Characteristics and evolution of geoheritages in Mentougou District in the Xishan area, Beijing

Mentougou District, the core region of Xishan in Beijing, is located at the junction of Yanshan and Taihang mountains, where mountainous areas account for 98.5%. Over the long geological history, it has remained rich geoheritages. The lack of systematic analysis on the distribution characteristics and evolution of geoheritages constraint their protection and utilization of geoheritages in this area. This study has systematically reviewed the types of geoheritages in this area through remote sensing, ground investigation, and rock and mineral identification. The results show that: (1) The rich geoheritages in this area are diverse; 100 types of geoheritages have been identified, including geological profiles, geological structures, paleontological fossils, and landscape geology. (2) The distribution of geological profile types such as the Qingbaikou Series and Malan loess is closely related to the exposure area of the Mesoproterozoic-Quaternary strata. Folds and faults are mainly distributed in the middle and high mountain areas from Miaofengshan Town to Zhaitang Town; the acidic rock mass of Yanshan period are mainly distributed along large faults; loess terraces, river terraces, gorges, and water landscape are mainly distributed along the main channel of the Yongdinghe River and its major tributaries. (3) Multiple marine intrusions in this area created lots of stratigraphic profile relics; the Qin Yu Movement, Jixian Movement, and Yanshan Movement led to many structural features, faults, and folds, which dominated the formation of multiple mineral deposits. This study can provide basic information for further in-depth research on geoheritages and their protection and utilization in this area.