Numerical Simulation Of Craton Destruction And Related Influencing Factors Caused By Subduction Process

Craton is a stable and cold continental block generally with thick Archean or Proterozoic rocks.The current research proves that some cratons have been experienced a period of destruction and show significant thinning of their lithosphere.We provide a reasonable mechanism to answer under what condition that cratonic lithosphere can be weakened and thinned.Recent research is basically classified into two main parts:one is by upwelling thermal erosion.The other one is the delamination of lithospheric mantle.Based on these,our research can be classified into three parts.First,our research puts forward that the subduction initiation can trigger the craton destruction during the supercontinent cycle and establish a series of numerical models.On the basis of a simplified force analysis between oceanic plate and craton,we suggest three key parameters playing a critical role in the destruction:the sub-continental lithospheric mantle(SCLM)thickness,the contact angle between the SCLM and the subducting oceanic plate and the coefficient of friction of SCLM.Besides,we took the mid-lithosphere discontinuity layer into consideration.It is worth noting that the existence of mid-lithosphere discontinuity layer controls the lithospheric mantle to detach in the deeper depth.The cratonic lithosphere can be destructed without directly contacting the subduction plate.Then we pay attention to plateau subduction.Plateau increases plate buoyancy during the subduction and changes the angle of subduction from steep slab to flatten slab.When plateau approaches subduction zone,thicker crust hinders the subduction and leads to collision at continental margins.This transition is followed by new subduction initiation and can cause the destruction of cratonic lithosphere.For further understanding of the evolution,we build a subduction model with plateau to verify the feasibility of our hypothesis.Our results tell that exotic block can collide with continental plate thus forms a new continental margin.The continental fitting promotes SCLM to bend and can develop into craton destruction.Our research shows that the strength of SCLM plays a huge influence on craton destruction.However,the detail motivation of the destruction is unclear which needs further study.Finally,we focus on the North China craton.It is generally accepted that its eastern part of cratonic lithosphere was destructed by paleo-Pacific subduction especially in late Cretacous.However,whether the northeast China experienced large-scale destruction is unclear.The current data reveals that lithosphere in the northeast China is much thinner than undetached North China craton.Since North China craton and the northeast China have different lithosphere thickness,this evolution demands a 3D model to show the behavior of oceanic slab under different lithosphere thickness.During the oceanic subduction,only the cratonic part of lithospheric mantle is peeled off.It proves that our 2D results can be applied into 3D model.The northeast China was not destructed because of its thin lithosphere.In our study,an innovative explanation is proposed for the destruction of craton.The interaction between the subduction zone and the craton is reasonably connected by our numerical models.