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Sr, Nd and Pb Isotopic Systematics of the Cenozoic Basalts of the Korean Peninsula and Their Implications for the Permo-Triassic Continental Collision Boundary |
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| Authors: | Kye-Hun Park Jun-Beom Park Chang-Sik Cheong Chang Whan Oh |
| Institution: | aDepartment of Environmental Geosciences, Pukyong National University, 599-1 Daeyeon-dong, Nam-gu, Busan 608-737, Korea bU.S. Army Corps of Engineers, Far East District, Seoul 100-195, Korea cGeochronology Team, Korea Basic Science Institute, Daejeon 305-333, Korea dDepartment of Earth and Environmental Sciences, Chonbuk National University, Jeonju 561-756, Korea |
| Abstract: | Sr, Nd and Pb isotopic compositions of the Cenozoic basalts were analyzed from Baengnyeongdo Island, Jeongok, Ganseong, and Jejudo Island of Korea. They reveal relatively enriched Sr and Nd isotopic compositions (87Sr/86Sr = 0.70330 0.70555, 143Nd/144Nd = 0.512980.51256) compared with MORB.207Pb/204Pb and 208Pb/204Pb values of all the analyzed Korean basalts lie above the Northern Hemisphere Reference Line (NHRL) defined by Hart (1984). Pb isotopic compositions of basalts from Jejudo Islands (206Pb/204Pb = 18.6119.12, 207Pb/204Pb = 15.5415.69, 208Pb/204Pb = 38.9839.72) are significantly more radiogenic than the rest (206Pb/204Pb = 17.7218.03, 207Pb/204Pb = 15.4415.58, 208Pb/204Pb = 37.7738.64). The Cenozoic Korean basalts thus can be divided into two groups based on their Sr, Nd and Pb isotopic compositions. The north group reveals mixing between DMM and EM1 while the south group displays DMM-EM2 mixing. Such a distribution is the same as Chinese Cenozoic basalts and it can be interpreted that the subcontinental lithospheric mantle under Korea represents simple lateral continuation of the South and North China Blocks. We suggest that Korean continental collision zone cross the Korean Peninsula through the region between the north and south basalt groups of Korea. |
| Keywords: | Cenozoic basalt subcontinental lithosphere continental collision enriched mantle component Korean peninsula |
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