Significance of the Damara Orogen in Gondwana Assembly: an Evaluation of Detrital Zircon Ages and Isotopic Compositions of Neoproterozoic Metasedimentary Rocks

在罗迪尼亚和冈瓦那超大陆旋回期间，将对刚果和卡拉哈里克拉通之间的关系的两种不同假设进行评估。国际科学与工程办公室为这项工作提供了共同资助。刚果和卡拉哈里目前居住在非洲境内，横跨新元古代-寒武纪达马拉-卢菲利安-赞比西造山系。围绕这两个克拉通在超大陆旋回中组装的主要争议集中在刚果和卡拉哈里在整个旋回中在地理上保持关联的程度，即两个克拉通在罗迪尼亚是直接相邻的，还是在冈瓦那合并之前一直是这样的，或者一个(或两个)根本不在罗迪尼亚，直到冈瓦那形成才连接起来？达马拉造山带内变质的沉积碎屑记录了这些地块与罗迪尼亚的分离和冈瓦那内部的增生。将测定变质岩中残留的锆石的U/Pb年龄和Hf同位素组成，以及全岩的Nd同位素，以确定缝合带大陆碎屑的成因。可供选择的假说的意义与Rodinia的构型、Gonwaana的合并(东西向或N-S最终缝合)以及Rodinia在解体时的碎裂程度有关。超大陆的吸积和扩散仍然是理解全球动力学和大陆随时间运动以及地幔岩石对流的最重要问题之一。前寒武纪晚期两个超大陆的生长和解体？罗迪尼亚和冈瓦那？它们对于理解超大陆循环特别重要，因为它们与沿其边缘的浅海中复杂生命形式的发展和扩散重叠。这个项目中测试的假设对浅海沉积物的扩散和来源、这些海洋早期生命的起源和繁殖、地球上不断演变的古气候系统，以及较年轻的盘古大陆周期开始的时间都有影响。

Two different hypotheses for the relationship between the Congo and Kalahari cratons, during the Rodinia and Gondwana supercontinent cycles, will be evaluated. Co-funding for this work has been provided by the Office of International Science and Engineering.Congo and Kalahari presently reside within Africa and are juxtaposed across the Neoproterozoic-Cambrian Damara-Lufilian-Zambezi orogenic system.The primary controversy surrounding the assembly of these two cratons in the supercontinent cycle centers on the extent to which Congo and Kalahari remained associated geographically throughout the cycle, i.e., were the two cratons directly adjacent to one another in Rodinia, and, did they remain so until amalgamated in Gondwana, or was one (or both) not in Rodinia at all and were not joined until Gondwana formed? The metamorphosed sedimentary detritus within the Damara orogenic zone records the separation of these blocks from Rodinia and accretion within Gondwana. The U/Pb age and Hf-isotopic compositions of detrial zircons from the metasedimenatry rocks, along with whole-rock Nd isotopes, will be measured to define the origin of the continental detritus in the suture zone. The significance of the alternative hypotheses relates to the configuration of Rodinia, the amalgamation of Gondwana (E-W or N-S final suturing), and the degree to which Rodinia was fragmented during break-up.The accretion and dispersal of supercontinents remains one of the most significant problems in understanding global dynamics and motions of continents through time and the convection of rock in the mantle. The growth and break-up of two supercontinents in late Precambrian time ? Rodinia and Gondwana ? are particularly significant for understanding the supercontinent cycle, because they overlap the development and dispersal of complex life forms in the shallow oceans along their margins. The hypotheses being tested in this project have implications for the dispersal and source of sediment in the shallow seas, the initiation and proliferation of early life in those seas,the evolving paleoclimatic system of the planet, and the time that theyounger supercontinent cycle of Pangea initiated.