Host rock characteristics and source of chromium and beryllium for emerald mineralization in the ophiolitic rocks of the Indus Suture Zone in Swat,NW Pakistan

Bodies of magnesite-rich rocks (magnesite ± talc ± quartz ± dolomite), locally containing emerald deposits, occur within the Swat Valley. These rocks, part of the Indus suture mélange group, are distributed mostly along contacts of serpentinized ultramafic rocks with carbonate ± graphite-bearing metasedimentary rocks. Their field association, petrographic details, mineralogical composition and geochemical characteristics show that they likely formed due to carbonate alteration of previously serpentinized ultramafic rocks by CO₂-bearing fluids released as a result of metamorphism of spatially associated, originally sedimentary rocks of the Indo-Pakistan plate.Locally, late-stage hydrothermal activity affected these highly fissile magnesite-rich rocks to produce veins and stockworks of quartz as well as emerald, Cr-rich tourmaline and Cr, Ni-rich muscovite. Detailed petrographic and mineral chemical investigations suggest that all three Cr-bearing silicates are genetically related and their Cr, as well as Ni and Mg found in Cr-rich muscovite and Cr-rich tourmaline, was derived from the original ultramafic protoliths.Detailed geochemical comparison reveals that relative to non-mineralized sections, magnesite-rich rocks in mineralized zones show significant enrichment in B and Be as well as As, Pb, Zr, Rb, Ba, W, Sn, Sr and Y. Boron and Be enrichment in these rocks appears to be structurally controlled. More extreme B and Be enrichment is evident in small granitic dikes cutting granite gneisses and in Miocene leucogranitic stocks at Malakand 45 km southwest. These geochemical features argue strongly for a leucogranite-associated source for Be-transporting fluids to the emerald's host rocks.     

Applications of remote sensing and geographic information systems for urban land-cover change studies in Mongolia

The aim of this study is to compare the changes that occurred in the main urban land-cover classes of Ulaanbaatar city, Mongolia, during a centralized economy with those that occurred during a market economy and to describe the socio-economic reasons for the changes. For this purpose, multi-temporal remote sensing and geographical information system (GIS) data sets, as well as census data, are used. To extract the reliable urban land-cover information from the selected remotely sensed data sets, a refined parametric classification algorithm that uses spatial thresholds defined from local and contextual knowledge is constructed. Before applying the classification decision rule, some image fusion techniques are applied to the selected remotely sensed data sets to define the most efficient fusion method for training sample selection and for defining local and contextual knowledge. Overall, the study indicates that during the centralized economy significant changes occurred in a ger area of the city, whereas during the market economy the changes occurred in all areas.     

Accumulation of butyltin compounds in finless porpoises (Neophocaena asiaeorientalis) from Korean coast: Tracking the effectiveness of TBT regulation over time

The concentrations of butyltin compounds (BTs) were measured in the livers of finless porpoises (Neophocaena asiaeorientalis) caught off the Korean coast in 2003 and 2010, to assess the effectiveness of legislative action against BTs. The concentrations of BTs ranged from 65.1 to 1432 (average: 370) ng/g wet weight, within the ranges reported by previous studies. The levels of BTs in almost all the samples exceeded the suggested threshold value, implying potential adverse health effects from the BT exposures. Concentrations of BTs were significantly correlated with body length, weight, and age of finless porpoises, but were not correlated with sex. Spatial differences in the concentrations of BTs were not observed between Yellow and South Seas, while there was a significant decrease in BTs between the sampling years of 2003 and 2010. Our result indicates that the effectiveness on TBT ban has reached to marine mammals in the coastal waters of Korea.     

