as the southernmost tectonic unit of the Eurasian continent, has long been a focal point of research in the international geoscience community [1; 2; 3]. Previous studies have defined the Early-Middle Jurassic volcanic-sedimentary sequence exposed in this terrane as the Yeba Volcanic Arc, based on lithological associations and geochronological constraints [4; 5]. This sequence has attracted considerable attention due to recording the early subduction and consumption of the Tethys Ocean [6]. The magmatic rocks of the Yeba Formation are mainly distributed between Lhasa City and Gongbo'gyamda County, extending in the east-west direction for approximately 399 km and spanning \(\sim\)30 km in the north-south direction [7; 8]. This region is characterized by several NWW-trending thrust nappe systems, resulting from the subduction and subsequent collision between the Indian and Eurasian plates [9; 10]. The southernmost structure is the Pongduo Thrust Nappe System, where Middle Jurassic-Early Cretaceous sedimentary strata form a compressional detachment belt in the southern frontal zone of this nappe system [11].  
The Yeba Formation has experienced multiple phases of complex ductile and brittle deformation, with each event closely linked to specific tectonic settings, including the subduction of the Neo-Tethys Ocean and the India-Asia collision. Previous studies on the deformation history and genesis of the Yeba Formation have been limited and remain highly contentious. For instance, [PERSON] et al. (2012, 2013) [12; 13] suggested that the Yeba Formation experienced two distinct ductile deformation phases, accompanied by multiple episodes of ductile-brittle deformation. The first phase was interpreted as being related to the northward subduction of the Neo-Tethys Ocean (94-85 Ma), while the second was attributed to the India-Asia collision (60-50 Ma).  
[PERSON] (2016) [14] proposed that the Yeba Formation underwent two phases of folding events. In contrast, [PERSON] (2017) [15] identified three distinct deformation phases in the Yeba Formation: phase 1 (D\({}_{1}\)), dated to \(\sim\)85-69 Ma, is associated with retroarc detachment structures formed under the subduction-related setting of the Neo-Tethys Ocean; phase 2 (D\({}_{2}\)), spanning \(\sim\)65-50 Ma, reflects the emplacement of collision-related granites during the India-Asia convergence, contributing to the development of the Lhasa Dome; phase 3 (D\({}_{3}\)), around \(\sim\)42 Ma, was dominated by the reactivation of the Qulong-Sangri-Woka Thrust Fault Zone, generating large-scale thrust structures through compressional overprinting.  
In summary, previous studies on the tectonic deformation of the Yeba Group remain relatively sparse and controversial. Therefore, this study systematically investigates the meso- and microstructural features of the Yeba Formation to delineate its deformation phases, applies \({}^{40}\)Ar-\({}^{39}\)Ar geochronology to constrain the timing of these tectonic events, and integrates regional tectonic evolution to interpret the dynamic setting and unravel the tectonic evolution of the formation. These findings provide critical insights into the structural evolution of the Yeba Group and its geodynamic significance within the broader regional context.