Late orogenic extension of the Betic Cordillera and the Alboran Domain: A lithospheric view
Late orogenic extension of the Betic Cordillera and the Alboran Domain: A lithospheric view
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贝蒂科迪勒拉和阿尔沃兰域的造山晚期延伸：岩石圈观点
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
D. Wal
中科院分区：
文献类型：
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作者：
R. Vissers;J. Platt;D. Wal
西班牙南部的贝蒂克山脉提供了一个明显的例子，说明碰撞造山带在边界板块继续会聚运动的同时经历了大规模的伸展塌陷。在系统外围的薄皮褶皱和冲断带中，通过同时代的缩短来适应延伸，该地区的大部分地区现在已经沉降，形成了一个大型海洋盆地。这些过程的热和变形记录保存在上地幔、结晶地壳和沉积盖层的岩石中。上地幔橄榄岩记录了从软流圈深处到地表的几个阶段折返的证据。早期剥露可能发生在中生代裂谷作用期间。在岩石圈中部深度的冷却反映大陆收敛，随后的加热表明大部分的底层岩石圈和软流圈上升的损失，而在中新世早期的最后阶段的折返时间反映伸展崩溃。Betic Cordillera内部区域的地壳岩石变质到50公里深，现在暴露在主要的低角度正常拆离带之下，这些拆离带将它们与上面严重断裂的低级岩石分开。相关糜棱岩的冷却年龄表明，这些碎屑岩活动于早中新世至中中新世。断层为界的山间盆地，在中新世早期至中期发展，包含粗糙的大陆沉积物严重影响正常的断层系统，其次是一个较小的变形晚中新世海洋序列。所有这些现象都可以解释为对流迁移的岩石圈根下的古近纪碰撞造山带，导致大规模的伸展，随后热沉降的系统的中心。
The Betic Cordillera of southern Spain provides a clear example of a collisional orogen that has undergone large-scale extensional collapse while convergent motion of the bounding plates continued. Extension was accommodated by coeval shortening in thin-skinned fold and thrust belts around the periphery of the system, and much of the region has now subsided to form a large marine basin. The thermal and deformational record of these processes is preserved in rocks from the upper mantle, crystalline crust, and sedimentary cover. Upper mantle peridotites record evidence for exhumation in several stages from asthenospheric depths to the surface. Early stages of exhumation probably occurred during Mesozoic rifting. Cooling at midlithospheric depths reflects continental convergence, and subsequent heating indicates loss of most of the underlying lithosphere and ascent of asthenosphere, whilst the final stages of exhumation in early Miocene time reflect extensional collapse. Crustal rocks in the internal zone of the Betic Cordillera were metamorphosed down to 50 km depth and are now exposed beneath major low-angle normal detachment zones that separate them from heavily faulted low-grade rocks above. Cooling ages of associated mylonites indicate that these detachments were active during the early to middle Miocene. Fault-bounded intramontane basins, developed during the early to middle Miocene, contain coarse continental sediments heavily affected by normal fault systems, followed by a less deformed late Miocene marine succession. All of these phenomena can be explained by convective removal of the lithospheric root beneath a Paleogene collisional orogen, leading to large-scale extension followed by thermal subsidence of the center of the system.