Collaborative Research: Late Cretaceous and Cenozoic Reconstructions of the Southwest Pacific

该奖项由极地方案办公室的南极地质和地球物理方案和海洋科学部的海洋地质和地球物理方案联合提供，支持为西南太平洋地区(太平洋、南极和澳大利亚板块之间，以及新西兰、南极洲西部、伊塞林海岸、东南极和澳大利亚的大陆碎片之间)开发改进的板块旋转模型的研究。改进后的自转参数将用于解决与东南极和西南极之间运动有关的构造问题，特别是主要热点群之间的相对漂移问题，以及关于该地区可能缺失的板块边界的争议。以前的工作记录了北北西走向的中第三纪海底在南极洲东部和西部之间扩散的磁异常，代表着罗斯海以北的阿达雷海槽大约150公里的开口。这并不足以解决板块运动与假定热点不变所得出的运动之间的明显差异。由于东南极和西南极之间的这种运动对应着一个非常小的自转，这表明需要高精度地确定描述这里各个板块运动的有限自转，特别是对于更古老的时代。现在，对于将在此项目中使用的数据集，这是可能的。这项工作将通过将现有数据与日本和意大利科学家最近在该区域巡航时提供的其他数据集的分析和解释结合起来完成。将通过在R/VIB纳撒尼尔·B·帕尔默的选定中转点上获取新的海洋地球物理数据来进一步加强这一点。该项目的具体目标包括：1)通过在计算澳大利亚-西南极运动时直接包括太平洋和澳大利亚板块之间的板块边界，改进南极东部和西部第三纪中期伸展的旋转模型；2)通过包括对以前没有在重建中使用的几条边界的新限制，改进白垩纪晚期和第三纪早期的重建；3)解决新的旋转模型对全球热点固定问题的影响；4)根据中新生代大规模伸展的模型，重新审查来自西罗斯湾的地球物理数据。

This award, provided jointly by the Antarctic Geology and Geophysics Program of the Office of Polar Programs and the Marine Geology and Geophysics Program of the Division of Ocean Sciences, supports research to develop improved plate rotation models for the Southwest Pacific region (between the Pacific, Antarctic, and Australian plates, and the continental fragments of New Zealand, West Antarctica, Iselin Bank, East Antarctica, and Australia). The improved rotation parameters will be used to address tectonic problems related to motion between East and West Antarctica, and in particular, the questions of relative drift between major hotspot groups and the controversy regarding a possible missing plate boundary in this region. Previous work has documented NNW-striking mid-Tertiary seafloor spreading magnetic anomalies between East and West Antarctica, representing about 150 km of opening of the Adare Trough, north of the Ross Sea. This is not enough motion to resolve the apparent discrepancy between the plate motions and motions inferred from assuming hotspot fixity. Because this motion between East and West Antarctica corresponds to a very small rotation, it points to the need for determination of finite rotations describing motions of the various plates here with a high degree of accuracy, particularly for older times. This is now possible with the datasets that will be used in this project. The work will be accomplished by integrating existing data with analysis and interpretation of other data sets recently made available by Japanese and Italian scientists from their cruises in the region. It will be further augmented by acquisition of new marine geophysical data on selected transits of the R/VIB Nathaniel B. Palmer. Specific objectives of the project include the following:1) improve the rotation model for mid-Tertiary extension between East and West Antarctica by including the plate boundary between the Pacific and Australia plates directly when calculating Australia-West Antarctica motion,2) improve the reconstructions for the Late Cretaceous and Early Tertiary times by including new constraints on several boundaries not previously used in the reconstructions,3) address the implications of new rotation models for the question of the fixity of global hotspots,4) re-examine the geophysical data from the Western Ross Sea embayment in light of a model for substantial mid-Cenozoic extension.