Geochronology and geochemistry of the Carboniferous felsic rocks in the central Great Xing'an Range, NE China: Implications for the amalgamation history of Xing'an and Songliao-Xilinhot blocks

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.