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：生产力-缺氧反馈和陆生植物-风化速率假说的检验（辛辛那提大学），阿里尔·安巴尔（亚利桑那州立大学），罗伯特·克雷瑟（阿尔伯塔大学），彼得·绍尔（印第安纳州大学），还有洛伦兹·史华克（科隆大学）摘要中晚泥盆世是一个以海陆生物多样性变化为特征的时期（包括“Frasnian/Famennian大灭绝”）、风化过程和土壤发育、全球气候和外生C-S循环。 主要的火流星的影响和丰富的数据记录海洋养分循环的长期变化的非决定性的证据有利于海洋学和/或风化率控制的基础上的内在过程。 基于这种机制的两个重要假设是生产力-缺氧反馈（Ingall等人，1993）和陆地植物风化率（Algeo等人，1995，2001）模型。 这些模型设想泥盆纪epicratonic海（富营养化的表面沃茨，初级生产力提高，底栖生物的氧气消耗）相似的环境条件，但不同的，但不相互排斥，控制。 生产力缺氧反馈模型调用增强的微生物循环的营养物在水柱结合hypolimmune反硝化，季节性水柱翻转，和N限制的初级生产力，而陆地植物风化率模型调用升高通量的风化衍生的营养物作为陆地植物的传播和强化成土作用的结果。 PI建议使用综合化学地层数据集（包括元素浓度数据、TOC-TIC、有机d13 C和d15 N、全岩187 Os/188 Os和d97/95 Mo、HI-OI和生物标志物），在阿巴拉契亚、伊利诺伊和阿尔伯塔盆地的岩芯中，在关键层位（相当于北美的Kellwasser和Hangenberg事件）内测试这些模型。 PI将通过将其数据导入CHRONOS系统和PaleoStrat，使其数据可供更大的科学界使用。 该项目的广泛影响是多种多样的，包括公共宣传，本科生和研究生的辅导，发展研究协同作用之间的地球科学专业人员的不同群体，并为广泛的科学意义的结果的潜力。 PI致力于推进公立学校的科学教育，建立通往大学科学课程的“桥梁”（特别是为妇女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.