Three‐dimensional responses of buried corrugated pipes and ANN‐based method for predicting pipe deflections

This study investigated localized responses, such as circumferential stresses, on corrugation and pipe deflections. Also, this study examined the effect of corrugation geometry on the overall and localized response of corrugated pipes with refined three‐dimensional modeling of the entire soil–pipe interaction system, including corrugation. To investigate the availability of the traditional two‐dimensional method, the results from the three‐dimensional finite element method (FEM) were compared with those from the two‐dimensional FEM. The soil–pipe modeling techniques of this study were verified by comparing the FEM results by Utah State University and analytical results. An artificial neural network (ANN)‐based model to predict vertical deflections of buried corrugated pipes was developed to overcome the shortcomings of existing methods and obtain results that are close to the level of accuracy of FEM results. In order to train an ANN, analyses on a large amount of data were executed with various standardized pipe geometries and burial depths regulated by the Korea Highway Corporation using the two‐dimensional FEM verified in this study. The widely used back propagation algorithm was adopted. The ANN‐based model developed in this study was shown to be an effective tool by comparing the results with test data and sensitivity analyses were executed based on the data from the developed ANN. Copyright © 2010 John Wiley & Sons, Ltd.     

Tropical cyclone activity in the northwestern Pacific associated with decaying Central Pacific El Niños

In this study, a comparative analysis was performed to reveal the relationship between the three types of temporal evolution of the Central Pacific (CP) El Niño (prolonged, abrupt, and symmetric decay) in the tropical Pacific Ocean and tropical cyclone (TC) activity in the Western North Pacific (WNP). TCs in the WNP were found to be sensitive to the different types of temporal evolution of the CP El Niño. During years of prolonged and symmetric decay, TCs were more frequent over East Asia with relatively strong TCs. In contrast, during years of abrupt decay, weak TCs with a relatively short lifespan more likely formed at slightly higher latitudes. The historical record of CP El Niño events is limited, but this study is expected to improve the understanding of complex natural systems and provide fundamental information for the scientific understanding and forecasting of TCs.     

Type II Radio Bursts with High and Low Starting Frequencies

We report on the detailed analysis of i) differences between the properties of type IIs with various starting frequencies (high: ≥100 MHz; low: ≤50 MHz; mid: 50 MHz ≤f≤ 100 MHz) and ii) the properties of CMEs and flares associated with them. For this study, we considered a sample of type II radio bursts observed by Culgoora radio spectrograph from January 1998 to December 2000. The X-ray flares and CMEs associated with these events are identified using GOES and SOHO/LASCO data. The secondary aim is to study the frequency dependence on other properties of type IIs, flares, and CMEs. We found that the type IIs with high starting frequencies have larger drift rate, relative drift rate, and shock speed than the type IIs with low starting frequencies. The flares associated with high frequency type IIs are of impulsive in nature with shorter rise time, duration and delay between the flare start and type II start times than the low frequency type IIs. There is a distinct power – law relationship between the flare parameters and the starting frequencies of type II bursts, whereas the trend in the CME parameters shows low correlation. While the mean speed of CMEs is larger for the mid-frequency group, it is nearly the same for the high and low frequency groups. On the other hand, the percentage of CME association (90%) is larger for low frequency type IIs than for the high frequency type IIs (75%).     

The significant increase of summer rainfall occurring in Korea from 1998

Using the techniques of empirical orthogonal function analysis and the change-point analysis to total summer rainfall from 60 weather observation stations, it was found that total summer (from June to September) rainfall in Korea has increased greatly since 1998. The increase level was higher in the season between Changma and late summer rainy season (from the end of July to early August) and in the season after late summer rainy season (after the early September). Among the reasons for increase of summer rainfall in Korea since 1998, the north-high and south-low pressure pattern formed around Korea drew attention. As northeasterlies and southeasterlies derived from these two pressure systems converged in Korea, rainfall and moisture convergence increased most in Korea of the East Asia regions (0–60°, 100–180° E). In addition, the atmosphere above Korea revealed that there were strong ascents from the ground to 200-hPa level with the warm air to 500-hPa level.     

Determining uraniferous host rocks and minerals as a source of dissolved uranium in granite aquifers near the central Ogcheon metamorphic belt,Korea

