Subduction of the primordial crust into the deep mantle  

作　　者：Hiroki Ichikawa Steeve Gréaux Shintaro Azum 

机构地区：[1]Geodynamics Research Center,Ehime University [2]Earth-Life Science Institute,Tokyo Institute of Technology [3]Department of Earth and Planetary Sciences,Faculty of Science,University of Kyushu

出　　处：《Geoscience Frontiers》2017年第2期347-354,共8页地学前缘（英文版）

基　　金：supported partly by KAKENHI 26800237 and 26287105

摘　　要：The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.

关 键 词：Primordial crust Anorthosite KREEP Subduction erosion Subduction channel 

分 类 号：P542.5[天文地球—构造地质学]