## 2 Regional Setting  
### Regional Geology of the East Junggar  
The East Junggar is located at the northeastern margin of the Junggar Basin (Figure 1a) and between the Early Paleozoic Chinese Altai arc and the Late Paleozoic Harlik arc, which are separated by the Kuerti ophiolite to the north and the Karamaili ophiolite belt to the south [15; 29]. The East Junggar comprises the Dulate arc in the north and southern Yemaquan island arc unit in the south formed during subduction-accretion processes of the southern Paleo-Asian Ocean [30; 31; 32], which are separated by Zhaheba-Aermantai ophiolite belt. The Zhaheba complex is located in Eastern Junggar in Xinjiang Province, China (Figure 1b), which is a significant the southwest segment of the Central Asian Orogenic Belt (CAOB). It is tectonically bounded by the Dulate arc in the north and the Yemaquan island arc in the south. The Dulate arc comprises mainly Devonian-Carboniferous volcanic and sedimentary rocks, including Nb-rich and potassic basalt [1] and associated Cu-Zn ore deposits [33]. The Yemaquan arc consists mainly of Devonian-Carboniferous coastal shallow marine elastic rocks and volcanic rocks, granitoids, and adakitic rocks [34; 35]. The Zhaheba-Armantai ophiolites passed through the Armantai mountain to the Beita mountain from east to west, in the NWW-trending belt of about 150 km long and 3-5 km wide, mingled in the Lower Devonian Tuoranggeku Formation and the upper Devonian Cassiweng formation (Figure 1c), in the faulted contact with surrounding rocks. The Zhaheba complex represents the northwestern section of the Zhaheba-Alamantai ophiolite belt (Figure 1c), which consists mainly of serpentinized peridotite, dunite, gabbro, pillow basalt, plagioclase granite, carbonate, and layered siliceous rock. Ultramafic rocks, the most widely distributed lithology in the study area, comprise harzburgite, dunite, and minor pyroxenite. The gabbro mainly comprises plagioclase and clinopyroxene. The gabbro and diorite form large bodies, respectively. Basalts are common and show pillow structure. Diabase dikes and the diorite porphyry intrude ultramafic rocks. Volcanicastic rocks comprise tuffs, tufaceous sedimentary rocks, and breccia. The strata in the area are fully exposed, most of which are Paleozoic strata. Devonian and Carboniferous strata are most widely distributed. Additionally, Silurian and Permian strata are distributed in the middle and southeast of the study area. Cenozoic strata are widely distributed in the east and southwest of the study area. The Silurian strata consists of siliceous siltstone, slate, and phyllite. The Devonian-Carboniferous strata are divided, from bottom to top, into the lower Devonian Tuoranggekuduke Formation (D1t), the Middle Devonian Beitashan Formation (D2t), the Upper Devonian Kaxiweng Formation (D3k), the Lower Carboniferous Batamayineishan Formation (C1 bt), Heishantou Formation (C1h) and Jiangbasitao (C1j), the Upper Carboniferous Betamayineishan Formation (C2 bt). The Tuoranggekuduke Formation is composed of tuff and sandstone. The overlying Beitashan Formation is composed of tuffaceous clastic rocks and medium basic crystalline clastic tuff. The Kaxiweng Formation is composed of fine clastic rocks and andesite porphyrite and tuff. The Heishantou Formation is composed of calcareous pyroclastic rocks and continental clastic rocks. The Jiangbasitao Formation is composed of conglomerate and sandy conglomerate. The Batamayineishan Formation is composed of volcanic lava, tuff, and tuff breccia. Permian strata are rarely exposed and mainly consist of A-type granites and felsic volcanic rocks. The fold structures in the study area are composed of a series of northeast trending tight linear folds. The ophiolite is exposed at the core of complex anticline, which is distributed in NW-SE direction, with an extension length of 11 km and a width of about 3 km. The main faults include Erqisi fault, Zhahaba-Aeramantiai fault, Kalamaili fault, and Fuyun fault. Each major fault has a strong thrust nappe property.