page_title: North China Craton
section_title: Other Models (Zhai's 7 Blocks Model, Faure and Trap 3 Blocks Model, Santosh Double Subduction Model)
hierarchical_section_title: North China Craton / Tectonic evolution / Precambrian Tectonics (4.6 billion years ago to 1.6 billion years ago) / Other Models (Zhai's 7 Blocks Model, Faure and Trap 3 Blocks Model, Santosh Double Subduction Model)
caption_attribution_description: English: Shows a micro block map of the model Zhao and Santosh proposed
context_page_description: The North China Craton is a continental crustal block with one of Earth's most complete and complex records of igneous, sedimentary and metamorphic processes. It is located in northeast China, Inner Mongolia, the Yellow Sea, and North Korea. The term craton designates this as a piece of continent that is stable, buoyant and rigid. Basic properties of the cratonic crust include being thick, relatively cold when compared to other regions, and low density. The North China Craton is an ancient craton, which experienced a long period of stability and fitted the definition of a craton well. However, the North China Craton later experienced destruction of some of its deeper parts, which means that this piece of continent is no longer as stable.
  The North China Craton was at first some discrete, separate blocks of continents with independent tectonic activities. In the Paleoproterozoic the continents collided and amalgamated and interacted with the supercontinent, creating belts of metamorphic rocks between the formerly separate parts. The exact process of how the craton was formed is still under debate.
context_section_description: Apart from the models which Kusky and Zhao proposed, there are some other models available to explain the tectonic evolution of the North China Craton. One of the models is proposed by Zhai.  He agreed with Kusky on the time frame of deformational events occurred in the North China Craton.  He also proposed that the continent grew from around 2.9 to 2.7 billion years ago, amalgamating 2.5 billion years ago and deforming around 2.0 to 1.8 billion years ago due to its interactions with the Columbia Supercontinent.  The mechanism behind these tectonic events is rift and subduction system, which is similar to the two models proposed by Kusky and Zhao.  There is a major difference of Zhai's theory with the above-mentioned models: he proposed that the North China Craton, instead of simply amalgamated and formed from the Eastern and Western Blocks, was amalgamated from a total of 7 ancient blocks.  Zhai found that the high-grade metamorphic rocks, a good indicator of amalgamation events, has been observed all over the craton, not just restricted to the Trans-North China Orogen or the Central Orogenic Belt.  He then proposed that there must have been more blocks that participated in the amalgamation process in order to explain the presence of belts of high-grade metamorphic rocks, which must have been formed in a strong deformation event that created a high pressure and high temperature environment.
  Faure and Trap proposed another model based on the dating and structural evidences they found. They used Ar-Ar and U-Pb dating methods and structural evidences including cleavages, lineation and dip and strike data to analyse the Precambrian history of the craton  The timing of final amalgamation in their model is in-line with the timing proposed by Zhao, also around 1.8 to 1.9 billion years ago, but another time of significant deformation (2.1 billion years ago) have also been suggested.  The division of micro-blocks deviated from Zhao's model.  Faure and Trap identified 3 ancient continental blocks, the Eastern and Western Blocks, same as Zhao's model, as well as the Fuping Block, differing from the Trans-North China Orogen in Zhao's model.  The 3 blocks were separated by two oceans, which were the Taihang Ocean and the Lüliang Ocean.  They have also proposed the sequence and timing of the events occurred.  Around 2.1 billion years ago, the Taihang Ocean closed with the Eastern Block and Fuping Block amalgamated through the Taihang Suture.  From 1.9 to 1.8 billion years ago, the Lüliang Ocean closed, promoting the amalgamation of the Eastern and Western Blocks.
  Santosh proposed a model to explain the rapid pace of amalgamation of the continental blocks, thus providing a better picture of the mechanisms of cratonization of the North China Craton.  For the time frame of the deformational events, he generally agreed with Zhao's model based on metamorphic data.  He provided a new insight to explain the subduction direction of the plates during amalgamation, where the 2.5 Ga craton amalgamation model suggested westward subduction, and the 1.85Ga craton amalgamation model suggested eastern subduction.   He did an extensive seismic mapping over the craton, making use of P-waves and S-waves.   He discovered traces of a subducted plate in the mantle, which indicated the possible direction of subduction of the ancient plate.   He finds that the Yinshan block (part of the Western Block) and the Yanliao block (part of the Eastern Block) subducted towards the centre around the Ordos Block (part of the Western Block), in which the Yinshan block subducted eastward towards the Yanliao block.   The Yinshan block further subducted to the south to the Ordos block.   The Ordos Block was therefore experiencing double subduction, facilitating the amalgamation of different blocks of the craton and its interactions with the Columbia Supercontinent.
caption: This map view diagram shows how Zhao proposed the micro blocks would have been oriented and amalgamated into North China Craton. He derived the map based on the age of the greenstone belts found in the Craton. He suggested that the greenstone belt was formed by collision of some micro blocks[20][21][22]. The green belt on the map shows a younger greenstone belt, formed 2.5 billion years ago, while the yellow one showed the greenstone belt formed 2.6–2.7 billion years ago[20][21][22].  (QH: Qianhuai Block, Jiaoliao Block:JL, Jining Block:JL, Xuchang Block: XCH, Xuhuai Block: XH, Alashan Block: ALS) Modified from Zhai, 2011[20]
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