• Proceedings of the Korean Geotechical Society Conference
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• 1989.10a
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• pp.1.3-25
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• 1989

This paper describes procedures and the results of mineralogical, fabric and pore sixte analyses perforied on four shales to understand time-dependent deforiation behav iour of swell ins shales better. Mineralogical compositions of theme shales are eBtablished froi the results of X-ray diffraction snalysis and chemical analyses. The importance of the fabric in the understanding of swelling behaviour of shales is demonstrated using Scanning Electron Microscope (SRI). The change in pore sixte distribution during the process of swelling is investigated by measuring pore size distribution before and after free swell test. The results Of the Present study imply that the swelling of Shales studied is not attributed to minerals like pyritei anhydrite or swelling clay minerals. The anisotropic swelling behaviour of shales studied ray be explained by fabrics of theme shales and the difference in them. The swelling of theme shales is found to be accoipanied by increase in the volute of pores.

• Geotechnical Engineering
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• v.6 no.1
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• pp.15-24
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• 1990

This paper describes the results of study on major factors influencing time-dependent deformation behaviour of swelling shales. The study was carried out by analyzing all the swell test results available for shales from southern Ontario. Major factors studied are (1) the presence of ambient water, (2) calcite content and (3) the applied stress. The results of the study on seven shales show that the swelling of shale is associated with the formation of cracks and the absorption of water in these cracks. The magnitude of swelling potential is related linearly to the amount of absorbed water. The presence of calcite inhibits the swelling of shales studied, reducing the swelling to zero at about 30% of calcite content. All the shales studied exhibit the stress-dependent swelling behaviour, though there Is a difference in the degree of dependency.

• Economic and Environmental Geology
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• v.9 no.3
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• pp.157-163
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• 1976

In this study, the oil bearing rock-sequence, U-hand-ri Formation (D.S. Lee et al., 1976), was subdivided into three members; the lower, the intermediate and the upper. The lower consists mainly of reddish purple tuff and sandy calcareous shales, the intermediate of an alternation of tuffs, sandstons, calcareous black shales, cherts and limestone and the upper of coarse grained variegated tuff and agglomerate. Oily matter was found from the black shales of the intermediate. Ten samples of black shales from drilled cores, 8 samples of black shales from different outcrops of the member, and 1 sample of grease-like seeping oil from black shales at U-hang-ri coast were chemically analyized. Among them, 9 samples contain remarkable amount of organic carbon (0.96~1.60%) and E.O.M. extract (0.176~0.718%), and mostly the bituminous material is saturated hydrocarbons as well as shown in infared spectroscopic analyses. The elemental analyses of MAE extracts and asphaltenes of some of thoese samples indicate that the transformation of organic material to crude oil is highly progressed. The authors suggest that the seeping oil and oily tinges in black shale layers are the products of natural cracking related with the igneous activities in the area nearby.

• Geomechanics and Engineering
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• v.3 no.3
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• pp.219-231
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• 2011

Waste fills resulting from coal mining should consist of large, free-draining sedimentary rocks fragments. The successful performance of these fills is related to the strength and durability of the individual rock fragments. When fills are made of shale fragments, some fragments will be durable and some will degrade into soil particles resulting from slaking and inter-particle point loads. The degraded material fills the voids between the intact fragments, and results in settlement. A laboratory program with point load and slake durability tests as well as thin section examination of sixty-eight shale samples from the Appalachian region of the United States revealed that pore micro-geometry has a major influence on degradation. Under saturated and unsaturated conditions, the shales absorb water, and the air in their pores is compressed, breaking the shales. This breakage was more pronounced in shales with smooth pore boundaries and having a diameter equal to or smaller than 0.060 mm. If the pore walls were rough, the air-pressure breaking mechanism was not effective. However, pore roughness (measured by the fractal dimension) had a detrimental effect on point load resistance. This study indicated that the optimum shales to resist both slaking as well as point loads are those that have pores with a fractal dimension equal to 1.425 and a diameter equal to or smaller than 0.06 mm.

