Records of palaeo-sea level and eruption duration in a coastal tuff ring, Jeju Island, Korea

Terra Nova ◽  
2016 ◽  
Vol 29 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Woo Seok Yoon ◽  
Seok Hoon Yoon ◽  
Chanwoo Sohn ◽  
Young Kwan Sohn
2021 ◽  
pp. SP520-2021-52
Author(s):  
Young Kwan Sohn ◽  
Chanwoo Sohn ◽  
Woo Seok Yoon ◽  
Jong Ok Jeong ◽  
Seok-Hoon Yoon ◽  
...  

AbstractThe Holocene tuff ring of Songaksan, Jeju Island, Korea, is intercalated with wave-worked deposits at the base and in the middle parts of the tuff sequence, which are interpreted to have resulted from fair-weather wave action at the beginning of the eruption and storm wave action during a storm surge event in the middle of the eruption, respectively. The tuff ring is overlain by another marine volcaniclastic formation, suggesting erosion and reworking by marine processes because of post-eruption changes of the sea level. Dramatic changes of the chemistry, accidental componentry, and ash-accretion texture of the pyroclasts are also observed between the tuff beds deposited before and after the storm invasion. The ascent of a new magma batch, related to the chemical change, could not be linked with either the Earth and ocean tides or the meteorological event. However, the changes of the pyroclasts texture suggest a sudden change of the diatreme fill from water-undersaturated to supersaturated because of an increased supply of external water into the diatreme. Heavy rainfall associated with the storm is inferred to have changed the water saturation in the diatreme. Songaksan demonstrates that there was intimate interaction between the volcano and the environment.


Author(s):  
Clyde A. Leys

ABSTRACTThe Recent Saefell tuff-ring on Heimaey, Iceland was formed by surtseyan activity in shallow seawater. The tuff-ring has a basal diameter of about 3 km, a maximum rim height of 188 m above sea-level and a crater diameter of 1300 m. Three tuff-units are recognised, separated by unconformities on and inside the crater rim due to syndepositional slumping. The crater contains a nested rim which was constructed above slumped crater tuffs. Directional data indicate strongly directed blasts to the SW at a late stage in the activity.Throughout the volcanic activity, base-surges formed antidunes, U-shaped channels, vesiculated tuffs, small ripples and plastering structures. One antidune reflects a decrease in surge flow power during deposition and subsequent slumping due to base-surge drag and instabilities developed during growth. On the basis of field characteristics, the structures are divided into those deposited by hot, dry, fast-moving surges and those by cooler, wet, slow-moving surges. Base-surges are compared with turbidity currents and deposition of distinct structures by the head, body and tail regions is interpreted.


1985 ◽  
Vol 122 (6) ◽  
pp. 649-661 ◽  
Author(s):  
James G. Moore

AbstractGlassy basalt tuff was the primary material cored in 1979 from a 181 m deep drill hole on the east tuff ring of Surtsey volcano. Despite the fact that the hole extends 122 m below sea level all the core is similar to the exposed tephra composing the two tuff rings of the island. The tuff includes abundant accretionary lapilli and tuff vesicles, indicating that it was all deposited subaerially. During the growth of the tuff rings, repeated hydromagmatic explosion cycles began with a series of intermittent tephra-finger explosions leading up to continuous uprush explosions which lasted for several minutes to several hours. This nozzle-like continuous activity produced eruption columns 100–250 m in diameter and 500–2000 m in height which probably quarried several hundred metres below the ground surface. The continuous-uprush explosion type provides a reasonable mechanism to excavate a diatreme from the top down. During construction of the tuff rings, concentric faults repeatedly downdropped a funnel-like structure (400–800 m in diameter) several hundred metres, thus accounting for the presence of subaerially deposited tephra in the drill core far beneath sea level. Ring dykes later intruded upward along these faults and fed small lava flows. Heat in the surface tephra probably originated primarily from these shallow intrusions.


2003 ◽  
Vol 119 (1-4) ◽  
pp. 1-20 ◽  
Author(s):  
Y.K Sohn ◽  
J.B Park ◽  
B.K Khim ◽  
K.H Park ◽  
G.W Koh
Keyword(s):  

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Yongsik Hong ◽  
Euijoo Kim ◽  
Eungpill Lee ◽  
Seungyeon Lee ◽  
Kyutae Cho ◽  
...  

Abstract Background To investigate the trends of succession occurring at the Pinus thunbergii forests on the lowlands of Jeju Island, we quantified the species compositions and the importance values by vegetation layers of Braun-Blanquet method on the Pinus thunbergii forests. We used multivariate analysis technique to know the correlations between the vegetation group types and the location environmental factors; we used the location environment factors such as altitudes above sea level, tidal winds (distance from the coast), annual average temperatures, and forest gaps to know the vegetation distribution patterns. Results According to the results on the lowland of Jeju Island, the understory vegetation of the lowland Pinus thunbergii forests was dominated by tall evergreen broad-leaved trees such as Machilus thunbergii, Neolitsea sericea, and Cinnamomum japonicum showing a vegetation group structure of the mid-succession, and the distribution patterns of vegetation were determined by the altitudes above sea level, the tidal winds on the distance from the coast, the annual average temperatures, and the forest gaps. We could discriminate the secondary succession characteristics of the Pinus thunbergii forests on the lowland and highland of Jeju Island of South Korea. Conclusions In the lowland of Jeju Island, the secondary succession will progress to the form of Pinus thunbergii (early successional species)→Machilus thunbergii, Litsea japonica (mid-successional species)→Machilus thunbergii (late-successional species) sequence in the temperate areas with strong tidal winds. In the highland of Jeju Island, the succession will progress to the form of Pinus thunbergii (early successional species)→Neolitsea sericea, Eurya japonica (mid-successional species)→Castanopsis sieboldii (late-successional species) sequence in the areas where tidal winds are weak and temperatures are relatively low. However, local differences between lowland and highland of Jeju Island will be caused by the micro-environmental factors resulting from the topographic differences and the supply of tree seeds. From the characteristics of succession study, we could properly predict and manage the Pinus thunbergii forest ecosystem on lowland and highland of Jeju Island.


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