The Agulhas Ridge, South Atlantic: The Peculiar Structure of a Fracture Zone
The Agulhas Ridge, South Atlantic: The Peculiar Structure of a Fracture Zone
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南大西洋阿加勒斯海岭：断裂带的特殊结构
DOI：
10.1007/s11001-005-1338-8
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
K. Gohl
中科院分区：
文献类型：
--
作者：
G. Uenzelmann‐Neben;K. Gohl
厄加勒斯海岭是一个突出的地形特征，与厄加勒斯-福克兰断裂带 (AFFZ) 平行。地震反射和广角/折射数据已导致将此特征分类为横脊。与山脊跳跃相关的扩展速率和方向的变化，加上厄加勒斯盆地内的不对称扩展，改变了整个断裂带的应力场。此外，在 80 至 69 Ma 之间经过厄加勒斯海岭的位置时，布维和绍纳热点可能向这部分 AFFZ 提供了多余的物质，从而改变了海脊的结构。厄加勒斯海岭北段的低地壳速度和过厚的地壳表明可能存在大陆亲缘关系，这表明它可能是由一小块大陆碎片形成的，在南大西洋开放期间，该大陆碎片被从莫里斯尤因浅滩切断。在渐新世早期，阿加勒斯山脊因构造岩浆作用而重新激活，正如基底高点的存在扰乱和破坏开普盆地沉积柱所记录的那样。我们将发现热点（Discovery Hotspot）视为岩浆物质的来源，该热点将羽流物质向南分布到整个 AAFZ。
The Agulhas Ridge is a prominent topographic feature that parallels the Agulhas-Falkland Fracture Zone (AFFZ). Seismic reflection and wide angle/refraction data have led to the classification of this feature as a transverse ridge. Changes in spreading rate and direction associated with ridge jumps, combined with asymmetric spreading within the Agulhas Basin, modified the stress field across the fracture zone. Moreover, passing the Agulhas Ridge’s location between 80 and 69 Ma, the Bouvet and Shona Hotspots may have supplied excess material to this part of the AFFZ thus altering the ridge’s structure. The low crustal velocities and overthickened crust of the northern Agulhas Ridge segment indicate a possible continental affinity that suggests it may be formed by a small continental sliver, which was severed off the Maurice Ewing Bank during the opening of the South Atlantic. In early Oligocene times the Agulhas Ridge was tectono-magmatically reactivated, as documented by the presence of basement highs disturbing and disrupting the sedimentary column in the Cape Basin. We consider the Discovery Hotspot, which distributes plume material southwards across the AAFZ, as a source for the magmatic material.