• Economic and Environmental Geology
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• v.24 no.3
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• pp.245-260
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• 1991

Surficial dispersion patterns of heavy metals and toxic elements (U, Mo, Cu, Zn, Fe, Mn, Co, Cr, V, Ni, Pb, and Cd) were investigated in the Dukpyungri, Goesan area covered with low grade uranium-bearing black shales. Maximum abundance of U in the black shale was 455ppm. Radioactivity was counted at a maximum of 7cps in black shales, and was less than 0.5cps in shales, slates, and oil shales of the control areas. Enrichment of Mo, V, Cu, Zn, Cd, and Pb in black shales is particularly characteristic compared with shales, slates, and oil shales of the control areas, whereas contents of Mn, Cr, Co, and Th in all rock samples tend to be almost similar. Residual top soils (0~15cm depth) over black shales show high contents of Mo, Cu, Zn, Ni, Cd, and V in comparison with the control areas. Contents of trace elements in subsoils (15~30cm depth) were higher about one and half times than those in topsoils. Average contents of Mo, Cu, Pb, Zn, Cd and V in garden soil and playground soil of an elementary school in Dukpyungri, Goesan area, were high about two to fifteen times compared with the control areas. Contents of trace elements in stream sediments were higher from two to eight times than those in residual soils. Sodium, AI, K, V, Cr, and Fe were more enriched in the roots of pine than in the twigs of pine. Contents of Li, AI, V, Ni, Cd, Fe, and Co were higher in the roots of azalea than in the twigs of azalea. Enrichment of P, Ca, and Mg was remarkable in the twigs of both pine and azalea. Biological absorption coefficients for essential elements (Zn, P, Mn, Ca and K)tend to be high, whereas those for the non-essential elements.(Ba, Ti, V, and Mo) and toxic elements(Cr, Co, Pb and Ni) be low. Less mobile elements (Pd, Cd, and Co) tend to show anomalies with higher contrast than more mobile elements(Mo, V, Zn, Cu and Ni) in the area covered with black shales.

• Geomechanics and Engineering
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• v.28 no.4
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• pp.375-384
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• 2022

The glacial tills and shales in Midwestern states of the USA often show strength degradation after construction. They are often in need of applying soil modification techniques to remediate their strength degradation with weathering process. This study investigated the weathering durability of these natural soils and biopolymer treated soils by comparing direct shear test results for wet-dry and wet-freeze-thaw-dry cycled specimens. The tests showed that untreated glacial tills maintained only 62% and 50% initial shear strength after eight wet-dry cycles and eight wet-freeze-thaw-dry cycles, respectively. These untreated soils could not withstand by themselves after 16 weathering cycles. The same soils treated with 1.5% (by dry weight) food-grade Xanthan gum maintained 140% and 88% initial shear strength of untreated soils after 16 weathering cycles for wet-dry cycles and wet-freeze-thaw-dry cycles, respectively. The same soils treated with 1.5% (by dry weight) Gellan gum maintained 82% and 60% initial shear strength of untreated ones after 16 weathering cycles, respectively. Similar results were obtained for crushed shales, manifesting that the biopolymerization method may be adopted as a new eco-friendly method to enhance the weathering durability of these problematic soils of glacial tills and shales.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.587-601
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• 1997

This study had three purposes: (1) to investigate the enrichment levels and dispersion patterns of potentially toxic elements in the rock-soil-plant system; (2) to evaluate the uptake ratios of heavy metals from soils into plants and (3) to assess the chemical speciation of heavy metals in soils. Rock, surface soil and plant samples were collected in the Boeun area underlain by black shales of the Okchon Zone. These samples were analyzed for multi-elements using INAA, ICP-AES and AAS. The maximum abundance of U in black shales is 16 mg/kg and radioactivity counts up to 300 cpm. In particular, Mo, V, Ba, Cd, Pb and U are enriched in black shales. Most of soils derived from black shales show high concentrations of U, As, Mo, Ba, Cu, Cd, Pb, Zn and mean concentrations of As and Mo in soils (20 mg/kg of As and 6.6 mg/kg of Mo) are higher than the permissible level suggested by Kloke (1979). Enrichment index values of soils are calculated and higher than 1.0 in the black shale area with the highest value of 6.4. Mean concentration of Cd in plants is higher than those of Cu, Pb and Zn. The concentration of Cd in plant species decreases in the order of Chinese cabbage > red pepper > soybean=sesame > rice stalk > com > rice grain. The biological absorption coefficients (BAC) in plants are in the order of Cd > Zn=Cu > Pb, which suggests that Cd is more bioavailable to plants than Cu, Pb and Zn. From the results of sequential extraction analysis of soils, relatively high proportion of Cu, Pb and Zn are present as residual fractions whereas that of Cd as non-residual fractions. Cadmuim occurs predominantly as exchangeable/water-acid soluble phase in soils, and Cd is more mobile and bioavailable than Cu, Pb and Zn.

