• Economic and Environmental Geology
• /
• v.18 no.3
• /
• pp.289-299
• /
• 1985

Sedimentary petrology and depositional environments of the Sindong Group, consisting of in ascending order the Nagdong, Hasandong and Jinju Formations, in the Euiseong Subbasin are studied. For these, the Sindong sequence over 1,000m thick is measured at the scale of 1:200 and 36 thin sections of sandstones of the Hasandong Formation are studied under the polarizing microscope. In addition, published paleontologic data are incorporated in the sedimentologic interpretation. Most of the sandstones are classified as arkose. They are moderately sorted, near symmetrical to fine skewed and mesokurtic. Relationship between the textural parameters suggests a fluviatile environment of the Hasandong Formation. The Sindong fauna and flora also indicate non-marine depositional environments. Sedimentologic data of the measured sections show that the Sindong Group is made up of from the bottom an alluvial fan (lower part of the Nagdong Formation), a fluvial plain (upper part of the Nagdong Formation and the Hasandong Formation) and a fluvial/lacustrine (the Jinju Formation) deposits.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.203-210
• /
• 2004

Consolidation properties were analysed by means of depositional environments. Depositional environments including geochemical properties, porewater chemistry, sediment structures, particle size distributions and carbon age dating were analysed using undisturbed samples retrieved successively from a boring hole in the study area. Laboratory oedometer tests and anisotropic consolidated triaxial tests(CKoUC) were performed to examine the overconsolidation phenomenons. Based on the carbon age dating results and profiles of geochemical properties, porewater chemistry, salinity and pH, it was founded that the upper silt/clay complex layer was deposited under marine condition while sand and clay layers were deposited under fluvial condition. Planar laminated structures of silts and clays were dominant in marine deposits. Although there was no clear evidences that geological erosion had been occurred in marine deposits, overconsolidation ratio obtained from oedometer tests were greater than unity. Stress paths of samples behaved similar to those of normally consolidated clays. Data plotted in stress state charts proposed by Burland(1990) and Chandler(2000) showed that the marine deposits were geologically normally consolidated. These apparent overconsolidations can be explained by the fabric and chemical bonding due to the difference of the rate of deposition.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.5
• /
• pp.49-58
• /
• 2004

Consolidation properties of Shihwa deposits were analysed by means of depositional environments. Depositional environments including particle size distributions, sediment structures, geochemical properties, porewater chemistries and carbon age dating were analysed using undisturbed samples retrieved successively from a boring hole in the study area. Laboratory oedometer tests and anisotropic consolidated triaxial tests (CKoUC) for undisturbed samples were performed to examine the overconsolidation phenomena. Based on the results of analysis of depositional environments, it was found that the upper silt/clay mixed layer was deposited under marine condition while underlying sand and clay layers were deposited under fluvial condition. Planar laminated structures of silts and clays were dominant in marine deposits. Although there was no clear evidences that geological erosion had occurred in marine deposits, overconsolidation ratios of the upper marine samples were greater than unity Stress Paths of the upper marine samples behaved similarly to those of normally consolidated clays. Data plotted in stress state charts showed that the marine deposits were normally consolidated in geological meaning. These apparent overconsolidation of the marine deposits can be explained by the structures i.e. chemical bonding due to the difference of the rate of deposition, not by geological erosions and ground water fluctuations.

• 한국해양학회지
• /
• v.21 no.1
• /
• pp.34-45
• /
• 1986

A Q-mode factor analysis for 115 surficial bottom sediments on the continental shelf off the southeast coast of Korean Peninsula(the Korea Strait) has been carried out to determine the depositional environments. The first four factors are taken as the "principal" factors, and the results are considered to represent the depositional history and sedimentary processes in relation to the Holocene sea-level changes. The fact implies that the sediments are grouped as outer-shelf relict sand sediments, inner-shelf modern muddy sediments, and finally the palimpsest sediments that are mainly distributed within and around the Korea Trough.

• Journal of The Geomorphological Association of Korea
• /
• v.28 no.2
• /
• pp.59-70
• /
• 2021

This study aims to determine the sunlight exposure according to depositional environment to improve the accuracy of optically simulated luminescence (OSL) dating. Sufficient sunlight exposure during transportation of sediment is a basic assumption of the OSL dating, and if the process does not occur enough, the results may be overestimated compared to the actual depositional age. Therefore, the main purpose of this study is to establish a correction method by determining residual or unbleachable dose after sunlight exposure in the actual deposition process, not in the laboratory measurement. Four samples from two sites were collected according to the depositional environment from rivers and coasts, and various OSL signals, including the size of residual dose, degree of dispersion between grains, and OSL signal sensitivity, were measured. As a result, it was confirmed that sediments formed under temporarily high energy environments, such as floods and surges, had relatively high residual dose or large dispersion of residual dose between particles. In further studies, the OSL signal characteristics of river sediments by flow velocity will be identified and the relationship between energy and OSL signal characteristics will be identified in more detail. Moreover, a method of reconstructing the paleo-environment at the time of deposition for existing sediments will be devised. It is expected to provide important information for the frequency of disaster recurrence and prediction of future climate change.

