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

该奖项由极地项目办公室的南极地质与地球物理项目和海洋科学部的海洋地质与地球物理项目联合提供，支持开发改进的西南太平洋地区板块旋转模型的研究（在太平洋、南极和澳大利亚板块之间，以及新西兰、西南极洲、伊瑟林银行、东南极洲和澳大利亚的大陆碎片）。改进后的旋转参数将用于解决与东南极洲和西南极洲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少板块边界的争议。先前的工作记录了东、西南极洲之间的中第三纪海底向北西方向扩展的磁异常，代表了罗斯海以北的阿达尔海槽开口约150公里。这不足以解决板块运动与假定热点不动推断出的运动之间的明显差异。因为东南极洲和西南极洲之间的这种运动对应于一个非常小的旋转，它指出需要确定有限的旋转，以高度精确地描述这里各种板块的运动，特别是对于更古老的时代。现在，对于将在本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游时提供的其他数据集的分析和解释相结合来完成。它将通过获取关于R/VIB Nathaniel B. Palmer选定凌日的新的海洋地球物理数据而得到进一步加强。该项目的具体目标包括：1)通过在计算澳大利亚-西南极洲运动时直接包括太平洋和澳大利亚板块之间的板块边界，改进中第三纪东、西南极洲之间伸展的旋转模型；2)通过在重建中包括以前未使用的几个边界的新约束，改进晚白垩世和早第三纪的重建；3)解决新旋转的影响4)根据大量中新生代伸展的模型，重新检查来自西罗斯海海湾的地球物理数据。

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.