The recently developed fluorite (U–Th)/He thermochronology (FHe) technique was applied to date fluorite mineralization and elucidate the exhumation history of the Mazandaran Fluorspar Mining District (MFMD) located in the east Central Alborz Mountains, Iran. A total of 32 fluorite single-crystal samples from four Middle Triassic carbonate-hosted fluorite deposits were dated. The presented FHe ages range between c. 85 Ma (age of fluorite mineralization) and c. 20 Ma (erosional cooling during the exhumation of the Alborz Mountains). The Late Cretaceous FHe ages (i.e. 84.5 ± 3.6, 78.8 ± 4.4 and 72.3 ± 3.5 Ma) are interpreted as the age of mineralization and confirm an epigenetic origin for ore mineralization in the MFMD, likely a result of prolonged hydrothermal circulation of basinal brines through potential source rocks. Most FHe ages scatter around the Eocene Epoch (55.4 ± 3.9 to 33.1 ± 1.7 Ma), recording an important cooling event after heating by regional magmatism in an extensional tectonic regime. Cooling of the heated fluorites, as a result of thermal relaxation in response to geothermal gradient re-equilibration after the end of magmatism, or exhumation cooling during extensional tectonics characterized by lower amount of erosion are most probably the causes of the recorded Eocene FHe cooling ages. Oligocene–Miocene FHe ages (i.e. 27.6 ± 1.4 to 19.5 ± 1.1 Ma) are related to the accelerated uplift of the whole Alborz Mountains, possibly as a result of the initial collision between the Afro-Arabian and Eurasian plates further to the south.

中文翻译：

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伊朗北部中厄尔布尔士山脉东部萤石矿化和折返事件的时间：萤石 (U-Th)/He 热计时法的限制

最近开发的萤石 (U-Th)/He 热年代学 (FHe) 技术用于确定萤石矿化的年代，并阐明位于伊朗中厄尔布尔士山脉东部的马赞达兰萤石矿区 (MFMD) 的折返历史。对来自四个中三叠统碳酸盐岩型萤石矿床的共 32 个萤石单晶样品进行了测年。呈现的 FHe 年龄范围介于C。85 Ma（萤石矿化年龄）和C。20 Ma（厄尔布尔士山脉挖掘过程中的侵蚀冷却）。晚白垩世 FHe 年龄（即 84.5 ± 3.6、78.8 ± 4.4 和 72.3 ± 3.5 Ma）被解释为矿化年龄，并证实了 MFMD 矿化的表观成因，可能是盆地卤水长时间热液循环的结果。潜在烃源岩。大多数 FHe 年龄分布在始新世（55.4 ± 3.9 至 33.1 ± 1.7 Ma）附近，记录了在伸展构造体系中区域岩浆作用加热后的重要冷却事件。加热的萤石冷却，由于岩浆作用结束后地热梯度重新平衡引起的热弛豫，以较少的侵蚀为特征的伸展构造期间的折返冷却或折返冷却最可能是记录的始新世FHe冷却年龄的原因。渐新世-中新世 FHe 年龄（即 27.6 ± 1.4 至 19.5 ± 1.1 Ma）与整个厄尔布尔士山脉的加速抬升有关，可能是由于更南端的非洲-阿拉伯和欧亚板块之间的初始碰撞。