The Early Cretaceous palaeogeography prior to the India‐Asia collision is still controversial. There are two end‐member models – an integrated passive margin versus an archipelago. Here, we report zircon U–Pb ages, Hf, and whole‐rock Nd isotopes of newly defined Cretaceous mica schists from the Main Central Thrust to constrain the Early Cretaceous palaeogeography of the Himalaya. The mica schists have Early Cretaceous zircons with ε_Hf(t) values of −21.1 to −9.2. The mica schists are characterized by T_DMC values of 1.8–2.5 Ga and whole‐rock ε_Nd(0) value of −24.0. These features imply that these zircons generated from partial melting of lower crust as a result of an extension in some older continental crust, which were transported and deposted to form the protolith of the Cretaceous mica schists. Age pattern comparisons indicate that the age populations of the Cretaceous mica schists are significantly distinct from those of other Cretaceous strata in the Himalaya. It is obvious that the protolith of the Cretaceous mica schists were formed in an independent terrane (Arun) in the Neo‐Tethys with significant tectonic separations proventing any inputs from the Tibetan Himalaya, Greater Himalaya, or Indian Craton since 120 Ma. Combined with published U–Pb ages and other geological data, our data supports the archipelago palaeogeography with rifted terranes in the Neo‐Tethys Ocean, shedding light on the multiple amalgamation events along the India‐Asia collision zone.

中文翻译：

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尼泊尔东部主要中央逆冲断层下盘的早白垩世地层的构造环境和成因：对新特提斯群岛古地理的启示

印度-亚洲碰撞之前的早白垩世古地理学仍存在争议。最终成员模型有两种-集成的被动边距与群岛。在这里，我们报告了新的白垩纪云母片岩的锆石U–Pb年龄，Hf和全岩Nd同位素，这些岩屑来自中部主推力，以约束喜马拉雅山的早白垩纪古地理。云母片岩具有早白垩锆石ε_的Hf（吨的-21.1至-9.2）值。云母片岩的特征在于Ť _DM Ç 1.8-2.5 Ga中的值和全岩ε_钕（0）值为-24.0。这些特征暗示这些锆石是由于一些较旧的大陆壳的扩展而导致下地壳部分熔融而生成的，这些锆石被运输和销毁后形成白垩纪云母片岩的原石。年龄模式的比较表明，白垩纪云母片岩的年龄种群与喜马拉雅山其他白垩纪岩层的年龄种群明显不同。显然，白垩纪云母片岩的原石形成于新特提斯的一个独立地层（阿伦）中，具有明显的构造分离，证明自120 Ma以来藏族喜马拉雅山，大喜马拉雅山或印度克拉通的任何输入。结合已公布的U–Pb年龄和其他地质数据，我们的数据支持了新特提斯海洋中裂谷化的群岛古地理，