The Xikang Group represents the main stratigraphic sequence of the Songpan–Ganzi complex (SGC), a flysch basin with a wide distribution and monotonous lithology. Strong tectonic deformation and accumulation of folds have led to destruction of the original sedimentary sequence and sedimentary structure of the strata, such that there exists no reasonable sedimentary model that can explain the massive flysch. Herein, we investigated in detail the sedimentary structures, paleocurrent direction, particle sizes, major and trace elements, and magmatic zircon and detrital zircon U–Pb ages of the typical sections of the Xikang Group in the eastern SGC. Our analysis led to the following findings: 1) The U–Pb zircon ages from the Galazi (215.6 ± 1.1 Ma), Sudi (214.5 ± 1.5 Ma and 221.1 ± 1.5 Ma), and Gulu (221.3 ± 1.2 Ma) plutons, which intrude the Xikang Group, and detrital zircon samples from the uppermost part of the Xinduqiao Fm. indicated the youngest mean age (YC1σ[2+]) of 222.4 ± 2.5 Ma. This in turn indicates a pre-221 Ma depositional age for the Xikang Group. 2) The provenance was derived from the North China Block and Qiangtang Terrane, Qinling–Dabie orogenic belt, South China Block, and East Kunlun–Qaidam, and the construction of the flysch in the SGC belongs to the multi-source or line source provided by the peripheral orogenic belt. 3) Trace elements suggested that the Xikang Group may have been deposited in a sedimentary basin associated with a continental island arc. 4) The sedimentary environment in this area belonged to the distal fan of a submarine, and the new sedimentation age and sedimentation rate indicate that the Carnian pluvial event may have been the trigger mechanism. 5) The formation of the flysch deposition in SGC related to the Paleo-Tethys Ocean underwent a scissor-like closure from east to west.

西康组代表了松潘—甘孜联合体（SGC）的主要地层层序，该松散盆地是一个分布广泛，岩性单调的盆地。强烈的构造变形和褶皱积聚导致原始沉积层序和地层沉积结构破坏，因此不存在合理的沉积模型可以解释大规模的飞石。在这里，我们详细研究了SGC东部典型地区西康组典型地区的沉积结构，古流向，粒径，主要和微量元素以及岩浆锆石和碎屑锆石的U–Pb年龄。我们的分析得出以下发现：1）U–Pb锆石年龄来自Galazi（215.6±1.1 Ma），Sudi（214.5±1.5 Ma和221.1±1.5 Ma）和Gulu（221.3±1.2 Ma）轻子，进入西康集团，并从新都桥组最上层提取碎屑锆石样品。表示最小平均年龄（YC1σ[2+]）为222.4±2.5 Ma。这反过来又表明了西康集团的221 Ma以前的沉积年龄。2）物源来自华北地块和Qian塘地层，秦岭-大别造山带，华南地块和东昆仑-柴达木，SGC中的复理石构造属于多源或线源。由外围造山带。3）微量元素表明，西康群可能已经沉积在与大陆岛弧相关的沉积盆地中。4）该区域的沉积环境属于潜水艇的远侧风机，新的沉积年龄和沉积速率表明，卡尔尼暴雨事件可能是触发机制。5）SGC中与古特提斯洋有关的复理沉积物的形成自东向西呈剪刀状封闭。