A Petrological Study of the Mudeungsan Tuff Focused on Cheonwangbong and Anyangsan

Jung, Woochul; Kil, Youngwoo; Huh, Min

doi:10.7854/jpsk.2014.23.4.325

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…Anyang due to fractional crystallization dominated by plagioclase (Jung et al, 2014). In the Late Cretaceous, micrographic granite and alkali feldspar granite were intruded into the Mudeungsan Tuff.…”

Section: Geologic Setting Geological Backgroundmentioning

confidence: 99%

Genesis of the columnar joints from welded tuff in Mount Mudeung National Geopark, Republic of Korea

Lim

Huh

et al. 2015

Earth Planet Sp

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Mount Mudeung National Geopark (MMNG), Gwangju, Republic of Korea (1187 masl), is known for its huge, broad occurrences of columnar jointed colonnades in the Cretaceous Mudeungsan Tuff. To understand the genesis of columnar joints infilling a volcanic vent, integrated geochemical and geophysical studies were conducted. Most colonnades in the Geopark are located in regions higher than 700 masl and show elevation-dependent variations in the mean face width of the columns. These mean widths are approximately 1.7, 1.3, 2.9, and 1.2 m for the summit (>1100 masl), upper (950-1100 masl), lower (850-950 masl), and lowest (700-850 masl) colonnades, respectively. This variation implies that columnar jointing resulted from discontinuous tuff depositions on relatively planar ground, which is associated with caldera structures and landslides from the emptied caldera rim. Geochemical analyses of major, minor, and trace elements show that the andesitic-dacitic Mudeungsan Tuff resulted from the arc magmatism associated with subduction of the Izanagi Plate and involved crustal components. Few geochemical variations of the Mudeungsan Tuff indicate that tuff originated from a single magma chamber. U-Pb age dating indicates that the Mudeungsan Tuff was deposited at~85 Ma except for the Chotdae-bong colonnades, which were dated to~87 Ma. However, a scaling analysis of the elevation-dependent variations of face widths and simplified numerical model calculations indicate that the variation in face widths with elevation indicates the sequential emplacement, cooling, and compaction of separate welded tuffs. Thus, the welded tuffs of MMNG can be thought to be formed by three discontinuous large explosive eruptions with periods of repose after each eruption. These tuffs include 1) the highest-elevation columnar joints of colonnades in the summit area (>1100 m), corresponding to the lower colonnades of the third tuff; 2) the intermediate-elevation columnar joints of colonnades, corresponding to the upper (950-1100 m) and lower (850-950 m) colonnades of the second tuff; and 3) the lowest columnar joints of colonnades (700-850 masl), corresponding to the upper colonnades of the first tuff.

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Section: Geologic Setting Geological Backgroundmentioning

confidence: 99%

Genesis of the columnar joints from welded tuff in Mount Mudeung National Geopark, Republic of Korea

Lim

Huh

et al. 2015

Earth Planet Sp

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“…In contrast, the zircon age data indicate that considerable amounts of sediments were transported from the southern Cretaceous volcaniclastic terrane to the central playa lake. Cretaceous volcanic activity in the Neungju Basin areas was generated from calk-alkaline magma, resulting in the deposition of felsic pyroclastic, andesitic to dacitic rocks, and rhyolite [58][59][60]. Although various types of volcanic rocks were formed, they are characterized by abundant plagioclase content.…”

Section: Contrasting Geochemical Signatures Of Tectonic Settings and Weathering Intensities In A Nonmarine Basinmentioning

confidence: 99%

Relationships between Alluvial Facies/Depositional Environments, Detrital Zircon U-Pb Geochronology, and Bulk-Rock Geochemistry in the Cretaceous Neungju Basin (Southwest Korea)

et al. 2020

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Zircon U-Pb geochronology and bulk-rock geochemistry analyses were carried out to investigate their relationship with depositional environments of the non-marine Neungju Basin sediments in South Korea. The Neungju Basin was formed in an active continental margin setting during the Late Cretaceous with associated volcanism. Detrital zircon age distributions of the Neungju Basin reveal that the source rocks surrounding the basin supplied sediments into the basin from all directions, making different zircon age populations according to the depositional environments. Mudstone geochemistry with support of detrital zircon U-Pb age data reveals how the heterogeneity affects the geochemical characteristics of tectonic setting and weathering intensity. The sediments in the proximal (alluvial fan to sandflat) and distal (playa lake) environments differ compositionally because sediment mixing occurred exclusively in the distal environment. The proximal deposits show a passive margin signature, reflecting their derivation from the adjacent metamorphic and granitic basement rocks. The distal deposits properly indicate an active continental margin setting due to the additional supply of reworked volcaniclastic sediments. The proximal deposits indicate a minor degree of chemical weathering corresponding to fossil and sedimentological records of the basin, whereas the distal deposits show lower weathering intensity by reworking of unaltered volcaniclastic detritus from unstable volcanic and volcaniclastic terranes. Overall, this study highlights that compositional data obtained from a specific location and depositional environments may not describe the overall characteristic of the basin.

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“…Kim et al (2002) reported a welded structure and proposed the Mudeungsan columnar joint to be welded tuff. In addition, Jung et al (2014) suggested that Cheonwangbong and Anyangsan in the Mudeungsan region were formed from calc-alkaline magma in the continental subduction zone [4]. Lim et al (2015) reported formation ages in the range from 84.73 to 87.72 Ma through zircon U-Pb dating of Mudeungsan tuff samples [5].…”

Section: Introductionmentioning

confidence: 99%

Mineralogy of the Mudeungsan Tuff (Republic of Korea) Using Synchrotron X-ray Powder Diffraction and Rietveld Quantitative Analysis

Seoung

Kim

et al. 2021

Applied Sciences

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Mudeungsan (Mount Mudeung) is an extinct volcano located in the southwestern part of South Korea that was formed in the Late Cretaceous period. This mountain, 1187 m above sea level, is adjacent to Gwangju Metropolitan City, which has a large population (about 1.4 million) and volcanic rocks, including columnar joints, which form various types of outcrops. Although this mountain was listed as a national geopark in 2014 and a UNESCO Global Geopark in 2018, much basic research has yet to be carried out. In particular, there are no mineralogical studies of volcanic rock samples despite the well-preserved variety of volcanic rocks. For this study, X-ray diffraction analysis was conducted using rock samples from Mudeungsan columnar joints known as tuff. We report that the rocks are mostly dacite, mainly composed of quartz, plagioclase, and sanidine through Rietveld quantitative analysis. In particular, α-cristobalite, a crystalline polymorph of silica, appears in the columnar joint rocks, indicating that Mudeungsan experienced an explosive eruption during the formation of the mountain.

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A Petrological Study of the Mudeungsan Tuff Focused on Cheonwangbong and Anyangsan

Cited by 5 publications

References 14 publications

Genesis of the columnar joints from welded tuff in Mount Mudeung National Geopark, Republic of Korea

Genesis of the columnar joints from welded tuff in Mount Mudeung National Geopark, Republic of Korea

Relationships between Alluvial Facies/Depositional Environments, Detrital Zircon U-Pb Geochronology, and Bulk-Rock Geochemistry in the Cretaceous Neungju Basin (Southwest Korea)

Mineralogy of the Mudeungsan Tuff (Republic of Korea) Using Synchrotron X-ray Powder Diffraction and Rietveld Quantitative Analysis

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