Trace-element composition of the Cretaceous Sindong Group, Gyeongsang Basin, Korea and its implication for provenance

The Sindong Group is the lowest stratigraphic sequence in the Cretaceous Gyeongsang Basin and comprises three stratigraphic units: the Nakdong, Hasandong, and Jinju formations in ascending order. A previous study reported the presence of Cr-spinel grains in Jinju sandstones, having been derived from ultramafic source rocks (Hisada et al., 2008). Ni and Cr show higher concentrations in mafic and ultramafic rocks. In this study the variation in Cr and Ni geochemistry of Sindong Group sediments was examined to address the possible existence of a source with an ultramafic component. Cr and Ni concentrations of the studied samples are slightly enriched compared with those of upper continental crust and active margin sediments, but are much lower than those derived from ultramafic rocks. The results of this study indicate that the Yeongnam Massif, the source area of the Sindong Group, may have been partially comprised of mantle-wedge peridotite before its denudation to deep-seated mountain roots, but the mass of peridotite seemed insignificant, resulting in the sediment trace-element geochemistry largely influenced by basement-rock components.