The island arc-accretionary wedge system is a special tectonic unit within subduction zones. It develops as magmatic arcs atop accretionary wedges and records the complete tectonic transition from subduction accretion to arc magmatism, representing a vital mechanism for continental crustal growth at convergent plate margins. Nevertheless, due to multi-stage tectonic overprinting and late-stage modification of accretionary terranes, there has long been no unified understanding of the temporal-spatial relationship between accretionary complexes and magmatic arcs, deep structural characteristics, and the mechanisms of continental crustal growth.

Figure 1 Schematic tectonic map of Asia showing major continental blocks and suture zones within the Central Asian Orogenic Belt. The black box denotes the study area, and red stars mark locations of comparative accretion-arc case studies.

These disputes stem from the fact that the Jilin-Heilongjiang high-pressure belt has undergone multi-phase subduction, accretion, metamorphism, magmatic intrusion and tectonic reworking, and insufficient coupling has been established between shallow geological records and deep structural signals. Traditional surface geological, geochronological and geochemical data can constrain rock formation ages and material sources, yet they impose limited constraints on the deep geometry of paleo-subduction zones, the spatial architecture of accretionary bodies, and the linkage between magmatic systems and accretionary wedges. Therefore, integrating geochronology, geochemistry and geophysical data to identify relics of paleo-subduction systems across surface-crust-lithosphere scales is the key to resolving the tectonic attributes of the accretion-arc system in the Jilin-Heilongjiang high-pressure belt and revealing the mechanisms of continental crustal growth.

Recently, the research team led by Professor Zhou Jianbo from Jilin University, titled "Superposition Processes of Northeast Asia and Large-Scale Mineralization", collaborated with institutions including the Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences. Taking the Jilin-Heilongjiang high-pressure belt as the research object (Figure 2), the study systematically integrated multi-source datasets including regional geochronology, geochemistry, deep seismic reflection and magnetotelluric sounding. It focused on comprehensive analyses of the temporal-spatial distribution (Figure 3), petrogenesis and deep architecture (Figure 4) of the Heilongjiang Complex and Zhangguangcai Complex. By comparing with typical accretion-arc examples such as the western Central Asian Orogenic Belt, the Nadanhada terrane and the southern margin of the Lhasa terrane, this study constructed a coupled geological-geophysical model for accretion-arc systems, and elucidated the characteristics, formation dynamics of the accretion-arc system in the Jilin-Heilongjiang high-pressure belt, as well as its implications for Mesozoic continental crustal growth.

Figure 2 Composition and geochronological framework of the island arc-accretionary wedge system in the Jilin-Heilongjiang high-pressure belt

(1) Integrated geophysical imaging (Figure 4) identifies a west-dipping high-resistivity, high-amplitude reflective structure within the lithospheric mantle, interpreted as relics of a fossil subduction zone. Combined with eastward-younging metamorphic ages of complexes (Figure 2) and the limited spatial extent of accretionary complexes, the results demonstrate that the Heilongjiang Ocean underwent sustained unidirectional westward subduction, resolving long-standing debates over subduction polarity.

Figure 3 (a) Ar-Ar, Rb-Sr and zircon U-Pb geochronological data from the Jilin-Heilongjiang high-pressure belt; (b) protolith formation ages of the Heilongjiang Complex and Zhangguangcai Complex; (c) metamorphic ages of the Heilongjiang Complex and Zhangguangcai Complex.

(2) The Jilin-Heilongjiang high-pressure belt represents a typical accretion-arc system. Comparative analyses of the Chinggis Arc, Sawur Arc, Nadanhada Arc, southern Lhasa terrane and other cases summarize the key characteristics of accretion-arc systems: a vertical binary structure of "accretionary complex overlain by arc magmatic rocks", manifested in geophysical models as an assemblage of small-scale superimposed reflectors of high-resistivity mélanges and deep inverted U-shaped reflectors (Figure 4). Arc magmatic rocks exhibit typical arc geochemical signatures, alongside systematic oceanward isotopic trends (decreasing ⁸⁷Sr/⁸⁶Sr ratios and increasing εHf(t) values), indicating substantial involvement of juvenile accreted materials in their magmatic sources. This feature distinguishes them from typical continental arc systems and highlights the critical role of partial melting of accretionary complexes in generating arc magmas.

Figure 4 (a) Seismic profile with superimposed high-amplitude reflectors across the Bayan-Huanan segment; (b) Resistivity model overlaid with seismic high-amplitude reflectors for the Bayan-Huanan segment.

(3) The formation of accretion-arc systems is governed by a two-stage dynamic evolution: early low-angle (flat-slab) subduction facilitates the accretion and emplacement of accreted materials. Subsequent slab retreat drives oceanward migration of arc magmatism, which intrudes the basement of pre-existing accretionary wedges (Figure 5).

Figure 5 Schematic illustration of geodynamic evolution of Heilongjiang Ocean plate subduction. (a) Initial subduction of the Heilongjiang Ocean accompanied by emplacement of the Zhangguangcai Complex; (b) Subducting slab retreat triggers migration of arc magmatism beneath the Zhangguangcai Complex; (c) Closure of the Heilongjiang Ocean coinciding with emplacement of the Heilongjiang Complex; (d) Present-day tectonic architecture constrained by geological and geophysical observations.

(4) Accretion-arc systems fully record the tectonic transition from accretionary wedge construction to arc magmatic intrusion. The input of juvenile accreted materials in the early stage and modification by late-stage arc magmatism introduce voluminous new crustal materials, constituting a major mechanism for continental crustal growth. As the world’s largest Phanerozoic accretionary orogen, the Central Asian Orogenic Belt generated massive juvenile crustal materials closely linked to the development of multi-stage accretion-arc systems.

Through multidisciplinary integrated geological-geophysical research, this work establishes for the first time a complete tectonic evolution framework spanning accretionary wedge formation to arc magmatism for the Jilin-Heilongjiang high-pressure belt. It systematically summarizes the characteristic features and formative dynamics of accretion-arc systems, and constructs a comprehensive geological-geophysical identification framework for such systems. The research outcomes not only advance understanding of Mesozoic tectonic evolution in Northeast Asia, but also provide a key case study for investigating continental crustal growth mechanisms in accretionary orogens globally.

Paper Information

This research was published in      Earth-Science Reviews. The first author is Dr. Xin Zhonghua from the College of Earth Sciences, Jilin University, and the corresponding authors are Professor Zhou Jianbo and Academician Xiao Wenjiao. This study was financially supported by the National Natural Science Foundation of China (Grant No. 42230303) and the National Major Science and Technology Project (Grant No. 2025ZD1004702).

Paper Link