## 1 Introduction  
Modern sedimentary investigation is the basis for studying the sedimentary process, analyzing the sedimentary environment, and establishing the sedimentary facies model. Most of the existing sedimentary models are derived from the investigation of modern sedimentation. Through the study of modern rivers [1, 2], river deltas [3, 4], lakes [5], alluvial fans [6], and dunes [7, 8], the study of sedimentary models is supported by a large amount of data. However, previous sedimentary model research mainly focused on the analysis of single sedimentary systems and single microfacies types, ignoring the interconnection between sedimentary systems within the basin. The prediction function of the sedimentary facies model established by this model is not strong, and it is difficult to adapt to the needs of deep and unconventional oil and gas exploration and development under the current high-cost and high-risk conditions. It is necessary to create a new, more predictive, and comprehensive sedimentary model [9]. The system tract refers to a series of sedimentary system assemblages formed in the same period [10]. This term comes from the field of sequence stratigraphy. Generally, within a sequence, it is divided into three system tracts according to the relative sea level position and its rising and falling trend at the time of its formation, namely, low-stand system tract (or continental shelf margin system tract), transgressive system tract, and high-stand system tract [11]. Subsequently, many scholars discussed in depth the types of sequence boundaries, put forward the concepts of forced regression system tract and descending (period) system tract, and suggested that the sequence architecture of the 'three-division' system tract should be revised to 'four-division'; that is, descending system tract, low-stand system tract, transgressive system tract, and high-stand system tract [12; 13; 14]. With the continuous rise in research, the concept of sedimentary system tract is not only used in the field of sequence stratigraphy but also gradually evolved into a series of interrelated sedimentary systems in the plane or vertical combination, which is also widely used in continental deposits. [PERSON] et al., 2007 [15] analyzed the general cycle of accommodation space or sediment supply change according to the fine adjustment of sequence definition and extended the application of sequence stratigraphy to all sedimentary environments. [PERSON] et al., 2000 [16] analyzed the sequence formation of the continental faulted basin. [PERSON] et al., 2010 [17]. divided the system tracts into conventional system tracts and unconventional system tracts. The conventional system tracts refer to the common system tracts defined in classical sequence stratigraphy. The unconventional system tracts refer to all system tracts related to specific sedimentary environments outside the conventional system tracts, including the high-capacity space system tracts and low-capacity space system tracts in the alluvial fan-river sedimentary system, the forced regression system tracts in the coastal shallow sea under a gentle gradient background, the descending system tracts of the shallow sea-deep sea system under the continental shelf background, and the coastal shallow sea (lake) environment. In 2014, based on the concept of unconventional system tract, [PERSON] [18] studied the sequence stratigraphic sequence of the coarse elastic rock series of the Gulanghekou Group in Gansu Province. The application of system tracts in continental sediments has promoted people's further understanding of regional sedimentary systems and provided new ideas for studying the scope of sedimentary systems. With the development of earth information science and technology, big data, and artificial intelligence technology, people can use remote sensing satellite images to obtain the characteristics of different sedimentary environments and sedimentary microfacies in large-scale sedimentary systems as well as the overall information about their relationships.