From Continental Hyperextension to Seafloor Spreading: New Insights on the Porcupine Basin From Wide-Angle Seismic Data
From Continental Hyperextension to Seafloor Spreading: New Insights on the Porcupine Basin From Wide-Angle Seismic Data
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DOI：
10.1029/2018jb016375
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发表时间：
2018-10-01
影响因子：
3.9
通讯作者：
Shannon, P. M.
中科院分区：
文献类型：
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作者：
Chen, C.;Watremez, L.;Shannon, P. M.
裂谷盆地的深部构造和沉积记录为认识岩石圈伸展的地质过程提供了重要的线索。利用3条广角地震剖面和13条精选地震反射剖面，研究了爱尔兰南部豪猪盆地的地壳结构和大尺度沉积构型。折射和反射行时联合反演得到的地震速度和地壳几何模型清晰地反映了盆地的深部构造。我们的研究结果表明，裂谷轴上存在三个不同的地壳域：(a)大陆地壳通过盆地从北向南逐渐超伸展，(b)性质不确定的过渡带，(c) 7- 8 km厚的海洋地壳带。后者上覆有类似8公里的上古-中生代压实层序和类似2公里的新生代地层。由于缺乏明确的磁异常和缺乏井控，解释洋壳的精确年龄是未知的。然而，我们可以根据区域背景确定晚侏罗世至晚白垩世的年龄范围。我们认为豪猪盆地存在一个向北扩展的裂谷作用，导致了裂谷轴上的应变变化。
The deep structure and sedimentary record of rift basins provide an important insight into understanding the geological processes involved in lithospheric extension. We investigate the crustal structure and large-scale sedimentary architecture of the southern Porcupine Basin, offshore Ireland along three wide-angle seismic profiles, supplemented by 13 selected seismic reflection profiles. The seismic velocity and crustal geometry models obtained by joint refraction and reflection traveltime inversion clearly image the deep structure of the basin. Our results suggest the presence of three distinct crustal domains along the rifting axis: (a) continental crust becoming progressively hyperextended from north to south through the basin, (b) a transitional zone of uncertain nature, and (c) a 7- to 8-km-thick zone of oceanic crust. The latter is overlain by an similar to 8-km compacted Upper Paleozoic-Mesozoic succession and similar to 2 km of Cenozoic strata. Due to the lack of clear magnetic anomalies and in the absence of well control, the precise age of interpreted oceanic crust is unknown. However, we can determine an age range of Late Jurassic to Late Cretaceous from the regional context. We propose a northward propagating rifting process in the Porcupine Basin, resulting in variations in strain along the rift axis.