Since 1980s, the research on Dabie orogenic belt has been deepened gradually. Xu Jiawei et al. (1987) first proposed that the Dabie Mountain collision zone was formed by the collision and docking of the North China and Yangtze landmasses in Mesozoic. Jing (Anhui),? (Hubei) cooperated with Zhang Shuye and Liang Wantong (formerly Changchun Institute of Geology) to systematically study blue schists in Anhui and Hubei provinces. After 1986, Liang Wantong, Jing, Pan Guoqiang cooperated with Liu Chongguang (Stanford University, USA) to study Zhangbaling blueschist (1986 ~ 1989) and Dabie eclogite (1988 ~/kloc-0). At the same time, Liu Chongguang and others expanded the research scope to Hubei, and compared with Liu (Hubei),? Such as research cooperation. At the same time, Okay A L, SengorA M and others (Istanbul University, Turkey) cooperated with Xu Shu (Anhui Institute of Geology) to study the evolution of Dabie orogenic belt. Because coesite (Xu Zhiqin,1987; Okay A L et al.1989; Wang x meters, etc.; Pan Guoqiang et al., 1990) and Diamond (Xu Shuren,1991; Zhang Shuye et al., 199 1), confirmed the existence of ultrahigh pressure metamorphism. Subsequently, with the support of the National Natural Science Foundation of China, the Institute of Geology of the Chinese Academy of Sciences has successively cooperated with domestic universities and research institutes and foreign countries to study the geological structure and material composition of the Dabie orogenic belt, especially the ultrahigh-pressure metamorphic belt represented by eclogite, and has obtained some important scientific research projects and achieved important results. Cheng, Zhou, Chang studied metamorphic rocks, structure and mineralization of Dabie orogenic belt, and made deep geophysical exploration of Dabie orogenic belt, and made important progress.
Through the above research, researchers have published many important monographs and papers, and comprehensively discussed the formation and evolution of Dabie orogenic belt and the formation and exhumation mechanism of ultrahigh pressure metamorphic belt, which has aroused great concern and attention of geologists at home and abroad. They believe that Dabie orogenic belt is one of the classic areas in the global orogenic belt and the most ideal field experimental base for revealing the dynamic process of the orogenic belt. Researchers generally believe that the Dabie orogenic belt is an Indosinian collision orogenic belt between North China and Yangtze River, and the ultrahigh pressure metamorphic belt was formed by deep subduction. However, there are still differences on some major geological issues, mainly as follows:
1) Where is the collision suture zone of Indochina plate? Is it the Mozitan-Xiaotian fault (Xu Shutong, 1992) between northern Dabie Mountain and northern Huaiyang, or the Yingshan-Shuihouling fault in Dabie Mountain (Dong Shuwen, 1997), or the Xiangfan-Guangji fault in southern Dabie Mountain (Yang, 19 1? Related to this is the structural attribution of the complex at the core of the Dabie orogenic belt, that is, the "North Dabie" structure, which belongs to the ancient island arc on the active continental margin of the southern margin of the North China plate, and the North Huaiyang area is a back-arc basin. It is also the subduction basement of the Yangtze plate.
2) Where is the oceanic crust representing the decrease of Indosinian period? Are ultrabasic rock belts distributed in the northern Dabie Mountains ophiolite suite (Xu Shutong, 1994)?
3) What is the formation model of Dabie orogenic belt? Is the Yangtze plate subducting into the North China plate (Xu Shuping, 1994)? Or did the North China Plate subduct southward (Jin Fu Quan Deng, 1995)? Or is the North China Plate and the Yangtze Plate offset, and the subduction of the North China Plate lags behind the southward subduction of the Yangtze Plate (Dong Shuwen et al., 1998)?
4) Where is the granite belt related to Indosinian plate collision? Where is the double metamorphic belt? Is there a metamorphic zoning from high-pressure blueschist to ultrahigh-pressure eclogite related to subduction depth from south to north in Dabie Mountain (Zhang Shuye et al., 1989)?
