page_title: Qinling orogenic belt
section_title: Evolution of belt and associated ocean (800 to 250 million years ago)
hierarchical_section_title: Qinling orogenic belt / Tectonic Evolution / Evolution of belt and associated ocean (800 to 250 million years ago)
caption_attribution_description: English: Diagram showing plate evolution 400 million years ago SCB: South China Block NCB: North China Block NQB: North Qinling Block SQB: South Qinling Block PEA: Proto-Erlangpng Arc
context_page_description: The Qinling orogenic belt is a tectonic feature that evolved throughout the Proterozoic and Phanerozoic eons due to a variety of tectonic activities. It is a part of the Central China Orogenic Belt, aligned in an east–west orientation across Central China, and spans portions of Shaanxi, Henan and Gansu provinces along the Qinling Mountains which are one of the greatest mountain ranges in China. The first materials involved in the Qinling orogenic belt formed around 2.5 billion years ago, whereas the main morphology of the belt now largely reflects the Triassic collision between the North China plate and the South China plate and Cenozoic extension across China. During these 2.5 billion years, various types of rocks have been formed here due to different tectonic processes and chemical reactions between rocks. Therefore, geologists are able to reconstruct the evolution of mountain belt based on evidence preserved in these rocks.
context_section_description: Later on in the middle Neoproterozoic (around 750 million years ago), the super-continent containing Proto-Erlangping arc, North Qinling Belt and South Qinling Belt was broken up. The two belts were transported to another place together. The oceanic part of South China block was broken and separated into two parts creating the Shangdan ocean. This is because divergent convection magma dominated at that period, when two parts separate, magma rise up from the gap of them creating a larger oceanic plate (as well as an ocean). On the other end of the oceanic plate, it collided with another oceanic plate coincidently. An island arc called 'DanFeng island arc' was formed.
  A similar process occurred at the North Qinling belt, North Qinling belt and Rodinia were separated. As a result, a new ocean formed as well. At this time North and South Qinling belt were still aligning next to each other, therefore they shared the same Shangdan ocean. By the time the North Qinling Belt moved away from Rodinia, it was colliding with the Proto-Erlangping arc as well. Therefore, two subduction processes occurred at the same time at the Proto-Erlangping arc.
  At the early Cambrian (around 540 million years ago), Gondwana (considered as super-continent by some geologists) started to develop. The North and South Qinling Belt were located at the Northeastern part of it. This was the time when North China Block first met the North Qinling belt, locating at the other end of Proto-Erlangping arc. During that period, the North Qinling belt was no longer located next to South Qinling belt, but facing it. As same as the situation before Cambrian, the North Qingling belt and South Qinling Belt still share the Shangdan ocean. What different was the subducting plate changed from one to another, at the Danfeng island.
  At late Cambrian (around 500 million years ago), the North China block migrated closer to North Qinling block. Consequently, the Proto-Erlangping ocean was closed as the whole oceanic plate had subducted to the mantle. This also implies the North Qinling belt collided with Proto-Erlangping belt after the closure of the ocean.
  From the late Ordovician to late Silurian (460 to 420 million years), the collided North Qinling belt and Proto-Erlangping belt were moved to a magma spreading centre, which split plates apart by divergent convection magma. This turn out the Erlangping ocean was opened again.
  At the early Devonian (around 400 million years ago), South Qinling belt and North China block moved towards each other, while extensive convergent convection magma occurred, although some geologists claimed it happened between 320 and 300 million years before. As a result, Erlangping arc, North Qinling belt, South Qinling belt and North China block all collided together. With all oceans closed up and blocks moving towards each other, rocks were then piled up within blocks. Meanwhile, Mianlue ocean was opened, since South China block and the rest of the block complex were separated by divergent convection magma current. The ocean created is also regarded as back-arc basin.
  During the middle Mississippian (around 300 million years ago), the Mianlue ocean stopped spreading. The South China plate moved towards the Qinling complex and North China Block. The oceanic part of South China Block subducted to the mantle and the ocean started closing.
caption: Diagram showing plate evolution 400 million years ago  SCB: South China Block   NCB: North China Block  NQB: North Qinling Block   SQB: South Qinling Block  PEA: Proto-Erlangpng Arc  DIA: Danfeng Intra-oceanic island arc. Modify from Dong et al., 2011.[24]
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