Slab tearing or slab retreat as triggers of extension at the Dinaric-Hellenic transition?

该项目将展示地壳如何响应从大陆岩石圈的回滚俯冲到倾斜大陆-大陆碰撞的沿走向转变。俯冲模式的横向转变是相关的，因为它们与地震活动的显著差异相吻合，对沿海和山区的社会造成了随之而来的危害。具体而言，我们将验证沿欧洲东南部第纳尔-希腊链俯冲模式变化的假设，即晚造山伸展作用向板块撕裂或板块回滚和弧化方向迁移。调查将首先集中在Dinarides和Hellenides的交界处，在那里我们的初步工作已经揭示了造山带平行断层和正常伸展断层重叠并重新激活了旧的逆冲断层。这是一个有利的起点，因为它与地球物理成像的地幔结构的一级差异相吻合，从Hellenides西北下方的向东南倾斜的大陆板块目前向西南撤退，到Dinarides下方的较短的板块几乎没有撤退。到目前为止，我们的工作表明，这个过渡时期的地壳结构以横向正断层（Shkoder-Peja正断层或SPNF）为标志，该断层可以容纳越来越多的造山带平行延伸，沿着其走向从西南向东北延伸，在那里它与米奥-上新世科索沃（Metohia）盆地接壤。然而，SPNF只是该地区几个断层中的一个，这些断层的年龄和运动学是理解地壳伸展是否与希腊回滚俯冲有关，与迪纳里德斯板块下的板块剥离或断裂有关，还是与这些机制的某种组合有关的关键。调查还将涵盖Dinarides-Hellenides的其他三个地点，那里的地层和推覆构造沿走向变化与造山带垂直断层相吻合。如果是这样的话，第纳尔-希腊转变可能是唯一记录岩石圈对板块汇聚模式变化的沿走向响应的过程。为了实现这些目标，我们将结合最先进的测年方法（断块的磷灰石裂变径迹和氦分析，断界沉积盆地的碎屑热年代学）和成熟的构造技术（断层滑动分析，构造作图）。

This project will show how Earths crust responds to an along-strike transition from roll-back subduction of continental lithosphere to oblique continent-continent collision. Lateral transitions in subduction mode are relevant because they coincide with marked differences in earthquake activity, with attendant hazards for society in coastal and mountainous areas. Specifically, we will test the hypothesis that a change in subduction mode along the Dinaric-Hellenic chain of SE Europe involved late orogenic extension which migrated in the direction either of slab tearing or of slab roll-back and arcuation.Investigation will initially focus on the junction of the Dinarides and Hellenides, where our preliminary work has revealed both orogen-parallel and -normal extensional faults that overprint and reactivate older thrusts. This is an auspicious place to start because it coincides with a first-order difference in geophysically imaged mantle structure, from a SSE-dipping continental slab beneath the northwestern Hellenides currently retreating to the SW, to a shorter slab beneath the Dinarides with little or no retreat. Our work so far suggests that the crustal structure at this transition is marked by a transverse normal fault (the Shkoder-Peja Normal Fault or SPNF) that accommodates increasing amounts of orogen-parallel extension along its strike from SW to NE, where it bounds the Mio-Pliocene Kosovo (Metohia) Basin. However, the SPNF is only one of several faults in this area whose age and kinematics are key to understanding whether crustal extension is related to the Hellenic roll-back subductions, to slab delamination or break-off beneath the Dinarides, or to some combination of these mechanisms. Investigation will also cover three other locations in the Dinarides-Hellenides where along-strike changes in stratigraphy and nappe structure coincide with orogen-perpendicular faults. If so, the Dinaric-Hellenic transition is possibly unique in recording the along-strike response of the lithosphere to changing modes of plate convergence.To realize these goals, we will combine state-of-the-art dating methods (apatite-fission track- and -helium analyses of faulted blocks, detrital thermochronology in fault-bounded sedimentary basins) and well-established structural techniques (fault-slip analysis, fabric mapping).