Major and trace element analyses of Cretaceous sedimentary rocks from the Euisong block, Gyeongsang Supergroup, Korea

Cretaceous fluvial-lacustrine sedimentary rocks of the Gyeongsang Supergroup crop out extensively in southeast Korea．This report contains whole-rock XRF analyses of 81 sandstones，siltstones and shales from the Sindong and Hayang Groups in the Kumi-Euisong area of the Euisong block．Analyses include major elements，CO_2，LOI，and 11-16 trace elements．Sample suites，petrography and broad elemental variations are also outlined．SiO_2 concentrations vary from ～55 wt．% in the mudrocks to over 85% in the sandstones，due to sorting fractionation．Most elements are positively correlated with Al_2O_3，indicative of residence in the clay fractionation．A small group of elements（Na_2O，CaO，Ba，Sr）tend to decrease with increasing Al_2O_3，reflecting partial residence in feldspar and diagenetic enrichment in sandstones．Zr shows no trend，typical of zircon control．Scatter to high values for several other elements（Th，Ce，Ni，Cr，and Y）may also be influenced by heavy mineral concentration．More detailed interpretation of the data will be published elsewhere．