Sedimenary Processes in the Wilkes Land Margin: A Record of Cenozoic East Antarctic Ice Sheet Evolution

Multichannel seismic data collected off Wilkes Land (East Antarctica) reveal four main units that represent distinct phases in the evolution of the Cenozoic depositional environment. A Cretaceous synrift succession is overlain by hemipelagic and distal terrigenous sequences deposited during Phase 1. Sediment ridges and debris-flow deposits mark the transition to Phase 2. Unit 3 records the maximum sediment input from the continent and is characterized by the predominance of turbidite deposits. During Phase 4 the sediment supply from the continental margin was reduced, and draping and filling were the dominant processes on the continental rise. Unit 4 also contains the deposits of sediment wave fields and asymmetric channel-levee systems. These four units are a response to the Cenozoic evolution of the East Antarctic Ice Sheet. During Phase 1, small ice caps were formed in the innermost continental areas. The ice volume increased under temperate glacial regimes during Phases 2 and 3, when large volumes of melt-water production led to high sediment discharge to the continental rise. Change to a polar regime occurred through Phase 4, when a thick prograding wedge developed on the continental shelf and slope and the sediment transport to the rise diminished, producing general starvation conditions.

采集于东南极洲威尔克斯陆缘（Wilkes Land）海域的多道地震数据（Multichannel Seismic Data），揭示了四套主要地层单元，这些单元分别对应新生代沉积环境演化的不同阶段。白垩纪同裂谷期沉积序列之上，覆盖着第一阶段沉积的半远洋远源陆源沉积序列。沉积脊与碎屑流沉积标志着向第二阶段的过渡。第三地层单元记录了来自大陆的最大沉积物供给量，其特征为浊流沉积占据主导地位。第四阶段中，大陆边缘的沉积物供给量有所降低，大陆隆上的主要沉积作用以披覆与充填为主。第四地层单元还包含沉积物波场与不对称水道-堤岸系统的沉积体。上述四套地层单元均响应于东南极冰盖（East Antarctic Ice Sheet）的新生代演化过程。第一阶段，大陆内陆腹地形成了小型冰盖。在第二、第三阶段的温带冰川环境下，冰体体积持续增长，此时大量融水产出，使得大陆隆接收的沉积物通量大幅升高。第四阶段逐步向极地冰川环境转变：大陆架与陆坡上形成了厚层进积楔体，向大陆隆的沉积物搬运量随之锐减，进而引发了普遍的饥饿沉积状态。