The Hailesitai volcanic basin, located in the northern part of Greater Hinggan Mountains, is one of the most important Mesozoic volcanic basins within Inner Mongolia. Systematic field and petrographic study shows that the Hailesitai volcanic basin consists of volcanic rocks of the Baiyin'gaolao Formation, which can be subdivided into two different lithological members that record a nearly complete eruption–sedimentation cycle. Seven types of volcanic facies are identified, delineating 17 V‐level volcanic structures that are controlled by NNE‐trending fractures. U–Pb isotope dating of zircon indicates that volcanism occurred during the Early Cretaceous between 132.8 and 131.5 Ma. The SiO₂ of Hailesitai volcanic rocks mostly range from 58.9 to 77.46 wt% (rhyolite to trachyandesite) and belong to the high‐K alkaline series (average value of the K₂O 4.07 wt%). The trace‐element characteristics of the rocks indicate that the magmas were derived from the mantle. ε_Nd(t) values lie between 3.78 and 3.87, The ε_Hf(t) values of obsidian and rhyolitic range from 5.53 to 10.83 and 3.95 to 11.82, respectively. T_DM2(Hf) range from 819 to 466 Ma and 657 to 311 Ma, respectively. The Nd isotopic composition of the rocks and the Hf isotopic composition of zircon suggest that the magma was derived from the partial melting of depleted mantle. We suggest that the Hailesitai volcanic rocks formed in a post‐orogenic extensional tectonic setting during closure of the Mongolian–Okhotsk Ocean due to subduction of the western Pacific Plate. The source of the magmas was depleted mantle with a minor contribution from the partial melting of Palaeozoic crustal rocks.

中文翻译：

---

内蒙古海列斯泰火山省的特征以及推断的岩浆源和构造环境

海勒斯泰火山盆地位于大兴安岭北部，是内蒙古最重要的中生代火山盆地之一。系统的田野和岩石学研究表明，海勒斯泰火山盆地由白音高劳组的火山岩组成，可以细分为两个不同的岩性段，它们记录了近乎完整的喷发-沉积循环。确定了七种类型的火山相，描绘了由NNE向断裂控制的17个V级火山构造。锆石的U–Pb同位素测年表明，火山活动发生在早白垩纪的132.8至131.5 Ma之间。SiO ₂Hailesitai火山岩的绝大部分含量在58.9％至77.46 wt％（流纹岩到菱锰矿）之间，属于高钾碱系列（K ₂ O的平均值4.07 wt％）。岩石的痕量元素特征表明岩浆来自地幔。ε_钕（吨）值处于3.78和3.87之间，所述ε_的Hf（吨）从5.53到10.83和3.95分别以11.82，黑曜石和流纹范围值。Ť _DM2（Hf）的范围分别为819至466 Ma和657至311 Ma。岩石的Nd同位素组成和锆石的Hf同位素组成表明，岩浆来自贫化地幔的部分熔融。我们认为，由于西部太平洋板块的俯冲作用，在蒙古-鄂霍次克海封闭期间，造山带形成后的伸展构造环境中形成了海列斯泰火山岩。岩浆的来源是地幔枯竭，而古生代地壳岩石的部分融化贡献很小。