Collaborative Research: Improved Cenozoic Plate Reconstructions of the Circum-Antarctic Region

该奖项由极地方案办公室南极地质和地球物理方案提供，为一个项目提供资金，该项目利用船舶重新定位凌日巡航收集与南大洋板块构造有关的地球物理信息，并支持学生培训活动。环南极地区受到良好约束的新生代板块重建对于研究一些具有全球地球物理意义的问题至关重要。这些问题包括，例如，将板块运动学与其在不同板块环路(太平洋-北美、澳大利亚-太平洋)中的地质后果联系起来；对驱动板块构造的因素的动力学理解(这需要有良好约束的运动学信息才能区分不同的地球动力学假说)；以及对板块本身的流变性的理解，包括它们可以支持的内部变形量，以及通过分裂现有板块形成新的板块边界的条件。通过更好地限制南极板块相对于其他板块的运动，以及更好地量化南极内部(东南极和西南极之间)的内部变形，将有助于解决这些其他基本问题。在这个项目中，将分析现有数据，以解决与南极板块运动有关的几个具体问题。首先，将对澳大利亚-太平洋-西南极-东南极运动的四板块解进行研究，以便最严格地约束约45-28 Ma(阿达雷盆地扩张系统)的东南极和西南极分离的旋转参数。这将通过关闭四个板块的电路并使用所有四个边界的相关海洋地球物理数据来实现。由此产生的旋转参数中的不确定性将根据数据点中的不确定性确定。然后，这些不确定性可以在平板电路中传播，用于解决上述各种全球地球动力学问题。第二，将使用最近获得的导航良好的帕尔默凌日数据和在本项目过程中可以获得的任何其他数据来确定第三纪期间太平洋-西南极的自转参数。这些参数及其不确定度将用于评估板块刚性，并纳入板块电路研究。在该项目的框架内，将以非常灵活的时间表完成新的海洋地球物理数据收集。这将通过收集具有重要地质意义的帕尔默过境邮轮的在航重力、磁力和带状水深数据来完成。自1997年以来，这已经在之前的八次帕尔默邮轮上成功完成，最近的四次邮轮是由加州理工学院和斯克里普斯公司的合作OPP拨款资助的，该拨款现已到期。在其中一次合适的过渡中，将举办一堂关于海洋地球物理的正式课程，将为来自加州理工学院、斯克里普斯学院以及其他机构的12名或更多研究生和本科生提供机会。这样，教育活动将与研究项目通常的科学数据收集目标相结合。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for a project to make use of ship-repositioning transit cruises to gather geophysical information relating to plate tectonics of the Southern Ocean and to support student training activities. Well-constrained Cenozoic plate reconstructions of the circum-Antarctic region are critical for examining a number of problems of global geophysical importance. These problems include, e.g., relating the plate kinematics to its geological consequences in various plate circuits (Pacific-North America, Australia-Pacific); a dynamical understanding of what drives plate tectonics (which requires well-constrained kinematic information in order to distinguish between different geodynamic hypotheses); and an understanding of the rheology of the plates themselves, including the amount of internal deformation they can support, and the conditions leading to the formation of new plate boundaries through breakup of existing plates. By obtaining better constraints on the motion of the Antarctica plate with respect to these other plates, and by better quantifying the internal deformation within Antarctica (between East and West Antarctica), contributions will be made to solving these other fundamental problems.In this project, existing data will be analyzed to address several specific issues related to plate motions involving the Antarctic plate. First, work will be done on four-plate solutions of Australia-Pacific-West Antarctica-East Antarctica motion, in order to most tightly constrain the rotation parameters for separation between East and West Antarctica for the time period from about 45 to 28 Ma (Adare Basin spreading system). This will be done by imposing closure on the four-plate circuit and using relevant marine geophysical data from all four of the boundaries. The uncertainties in the resulting rotation parameters will be determined based on the uncertainties in the data points. These uncertainties can then be propagated in the plate circuit for use in addressing the various global geodynamic problems mentioned above. Second, rotation parameters for Pacific-West Antarctica during Tertiary time will be determined using recently acquired well-navigated Palmer transit data and any additional data that can be acquired during the course of this project. These parameters and their uncertainties will be used in assessments of plate rigidity and included in the plate circuit studies.In the framework of this project, new collection of marine geophysical data will be accomplished on a very flexible schedule. This will be done by collecting underway gravity, magnetics, and swath bathymetric data on Palmer transit cruises of geological importance. This has been successfully done on eight previous Palmer cruises since 1997, the most recent four of which were funded under a collaborative OPP grant to CalTech and Scripps which is now expiring. On one of the suitable transits, a formal class in marine geophysics will be conducted that will afford an opportunity to 12 or more graduate and undergraduate students, from CalTech and Scripps as well as other institutions. In this way, educational activities will be integrated with the usual scientific data collection objectives of the research project.