Timing and geometry of early Gondwana breakup -: art. no. 2428
Timing and geometry of early Gondwana breakup -: art. no. 2428
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DOI：
10.1029/2002jb001802
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发表时间：
2003-09-16
影响因子：
3.9
通讯作者：
Meyer, U
中科院分区：
文献类型：
--
作者：
Jokat, W;Boebel, T;Meyer, U
[1]南美洲、非洲和南极洲之间的南大洋的中生代开放历史是关于该区域演化的最大认识空白之一。在过去的二十年里，相互竞争的地球动力学模型被发表，以解释地球物理和地质观测。这里我们报道了南极东部海岸五个季节的航磁数据。这些数据为冈瓦那早期解体的时间和几何形状提供了新的约束。在Riiser-Larsen海/莫桑比克盆地，非洲和南极洲之间的第一个洋壳形成于155 Ma左右。在西部，韦德尔裂谷在克莱恩斯M19N和M17N之间以63公里/英里的速度从西向东传播。在chron M14N，南美洲和非洲最终从南极大陆分裂出来。南大西洋地区的伸展最晚从155年开始。南美洲和非洲不同的扩张速度和方向在南大西洋的M9N形成了第一个洋壳。一个新的模型表明，Karoo和Dronning Maud陆地的岩浆作用早在任何新的海底形成之前就发生了，因此第一次新洋壳的形成不可能直接与羽流相互作用有关。
[1] The Mesozoic opening history of the Southern Ocean between South America, Africa, and Antarctica is one of the largest gaps in knowledge on the evolution of this region. Competing geodynamic models were published during the last two decades to explain the geophysical and geological observations. Here we report on aeromagnetic data collected along the East Antarctic coast during five seasons. These data provide new constraints on the timing and geometry of the early Gondwana breakup. In the Riiser- Larsen Sea/ Mozambique Basin, the first oceanic crust between Africa and Antarctica formed around 155 Ma. In the west the Weddell Rift propagated from west to east with a velocity of 63 km/Myr between chrons M19N and M17N. At chron M14N, South America and Africa finally were split off the Antarctic continent. Stretching in the area of the South Atlantic started at the latest from 155 Myr onward. The different spreading velocities and directions of South America and Africa created at chron M9N the first oceanic crust in the South Atlantic. A new model indicates that the Karoo and Dronning Maud Land magmatism occurred well before any new ocean floor was created and therefore the first formation of new oceanic crust cannot directly be related to a plume interaction.