The geodynamic evolution of the Western Mediterranean for the past 35 My is a matter of debate. Present-day structure and composition of the lithosphere and sublithospheric mantle may help in constraining the geodynamic evolution of the region. We use an integrated geophysical-petrological modeling to derive and compare the present-day thermal, density and compositional structure of the lithosphere and sublithospheric mantle along two NNW-SSE oriented transects crossing the back-arc Alboran and Algerian basins, from onshore Iberia to the northern Africa margin. The crust is constrained using available seismic data and geological cross-sections, whereas seismic tomography and mantle xenoliths constrain the upper mantle structure and composition. Results show a thick crust (37 and 30 km) and a relative deep LAB (130 and 150 km) underneath the HP/LT metamorphic units of the Internal Betics and Greater Kabylies, respectively, which contrast with the 16 km thick magmatic crust of the Alboran Basin and the 10 km thick oceanic crust of the Algerian Basin. The sharp change in lithosphere thickness, from the orogenic wedge to the back-arc basins, contrasts with the gentler lithosphere thickening toward the respective opposed margins. Our results confirm the presence of detached slabs ∼400 °C colder than upper mantle and a fertile composition than the continental lithospheric mantle beneath the External Betics and Saharan Atlas. Presence of detached quasi-vertical sublithospheric slabs dipping toward the SSE in the Betics and toward the NNW in the Kabylies and the opposed symmetric lithospheric structure support an opposite dipping subduction and retreat of two adjacent segments of the Jurassic Ligurian-Tethys realm.

中文翻译：

---

阿尔博兰和阿尔及利亚盆地及其边缘（西地中海）岩石圈结构的相反对称性：地球动力学意义

过去 35 My 西地中海的地球动力学演化是一个有争议的问题。岩石圈和亚岩石圈地幔的现代结构和组成可能有助于限制该地区的地球动力学演化。我们使用综合地球物理-岩石学模型来推导和比较岩石圈和亚岩石圈地幔的当前热、密度和成分结构，沿着两个 NNW-SSE 定向的横断面穿过弧后阿尔博兰和阿尔及利亚盆地，从陆上伊比利亚到北非边缘。地壳受到可用地震数据和地质横截面的约束，而地震层析成像和地幔包体约束上地幔结构和成分。结果显示内部 Betics 和 Greater Kabylies 的 HP/LT 变质单元下方分别有一个厚地壳（37 和 30 公里）和一个相对较深的 LAB（130 和 150 公里），这与 16 公里厚的岩浆地壳形成对比。阿尔博兰盆地和阿尔及利亚盆地 10 公里厚的洋壳。岩石圈厚度的急剧变化，从造山楔到弧后盆地，与向各自相对边缘增厚的较缓岩石圈形成对比。我们的结果证实了存在比上地幔低约 400°C 的分离板片，以及比外贝蒂奇和撒哈拉阿特拉斯图下方的大陆岩石圈地幔的肥沃成分。