The Northern Alpine Foreland Basin ( Molasse Basin) developed due to flexural subsidence from slab- and topographic loading during continental collision between the Adriatic and European plates. Previous studies highlight a diachronous transition from underfilled- to overfilled conditions in the Molasse Basin in response to orogen-parallel variations in flexural subsidence and sediment supply. In this contribution, we investigate the lithospheric- and crustal-scale orogenic process(es) that generated this diachronous transition. For this, we conducted a tectonostratigraphic analysis of the Molasse Basin. Firstly, we constructed a 3D geological model to derive the architecture of the European margin during the Eocene onset of flexure. Second, 2D/3D reflection seismic- and borehole data were used to characterise the spatiotemporal development of depositional environments and syn-flexural normal fault kinematics in the German Molasse. Our data show a stepwise rather than continuous eastward migration of the underfilled- to overfilled transition. Furthermore, syn-flexural fault kinematics document a Rupelian to early Burdigalian northward younging trend and higher cumulative Cenozoic offsets in the Eastern German Molasse (< 230 m) compared to the Western German Molasse (< 150 m). This implies a west-to-east increase in the curvature of bending of the European plate, induced by along-strike variations in the magnitude of applied loads and/or European lithospheric strength variations. These variations drove lateral variations in accommodation space and sediment supply. Subsequently, this led to the diachronous underfill-to-overfilled transition in the Molasse Basin. Taken together, we suggest that the diachronous transition was driven by spatiotemporal variations in the thickening of the orogenic wedge supported by slab detachment, promoted by subduction- and collision of the irregular European margin.

中文翻译：

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岩石圈和地壳尺度对北高山前陆盆地前陆盆地发育变化的控制

北高山前陆盆地（莫拉斯盆地）是由于亚得里亚海板块和欧洲板块碰撞期间板片和地形载荷造成的弯曲沉降而形成的。先前的研究强调了莫拉斯盆地从欠充填条件到满充条件的历时转变，以响应造山带平行沉降和沉积物供应的变化。在这篇文章中，我们研究了产生这种历时转变的岩石圈和地壳尺度的造山过程。为此，我们对莫拉斯盆地进行了构造地层分析。首先，我们构建了一个 3D 地质模型，以得出始新世弯曲开始期间欧洲边缘的结构。其次，利用 2D/3D 反射地震和钻孔数据来表征德国莫拉塞沉积环境的时空发育和同弯曲正断层运动学。我们的数据显示，从填充不足到填充过度的过渡是逐步而非连续的向东迁移。此外，同弯曲断层运动学记录了鲁佩尔期到布尔迪加期早期的向北年轻化趋势，以及与德国西部莫拉斯 (< 150 m) 相比，德国东部莫拉斯 (< 230 m) 的累积新生代偏移量更高。这意味着欧洲板块的弯曲曲率从西向东增加，这是由所施加载荷大小的沿走向变化和/或欧洲岩石圈强度变化引起的。这些变化导致了住宿空间和沉积物供应的横向变化。随后，这导致了莫拉斯盆地历时的欠充到满溢的转变。综上所述，我们认为历时转变是由板片脱离支撑的造山楔增厚的时空变化驱动的，不规则欧洲边缘的俯冲和碰撞促进了造山楔的增厚。