Toward an understanding of Neogene plate dynamics: Completion of a high-resolution, closure-enforced chronology of global plate motions since 20 Ma

了解新近纪板块动力学：完成 20 Ma 以来全球板块运动的高分辨率、封闭强制年表

• 批准号: 1433323
• 负责人: Dennis DeMets
• 金额: $ 30.23万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1433323&HistoricalAwards=false
• 关键词: Toward; understanding; Neogene; plate; dynamics

Motivated by work to date, which documents changes in the motions of all the major tectonic plates during the Neogene period (~23-2.5 million years ago), the proposed effort will systematically quantify the geographic scope, nature, and timing of global plate motion changes since 20 million years ago. The Principle Investigators will create a first-ever kinematic framework that will be broadly useful for understanding the relationship of instantaneous plate movements measured by geodetic techniques to movements over millions of years, as well as for modeling the forces that have determined plate motions during the Neogene. The results will be broadly useful to geoscientists, particularly geodesists, paleomagnetists, seismologists, structural geologists, and plate dynamicists. Key papers published on this topic over the past few decades have been cited thousands of times and provide an essential conceptual and quantitative framework for teaching and understanding the Neogene tectonic and geologic evolution of the ocean basins and nearly all the continents. The Principle Investigators will complete a high-resolution chronology of global plate motions since 20 million years ago, comprising most of the Neogene period. Sequences of closure-enforced plate rotations, at ~1 million year intervals, will describe the relative motions since 20 million years ago of all the major plates. The path to completing the study is well defined and consists of (1) new identifications of magnetic reversals from the southern Mid-Atlantic Ridge and Southeast Indian Ridge, as well as compilation of suitable fracture zone and transform fault flow lines along these and other spreading centers, (2) updates to largely complete sets of magnetic anomaly identifications from the southern Central Indian Ridge and Gulf of Aden, (3) compilations of existing reversal identifications from Pacific Basin spreading centers, if suitable, or new identifications for some Pacific Basin spreading centers, (4) methodological upgrades to estimate rotations consistent with plate circuit closures, to search more efficiently for best solutions, to include random and systematic data errors and the influence of the data geometry in rotation uncertainties, and to use a Bayesian methodology to suppress random noise in the rotation sequences. Half or more of the work needed to build the Neogene model has already been accomplished, partly by the Principle Investigator and a Russian collaborator via two NSF-funded projects that have spanned the past decade and partly by other investigators who have worked on the Neogene plate tectonics of the Pacific Basin. The existing data already include nearly 40,000 magnetic reversal identifications interpreted by the Principle Investigator for existing projects and 15,000 crossings of oceanic fracture zones and transform faults. Abundant data are available for completing the proposed analysis, including high-quality aeromagnetic data from the southern Mid-Atlantic Ridge that were previously unavailable for this kind of work.

迄今为止的研究工作记录了新第三纪时期（~ 2300万- 250万年前）所有主要构造板块的运动变化，受此工作的激励，该计划将系统地量化2000万年前以来全球板块运动变化的地理范围、性质和时间。主要研究人员将创建有史以来第一个运动学框架，该框架将广泛用于理解由大地测量技术测量的瞬时板块运动与数百万年的运动之间的关系，以及对新近纪决定板块运动的力进行建模。这些结果将对地球科学家，特别是测地线学家、古地磁学家、地震学家、构造地质学家和板块动力学家有广泛的帮助。在过去的几十年里发表的关于这一主题的重要论文被引用了数千次，为教学和理解新近纪构造和海洋盆地和几乎所有大陆的地质演化提供了一个重要的概念和定量框架。主要研究人员将完成2000万年前以来全球板块运动的高分辨率年表，包括大部分新近纪时期。每隔约100万年的闭合性板块旋转序列，将描述自2000万年前以来所有主要板块的相对运动。完成研究的路径是明确的，包括：(1)对中大西洋脊南部和东南印度脊的磁反转进行新的识别，并沿着这些和其他扩张中心编制合适的断裂带和转换断层流线；(2)对中印度脊南部和亚丁湾的基本完整的磁异常识别进行更新。(3)汇编来自太平洋盆地扩张中心的现有反转识别，如果合适的话，或对某些太平洋盆地扩张中心的新识别；(4)升级方法，以估计与板块闭合相一致的旋转，更有效地寻找最佳解决方案，包括随机和系统数据误差以及旋转不确定性中数据几何形状的影响；并使用贝叶斯方法来抑制旋转序列中的随机噪声。建立新第三纪模型所需的一半或更多的工作已经完成，部分是由首席研究员和一位俄罗斯合作者通过两个跨越过去十年的nsf资助项目完成的，部分是由其他研究太平洋盆地新第三纪板块构造的研究人员完成的。现有的数据已经包括由现有项目的首席研究员解释的近40,000个磁反转识别，以及15,000个海洋断裂带和转换断层的交叉。丰富的数据可用于完成建议的分析，包括来自大西洋中脊南部的高质量航磁数据，这些数据以前无法用于此类工作。