Accretionary complex: Geological records from oceanic subduction to continental deep subduction
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cretionary complex: Geological records from oceanic subduction to continental deep subduction 1,2*
Jianbo ZHOU 1
Key Laboratory for Evolution of Past Life and Environment in Northeast Asia (Jilin University), Ministry of Education, 2
Changchun 130026, China; College of Earth Sciences, Jilin University, Changchun 130061, China
Received December 26, 2019; revised May 24, 2020; accepted June 24, 2020; published online August 24, 2020
Abstract Accretionary complex was usually formed by offscraping of the subducting crustal material over the trench and thus often referred to as subduction zone mélange. The structure, composition and forming process of accretionary wedges can provide important insights into the evolution history of ocean basin, ocean-continent material cycle, continental accretion and thus contribute to understanding of the origin of plates and the growth of continents. Accretionary complex is characterized by a block-in-matrix structure associated with imbricate thrusts and isoclinal folds, diversified metamorphic types and intense waterrock interactions, which are distinct to the traditional stratigraphy. Since the proposal of the concept of accretionary wedge over a hundred years ago, great progress has been made in a variety of research focuses, such as the identification of the distribution of accretionary complexes, their compositions and formation mechanisms, the affinities of the matrix and igneous rocks, the recognition of the Ocean Plate Stratigraphy (OPS), the reconstruction of oceanic basin, the dynamic background of the tectonic evolution, the relationship between subduction zone and orogenic belt and, in particular, the accretionary complexes in continental subduction zones. These studies have significantly improved our understanding of the plate tectonic theory. Challenges remain in the identification of ancient accretionary complexes, the detailed analysis of accretionary complex zones, the accretion characteristics during continental collision, and the geochemical tracing of water-rock interaction during the accretion. China contains representative orogenic belts and accretionary complex zones in the world, and its geological records provide the best opportunity to make new breakthroughs in understanding of the plate tectonics. Keywords Accretionary complex, Subduction of oceanic plate, Tectonic scraping, Accretionary orogenic belt, Collisional orogenic belt Citation:
Zhou J. 2020. Accretionary complex: Geological records from oceanic subduction to continental deep subduction. Science China Earth Sciences, 63, https://doi.org/10.1007/s11430-019-9652-6
1. Introduction A typical accretionary complex consists of autochthonous sediments together with a mixture of sedimentary covers and oceanic crust fragments, which are offscraped from the subducted oceanic crust before it enters into the trench. Thus, it is often called the subduction zone mélange. An accretionary wedge is usually distributed between the trench and * Corresponding author (email: [email protected])
arc in the ocean
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