Pulsed Mesozoic Exhumation In Northeast Asia: New Constraints From Zircon U-Pb And Apatite U-Pb, Fission Track And (U-Th)/He Analyses In The Zhangguangcai Range, Ne China

Northeast Asia located at the margin of the Paleo-Pacific/Pacific plate provides a detailed record of subduction-related omgenic activity. In order to shed light on Mesozoic-Cenozoic tectonic processes arising from the complex interaction and juxtaposition of multiple tectonic domains, we performed zircon U-Pb and apatite U-Pb, fission-track (FT) and (U-Th)/He analyses in the Zhangguangcai Range, a major mountain range in northeastern Asia. Our zircon and apatite U-Pb results indicate that most granites in the Zhangguangcai Range were emplaced at shallow crustal levels in the early Jurassic (similar to 200-173 Ma) along with a minor amount of Triassic granites (similar to 232 Ma). Volcanic rocks of the Maoershan and Ningyuancun formations were erupted at similar to 190-175 Ma and similar to 182-177 Ma, respectively. This Early Mesozoic magmatic activity is related to subduction of the Mudanjiang oceanic plate that separated the Jiamusi and Songliao blocks. Apatite FT analysis of granites and volcanic rocks reveals three groups of cooling ages clustering at similar to 193-171 Ma, similar to 158-129 Ma and similar to 118-102 Ma, while AHe analysis of granites yielded three groups of cooling ages at similar to 149-135 Ma, similar to 106-85 Ma and similar to 57-48 Ma. Based on these data and thermal history modelling, we propose that the central Zhangguangcai Range experienced episodic, multi-stage exhumation at shallow crustal levels since the Jurassic. Early-Middle Jurassic exhumation took place during the closure of the Mudanjiang Ocean, which resulted in unroofing of granites in the central Zhangguangcai Range and topographic growth of the Songliao block. Late Jurassic-Early Cretaceous exhumation occurred within an extensional tectonic setting, which has previously been documented across northeast Asia. Such exhumation could have been linked to lithosphere delamination and resulted in basin and range topography style, prior to the change in subduction parameters of the Paleo-Pacific plate and/or collision and strike-slip translation of the Okhotomorsk block in the Late Cretaceous.