Korea has suffered from high U concentrations in some groundwater, especially in Daejeon near the central Ogcheon metamorphic belt. However, clear explanation has not been yet reported for the uranium sources in groundwater. This study is focused on identifying the potential uraniferous host rocks and finding the exact U-minerals serving as uranium sources in groundwater near Daejeon, Korea. For this work, we performed an in situ gamma ray spectrometer survey and a laboratory microscopic study with electron micro-probe analysis. The measurements for radioactive element content did not show any prominent K- and Th-anomaly spots, but they did result in several observations of considerable U-anomalies in pegmatite and hydrothermally altered granite, in which uraninite, coffinite and uranophane were found by electron micro-probe analysis. The occurrences of U-minerals are the first such discovery except in the low-grade U deposits of the Ogcheon metamorphic belt in Korea. All observed U-minerals were intimately associated with hydrothermal alteration. The remarkably low Th/U ratios in the studied uraniferous rocks also suggest that the U enrichment was genetically related to a post-magmatic hydrothermal process. However, many of the uraniferous parts were controlled by a reducing environment and occurred near the border between graphite-rich mica-schist and Jurassic leucocratic granite. The findings on these uraniferous rocks can be used in elucidating the source of highly enriched U groundwater in granite aquifers as well as in understanding the occurrence of igneous U-minerals, which has not been previously reported in Korea.     

Surface circulation and vertical structure of current off the Keum River estuary,Korea in later spring 2008

To examine the surface circulation and vertical structure of currents in the region of the Keum River (KR) plume, we analyzed the subinertial surface currents obtained by high frequency radar and the vertical profiles of currents measured at a station (M1) located 10 km distance from the estuary mouth for one month in late spring 2008. Monthly-mean surface circulation is composed of the westward flow from the estuary mouth and the northward flow in the offshore. These surface mean currents are a gradient (geostrophic) current around the monthly-mean plume bulge. Dominant variabilities of the surface currents, winds, and KR-outflow are decomposed by the Empirical Orthogonal Functions (EOF). The first current EOF mode, explaining 39% of total variation, is primarily related to the first wind EOF mode varying along the coast and the second current mode, explaining 33% of total variation, is mainly related to the first KR-outflow EOF mode varying along the mean KR-outflow direction. Meanwhile, vertical profile of the monthly-mean current at M1 shows a two-layer structure of the current flowing offshore (onshore) in the upper (lower) layer because the water column is divided by a pycnocline at 7-9 m depths below the plume water. This two layer structure is a background persisting current structure, at least in spring, maintained by the geostrophic balance induced by the sea level slope and density gradient along the line normal to the westward mean surface current direction due to monthly-mean plume bulge off the KR estuary. EOF analysis of vertical current profiles reveals that the first mode, explaining 43% of total variation, represents the two-layer structure of the current variability. The upper-layer current varies along a line normal to the mainland coastline and the low-layer one varies approximately along a line parallel to the coastline, with direction difference of about 115° between the upper-and low-layer. From the correlation analysis it is found that 60% of the first mode variation is influenced by the first mode of KR-outflow and 36% by the first mode of wind. Any forcing modes of KR-outflow and wind influencing the other current vertical modes could not be found in the present study.     

Spawning characteristics of <Emphasis Type="Italic">Clupea pallasii</Emphasis> in the coastal waters off Gyeongnam,Korea, during spawning season

The purpose of this study is to research the characteristics of spawning grounds of Clupea pallasii found at 1 spawning ground located in the coast of Yeongun-ri, Tongyeong, Gyeongnam, and 3 stations in Jinhae Bay. Diving observation was performed from January to June, 2014 at the coast of Yeongun-ri, and from February to June, 2016 at Jinhae Bay after total 4 stations (A: Gusan-myeon, B: Haengamdong, C: Hacheong-myeon, D: Jam-do) were constituted. During observation period, 1 spawning ground was found in Tongyeong area in January. In Jinhae Bay spawning grounds were found at 3 stations (A, B, D) out of 4 stations in February. Regarding the surrounding environment of spawning ground found at Yeongunri, Tongyeong, various kinds of seaweeds were distributed up to 1–5 m depth, and many branch type red algae were distributed. In case of Jinhae Bay, seaweeds were widely distributed from shallow water to 5 m depth. In addition, the scope that eggs were attached was considerably wide compared to Tongyeong area, and they were found at all the 3 spots, so C. pallasii is thought to use Jinhae Bay for its spawning ground widely. Eggs were attached from the surface to 3–4 m, and like Tongyeong area, eggs were attached to mostly branch type of red algae. The results of this study suggest that the spawning season of the C. pallasii in coast waters off Gyeongnam is until mid-February.