Stratigraphic and structural constraints on catastrophic geohazards in Wumeng Mountain area and risk prevention and control recommendations

Objective Wumeng Mountain is located in the hinterland of the Yunnan-Guizhou Plateau, with complex topography and strong tectonic activity. The widely distributed Feixianguan Formation and its contemporaneous heterogeneous Yelang formation（hereinafter referred to as the Feixianguan Formation） in the area is an important target layer for geohazards. How the geological background conditions under the control of lithofacies and stratigraphic structure of Feixianguan Formation contribute to the frequent occurrences of catastrophic geohazards remains to be further studied. Methods This paper took three typical catastrophic geohazards as the research objects. The development characteristics of the Feixianguan Formation and its geohazards control law on catastrophic geohazards are studied by means of on-site investigation, profile measurement, experimental testing, comparative analysis of sequence stratigraphy, combined with lithofacies paleogeographic mapping. Results The results show that the Feixianguan Formation in Wumeng Mountain area mainly developed in a transitional environment between land and sea. The mixed sedimentation of terrestrial debris and marine carbonate rocks laid the material foundation for geohazards; Multi-scale combination of soft and hard strata, including Formation- Section- Lithological layer, is a key disaster control structure，and the 2nd and 3th members of the Feixianguan Formation are the key disaster causing layers for catastrophic geohazards under the control of the third-order sequence stratigraphic structure; The high and steep "boot shaped" terrain in the wide and gentle syncline belt is a favorable terrain condition for disaster development. Fractured structures are widely developed in the Feixianguan Formation，such as vertical joint fissures, slip deformation, staggered crushing deformation, interlayer dissolution，which are important disaster-prone geological structures. Conclusions It is concluded that the next step of geohazard investigation in Wumeng Mountain should focus on the distribution area of the 2nd and 3th members of the Feixianguan Formation with the "boot-shaped" terrain, and the dip slope area with carbonate interlayers. This study will provide scientific guidance for the accurate identification and prevention of potential geohazards in the Feixianguan Formation of the Wumeng Mountain area.