• The Korean Journal of Petroleum Geology
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• v.4 no.1_2 s.5
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• pp.20-26
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• 1996

In order to uncover the subsurface geological structure in the southwestern rim of the Ogcheon Fold Belt including the Cretaceous Neungju Sedimentary Basin, we analysed and interpreted the aeromagnetic anomalies over the region. The study area belongs to Muan-gun, Yeongam-gun, Gangjin-gun, Jangheung-gun, and eastem Haenam-gun. From the qualitative analysis and quantitative modeling of the reduced-to-the-pole magnetic anomalies, following things are revealed or suggested; Even though the porphyry of higher susceptibility is not crop out in the Donggang Myeon in the northwestern part of the study area, it is supposed to have intruded the Precambrian gneiss and the Cretaceous Bulgugsa granite of lower susceptibility. Two-dimemsional modeling of profile data across the sedimentary basin of Neungiu Group reveals that the northern part of the basin is deeper than the southern part, and that the maximum depth of the basin is supposed to be $3\cal{km}$ below the surface. The western flank of the basin bottom is steeper than the eastern flank. The high susceptibility value of the Neungju Group sedimentary rocks indicates that the rocks comprises large amount of volcanic materials. This fact implies that it is hard to expect hydrocarbon reservoir in the sedimentary rocks of the Neungiu Basin.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.104-105
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• 2010

울산 퇴적 분지에 분포하는 신현층의 이암층 노두에서 이매패에 속하는 Anadara 를 비롯한 여러 종류의 연체동물 화석을 채집하였다. Anadara 화석은 해성 기원의 연체동물로 Vicarya japonica Yabe and Hatai와 함께 소위 Vicarya-Anadara 군집에 속한다. 이 군집은 우리나라의 제3기 생층서를 이해하는데 가장 중요한 정보를 제공한다. 여기에서는 Andara 화석의 형태적 특징과 내부 구조를 고찰하고, 현생종과 비교하였다. 신현층에서 산출된 Anadara 화석은 1속 2종으로 구성된다. 각의 형태적 특징은 각의 외형이 삼각형에 가깝고, 표면에 25~30개의 방사륵이 발달해 있으며 인대면은 삼각형 모형으로, 교치선은 직선이다. 각의 내부 구조를 박편상에서 관찰한 결과, 4개의 층으로 구성되어 있다. Anadara 화석과 현생종 Scapharca subcrenata 을 비교한 결과, 각의 외형은 조금 다르나 내부구조는 서로 거의 유사하다. A. (H.) kakehataensis의 내부 구조는 최외층, 외층, 광휘층, 내층으로 구성되어 있다. 외층은 교차판 구조(crossed- lamellar structure)로 되어 있다. 또한 성장선이 발달되어 있으며, 복연부에 불규칙한 균열이 부분적으로 나타난다. 이는 외부로 노출되어 건조되고 다시 물기를 머금은 상태가 반복되어 수축 팽창에 의한 것이라고 생각되며, 별개의 층은 아니다. 내층은 엽상구조(foliated structure)가 관찰된다. 외층과 내층 사이에 아라고나이트로 구성된 광휘층이 나타나며, 능주 구조(prismatic structure)를 보이는 얇은 층이다. 최외층이 나타난다. A. (H.) daitokudoensis의 내부 구조는 A. (H.) kakehataensis와 서로 거의 유사하고, 내층, 외층, 광휘층 및 최외층의 4개의 층으로 구성된다. 엽상 구조인 내층, 교차판 구조인 외층, 능주 구조인 광휘층 및 최외층은 유기질층으로 되어있다.

• The Journal of the Petrological Society of Korea
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• v.23 no.4
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• pp.325-336
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• 2014

Even though Mesozoic Mudeungsan tuff, located within Neungju Basin, has been named several rock names, it should be named as Mudeungsan tuff due to several evidences, such as fiamme, welded texture and rock fragments in the Mudeungsan tuff. Volcanic eruption boundary between the Cheonwangbong and Anyangsan areas is not clear, but petrochemical and mineral chemical evidences with different ages indicate clear petrological boundary between Cheonwangbong and Anyangsan. The Mudeungsan tuffs from Cheonwangbong and Anyangsan is welded crystal tuff with dacitic composition and were generated from cogenetic calc-alkaline magma in the volcanic arc environment. Geochemical events indicate that magma beneath Cheonwangbong was seems to have been evolved from the magma beneath Anyangsan due to fractional crystallization dominated by plagioclase.

• Journal of the Korean earth science society
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• v.21 no.6
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• pp.683-694
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• 2000

Abstrace: The palaeodepositional environment and age of the Cretaceous Hampyeong Basin (southwestern Korea) are reassessed based on new geochemical, lithological, sedimentological, and palaeobotanical data. Results indicate that the Hampyeong Basin was a tectonically active basin comprising predominantly fluvial and lacustrine sediments. Four distinctive facies types have been identified (acidic tuff, black shales/sandstones, red beds, intermediate tuff with tuffaceous conglomerate) and these reflect periods of significant environmental change within the basin and its neighbouring terrains. Volcanism driven by tectonic events provides a source for much of the sediment. The sedimentary sequences compare well with those in the neighbouring Haenam Basin. Sediments of volcanic origin are similar to those of the Neungju Formation of the Yuchon Group. The widespread occurrence of black shales is indicative of extended periods of deposition under anoxic conditions. Measurements of total organic carbon show that the values for the black shales (0.81% to 1.75%) are the average for petroleum source shales. Fossil plants occurred in the black shales and sandstones. The occurrence of platanoid leaves places these sediments in Oishi's angiosperm series, which is consistent with an Aptian/Albian or younger age.