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The tectonic evolutionary history between the Xing'an Block (XB) and Songliao-Xilinhot Block (SXB) has been hotly debated. Here, we present precise geochronological ages and whole-rock geochemical data in the central Great Xing'an Range for the Carboniferous felsic rocks to reveal this tectonic history, as the petrogenesis of these rocks were closely related to tectonic activity between the XB and SXB. The age data with detailed geochemical analyses indicate three important stages of magmatism: early Carboniferous, early Late Carboniferous, and middle Late Carboniferous. The early Carboniferous granodiorites formed from the partial melting of metavolcanic rocks at mantle depths and show I-type features. The early Late Carboniferous monzogranites were generated by the partial melting of metagreywackes at middle to lower crustal depths, and they are S-type granites. The middle Late Carboniferous rhyolites formed from the partial melting of a thinned lower crust, and they display A-type characteristics. The data reveal three tectonic evolutionary stages between the XB and SXB during the Carboniferous era: from early Carboniferous subduction to early Late Carboniferous syn-collision, and to middle Late Carboniferous post-collisional extension. The accretionary mechanism of each stage featured horizontal accretion above subduction zones, amalgamation of different blocks, and vertical accretion fed by deep mantle materials, respectively.

The timing and direction of narrowing and closure of the Nenjiang Ocean (NJO) by plate subduction remain poorly constrained. This paper presents geochemical, isotopic, and geochronological results for Late Devonian to early Carboniferous intrusive rocks in the western Songliao–Xilinhot block to constrain the evolution of subduction in the NJO region. The Late Devonian syenogranites and monzogranites formed at 366–360 Ma and are classified as A‐type granites. The wide range of εHf(t) values (−17.62 to +8.13) and TDM2 ages (789–2,208 Ma) of the syenogranites indicate that the primary magma was derived from partial melting of multiple sources, including both young accreted continental crust and old lower crust rocks. The early Carboniferous granitic mylonites formed at 342 Ma and are I‐type granites. Their high SiO2 and K2O contents, εHf(t) values of +6.61 to +9.86, and young TDM2 ages of 675 to 857 Ma suggest a preexisting juvenile crustal material source region. The early Carboniferous hornblende gabbros formed at 334 Ma and are part of an appinite suite. The gabbros have low silica and high MgO contents, E‐MORB‐like trace element features, εHf(t) values of +1.34 to +8.97, and young TDM1 ages of 595 to 902 Ma, which together suggest a primitive magmatic source including juvenile MORB and/or enriched lithospheric mantle. Magmatism in the western Songliao–Xilinhot block formed a late Palaeozoic magmatic arc stretching along the eastern Hegenshan–Heihe suture. A new model of the evolution of subduction in the NJO region and associated coeval magmatic events is proposed that includes westward subduction of NJO oceanic crust during the Late Devonian at 366–360 Ma, bidirectional subduction during the early Carboniferous at ~342 Ma, and break‐off/delamination of the eastward subducting slab at ~334 Ma.