Abstract:
The orocline, as an orogenic-scale structure, records key information of the orogenic evolution in 4D, and has a fundamental impact on the magmatic, structural, sedimentary evolution of orogenic belts. However, the geodynamic origin of oroclinal bending remains controversial. Here I focus on the Kazakhstan Orocline in the western Central Asian Orogenic Belt, which is an ideal candidate for studying the mechanism of oroclinal bending in accretionary orogens given its continuous record of plate subduction. I review available geological and paleomagnetic data around the Kazakhstan Orocline, which allows to conclude that major phase of bending during the Late Devonian to Early Carboniferous was likely driven by along-strike variation in trench migration, similarly as the formation of arcuate subduction systems around the Pacific margin. A later stage of bending during the Late Carboniferous to Permian might be associated with the amalgamation of the Siberian, Tarim and Baltic cratons. To further understand the origin of the Kazakhstan Orocline would benefit from structural constraints around the hinge of the Kazakhstan Orocline, as well as 4D reconstruction of the Junggar subduction system along two limbs of the orocline (West Tianshan and West Junggar in NW China) and around the hinge of the orocline (Balkhash area in Kazakhstan).