Journal
GEOPHYSICAL RESEARCH LETTERS
Volume 45, Issue 15, Pages 7425-7433Publisher
AMER GEOPHYSICAL UNION
DOI: 10.1029/2017GL076948
Keywords
craton destruction; delamination; midlithosphere discontinuity; lower crust; intraplate orogeny
Categories
Funding
- National Natural Science Foundation of China [41572203, 40821061]
- Ministry of Education of China [B07039]
- MOST Special Fund from the State Key Laboratory of GPMR [MSFGPMR02-3]
- Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) [CUG180621]
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Delamination is an important mechanism of continental lithosphere removal and recycling. It has been invoked as a likely cause for the observed thinning in the eastern North China (North China Craton) and several other cratons, returning thick depleted cratonic roots to the deep mantle. However, how delamination occurred, its lateral extent, and detachment depth of delamination are still debated. Here we test this process by means of 2-D numerical modeling and find that delamination below lower crustal depths can only initiate near cratonic margins, where thickening-induced eclogitization can significantly destabilize the lower part of the lithosphere, allowing it to detach and leading to intraplate orogeny. When a weak midlithosphere discontinuity is present, widespread delamination can initiate near cratonic margins and easily propagate to cratonic interiors, yet without obvious intraplate deformation. We illustrate how this delamination mechanism can recycle large volumes of depleted Archean subcontinental lithospheric mantle using numerical models. Our models explain the large-scale delamination in the North China Craton, where a midlithosphere discontinuity is inferred by geophysical studies and shows that large portions of subcontinental lithospheric mantle can be recycled in the deep mantle potentially affecting mantle heterogeneity. Plain Language Summary We use numerical modeling mothed to study the lithosheric delamination in cratonic areas along the intralithosphere weak layers, including the lower crust and the midlithosphere dicontinuity. Our results show that delamination along the midlithosphere discontinuity can take place both near cratonic margins and within cratonic interiors without obvious intraplate deformation. However, delamination along lower crustal depths is mainly initiate at cratonic margins and can lead to intraplate orogeny.
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