## 5 Discussion
### Crustal Structure Beneath Yemaquan and Dulate Arc  
The shallow part of crust beneath the Yemaquan arc is characterized by complex electrical structure and block high resistance bodies are separated by high conductors. These block high resistance bodies are interpreted as the granite bodies which are widely distributed in the Yemaquan arc. The local low-resistivity zones represent the faults produced by the thrust nappe structure function in the subduction-collision-accretion process. The upper crustal structure beneath Yemaquan arc is characterized by uniform and stable resistance, which indicates it does not belong to the Paleozoic crust basement. Middle Ordovician metamorphic rocks were found in the Kalamaili Mountain [48] and a large number of Precambrian detrital zircons were obtained from Devonian sandstones [49], which indicates the basement can potentially be identified as a Precambrian continental block. In addition, Ordovician-Silurian granites in the Taheir exhibit some distinct evidence of Andean-type arc continental arcs and igneous rocks are mixtures of the juvenile material and old crust, which is not likely the oldest oceanic crust in East Junggar [2]. In a geophysical point of view, the mafic lower-crustal composition was interpreted in the seismic section [50]. The crustal basement is characterized by deep-seated and highly magnetic and density anomalies and high velocity [24; 25], which can be interpreted as mafic rocks. Some researchers reported that the felsic rocks are related to the mafic magmas and the petrogenetic models are still controversial [34; 51; 52; 53]. The partial melting of crustal rocks model conflict with the high resistivity and velocity of the crustal basement. In addition, mafic magma underplating and intrapalting cannot cause thick and homogeneous upper crust. The resistive crust is probably formed before the Cambrian, as the residual continental crust. The north-dipping resistive crust indicates the northward subduction of the Zhaheba-Almantai ocean. A low-resistivity zone in the crust between the Junggar Basin and the Yemaquan arc is interpreted as the splicing zone between residual continental margin arc and island arc.  
The shallow part of crust beneath the Dulate arc is characterized by low resistivity, which represents the Zhaheba depression composed of the Devonian-Permian volcanic and sedimentary rocks according to the study from surface exposures and Well Fuqian-1 [52] and Xinfudi-1 [53]. Underlying high resistivity bodies are interpreted as the granite bodies which are widely distributed in the Dulate arc. The crust beneath the Dulate arc is characterized by low resistivity in general, which is significantly different from that of the Yemaquan arc. Several mechanisms were proposed to explain the conductive anomalies in the crust. Partial melting is probably an appropriate candidate for the East Junggar tectonic belt. However, the range of crustal geothermal values in the Junggar basin are 18.8-26 mW/m\({}^{2}\) and the range of mantel geothermal values are 16.5-23.7 mW/m\({}^{2}\), whichis also lower than the average value of terrestrial heat flow in mainland China [54]. Therefore, the cold crust and mantle in the East Junggar do not support the partial melting. Sulfides and the interconnected graphitic thin films are also the candidates to cause low resistivity. The Cu-Ni sulfide deposit [55], Cu-Zn deposit [33], Au deposits [56], and graphite deposit [57] in the study area are developed and have been studied for decades. The metallogenic mechanisms of metal and graphite deposit are related to the magmatism of the plate subduction collision. Therefore, the low resistivity belt is probably the metal ore-bearing magma channel.