• The Korean Journal of Quaternary Research
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• v.17 no.1
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• pp.27-37
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• 2003

The Neolithic relics containing sedimentary deposits have been found in the Moonamni coastal zone of the East Sea, Korea. The purpose of this research is to establish the late Quaternary stratigraphy of the coastal dune deposit and to elucidate its depositional environment of the Neolithic-site sediments on the basis of analytical properties of grain size population and mineralogy of the sediments. As a result, the vertical sections of the sediments from three trenches are characterized by three major stratigraphic depositional units of Unit 3, Unit 2 and Unit 1 in ascending order. Unit 3 and 2 can be further divided into tow sub-units. Unit 3 is composed of massive sands in the lower part and muddy sand in the upper part. It is considered that the Unit 3 is a typical dune deposit showing well-sorted sands. Unit 2 is characterized by the cross-bedding, and include archaeological remains such as pottery shards. This unit can be further divided into two sub-units of muddy sand in the lower part and sand in the upper part. Unit 1 occupies the top section and consists of modem dune sediment. The Neolithic cultural remains would be accumulated in the coastal dune area in relation to dynamic condition of beach system under the high stand of Holocene sea-level at about 7,800∼6,500 yr B.P. or so.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.17-27
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• 2012

Coastal dunes help stabilize the coastal landscape and protect the hinterland through dynamic interaction with sand beaches. Sometimes dune erosion occurs during the tropical cyclones, while dune recovery may naturally follow after the event. As the typhoon Kompasu passed through the Korean Peninsula early-September in 2010, it caused a rise in water in association with the storm, wave run-ups, and heavy rains in coastal areas. As the result, coastal dunes along the west coast of Korea were severely damaged during the storm. However, the degree and extent of erosion and recovery of dunes were found to be related with the condition of beach-dune systems including gradients of foreshore and front slope of the dune, sediment supply, vegetation, wind activity, and human interferences. Some dunes retreated landward more and more after the erosional event, while others recovered its original profile by aeolian transport processes mainly during the winter season. Vegetated dunes with pine trees were less recovered after the erosion than grass-covered dunes. In addition, dunes with artificial defense were more eroded and less recovered than those without hard constructions. According to the observation after the severe storm, it is likely that the sand transport process is critical to the dune recovery. Therefore, the interactions between beach and dune must be properly evaluated from a geomorphological perspective for the effective management of coastal dunes, including natural recovery after the erosion by storm events.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.115-115
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• 2001

경주시 양남면의 4기 단층으로 추정되는 수렴단층에 의해 절단되는 해안단구 퇴적층 풍화단면에서 저결정질 광물인 앨로패인 교결층을 기재하였다. 이들은 자갈퇴적층 내에 협재하는 수조의 모래층에 한정되어 형성되어 있으며, 3-17 cm 두께로 연장성이 매우 좋다. 편광현미경 관찰에 의하면 모래층에는 사장석편들이 다량 함유되어 있으며 앨로패인은 광학적 등방성의 치밀한 점토집합체들로서 사장석 입자를 선택적으로 교대하거나 자갈과 모래입자들을 피복하고 있다. 앨로패인은 광학적 이방성인 상하위층의 고령토질 점토피복물과 명확히 구분된다. 앨로패인의 전자현미분석에 의하면, Al/Si 원자비가 1.3-1.7 범위이고 평균값은 1.5이다. X선회절분석 결과 3.49$\AA$과 2.26$\AA$에서 두 개의 넓은 회절대가 관찰된다. 주사 및 투과전자현미경관찰에 의하면 앨로패인을 특정한 입자형태 없이 치밀한 겔상태를 이루고 있다. 열분석에 의하면 96$^{\circ}C$에서 큰 흡열피크와 992$^{\circ}C$에서 발열피크가 관찰되며, 총 45% 정도의 중량감소를 보인다. 사장석의 평균조성은 An$_{87}$이며, 사장석내 유리포유물의 전자현미분석결과는 화산암 화학분류도에서 현무암 영역에 도시된다. 이 지역의 기반암은 현무암질 라필리응회암이나 사장석편을 제외하고 벤토나이트화되어 있다. 따라서 해빈환경에서 사장석이 벤토나이트에서 분리되어 퇴적한 것으로 보인다. 앨로패인 교결층은 해수면 강하로 단구퇴적층이 지표로 노출된 후, Al의 함량이 높고 비교적 풍화에 약한 사장석이 선택적으로 풍화되어 생성되었다. 앨로패인으로 피복된 모래층 내의 자갈은 풍화반응이 지체되어 상하위층의 자갈과 비교하여 풍화도에 있어서 현저한 차이를 보인다.. 파이프 중심에서 외곽부로 갈수록 전기석의 함량은 줄어들고 있고 장석들이 알바이트ㆍ칼스베드 쌍정을 보이며, 흑운모가 각섬석보다는 우세하게 나타나고 있다. 전기석은 주상 결정, 자형 내지 반자형의 입자로 다색성을 보이며, 결정 중심에서 가장자리로 갈수록 파란색과 황갈색의 광학적 누대구조를 관찰할 수 있다. 일광광산에서 산출되는 전기석에 대한 현미경 관찰은 열수기원임을 지시하고 있다. 야외조사와 현미경 관찰의 예비조사에 의하면 일광광산의 전기석이 형성된 환경은 다른2가지 화학적인 저장소의 혼합 효과의 결과로 생성되어진 것으로 예상된다. 일광의 화강암류를 만든 마그마는 전기석을 형성할 만큼의 Fe-Mg성분이 충분하지 않았을 것이다. 화강암 내에 흑운모와 각섬석의 결정작용에 의해 마그마의 Fe-Mg성분이 고갈되어지고 이로 인해 그 함량이 감소하며 상대적으로 마그마 내에 남은 붕소(B$_2$O$_3$)는 열수로 용리되고 흑운모, 각섬석과 평형을 유지하며 열수에 남아있게 된다. 잔류용융체에 남은 붕소의 함량은 전기석을 만들기에 충분함에도 불구하고, Fe-Mg 함량이 부족하여 마그마 기원의 전기석 결정을 만들 수가 없다가 광맥이 형성된 시기에 또 다른 열수가 공급되면서 이전의 평형이 깨지고 기존의 흑운모와 같은 염기성 광물이 붕소(B)를 함유한 새로운 열수와 반응하여 전기석을 형성한 것으로 예상한다. 앞으로 전암과 광물에 대해 지화학적 연구를 통해 화강암류와 전기석과의 지화학적 연관성, 주성분 원소와 열수의 특성과의 상관관계, 전기석의 기원(마그마 기원인지 열수기원인지)이 보다 정확하게 파악될 것이다. 마그마 진화에 따른 전기석의 성분변화와 기원을 이용하여 일광광산의 동광화대를 형성한 마그마 계에서 열수계로 이어지는 지질학적 과정을 이해할 수 있을 것이며, 암석 성인론적 지시자로서

