• The Journal of the Petrological Society of Korea
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• v.14 no.2 s.40
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• pp.108-115
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• 2005

Gyeonggi metamorphic complex in the Gwangju area include banded biotite gneiss and quartzofeldspathic gneiss. Detailed structural analysis suggests that structural elements in the study area were formed by at least five phase of deformations. Penetrative compositional foliations(S1) formed in the banded gneiss during the first metamorphism and deformation (D1). After intrusion of plutonic rocks, the second deformation (D2) produced S2 foliations in the banded gneiss and quartzofeldspathic gneiss during the second metamorphism. D3 structures are represented by isoclinal folds (F3) whose axial surfaces are parallel to S3 foliations. The N-S oriented shortening (D4) was accommodated by closed upright F4 fold with about 100m of axial surface separation. F4 fold is refolded by regional F5 folding resulting in different orientation and fold style of F4 fold according to the position of F5 fold. The F4 fold with tight interlimb angle is subparallel to the axial surface (north-south) of F5 fold in the core of the F5 fold. In contrast the F4 fold trends northeast in the western limb and northwest in the eastern limb of F5 fold. The interlimb angle is larger in the limbs than that in the core of F5 fold. The trace of foliations is constrained by mainly F4 and F5 folds. Joint fanning around fold is developed in the limbs of F5 fold and bc joints are dominant in the hinge area of F5 fold. A strike-slip fault had developed in tile central part of the study area after F5 folding. The orientation of joint and foliation is rotated anticlockwise about $15^{\circ}$ by the landslide occurred during the Quaternary.

• The Journal of the Petrological Society of Korea
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• v.26 no.3
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• pp.201-219
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• 2017

The Jinan Basin which includes Maisan locates in the central part of the northern boundary of the Yeongnam Massif. The basement rocks of the Jinan Basin and surrounding area are Precambrian gneiss and Mesozoic granite which were exposed on the surface before Cretaceous. The Jinan Basin, one of the Cretaceous pull-apart basins in South Korea, formed along the Yongdong-Gwangju fault system. Maisan is composed of conglomerate deposited in the eastern slope of the Jinan Basin showing the shape of horse ears and the unusual topography where many tafonies were developed. The strike slip fault that caused the Jinan Basin was connected to the deep depth so that the magma formed at 200 km depth could have extruded on the surface causing active volcanic activity in and around the Jinan basin. As a result, Cheonbansan composed of pyroclastic rocks, Gubongsan consisting of volcanic neck and WoonilamBanilam formed by the lava flow, appear around Maisan forming a specific terrain. After the formation of the Jinan Basin and surrounding volcanic rocks, they uplifted to form mountains including Masian; the uplifting time may be ca. 69-38 Ma. At this time, the Noryeong mountain range may be formed in the regions which extended from Chugaryeong through Muju and Jinan to Hampyeong dividing the Geumgang and Seomjingang water systems. Due to the ecological barrier, the Noryeong mountain range, Coreoleuciscus splendidus living in the Geumgang water systems was differentiated from that in the Soemjingang water system. In addition, the Geumgang and Mangyeong-Dongjingang water systems were separated by the Unjangsan, which developed in the NNW direction. As a result, diverse ecosystem have been established in and around Maisan and at the same time, diverse cultural and historical resources related to Maisan's unique petrological features, were also established. Therefore, Maisan and surrounding area can be regarded as a place where a geotourism can be successfully established by combining the ecological, cultural and historical resources with a geological heritage. Therefore Maisan and surrounding areas have a high possibility to be a National Geopark and UNESCO Global Geopark.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.717-731
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• 2021

We analyzed the characteristics of the habitat environment for the Seonam study area in Ulsan, the southern shore of the East Sea using bathymetry and seafloor environment data. The depth of the study area ranges from about 0 m to 23 m. In the west of the study area, the water depth is shallow with a gentle slope, and the water depth becomes deeper with a steep slope in the east. Due to the right-lateral strike-slip faults located in the continental margin of the East Sea, the fracture surfaces of the seabed rocks are mainly in the N-S direction, which is similar to the direction of the strike faults. Three seafloor types (conglomeratic-grained sandy, coasre-graiend sandy, fine-grained sandy) and rocky bottom area have been classified according to the analyses of the bathymerty, seafloor image, and surface sediment data. The rocky bottom areas are mainly distributed around Seaoam and in the northern and southern coastal area. But the intermediate zone between Seonam and coastal area has no rocky bottom. This intermediate area is expected to have active sedimentation as seawater way. The sandy sediments are widely distributed throughout the study area. Underwater images and UAV images show that Cnidarians, Brachiopods, Mollusks are mostly dominant in the shallow habitat and various Nacellidae, Mytilidae live on the intertidal zone around Seonam. Annelida and Arthropod are dominant in the sandy sediments. The distribution of marine organism in the study area might be greatly influenced by the seafloor type, the composition and particle size distribution of the seafloor sediments. The analysis of habitat environment mapping with bathymetry, seafloor data and underwater images is supposed to contribute to the study of the structure and function of marine ecosystem.