PUNCTUATED OROGENY DURING THE ASSEMBLY OF ASIA: PROTEROZOIC-PALEOZOIC GEOLOGIC HISTORY OF THE NORTH CHINA CRATON AND TIBETAN PLATEAU

The assemblage and post-assemblage tectonic modification of the Eurasian continent occurred from the Proterozoic to the Cenozoic over a time span of nearly one billion years. The Proterozoic-Phanerozoic evolution of the Tarim and North China cratons is integral to the construction of the Eurasian continent. Throughout the Paleozoic, these continents bound the Paleo-Asian and Tethyan Oceans to the north and south, respectively, and thus determining their paleogeography is critical to reconstruction of the bounded oceanic domains. Specifically, it remains uncertain whether the Tarim and North China cratons were contiguous during the Paleozoic. Geologic observations across the boundary between the Qaidam continent and North China craton provide valuable information regarding the paleotectonic relationships among these continental domains. Here we present detailed field, geochronological, and geochemical observations from several key locations in the Qilian Shan, Hexi Corridor and Longshou Shan areas to decipher complex relationships between the Tarim, North China, and Qaidam continents. This region has been deformed during at least five phases of orogeny since the Proterozoic, including (1) regional granulite-facies metamorphism in the Paleoproterozoic, (2) an enigmatic Neoproterozoic arc-collision, (3) the early Paleozoic Qilian arc development and its amalgamation with the Qaidam continent and the North China, (4) Permian-Triassic magmatism and deformation related to the closure of the Paleo-Asian Ocean to the north, and (5) the most recent Cenozoic contractional deformation related to the India-Asia convergence.