Permian to Cretaceous tectonic evolution of the Jiamusi and Songliao blocks in NE China: Transition from the closure of the Paleo-Asian Ocean to the subduction of the Paleo-Pacific Ocean

Abstract

Zhangguangcailing Orogen constitutes a significant part of the Eastern Asian Continental margin. Its evolution was constrained by the oceanic consumption processes between the Jiamusi and Songliao blocks during late Paleozoic and Mesozoic time, resulted from the closure of the Paleo-Asian Ocean and subsequent Paleo-Pacific Ocean subduction. Considerable and continuing controversy has surrounded when, where, and how the ocean was subducted and the two blocks were eventually amalgamated, which plays a crucial role in understanding the tectonic transition from the closure of the Paleo-Asian ocean to the subduction of the Paleo-Pacific Plate, especially the initial formation of the Mesozoic foreland basin of the Songliao Basin. This review synthesizes the most recent data and geologic evidence that place critical constraints on the evolution of this oceanic domain. Available data and geological evidence indicate that there exists a stable micro-continent consisting of several microblocks of NE China and adjacent area within the Paleo-Asian Ocean regime during the Late Paleozoic. In the early Permian, voluminous magmatism occurred in an extensional setting induced by the subduction of the Paleo-Asian Ocean to the south and the Mongol-Okhotsk Ocean to the northwest. As the crustal extension continued, a continental rifting was initiated and further developed into an oceanic domain (the Heilongjiang Ocean or the Mudanjiang Ocean) separating the Jiamusi and Songliao blocks during Permian and Early Triassic time. Later, an active continental margin was situated along the Zhangguangcailing Orogen due to the subduction of the Heilongjiang oceanic plate in the Late Triassic, followed by a change in the regional stress regime controlled by Paleo-Pacific plate subduction. The high-pressure metamorphism occurred synchronously with the subduction/collision between the Jiamusi and Songliao blocks, forming the Heilongjiang Complex. The oceanic closure and collision events were sequentially followed by the A-type granitic magmatism, which commenced in the earliest Cretaceous.