The topography and subsidence history of sedimentary basins are commonly related to crustal and lithospheric thinning linked to isostasy, also influenced by flexure and dynamic topography. The static component of the topography relative to a reference level can be calculated by the assumption that a lithospheric column consisting of crustal layers and a lithospheric mantle lid float within the asthenosphere. Here, we discuss the observed and calculated residual topography of the Pannonian Basin, i.e. the difference between the actual and calculated isostatic topography. The residual topography calculation is based on new geophysical constraints on the sedimentary, upper and lower crustal and lithospheric thicknesses based on reflection seismic and new receiver function analysis. The crustal thickness decreases from 40 to 45 km beneath the Eastern Alps to 22 km in the eastern Great Hungarian Plain that is floored by less than 60 km thick lithosphere affected by Miocene extension. The sedimentary thickness reaches more than 6 km in the deepest depocenters. The crust is much less attenuated in the Transdanubian Range (28 km), Apuseni Mountains or Transylvanian Basin (32.5–35 km). The interpreted lower crustal thickness reaches maximum 15–20 km in the Eastern Alps, 12–15 km in the Apuseni Mountains, 10 km in the Transdanubian Range and thins to 5 km in the Great Hungarian Plain. The new four-layer lithospheric model shows a much lower residual topography value than previously suggested for the Pannonian Basin. Only the Transdanubian Range is affected by maximum 300 m of positive residual topography, whereas the Transylvanian Basin shows 300–400 m of negative residual topographic values. The former is interpreted to be affected by small-scale asthenospheric upwelling effects, likely also contributing to the Miocene-Pliocene volcanic activity of the area. While the currently uplifting Transylvanian Basin undergoes tectonic re-adjustment linked to the gradual Vrancea slab break-off. Our results demonstrate the important effects of the thick sedimentary succession and the different crustal thinning values on the observed and predicted topographic variations in extensional sedimentary basins.

中文翻译：

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大陆背弧中的上下地壳变形和残余地形：来自潘诺尼亚-特兰西瓦尼亚盆地的推论


沉积盆地的地形和沉降历史通常与与等稳态相关的地壳和岩石圈变薄有关，也受到弯曲和动态地形的影响。地形相对于参考水平的静态分量可以通过以下假设来计算：由地壳层和岩石圈地幔盖组成的岩石圈柱漂浮在软流圈内。在这里，我们讨论了潘诺尼亚盆地的观测和计算的残余地形，即实际和计算的等静压地形之间的差异。残余地形计算基于反射地震和新的接收器函数分析，对沉积、上下地壳和岩石圈厚度的新地球物理约束。地壳厚度从东阿尔卑斯山下的 40 到 45 公里减少到匈牙利东部大平原的 22 公里，该平原的底部是受中新世延伸影响的不到 60 公里厚的岩石圈。在最深的沉积中心，沉积层厚度达到 6 公里以上。外多瑙河山脉（28 公里）、阿普塞尼山脉或特兰西瓦尼亚盆地（32.5-35 公里）的地壳衰减要小得多。解释的下地壳厚度在东阿尔卑斯山达到最大 15-20 公里，在阿普塞尼山脉达到 12-15 公里，在外多瑙河山脉达到 10 公里，在匈牙利大平原变薄到 5 公里。新的四层岩石圈模型显示的残余地形值比以前建议的潘诺尼亚盆地低得多。只有外多瑙河山脉受到最大 300 m 正残余地形的影响，而特兰西瓦尼亚盆地则显示 300-400 m 的负残余地形值。 前者被解释为受到小规模软流层上升流效应的影响，也可能有助于该地区的中新世-上新世火山活动。而目前隆起的特兰西瓦尼亚盆地正在经历与 Vrancea 板块逐渐断裂相关的构造重新调整。我们的结果表明，厚沉积演替和不同的地壳变薄值对伸展沉积盆地观测和预测的地形变化有重要影响。