TY - JOUR
T1 - Similar crust beneath disrupted and intact cratons
T2 - arguments against lower-crust delamination as a decratonization trigger
AU - Ma, Qiang
AU - Xu, Yi-Gang
AU - Deng, Yangfan
AU - Zheng, Jian-Ping
AU - Sun, Min
AU - Griffin, William L.
AU - Xia, Bing
AU - Wang, Christina Yan
PY - 2019/1/5
Y1 - 2019/1/5
N2 - The continental lithosphere is not forever; some cratons have lost their original roots during the course of their evolution. Yet, it is not clear whether gravitational instability of dense lower crust is the primary driver of decratonization. This is addressed here with emphasis being placed on the North China Craton (NCC), because it represents one of the best examples of craton-root disruption in the world, and a place where models can be tested. If lower-crustal delamination was the trigger for decratonization, we would expect a clear contrast in crustal structure and composition between disturbed (rootless) and intact cratons. However, the eastern (disturbed) and western (intact) parts of the NCC show virtually identical physical structure and composition (a thin mafic lower crust and a predominantly intermediate composition overall) although the crust in the disturbed part is thinner than in the intact craton. This suggests that delamination of the lower crust was not a viable mechanism of craton-root disruption in the NCC case. Indeed, the crust beneath the NCC largely resembles those of stable Archean cratons worldwide. Therefore the delamination, if it occurred, may have taken place much earlier (Archean) than previously thought, rather than in the Mesozoic. Delamination may have been a common phenomenon in the early evolution of cratons, probably due to relatively higher mantle temperatures in the Archean Eon.
AB - The continental lithosphere is not forever; some cratons have lost their original roots during the course of their evolution. Yet, it is not clear whether gravitational instability of dense lower crust is the primary driver of decratonization. This is addressed here with emphasis being placed on the North China Craton (NCC), because it represents one of the best examples of craton-root disruption in the world, and a place where models can be tested. If lower-crustal delamination was the trigger for decratonization, we would expect a clear contrast in crustal structure and composition between disturbed (rootless) and intact cratons. However, the eastern (disturbed) and western (intact) parts of the NCC show virtually identical physical structure and composition (a thin mafic lower crust and a predominantly intermediate composition overall) although the crust in the disturbed part is thinner than in the intact craton. This suggests that delamination of the lower crust was not a viable mechanism of craton-root disruption in the NCC case. Indeed, the crust beneath the NCC largely resembles those of stable Archean cratons worldwide. Therefore the delamination, if it occurred, may have taken place much earlier (Archean) than previously thought, rather than in the Mesozoic. Delamination may have been a common phenomenon in the early evolution of cratons, probably due to relatively higher mantle temperatures in the Archean Eon.
KW - Lower-crust delamination
KW - Decratonization
KW - Crust
KW - Adakite
KW - North China craton
UR - http://www.scopus.com/inward/record.url?scp=85056621697&partnerID=8YFLogxK
U2 - 10.1016/j.tecto.2018.11.007
DO - 10.1016/j.tecto.2018.11.007
M3 - Article
AN - SCOPUS:85056621697
SN - 0040-1951
VL - 750
SP - 1
EP - 8
JO - Tectonophysics
JF - Tectonophysics
ER -