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

达马拉造山带在冈瓦纳造山带中的意义：新元古代变质沉积岩碎屑锆石年龄和同位素组成的评价

• 批准号: 0738874
• 负责人: David Foster
• 金额: $ 29.1万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0738874&HistoricalAwards=false
• 关键词: Significance; Damara; Orogen; Gondwana; Assembly

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.

两种不同的假设之间的关系刚果和卡拉哈里盆地，在Rodinia和冈瓦纳超大陆周期，将进行评估。这项工作的共同资金由国际科学与工程办公室提供。刚果和卡拉哈里目前居住在非洲境内，并在新元古代-寒武纪达马拉-卢菲利安-赞比西造山系统中并列。围绕这两个板块在超大陆旋回中的组装的主要争议集中在刚果和卡拉哈里在整个旋回中保持地理联系的程度上，即，这两个古罗马人在罗迪尼亚是直接相邻的吗？他们是一直这样直到冈瓦纳合并，还是其中一个（或两个）根本不在罗迪尼亚，直到冈瓦纳形成才合并？ 达马拉造山带内的变质沉积碎屑记录了这些地块与Rodinia的分离和冈瓦纳内的加积。 通过测定变质沉积岩中碎屑锆石的U/Pb年龄、Hf同位素组成沿着全岩Nd同位素组成，确定缝合带中碎屑岩的成因。 这些假说的意义涉及Rodinia的构造、冈瓦纳的融合（东西或南北最终融合）以及Rodinia在分裂过程中的破碎程度。超大陆的增生和扩散仍然是理解全球动力学和大陆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分裂？Rodinia和Gondwana？对于理解超大陆循环特别重要，因为它们与沿着其边缘的浅海中复杂生命形式的发展和扩散重叠。 在这个项目中正在测试的假设有影响的分散和来源的沉积物在浅海中，在这些海洋中的早期生命的启动和增殖，不断演变的古气候系统的行星，和时间，theyounger超大陆周期的泛古陆开始。