• 한국해양학회지
• /
• v.26 no.1
• /
• pp.13-23
• /
• 1991

For the purpose of examining the depositional sedimentary environments in the Han River estuary and around the Kyunggi Bay posterior to the Han river's developments, a hydrological and sedimen-tological survey was carried out. According to the hydrological and sedimentological conditions, the studied area can be divided into 3 depositional sedimentary environments: Fluvial, Estuarine and coastal-Bay. Posterior to the Han river's developments, however, the alterations of hydrodynamic condition in the Han river have caused a substantial change of the sedimentary environments in the lower Han river and its estuary. That is, the contents of total suspended sediment anterior to the Developments decreased from 37mg/l (in the lower Han River) and 500-1750 mg/l (at the Kanghwa Bridge) to 18 mg/l and 208-1142 mg/l posterior to the developments. these changes seem to have caused the siltation near the sin-gok Underwater Dam. Thus the characters of the boundary condition between the fluvial and the estuarine environments have rapidly changed. It is considered that these changes result mainly from the construction of the two underwater dams for the maintenance of the water level of the Han river. As the estuary is a transition zone between land and sea, these changes in the Han River estuary might affect the sedimentary environments around the Kyunggi Bay. In order to verify the effects of these changes, it is necessary that a detailed survey be carried out around the Han River estuary including the Imjin and Yesong River estuaries.

• Economic and Environmental Geology
• /
• v.55 no.3
• /
• pp.295-307
• /
• 2022

We studied the Cretaceous Jeonggaksan Formation to determine depositional processes of pyroclastic density currents entering into the lacustrine environments. This formation is composed largely of sandstone-mudstone couplets and (tuffaceous) normally graded sandstones deposited in lacustrine environments, interbedded with two pyroclastic beds: welded massive lapilli tuff and normally graded lapilli tuff. The welded massive lapilli tuff (10 m thick) is composed of poorly sorted, structureless lapilli supported by a welded ash matrix. The normally graded lapilli tuff (4 m thick) is characterized by moderately to well sorted natures and multiple normally graded divisions in the lower part of the bed with internal boundaries. The contrasting depositional features between these lapilli tuff are suggestive of different physical characteristics and depositional processes of pyroclastic density currents in the lake. Overall poorly sorted and massive natures of the thick, welded massive lapilli tuff are interpreted to have been formed by rapid settling of pyroclastic sediments from highly concentrated and sustained pyroclastic density currents. In this case, the pyroclastic density currents were able to displace lake water from shoreline and the pyrolclastic density currents preserved their own heat except for frontal parts of the currents. As a result, welded textures can be formed despite entrance of pyroclastic density currents into the lake. The internal boundaries of the normally graded lapilli tuff reflect unsteady natures of the pyroclastic density currents at the time of the deposition and the pyroclastic density currents can not provide sufficient pressure to displace lake water. As a consequence, the pyroclastic density currents transformed into water-saturated turbidity currents, forming relatively well sorted, normally graded lapilli tuff.

• 한국지구과학회:학술대회논문집
• /
• 2004.02a
• /
• pp.59-59
• /
• 2004

• Proceedings of the Zoological Society Korea Conference
• /
• 2000.10a
• /
• pp.160.2-160
• /
• 2000

No Abstract, See Full Text

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.882-887
• /
• 2006

Sedimentological, geochemical, geophysical and micropaleontological analyses of 10 borehole cores were carried out to understand depositional environment and sequence stratigraphy of late Quaternary sedimentation in the estuary of the Nakdong River. Holocene Formation in study area is classified into five sedimentary units. Early Holocene freshwater lower pebbly sandy deposit(Unit I), lower muddy deposit(Unit II), middle thin sandy deposit(Unit III), upper muddy deposit(Unit VI), and upper sandy deposit(Unit V), in ascending order contolled by global sea-level change since interglacial period(about 15,000 yrs B.P.). Unit I deposited in erosional environments before marine trangression. Unit II and Unit VI composed of clay were deposited in cold and worm currents for marine trangression., respectively.