• Economic and Environmental Geology
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• v.30 no.1
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• pp.1-14
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• 1997

The shales from the Euiseong area are interbedded along the bedding in Cretaceous Gyeongsang Supergroup, which are composed mainly of quartz, plagioclase, K-feldspar and associated with trace amount of biotite, muscovite, chlorite, pyrite, hematite, carbonate and clay minerals. The ratio of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in shales from the Shindong Group are ranged from 9.16 to 24.32 and from 1.70 to 5.97, and the Hayang Group ranged from 2.76 to 8.89 and from 0.42 to 2.74, which are negative correlated between $K_2O/Na_2O$ and $Al_2O_3/Na_2O$ against $SiO_2/Al_2O_3$ respectively. Those are suggested that controlled of mineral compositions in shales due to substitution and migration of elements by sedimentation and diagenesis. These shale formation were deposited in basin of terrestrial environments originated from the igneous rocks, and the REE of these rocks are not influenced with diagenesis and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, Zr versus Yb, the ratios of La/Ce (0.43 to 0.62) and Th/U (1.11 to 10.71). The narrow range in trace and REE element characteristics as Co/Th (0.63 to 1.92), La/Sc (1.98 to 5.90), Sc/Th (0.58 to 1.30), V/Ni (0.90 to 3.25), Cr/V (0.45 to 1.78), Ni/Co (1.88 to 6.67) and Zr/Hf (30.04~60.87) of these shales argues for inefficient mixing of the simple source lithologies during sedimentation. These rocks also show much variation in $La_N/Yb_N$ (6.90 to 17.02), Th/Yb (4.17 to 13.68) and La/Th (1.98 to 5.90), and their origin is explained by derivation from a mixture of intermediate to acidic igneous rocks.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.89-103
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• 1997

The purpose of this research is to investigate the enrichment and distribution patterns of naturally occurring potentially toxic elements in soils derived from black shales and slates. Soil samples were collected from the Chubu area covered with uranium-enriched black shales and slates of the Changri Formation of the Okchon Super Group, and analysed for multiple-elements using INAA, ICP-AES and AAS. Soil pH and loss-an-ignition were also measured. Trace element contents in black shale and slate of the Chubu area are relatively lower than those in black shales, and higher than those in black slates reported elsewhere (Chon, Jung, 1991; Chon et al., 1996). Soil pH values range from 3.5 to 6.5, and loss-an-ignition values are in the range from 3 to 10%. Potentially toxic elements including As, Ba, Cr, Cu, Mo and U are highly enriched in residual soils with maximum content of $540{\mu}g/g$, $35,000{\mu}g/g$, $280{\mu}g/g$, $300{\mu}g/g$, $240{\mu}g/g$ and $860{\mu}g/g$, respectively. Significant concentrations of those elements were found in soils taken from the Tojangkol, the Chubu tunnel and the Meokti areas. Soils derived from black shales and slates, calcareous and phyllitic rocks, and intrusions were discriminated in terms of As, Ba, Co, Cr, Cu, Mo, Sc and U contents. Enrichment index was calculated using the concentrations of As, Ba, Cr and Mo, and enrichment index map shows very similar trend with U distribution in soils.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.495-508
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• 1996

This study had three purposes: (1) to investigate dispersion and enrichment level of potentially toxic elements; (2) to identify uranium-bearing minerals in black shales; and (3) to assess the chemical speciation of heavy metals in soils and sediments. Rock, surface soil and stream sediment samples were collected in the Chungjoo area covered with black shales in Korea. These samples were analyzed for multi-elements using INAA and ICP-AES. The maximum abundance of U in black shales is 56 ppm and radioactivity counts up to 240CPM. Molybdenum, V, Ba, Cu, and Pb are enriched in black shales and most of soils show high concentrations of U, Mo, Ba, Cu, Pb and Zn. Concentrations of potentially toxic elements decrease in the order of mountain soil > farmland soil > paddy soil. Enrichment index of soils and sediments are calculated and higher than 1.0 in the black shale area with the highest value of 6.1. In order to identify U-bearing minerals, electron probe micro analysis was applied, and uraninite and brannerite in black shale were found. Uraninite grains are closely associated with monazite or pyrite with the size of $2{\mu}m$ to $10{\mu}m$ in diameter whereas brannerite occurs as $50{\mu}m$ euhedral grains. With the results of sequential extraction scheme, residual fractions of Cu, Pb and Zn in soils are mainly derived from weathering of black shale but Cu, Pb and Zn in sediments are present as non-residual fractions. Lead is predominantly present as oxidizable phase in soils whereas Zn is in exchageable/water-acid soluble phase in sediments.