## 1 Introduction  
The significant volcanic event--the Emeishan large igneous province (Emei LIP)--was recorded in the Guadalupian Series of the Middle Permian in China [1; 2], which witnessed the development of a series of bio-geological events such as large-scale magmatism, plate rupture, magnetic pole reversal, ecological collapse, and the extinction of pre-Lopingian organisms (about 260 Ma ago) [3; 4]. Current research has mostly focused on the pre-Lopingian biological crisis, with the research data concentrated on the Capitanian of the Guadalupian. It is believed that the overlay effect of large-scale tectonic activity, volcanic eruptions, and climate events led to the demise of life [3; 4; 5]. All these geological events were widely recorded in the Middle Permian strata of the Yangtze region in South China. For example, (i) Layered tuff represents periodic volcanic eruptions; (ii) Upwelling of deep hydrothermal fluids causes the metamorphism of the strata, and large amounts of siliceous rocks are found in the strata; (iii) Plate activity caused the original sedimentary paleo-geomorphology to change, and large amounts of gravity flow sediments are found in the profile, etc. However, the chronological and causal relationships among different geological events and the isochroneity on a global scale have been less studied. The morphology of conodonts changes over time, so different types of conodonts can be used as a measure of past time. However, the following problems still exist in the study of Permian conodont fossils: (i) Conodont fossils are difficult to compare across different regions. The Middle Permian organisms were clearly divided by paleogeography, and their appearance and evolutionary sequences were different, making it challenging for cross-region comparison. (ii) Missing strata: During the Permian sedimentation period, the supercontinent was uplifted as a whole [5; 6; 7; 8], causing the ancient strata to be lifted to the surface and eroded [9; 10; 11]. Therefore, the fossil record may be incomplete. The above problems make it difficult to effectively determine the initial activation time of geological events, leading to ongoing debates about the exact sequence of events during the Permian [12; 13; 14; 15]. The northern part of the Sichuan Basin is located on the northwestern edge of the upper Yangtze Craton and is one of the areas with the most complete stratigraphic records and the richest fossil record in the world [5; 16; 17]. The Yangtze plate is part of the Tethys multi-island ocean system [18; 19]. As independent islands, their sedimentary features are more susceptible to tectonic and small-scale sea-level fluctuations, and the records of geological events were well preserved. Therefore, the Permian Yangtze Plate may provide valuable information about both the region's past rifting activities and the eruption history of the Emei LIP [18; 19; 20; 21]. The identification of conodont sequences can provide a relatively accurate age framework for the study of regional geological events [22; 23], such as (i) The size of conodont fossils is determined by the oxygen content in the air, so they can be used to reflect the oxygen concentration at that time. (ii) The morphology of conodonts changes significantly over time and can be used as a timer for the age of the strata. In addition, the wells located in the deep-water basin in the Yangtze region of South China may retain complete astronomical cycle signals [24]. In this study, eight sections and one well with complete Permian exposure were selected for systematic sampling and conodont identification to establish absolute age anchors, combining astochronological analysis, C isotope analysis, and sedimentological profile measurements. This work aims to (1) Estimate the timing and duration of the conodonts; (2) Explain the evolution of the sedimentary environment of the section; (3) Investigate the long-period behavior of the Earth's orbital parameters; (4) Explore the coupling relationship between various geological events and their sedimentary responses.