Timing and style of closure of the Mongol-Okhotsk Ocean: paleomagnetic constraints from the northeastern Mongolia and Russian Far East

01.02.2017 bis 31.01.2019

(Humboldt Research Fellowship Dr.Pan Zhao) The Mongol-Okhotsk Orogenic Belt, as the most important orogeny that built the modern topography of the northeastern Asia, recorded the collisional process between the Siberian Block and Mongolia-North China Block that caused the closure of the Mongol-Okhotsk Ocean. Although its important tectonic significance, its evolution is still hotly debated since the last 3 decades on the timing and style of the closure of the Mongol-Okhotsk Ocean due to the shortage of research. The debate is mainly focused on whether it is a long-lasting (from Permian to Early Cretaceous) scissor-like closure due to relative rotations of the Siberia and Mongolia-North China blocks or an ordinary simultaneous closure in the Early Cretaceous ascribe to forward approaching of these two blocks. Therefore, in order to decipher how and when the closure occurred, we choose four segments of this belt in the northeastern Mongolia and Russian Far East areas and carry out paleomagnetic, geochronology and sedimentological studies on the Late Paleozoic-Mesozoic sedimentary and volcanic strata. From this multidisciplinary study, we aim to obtain following constraints on the evolution of the Mongol-Okhotsk Ocean: 1) The closure timing of the Mongol-Okhotsk Ocean in different segments; 2) The style for the closure of the Mongol-Okhotsk Ocean; 3) Quantity of the crustal shortening of this orogeny. From this study, we will hopefully make a full understanding of the tectonic evolution of the Mongol-Okhotsk Ocean and give a paleogeographic reconstruction of the northeastern Asia. Meanwhile, if a scissor-like closure of the Mongol-Okhotsk Ocean is approved by our new results, this will make important contribution to the knowledge of the rotation-related orogen.