• Journal of The Geomorphological Association of Korea
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• v.17 no.2
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• pp.87-98
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• 2010

There have been growing concerns for the sea level rise due to global warming in recent years. Sea level rise is a serious problem to densely populated coastal areas, because it may affect the coastal landforms to be damaged. Especially coastal sand deposits like coastal dunes are more sensitive than the other coastal landforms. In this paper, Ground Penetrating Radar (GPR) and Optically Stimulated Luminescence (OSL) dating method were used to identify the Holocene geomorphic changes of coastal dune field in Shinduri located at the western coast. The main results in this study that are the dunefield in the study area may have begun to form at around 6.8 ka and it has grown seaward thereafter. Then, dunefield appears to have extensively developed since 3.7 ka. This result, together with previous works on the sea level and climatic changes in the western coast of Korea suggest that the dunefield has been affected by the sea level regression since the Holocene high stand in the Holocene at around 6 ka and climatic change from warm and humid to cold and dry conditions occurred at 4.5 ka.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.434-449
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• 2019

In this study, we develop a new cross-shore sediment module which takes the effect of infra-gravity waves of bound mode, and boundary layer streaming on the sediment transport into account besides the well-known asymmetry and under-tow. In doing so, the effect of individual random waves occurring during the unit observation period of 1 hr on sediment transport is also fully taken into account. To demonstrate how the individual random waves would affect the sediment transport, we numerically simulate the non-linear shoaling process of random wavers over the beach of uniform slope. Numerical results show that with the consistent frequency Boussinesq Eq. the application of which is lately extended to surf zone, we could simulate the saw-tooth profile observed without exception over the surf zone, infra-gravity waves of bound mode, and boundary-layer streaming accurately enough. It is also shown that when yearly highest random waves are modeled by the equivalent nonlinear uniform waves, the maximum cross-shore transport rate well exceeds the one where the randomness is fully taken into account as much as three times. Besides, in order to optimize the free parameter K involved in the long-shore sediment module, we carry out the numerical simulation to trace the yearly shoreline change of Mang-Bang beach from 2017.4.26 to 2018.4.20 as well, and proceeds to optimize the K by comparing the traced shoreline change with the measured one. Numerical results show that the optimized K for Mang-Bang beach would be 0.17. With K = 0.17, via yearly grand circulation process comprising severe erosion by consecutively occurring yearly highest waves at the end of October, and gradual recovery over the winter and spring by swell, the advance of shore-line at the northern and southern ends of Mang-Bang beach by 18 m, and the retreat of shore-line by 2.4 m at the middle of Mang-Bang beach can be successfully duplicated in the numerical simulation.