We present geochemical and isotope results (Sr, Nd, Pb) on submarine basalts dredged from the southeastern margin of the South Korea Plateau. The present data are the first geochemical result obtained on submarine basaltic lavas recovered from the Korea Plateau, which is considered to be one of rifted remnants of continent in the East Sea (Sea of Japan) and partially segmented from the Korean Peninsula. The South Korea Plateau basalts (SKPB) show alkali affinities and are characterized by Ocean Island Basalts (OIB)-like trace element compositions relatively enriched in Ba, Nb and Pb. They display relatively flatter [(Ce/Yb)n = 4.49~5.46] and less fractionated HREE [(Dy/Yb)n = 1.11~1.29] patterns compared to average OIB, implying that the SKPB were derived from a relatively shallower mantle depth with a larger degree of partial melting. The Sr, Nd and Pb isotopic compositions of the SKPB display a range of values for 87Sr/86Sr (0.70378 to 0.70409), 143Nd/144Nd (0512846 to 0.512860) and 206Pb/204Pb (17.88-18.44). They show a considerably high range of 207Pb/204Pb (15.48-15.62) and 208Pb/204Pb (37.86-38.46) values, indicating the involvement of a DUPAL-like MORB source. According to our two-stage magma mixing model, the isotopic compositions of SKPB can be explained by magma source mixing by the addition of an EMII-like mantle component (up to 2%) to the DUPAL-like MORB source embedded with endogenous EMI-like material (about 2%).
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ACKNOWLEDGMENTS: We would like to thank H.M. Lee and K.J. Kim for their assistance with analytical work. We also would like to thank Dr. G. Lugmair, Scripps Institute of Oceanography, UCSD, for sending us aliquots of La Jolla standard solution. The manuscript was greatly improved by constructive comments and reviews by K.H. Park and an anonymous reviewer. This work was supported by KOPRI (PM10070) and KORDI (PM55893) projects.
All Science Journal Classification (ASJC) codes
- Environmental Science(all)
- Earth and Planetary Sciences(all)