Late Mesozoic magmatism in the Jiaodong Peninsula, East China:
Implications for crust–mantle interactions and lithospheric thinning of the
eastern North China Craton
-
Abstract
A section from the Linglong gold deposit on the northwestern Jiaodong Peninsula, East China, containing Late
Mesozoic magmatic rocks from mafic and intermediate dikes and felsic intrusions, was chosen to investigate the
lithospheric evolution of the eastern North China Craton (NCC). Zircon U–Pb data showed that low-Mg adakitic
monzogranites and granodiorite intrusions were emplaced during the Late Jurassic (~145 Ma) and late Early
Cretaceous (112–107 Ma), respectively; high-Mg adakitic diorite and mafic dikes were also emplaced during the
Early Cretaceous at ~139 Ma and ~118 Ma, and 125–145 Ma and 115–120 Ma, respectively. The geochemical
data, including whole-rock major and trace element compositions and Sr–Nd–Pb isotopes, imply that the mafic
dikes originated from the partial melting of a lithospheric mantle metasomatised through hydrous fluids from a
subducted oceanic slab. Low-Mg adakitic monzogranites and granodiorite intrusions originated from the partial
melting of the thickened lower crust of the NCC, while high-Mg adakitic diorite dikes originated from the mixing
of mafic and felsic melts. Late Mesozoic magmatism showed that lithosphere-derived melts showed a similar
source depth and that crust-derived felsic melts originated from the continuously thickened lower crust of the
Jiaodong Peninsula from the Late Jurassic to Early Cretaceous. We infer that the lower crust of the eastern NCC
was thickened through compression and subduction of the Palaeo-Pacific plate beneath the NCC during the
Middle Jurassic. Slab rollback of the plate from ~160 Ma resulted in lithospheric thinning and accompanied Late
Mesozoic magmatism.
-
-