Extremes of Ocean Biogeochemistry: Focus on the Permian-Triassic Boundary

海洋生物地球化学的极端情况：关注二叠纪-三叠纪边界

• 批准号: 0208119
• 负责人: Lee Kump
• 金额: $ 25万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-15 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0208119&HistoricalAwards=false
• 关键词: Extremes; Ocean; Biogeochemistry; Focus; Permian

Project Summary Geologic evidence indicates that many periods of biotic and environmental crisis coincided with times when the world's oceans were highly stratified in their chemical and isotopic composition, with deep waters that were devoid of oxygen and likely strongly enriched in carbon dioxide and hydrogen sulfide. The Late Permian, notable as the time of the largest mass extinction in the fossil record (251 million years ago), is thought to represent such an interval. Stagnation of ocean circulation has been invoked to explain extreme oceanic conditions of widespread anoxia during this time, and reinvigoration of circulation has been suggested as a mechanism to bring toxic waters to the ocean's surface in a global Lake Nyos-type event, leading to mass extinction. The project proposed here will explore the relationship between ocean stagnation and chemical stratification, and the mechanisms that sustain shallow-water anoxia in the face of wind-driven mixing, using numerical models to ensure that the scenarios proposed are consistent with fundamental principles of mass, energy, and isotopic balance. Model results will be compared with existing isotopic and lithologic data. In addition, new sulfur isotopic data will be obtained from one of the most continuous and well-studied Permian-Triassic boundary sections in the world, providing an important missing piece of biogeochemical information against which to evaluate the models. The modeling will also provide motivation and guidance for further data collection in specific locales. The model will have the unique ability to explore the chemistry of an anoxic ocean, and as such, its availability should be of great interest to the scientific community. The intuition developed should help to guide subsequent formulation of conceptual models concerning the relationship between climate, ocean circulation, ocean biogeochemistry, and biological response.

地质学证据表明，许多生物和环境危机时期都与世界海洋的化学和同位素组成高度分层的时期相吻合，深层沃茨缺乏氧气，可能富含二氧化碳和硫化氢。晚二叠世，作为化石记录中最大的大规模灭绝（2.51亿年前）而闻名，被认为代表了这样一个间隔。海洋环流的停滞被用来解释在这段时间内广泛缺氧的极端海洋条件，而环流的重新活跃被认为是在全球Nyos湖型事件中将有毒沃茨带到海洋表面的一种机制，导致大规模灭绝。这里提出的项目将探索海洋停滞和化学分层之间的关系，以及在风驱动的混合面前维持浅水缺氧的机制，使用数值模型，以确保提出的方案符合质量，能量和同位素平衡的基本原则。模型结果将与现有的同位素和岩性数据进行比较。此外，新的硫同位素数据将从世界上最连续和研究最充分的二叠纪-三叠纪界线剖面之一获得，提供了一个重要的地球化学信息，以评估模型。建模还将为在特定地区进一步收集数据提供动力和指导。该模型将具有探索缺氧海洋化学的独特能力，因此，其可用性应引起科学界的极大兴趣。发展的直觉应有助于指导随后关于气候、海洋环流、海洋地球化学和生物反应之间关系的概念模型的制定。