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Woo I.,Kunsan National University | Kim J.G.,Korean Institute of Geosciences and Mineral Resources | Lee G.H.,Korea Gas Corporation | Park H.J.,Sejong University | Um J.G.,Pukyong National University
Environmental Earth Sciences | Year: 2013

Pyrite is a common and abundant sulfidic mineral subject to oxidation. The weathering characteristics of rock-bearing pyrite sometimes impose serious influences on the surrounding environment as the oxidation of pyrite (FeS2) generates acid drainage that results in the acceleration of rock weathering and the discharge of heavy metals into the environment. Such an accelerated weathering of rocks can reduce its mechanical properties and therefore menace the stability of rock structures, such as excavated slopes and tunnels. The evolution of physical properties of rocks and the chemical composition of drainage were evaluated in this study by a weathering test using a double Soxhlet extractor for 1 month in a laboratory setting. Three groups of biotite gneiss classified according to their pyrite content were used for the Soxhlet extraction experiment (group A with less than 0.1 wt% of pyrite; group B with about 3.3 wt% of disseminated pyrite; group C with about 5.65 wt% of vein type pyrite). The massive groups A and B had limited weathering on the surface; however, group C with the pyrite vein experienced weathering on the surface as well as along the pyrite vein. The weathering type regulated by the occurrence of pyrite apparently controlled the mechanical properties of the rock samples and the chemistry of the drainage. Groups A and B showed no significant quick absorption ratio after the 1-month experiment; however, group C had about 10 % increase in value. The uniaxial compressive strength of the three groups decreased about 20, 10 and 45 % for groups A, B and C, respectively. The mechanical properties of the samples and the chemical compositions of the drainage indicate that the oxidation of pyrite contained in the samples accelerated weathering, resulting in deterioration of mechanical properties of the rocks, and could result in the discharge of heavy metals and acid into the environment with the drainage. © 2012 Springer-Verlag Berlin Heidelberg.

Shen B.,CSIRO | Shen B.,Shandong University of Science and Technology | Jung Y.-B.,Korean Institute of Geosciences and Mineral Resources | Park E.-S.,Korean Institute of Geosciences and Mineral Resources | Kim T.-K.,SK Engineering and Construction
Geosystem Engineering | Year: 2015

Underground storage of liquefied natural gas (LNG) has many advantages over the conventional above-ground LNG storage due to its safety and energy efficiency. One of the key technical challenges for the underground storage of LNG is to understand the behaviour of the rock mass in the vicinity of the LNG cavern and hence to take measures to prevent leakage caused by possible rock fracturing in response to the cooling of the rock mass. With the extremely low temperature of the LNG ( − 162°C) in the storage cavern, sub-zero temperatures will be induced in the surrounding rock mass, which on one hand may cause tensile stress due to thermo-mechanical effect and on the other will cause the formation of ice in pores and cracks of the saturated rock mass. Ice formation is likely to cause compressive stress in the rock mass due to its expansion in volume. The combined effect of rock cooling and ice swelling is complicated as cooling tends to create open fractures whereas ice swelling tends to cause compression and the closure of these discontinuities. Understanding this effect is crucially important as it is related to the integrity of the surrounding rock mass for leakage prevention. This study presents recent developments of the thermal-mechanical coupling and ice swelling functions in FRACOD, a numerical code designed to predict rock fracturing processes in fractured rock masses. The new functions enable us to investigate the complicated response of an in situ rock mass to the excavation of LNG cavern and the storage of low temperature LNG in a most realistic way. The pilot LNG storage cavern experiment at Daejeon Korea is used as a case study site, and the measured temperature in the surrounding rock mass are used to validate the numerical model and the modelling method. The ice swelling effect was modelled by introducing a large number of random cracks in the rock mass, which have certain hydraulic apertures to hold water. When the local rock temperature is below zero, the aperture water will become ice and cause crack expansion. It has been found in the study that ice swelling has a major effect on the displacement and stress distribution in the rock mass. It causes a compression zone around the LNG cavern, and effectively prevents tensile fracturing and fluid leakage. © 2015 The Korean Society of Mineral and Energy Resources Engineers (KSMER).

Parfenov L.M.,Russian Academy of Sciences | Gombosuren Badarch,Mongolian Academy of science | Berzin N.A.,Russian Academy of Sciences | Hwang D.H.,Korean Institute of Geosciences and Mineral Resources | And 9 more authors.
US Geological Survey Professional Paper | Year: 2010

The major purpose of this volume is to provide a com-prehensive synthesis of the regional geology, tectonics, and metallogenesis of Northeast Asia for readers who are unfa-miliar with the region and for researchers who desire detailed information on the region. The major parts of the volume are (1) an introductory chapter; (2) a chapter on methodology of regional metallogenic and tectonic analysis; (3) a chapter on mineral deposit models for the region; (4) five chapters that describe the regional metallogenesis and tectonics of the region from the Archean through the Present for successive time stages; (5) a chapter on a metallogenic and tectonic model for the region; and (6) three appendixes, including on a description of the project and products, a description of map units for the Northeast Asia geodynamics map, and a summary table of metallogenic belts for the region. An important goal of the volume is to demonstrate how a high-quality metallogenic and tectonic analysis, including construction of an associated metallogenic-tectonic model, greatly benefits other mineral resource studies by (1) syn-thesizing of mineral-deposit models, (2) improving predic-tion of undiscovered mineral deposits as part of quantitative mineral-resource-assessment studies, (3) assisting land-use and mineral-exploration planning, (4) improving knowledge of regional geology; (5) improving interpretations of the ori-gins of host rocks, mineral deposits, and metallogenic belts, and (6) suggesting new research. Research on the metallogenesis and tectonics of such major regions as Northeast Asia requires a complex meth-odology including (1) definitions of key terms, (2) compila-tion of a regional geologic base map that can be interpreted according to modern tectonic concepts and definitions, (3) compilation of a mineral-deposit database that enables a determination of mineral-deposit models and clarification of the relations of deposits to host rocks and tectonic origins, (4) synthesis of a series of mineral-deposit models that characterize the known mineral deposits and inferred undis-covered deposits in the region, (5) compilation of a series of metallogenic-belt belts constructed on the regional geologic base map, and (6) construction of a unified metallogenic and tectonic model. The Northeast Asia study area consists of eastern Russia (most of eastern Siberia and the Russian Far East), Mon-golia, northern China, South Korea, Japan, and adjacent offshore areas. Major cooperative agencies are the Russian Academy of Sciences; the Academy of Sciences of the Sakha Republic (Yakutia); VNIIOkeangeologia and Ministry of Natural Resources of the Russian Federation; the Mongolian Academy of Sciences; the Mongolian University of Science and Technology; the Mongolian National University; Jilin University, Changchun, People's Republic of China; the China Geological Survey; the Korea Institute of Geosciences and Mineral Resources; the Geological Survey of Japan/ AIST; the University of Texas, Arlington; and the U.S. Geo-logical Survey (USGS). This study builds on and extends the data and interpreta-tions from a previous project on the Major Mineral Depos-its, Metallogenesis, and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera conducted by the USGS, the Russian Academy of Sciences, the Alaska Division of Geological and Geophysical Surveys, and the Geological Survey of Canada. The major products of the Northeast Asia project are described in appendix A.

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