The Zagros Collision Zone is a complex tectonic region formed as a consequence of the collision between Arabia and Eurasia after the subduction of the Neo-Tethys ocean. The NW-SE striking Zagros orogen consists of the following parallel tectonic units (from SW to NE): Zagros Fold and Thrust Belt (ZFTB), Sanandaj–Sirjan Metamorphic Zone (SSZ), and Urumieh–Dokhtar Magmatic Arc (UDMA). In this study, we perform a combined analysis of recent geophysical data, revealing pronounced differences in the crustal and lithospheric structure along the Zagros Mountains. The northwestern sector shows a fairly uniform crustal thickening across the broad symmetric orogen from the ZFTB to the UDMA. In contrast, in the central Zagros, the transition from a relatively narrow zone of high elevations and high-frequency relief in the ZFTB to a smoother surface topography of the SSZ and UDMA occurs with an abrupt increase in Moho depth below the SSZ. The last observation has recently been interpreted as a result of “relamination” process, where the felsic upper crust of the Arabian plate underthrust the mafic crust of the Iranian plate. We present geodynamic numerical models of crustal relamination during continental collision and compute static gravity field of the resulting structures. We show that oblique closure of the Neo-Tethys affects lateral variations in the style and extent of crustal relamination, which control the observed along-strike changes in crustal configuration and orogen altitude. In particular, a narrow and higher orogen (as in the central Zagros) develops in the experiments with a young and wide oceanic plate, whereas an old and narrow subducting plate tends to form a broad and lower topography (as in the northwestern Zagros). This is geometrically consistent with the progressive closure of the Neo-Tethys from NW to SE during the oblique continental collision between Arabia and Eurasia.

中文翻译：

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是什么控制着扎格罗斯碰撞区沿线的结构变化？来自地球物理观测和热机械建模的见解


扎格罗斯碰撞带是新特提斯洋俯冲后阿拉伯半岛与欧亚大陆碰撞而形成的复杂构造区。西北-东南走向的扎格罗斯造山带由以下平行构造单元（从西南到东北）组成：扎格罗斯褶皱冲断带（ZFTB）、萨南达季-锡尔詹变质带（SSZ）和乌鲁米耶-多赫塔尔岩浆弧（UDMA）。在这项研究中，我们对最近的地球物理数据进行了综合分析，揭示了扎格罗斯山脉沿线地壳和岩石圈结构的显着差异。西北地区从 ZFTB 到 UDMA 的广阔对称造山带显示出相当均匀的地壳增厚。相比之下，在扎格罗斯中部，从 ZFTB 中相对狭窄的高海拔和高频地形区域过渡到 SSZ 和 UDMA 的更平滑的表面地形，同时 SSZ 下方莫霍面深度突然增加。最近的观察结果被解释为“再分层”过程的结果，其中阿拉伯板块的长英质上地壳冲向伊朗板块的镁铁质地壳。我们提出了大陆碰撞期间地壳再分层的地球动力学数值模型，并计算了所得结构的静态重力场。我们表明，新特提斯洋的倾斜闭合影响了地壳再贴合的方式和程度的横向变化，这控制了观察到的地壳构造和造山带高度的沿走向变化。特别是，在年轻而宽阔的海洋板块的实验中，会形成狭窄且较高的造山带（如扎格罗斯中部），而古老而狭窄的俯冲板块往往会形成宽阔且较低的地形（如扎格罗斯西北部）。 这在几何上与阿拉伯和欧亚大陆倾斜大陆碰撞期间新特提斯洋从西北向东南逐渐闭合是一致的。