• Title/Summary/Keyword: 구암

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SHRIMP U-Pb Dating and Volcanic Processes of the Volcanic Rocks in the Guamsan Caldera, Cheongsong, Korea (청송 구암산 칼데라 화산암류의 SHRIMP U-Pb 연령측정과 화산과정)

  • Hwang, Sang Koo;Jo, In Hwa;Yi, Keewook
    • Economic and Environmental Geology
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    • v.50 no.6
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    • pp.467-476
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    • 2017

  • Volcanic rocks related to the Guamsan cadera, which find in the southeastern Cheongsong, are divided into Volcanic breccia, Guamsan Tuff and Post-collapse intrusions. We determined their eruption, intrusion and caldera-forming timings based on SHRIMP U-Pb zircon dating. The dating results yield earlier eruption age of $63.77{\pm}0.94Ma$ from the lower ash-flow tuff and an later eruption age of $60.1{\pm}1.8Ma$ from the upper ash-flow tuff of the Guamsam Tuff, and intrusion age of $60.65{\pm}0.95Ma$ from the rhyolite ring dyke of the Post-collapse intrusions. The age data suggest that the Guamsan caldera is formed in 60.65~60.1 Ma between eruption of the upper ash-flow tuff and intrusion of the rhyolite ring dyke. The Guamsan cadera exhibits the volcanic processes of a perfect igneous cycle passing from ash-flow eruptions through caldera collapse to ring intrusions during 63.77~60.1 Ma.

  • https://doi.org/10.9719/EEG.2017.50.6.467 인용 PDF KSCI

A Study on Guam LeeJung's Publication of Books (구암(龜巖) 이정(李楨)의 도서간행(圖書刊行)에 관한 연구(硏究))

  • Ahn, Hyeon-Ju
    • Journal of Korean Library and Information Science Society
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    • v.42 no.1
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    • pp.339-367
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    • 2011

  • This study presents the publication of books by Guam LeeJung who is a Confucian scholar and a public official in 16th century. He played important roles in editing, correcting, and publishing of 20 books, of which 3 books were edited and published by him; 4 books corrected and published; and 12 books published. His works were helped by contemporary scholars and officials such as LeeWhang, NamgungChim, KimChungkap, and KimHong. All the books are related with Confucian studies except one book, and they were published in the period from 1554 and 1566 when he serve as the head of counties, Sungju(성주), Kyungju(경주), and Sunchun(순천). The publication record of one book is unclear, and all others were printed with woodblocks.

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Eruptive Phases and Volcanic Processes of the Guamsan Caldera, Southeastern Cheongsong, Korea (구암산 칼데라의 분출상과 화산과정)

  • ;;;A.J. Reedman
    • The Journal of the Petrological Society of Korea
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    • v.11 no.2
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    • pp.74-89
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    • 2002

  • Rock units, relating with the Guamsan caldera, are composed of Guamsan Tuff and rhyolitic intrusions. The Guamsan Tuff consists almost entirely of ash-flow tuffs with some volcanic breccias and fallout tuffs. The volcanic breccia comprises block and ash-flow breccias of near-vent facies and caldera-collapse breccia near the ring fracture. The lower ash-flow tuffs are of an expanded pyroclastic flow phase from the pyroclastic flow-forming eruption with an ash-cloud fall phase of the fallout tuffs on the flow units, but the upper ones are of a non-expanded ash-flow phase from the boiling-over eruption. The rhyolitic intrusions are divided into intracaldera intrusions and ring dikes that are subdivided into inner, intermediate and outer dikes. We compile the volcanic processes along a single cycle of cadela development from the eruptive phases in the Guamsan area. The explosive eruptions began with block and ash-flow phases from collapse of glowing lava dome caused by Pelean eruption, progressed through expanded pyroclastic flow phases and ash-cloud fallout phases during high column collapse of pyroclastic flow-forming eruption from a single central vent. This was followed by non-expanded ash-flow phases due to boiling-over eruption from multiple ring fissure vents. The caldera collapse induced the translation into ring-fissure vents from a single central vent in the earlier eruption. After the boiling-over eruption, there followed an effusive phase in which rhyolitic magma was injected and erupted to be progressively emplaced as small plugs/dikes and ring dikes with many lava domes on the surface. Finally rhyodacitic magma was on emplaced as a series of dikes along the junction of both outer and intermediate dikes on the southwestern side of the caldela.

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