Regional variations in the lead isotopic composition of galena from southern Korea with implications for the discrimination of lead provenance

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• 作者：Youn-Joong Jeong^a ; Chang-sik Cheong^a ; ^{ccs@kbsi.re.kr} ; Dongbok Shin^b ; Kwang-Sik Lee^a ; Hui Je Jo^a ; Mukesh Kumar Gautam^a ; Insung Lee^c
• 关键词：Galena ; Ore ; Lead isotope ; Korea ; Provenance
• 刊名：Journal of Asian Earth Sciences
• 出版年：2012
• 出版时间：15 November, 2012
• 年：2012
• 卷：61
• 期：Complete
• 页码：116-127
• 全文大小：1205 K

文摘

This study presents a comprehensive database (n = 215) of lead isotopes in galena from the southern Korean peninsula using new and published data. Of the 69 metal mines examined, predominantly skarn- and hydrothermal-type Pb-Zn-Au-Ag-Cu deposits were observed and were associated with Mesozoic magmatic activities. Galena samples from each geotectonic unit showed discrete lead isotopic signatures. The Gyeongsang basin samples were characteristically unradiogenic and had restricted variations in lead isotopic composition (²⁰⁶Pb/²⁰⁴Pb = 18.16-18.59, ²⁰⁷Pb/²⁰⁴Pb = 15.48-15.64, ²⁰⁸Pb/²⁰⁴Pb = 37.87-38.77). Their ²⁰⁸Pb/²⁰⁴Pb range indicated an involvement of source materials less thorogenic than the associated granites. The galena samples from Cambro-Ordovician carbonate rocks of the northeastern Yeongnam massif and eastern Taebaeksan basin had the most radiogenic ²⁰⁶Pb/²⁰⁴Pb (19.28 ¡À 0.14) and ²⁰⁷Pb/²⁰⁴Pb (15.833 ¡À 0.027) ratios. Their lead isotopic trend indicated a combined contribution of ore lead from granitic magmas, Precambrian basements, and overlain host rocks. Less radiogenic galena samples from the middle to southwestern parts of the Yeongnam massif and Okcheon belt showed limited lead isotopic variations (²⁰⁶Pb/²⁰⁴Pb = 18.332 ¡À 0.065, ²⁰⁷Pb/²⁰⁴Pb = 15.693 ¡À 0.012, ²⁰⁸Pb/²⁰⁴Pb = 38.93 ¡À 0.07 on average), probably resulted from mixing with a common crustal basement. The differences in lead isotopes between the radiogenic and unradiogenic groups from the Yeongnam massif and Okcheon belt may reflect the spatial dissimilarity of involved crustal rocks. The old crust appears to have significantly contributed ore lead to galenas from the western Gyeonggi massif, but the geochronological meaning of their steep ²⁰⁷Pb/²⁰⁴Pb-²⁰⁶Pb/²⁰⁴Pb trend is not clear. The comprehensive database constructed by the present study suggests that lead province in the southern Korean peninsula may be subdivided into four discrete zones. Linear discriminant analysis showed that more than 90 % of the compiled data were correctly reclassified within their a priori zones. Such discrimination may be useful for a wide range of applications, including mineral exploration, archaeological correlation, and environmental characterization.