Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula
Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula
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DOI：
10.1016/j.tecto.2008.02.013
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发表时间：
2009-01-20
期刊：
影响因子：
2.9
通讯作者：
Thorkelson, Derek J.
中科院分区：
文献类型：
--
作者：
Breitsprecher, Katrin;Thorkelson, Derek J.
巴塔哥尼亚板窗是南美洲南部纳斯卡-南极扩张脊系统（智利海隆）俯冲形成的地下构造特征。板块窗的几何形状尚未严格定义，部分原因是东南太平洋地区洋脊俯冲历史的复杂性，其中包括20 Ma以来四个相互关联的扩张洋脊系统：首先是南美洲下面的纳斯卡-菲尼克斯海脊，然后是南美洲下面的纳斯卡-南极和北方菲尼克斯-南极扩展海脊系统的同时俯冲，以及南极洲下方的南凤凰城-南极扩展脊系统。所有相关板块对（纳斯卡，凤凰城，南极，南美洲）的脊古地理和旋转极可从20马向前，并形成我们的运动学重建的巴塔哥尼亚和南极板块窗口的几何形状通过新近纪时间的数学基础。在大约18 Ma，纳斯卡-菲尼克斯-南极大洋（脊-脊-脊）三联点进入南美海沟;我们认为这种情况是不稳定的四重连接。在这个接合处和在前弧下面的一段距离内的热流，将比一般所认识到的在洋脊俯冲的情况下的热流高得多。从16 Ma起，巴塔哥尼亚板片窗的几何形状是由前大洋三联点的拖曳臂俯冲而来的。大部分的板块窗口的面积范围和几何形状是由高度倾斜（近平行）的纳斯卡-南极海脊系统的俯冲角，并通过这两个板块之间的相对收敛率相对于南美洲的高对比度控制。南极板块非常缓慢的收敛速度表现在板块边缘达到的浅水平（
The Patagonian slab window is a subsurface tectonic feature resulting from subduction of the Nazca-Antarctic spreading-ridge system (Chile Rise) beneath southern South America. The geometry of the slab window had not been rigorously defined, in part because of the complex nature of the history of ridge subduction in the southeast Pacific region, which includes four interrelated spreading-ridge systems since 20 Ma: first, the Nazca-Phoenix ridge beneath South America, then simultaneous subduction of the Nazca-Antarctic and the northern Phoenix-Antarctic spreading-ridge systems beneath South America, and the southern Phoenix-Antarctic spreading-ridge system beneath Antarctica. Spreading-ridge paleo-geographies and rotation poles for all relevant plate pairs (Nazca, Phoenix, Antarctic, South America) are available from 20 Ma onward, and form the mathematical basis of our kinematic reconstruction of the geometry of the Patagonia and Antarctic slab windows through Neogene time. At approximately 18 Ma, the Nazca-Phoenix-Antarctic oceanic (ridge-ridge-ridge) triple junction enters the South American trench; we recognize this condition as an unstable quadruple junction. Heat flow at this junction and for some distance beneath the forearc would be considerably higher than is generally recognized in cases of ridge subduction. From 16 Ma onward, the geometry of the Patagonia slab window developed from the subduction of the trailing arms of the former oceanic triple junction. The majority of the slab window's areal extent and geometry is controlled by the highly oblique (near-parallel) subduction angle of the Nazca-Antarctic ridge system, and by the high contrast in relative convergence rates between these two plates relative to South America. The very slow convergence rate of the Antarctic slab is manifested by the shallow levels achieved by the slab edge (