5) Are the protoliths of eclogites in ultrahigh pressure metamorphic belt all volcanic rocks? Is there magma origin? The formation times are Jinning period (Cheng et al., 1999), Caledonian period (Jianping, 1998) and Indosinian period (,1989)? Is the formation depth and temperature pressure conditions greater than 90 kilometers (from Berlin, etc. , 1999) or 32 km (Lu Guxian, 1999), is it related to the deep subduction of the mainland?
6) There are many models for the formation and exhumation of ultrahigh pressure metamorphic belt. If it is confirmed that ultra-high pressure metamorphic rocks are continental crustal rocks that dive to the ground more than 90 kilometers through the plate and then return to the surface quickly through ultra-high pressure metamorphism, what are the records of deformation and metamorphism experienced by rocks in this process? Is the nature of the contact relationship between ultra-high pressure rock and * * * living surrounding rock in situ or in different places? In particular, what is the basis of macro deformation records reflected by detailed structural mapping?
In recent ten years, the author and others have made some important discoveries through detailed mapping and special research on the Dabie orogenic belt, mainly including the following contents:
1) Neoproterozoic shallow metamorphic pyroclastic rocks (Tong Jiafu et al.,1995; Dong Shuwen et al., 1996), further confirmed the existence of the Yangtze Sinian to Early Cambrian strata in North Huaiyang area (Tong Jiafu et al., 1995), and the disintegration of the original Susong Group and the reconstruction of the tectonic stratigraphic sequence, indicating that the Dabie orogenic belt belongs to the northern margin of the Yangtze block.
2) Foziling Rock Group (Tong Jiafu et al.,1995; Qian Cunchao et al., 2000), determined that the fault is an undivided fault zone, not to mention the plate collision suture zone.
3) In the hinterland of Dabie Mountains, Mesozoic volcanic rocks and volcanic structures were discovered in Taoyuanzhai on the north side of ultrahigh-pressure metamorphic belt, with the formation age of 130Ma (Liu Dunyi et al., 2002), and their geochemical characteristics were similar to those of the late Jurassic Maotanchang Formation in North Huaiyang area, indicating that the core of Dabie orogenic belt had similar structural attributes with North Huaiyang area before the early Cretaceous (Zhou Cunting et al.,1.
4) Decompose the original Dabie Group, and decompose metamorphic supracrustal rocks, metamorphic ultramafic rocks and metamorphic granite. The latter is mostly Neoproterozoic deformed granite (Zhou Cunting et al.,1995; Tonga Fu et al., 1997). Further determination of eclogite in North Dabie (Wei Chunjing et al.,1997; Zhou Cunting et al., 2000), a deformed granite with similar age and series to the north and south, shows that the north and south do not belong to two different plates: North China and Yangtze.
5) Vein eclogite (Gaotianshan, etc.,1997; Tonga Fu et al., 2000). According to the contact relationship between eclogite and surrounding rocks, relevant data and dating results, it is indicated that eclogite may be mainly formed in Neoproterozoic (Tong Jiafu et al., 2000) and belongs to mantle rock origin. Glaucophane in the blue schist belt in Zhangbaling area was formed on S 1 foliation, which was related to the early extensional deformation of Indosinian (Tong Jiafu et al., 1995).
6) Through the detailed structural mapping and anatomy of the Dabie orogenic belt, it is determined that the main deformation pattern of the orogenic belt and its adjacent areas is the "Cobb structure" of bidirectional compression (Tong Jiafu et al., 1995). There are three stages in the deformation sequence. In the early stage, under the extensional tectonic body, it was characterized by the formation of westward overthrust folds parallel to the direction of orogenic belt and perpendicular to the direction of present orogenic belt, and the superposition of structural sheets between layers. The main stage is compression-contraction system, forming compression folds parallel to the current mountain range direction; Late magma diapir intruded, forming a "back dome" in the core and a "chain dome" structural belt, and forming a thrust structure sliding towards the outer basin at the edge of the orogenic belt.
To sum up, the formation and evolution of Dabie orogenic belt and the formation and exhumation of ultrahigh pressure metamorphic belt need to be reinterpreted and discussed on the basis of new data, which will be explained in detail in relevant chapters of this book.