Crustal structure of the Goban Spur rifted continental margin, NE Atlantic
Crustal structure of the Goban Spur rifted continental margin, NE Atlantic
复制标题
DOI：
10.1111/j.1365-246x.1994.tb00909.x
复制
发表时间：
1994-10
影响因子：
2.8
通讯作者：
S. Horsefield;K. Whitmarsh;R. White;J. Sibuet
中科院分区：
文献类型：
--
作者：
S. Horsefield;K. Whitmarsh;R. White;J. Sibuet
摘要 我们提出了限制典型“非火山”裂谷大陆边缘（大西洋东北部戈班山刺）地壳结构的结果。广角海底地震仪剖面的走时和振幅模型表明，大陆地壳在破裂之前向海方向变薄至约 7 公里，从而形成新的海洋传播中心。由重力异常推断的地壳速度结构、拉伸因子和密度分布与裂谷大陆边缘发育的整体纯剪切拉伸一致。减薄的大陆地壳的地震速度结构表明，减薄仅伴随着上地壳有限的火成岩侵入和挤压。邻近的洋壳异常薄（5.4公里）。这最容易解释为在非常缓慢的扩张中心（大约11毫米年的全速率）的增生，尽管当母地幔在拉伸和变薄的大陆岩石圈下方缓慢上升时，由于母地幔的传导热损失而产生额外的冷却，再加上少量的火成岩侵入和表面流到邻近的大陆地壳上，也可能减少了紧邻大陆-海洋过渡区的海洋火成岩的厚度。
SUMMARY We present results that constrain the crustal structure across a typical ‘non-volcanic’ rifted continental margin, the Goban Spur in the NE Atlantic. Traveltime and amplitude modelling of wide-angle ocean-bottom seismograph profiles shows that the continental crust thins in a seaward direction to about 7 km before it breaks to allow a new oceanic spereading centre to develop. The crustal-velocity structure, the stretching factors and the density distribution inferred from gravity anomalies are consistent with bulk pure shear stretching for the development of the rifted continental margin. The seismic-velocity structure of the thinned continental crust suggests that thinning was accompanied by only limited igneous intrusion and extrusion in the upper crust. The adjacent oceanic crust is abnormally thin (5.4km). This is explained most readily by accretion at a very slow spreading centre (approx 11 mm yr-’ full rate), although additional cooling by conductive heat loss from the parent mantle as it rose slowly beneath the stretched and thinned continental lithosphere, together with minor igneous intrusion into, and surface flows onto, the adjacent continental crust may also have reduced the oceanic igneous thickness immediately adjacent to the continent-ocean transition.