，使用综合化学地层数据集，包括元素浓度数据、TOC-TIC、有机d13C和d15N、全岩187Os/188Os和d97/95Mo、HI-OI和生物标志物。这些数据集来自Appalachian、Illinois和Alberta盆地的钻井岩心。pi将通过将他们的数据导入CHRONOS系统和古地层，使他们的数据可供更大的科学界使用。该项目的广泛影响是多方面的，包括公众宣传、本科生和研究生的指导、不同地球科学专业人员群体之间研究协同效应的发展，以及具有广泛科学意义的成果的潜力。ppi致力于推进公立学校的科学教育，为大学水平的科学项目搭建“桥梁”（特别是为女性和代表性不足的少数民族），并培养下一代科学家。

Middle and Upper Devonian Black Shales: Testing the Productivity-Anoxia Feedback and Land Plant-Weathering Rate HypothesesThomas Algeo (University of Cincinnati), Ariel Anbar (Arizona State University), Robert Creaser (University of Alberta), Peter Sauer (Indiana University), and Lorenz Schwark (University of Cologne)EAR-0618003ABSTRACTThe Middle to Late Devonian was characterized by profound changes in marine and terrestrial biotas (including the "Frasnian/Famennian mass extinction"), weathering processes and soil development, global climate, and the exogenic C-S cycle. Inconclusive evidence for major bolide impacts and a wealth of data documenting long-term changes in marine nutrient cycles favor intrinsic processes based on oceanographic and/or weathering rate controls. Two important hypotheses based on such mechanisms are the productivity-anoxia feedback (Ingall et al., 1993) and land-plant weathering rate (Algeo et al., 1995, 2001) models. These models envision similar environmental conditions in Devonian epicratonic seas (eutrophic surface waters, elevated primary productivity, and benthic oxygen depletion) yet different, but not mutually exclusive, controls thereon. The productivity-anoxia feedback model invokes enhanced microbial recycling of nutrients within the water column in combination with hypolimnial denitrification, seasonal water-column overturn, and N limitation of primary productivity, whereas the land plant-weathering rate model invokes elevated fluxes of weathering-derived nutrients as a consequence of the spread of land plants and intensified pedogenesis. PIs propose to test these models within key horizons (the North American equivalents of the Kellwasser and Hangenberg events) in drillcores from the Appalachian, Illinois, and Alberta basins using integrated chemostratigraphic datasets that will include elemental concentration data, TOC-TIC, organic d13C and d15N, whole-rock 187Os/188Os and d97/95Mo, HI-OI, and biomarkers. PIs will make their data available to the larger scientific community by importing them into the CHRONOS System and PaleoStrat. The broader impacts of this project are varied and include public outreach, mentoring of undergraduate and graduate students, development of research synergies among a diverse group of geoscience professionals, and the potential for results of broad scientific significance. The PIs are committed to advancing science education in the public schools, to building "bridges" (especially for women and underrepresented minorities) to college-level science programs, and to training the next generation of scientists.