Early Cretaceous oceanic island basalt-type magmatism in northern Guangdong: Implications for lithospheric thinning in the South China Block
Posted on 19.04.2022 - 13:26
Abstract: South China Block (SCB) underwent a tectonic switch from compression to extension between Late Jurassic and Early Cretaceous, but the extension process has not been well understood. Here we report the Meiziwo lamprophyres in northern Guangdong formed at Early Cretaceous (ca. 136 Ma; 40Ar/39Ar dating) are characterized by oceanic island basalt (OIB)-like geochemical signatures and Pb enrichment, together with moderately high (87Sr/86Sr)i (0.70642-0.70766), positive εNd(t) (+4.6 to +5.1), intermediate (206Pb/204Pb)i (18.579-18.602), (207Pb/204Pb)i (15.727-15.733), (208Pb/204Pb)i (38.871-38.909). The lamprophyres were derived from an asthenosphere-dominated source, with recycled oceanic crust and terrigenous sediments contribution. In contrast, the previously reported ca. 154 Ma mafic dyke in eastern Guangdong, and the ca. 165-155 Ma A-type granite belt in southern Hunan and nearby regions, show arc-like signatures and unradiogenic Nd but moderately radiogenic Pb isotopes, suggesting magma derivation from a lithospheric mantle. Hence, the change from lithospheric to asthenospheric sources may be caused by progressive lithospheric extension and thinning associated with the rollback and tearing of the paleo-Pacific plate. The 136 Ma Meiziwo lamprophyres, together with the 140 Ma asthenosphere-derived OIB-like mafic rocks nearby, signify the petrologic response to regional extension in the South China Block from ca. 140 Ma onward.
CITE THIS COLLECTION
Jiang, Hai; Shao, Shang; Jiang, Shao-Yong; Yang, Shui-Yuan; Zhao, Kui-Dong (2022): Early Cretaceous oceanic island basalt-type magmatism in northern Guangdong: Implications for lithospheric thinning in the South China Block. Geological Society of London. Collection. https://doi.org/10.6084/m9.figshare.c.5953720.v1
Select your citation style and then place your mouse over the citation text to select it.
terrigenous sediments contributionsuggesting magma derivationsouth china blockrecycled oceanic crustoceanic island basaltasthenospheric sources may70766 ), positivesr /< sup87 </ sup86 </ sup40 </ sup39 </ sup208 </ sup207 </ sup206 </ sup204 </ suptype granite beltpb /< supar /< supsr )< subpreviously reported capb )< subnorthern guangdong formedprogressive lithospheric extension</ subnorthern guangdongpb enrichmenttype magmatismar datingeastern guangdongwell understoodunradiogenic ndthinning associatedtectonic switchsouthern hunanshow arcregional extensionpetrologic responsepacific platenearby regionsmafic dykelithospheric thinninglithospheric mantlelike signatureslate jurassicextension processearly cretaceousdominated source909 ).(+ 4