• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.148-156
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• 2001

We report $^{230}Th/^{234}U$ disequilibrium ages of fracture-filling carbonate veins from the Ipsil and Janghangri fault zones, Gyeongju, Korea by multiple collector inductively coupled plasma mass spectrometry. The U and Th fraction was extracted from totally dissolved samples by rapid and convenient coprecipitation and ion exchange chemistry. The recovery was around 80% for Th and 70% for U. The $^{234}U/^{238}U,\;^{230}Th/^{232}Th$ ratios were analysed for this preconcentrated fraction and the U/Th ratio was directly analysed for untreated sample solution. The $^{234}U-^{230}Th$ system is in secular equilibrium for the Ipsil carbonate samples, supporting previously reported ESR ages. The detrital-corrected $^{230}Th/^{234}U$ age of the Janghangri carbonate samples is $48\pm$41 ka, which constrains the minimum age of the fracture zone.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.229-237
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• 2014

The Lu-Hf isotope system, coupled with the advent of multiple collector inductively coupled plasma source mass spectrometry, is now widely utilized as a tracer for geological processes. The paper presents a comprehensive review on the principles of the Lu-Hf isotopes, and its current and potential applications to both geochronology and petrogenesis. Finally, based on the Lu-Hf isotopic data from Korean mafic and ultramafic rocks, its has been discussed evolution of the mantle beneath the Korean Peninsula.