Petrology and Geochemistry of the Cretaceous Palgongsan Granite, Southern Korea

백악기(白堊紀) 팔공산(八公山) 화강암(花崗岩)의 암석학적(岩石學的) 및 지구화학적(地球化學的) 연구(硏究)

  • Hong, Young Kook (GeochemicaI Exploration Division, Korea Institute of Energy and Resources (KIER))
  • Published : 1983.06.30

Abstract

The Cretaceous Palgongsan granite is a typical, calc-alkaline, subsolvus monzogranite and shows characteristics of "I-type" granite by mineralogy and chemical composition. Many of the major and trace element characteristics of the Palgongsan granite are consistent with a relationship by fractional crystallisation to form a chemically zoned pattern. The granite show light REE enrichment with (Ce/Yb)N ratios of 5.78-9.50. All the REE patterns show Eu negative anomalies which become larger from the margin ($Eu/Eu^*=0.75$) to the core ($Eu/Eu^*=0.24$) of the pluton, mainly due to feldspar fractionation. Mineral geochemistry (alkali-feldspar, plagioclase & biotite) studies also show the zonal structure of the Palgongsan granite. The two-feldspar geothermometer shows that the temperature difference between the margin and the core part of the pluton is about $200^{\circ}C$ at various assumed pressures.

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