A new tectonic framework for the composite orogenic metallogenic systems in the east of North China: The role of the Heilongjiang Ocean in the Late Paleozoic to Mesozoic

Abstract

Since the Paleozoic, the composite orogenic belt in the east of North China (the eastern Central Asian Orogenic Belt) has undergone multiple stages of subduction-accretion, tectonic superposition and destruction driven by multiple tectonic domains, e.g., the Paleo-Asian Ocean, the Panthalassa, and the Paleo-Pacific Ocean. Multiple episodes of tectono-magmatic activities and associated composite orogenic metallogenic systems have also been occurred. However, the tectonic affinities of these composite orogenic metallogenic systems are still not well understood, due to the poor knowledge of the temporal and spatial transitions among the three tectonic domains. Recently, a regional ocean, namely the Heilongjiang Ocean, has been proposed to be a critical link among the three tectonic domains that drove the Paleozoic tectonic evolution of the eastern Central Asian Orogenic Belt. To constrain the tectonic history of the Heilongjiang Ocean, here we reported new petrological, whole-rock major and trace elemental, and zircon U-Pb geochronological data of sedimentary and magmatic rocks from the western edge of the Jiamusi-Khanka Massif in the east of Heilongjiang Province. Integrating our new results with previous studies in the region, we established a novel tectonic framework for the eastern Central Asian Orogenic Belt: (1) During 380–310 Ma, a tectonic switch occurred in the region from weakened influence of the Paleo-Asian Ocean domain in the south to enhanced influence of the westward subduction of the Panthalassa into the eastern Jiamusi-Khanka Massif; the latter induced back-arc extension and eventually the opening of the Heilongjiang Ocean, which drove the Jiamusi-Khanka Massif to drift eastward away from the Central Asian Orogenic Belt; (2) during 300–270 Ma, subduction of the Heilongjiang Ocean was triggered in its eastern margin, producing arc-type magmatism in the west edge of the Jiamusi-Khanka Massif; by 270–210 Ma, subduction of the Heilongjiang Ocean expanded to its west margin (beneath the Songliao Massif); (3) following the eventual closure of the Heilongjiang Ocean in ~ 180 Ma and subduction of the Paleo-Pacific Ocean in the east, the Jiamusi-Khanka Massif rejoined the conterminous Central Asian Orogenic Belt, marking the final amalgamation of the Central Asian Orogenic Belt; since then, the tectonic history of the composite orogenic metallogenic systems in the east of North China was taken over by the Paleo-Pacific domain. This new tectonic model not only links the evolution of the three tectonic domains, but also provides a vital basis for the geodynamic framework of the contemporary endogenetic metallogenesis in this region.