Lithospheric mantle signatures as revealed by zircon Hf isotopes of Late Triassic post‐collisional plutons from the central Korean peninsula, and their tectonic implications

Abstract

The Mesozoic tectonic architecture of the Korean peninsula is largely governed by the continental collision between the North and South China blocks. Zircon Hf isotopic compositions presented in this study and whole-rock geochemical and SrNd isotope data in the literature collectively suggest that the lithophile-elements-enriched signature of the Late Triassic post-collisional plutons from the Gyeonggi massif in central Korea is a primary feature inherited from the metasomatized mantle lithosphere. Highly negative zircon e Hf (t) values (À23 to À19) of plutons from the middle and eastern parts of the massif indicate an ancient metasomatism of their mantle source. Distinctly higher zircon e Hf (t) values (À15 to À12) from the southwestern plutons are ascribed to a contribution from an accreted component of the South China-like block. The involvement of asthenospheric mantle is not recognized in zircons from either group. The implications of these isotopic features are discussed in the context of Mesozoic collisional tectonics.

Geochemical and Sr–Nd isotopic constraints on the petrogenesis of the Goesan monzodiorite pluton in the central Okcheon belt, Korea

“…, ; Cheong et al . ), and comparable with the age of a biotite syenite (224 ± 4 Ma; Peng et al . ) reported from the North Korean territory near the Imjingang belt.…”

“…, , ; Cheong et al . , ) may suggest an emplacement under the same tectonic regime. It is, therefore, most likely that the Late Triassic post‐collisional environment produced the “Caledonian‐type” metaluminous and alkali‐calcic intrusives including the Goesan pluton, whereas the Middle Jurassic arc environment yielded the “Cordilleran‐type” peraluminous and calc‐alkalic plutons prevalent in the Okcheon belt and the Gyeonggi massif.…”

“…; Cheong et al . ). Potassic igneous rocks typically occur during periods of relaxation after the culmination of collisional events (Barbarin , ; Bonin et al .…”

Fast cooling following a Late Triassic metamorphic and magmatic pulse: implications for the tectonic evolution of the Korean collision belt

“…The Haemi intrusion in the Hongseong area (Fig. 4) has the same age (230-234 Ma;Choi et al, 2009;Seo et al, 2010;Cheong et al, 2014), which is identical within uncertainty with the hornblende and biotite 40 Ar/ 39 Ar plateau ages in the Deokjeongri Complex, and the average rim age of zircons in this area. Therefore, the Late Triassic metamorphism and magmatism that strongly affected rocks at structurally different levels probably have a common tectonic cause.…”

“…7). Late Triassic postcollisional magmatic activity is manifest by Haemi pluton (230-234 Ma; Choi et al, 2009;Seo et al, 2010;Cheong et al, 2014) in the Hongseong area (Fig. 4), and the Mongsanpo intrusion (229.6 ± 3.5 Ma; Han, 2014) on Anmyeon Island (Fig.…”