A preliminary study of natural environmental change and its impact on early Late Paleolithic people in the northeast central Korean Peninsula during Marine Istope Stage 3 (40–30k cal a bp)

We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ¹⁸O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.     

Testing the ability of surface arrays to monitor microseismic activity

Recently there has been much interest in the use of data from surface arrays in conjunction with migration‐based processing methods for passive seismic monitoring. In this study we use an example of this kind of data recorded whilst 18 perforation shots, with a variety of positions and propellant amounts, were detonated in the subsurface. As the perforation shots provide signals with known source positions and origin times, the analysis of these data is an invaluable opportunity to test the accuracy and ability of surface arrays to detect and locate seismic sources in the subsurface. In all but one case the signals from the perforation shots are not visible in the raw or preprocessed data. However, clear source images are produced for 12 of the perforation shots showing that arrays of surface sensors are capable of imaging microseismic events, even when the signals are not visible in individual traces. We find that point source locations are within typically 45 m (laterally) of the true shot location, however the depths are less well constrained (～150 m). We test the sensitivity of our imaging method to the signal‐to‐noise ratio in the data using signals embedded in realistic noise. We find that the position of the imaged shot location is quite insensitive to the level of added noise, the primary effect of increased noise being to defocus the source image. Given the migration approach, the array geometry and the nature of coherent noise during the experiment, signals embedded in noise with ratios ≥0.1 can be used to successfully image events. Furthermore, comparison of results from data and synthetic signals embedded in noise shows that, in this case, prestack corrections of traveltimes to account for near‐surface structure will not enhance event detectability. Although, the perforation shots have a largely isotropic radiation pattern the results presented here show the potential for the use of surface sensors in microseismic monitoring as a viable alternative to classical downhole methods.     

Biomonitoring of trace metals using transplanted mussels, <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis>, in coastal areas around Ulsan and Onsan Bays,Korea

Mediterranean (blue) mussels (Mytilus galloprovincialis) collected from a reference site were transplanted to 15 stations in coastal areas around Ulsan and Onsan Bays, an extensively metal polluted area in Korean coastal waters, to assess metal contamination in the coastal oceans of Korea. During the biomonitoring periods (June 30 to July 20, 2003; 21 days), transplanted mussels, seawater, and particulate materials were collected for analysis of 15 metals (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, Sn, and Zn). Transplanted mussels showed metal enrichment compared to initial concentrations and spatial gradients consistent with dissolved and/or particulate metal concentrations in seawaters. Based on Q mode factor analysis, stations were clustered into three groups. The first group, located on Onsan Bay, showed high Ag, Cd, Cu, Hg, Pb, Sb and Zn enrichment, presumably arising from non-ferrous metal refineries and chemical industries in this area. The second group was located near the mouth of the Oehwang River and was enriched in Co from petrochemical industries. The third group comprised a site intermediate between Group 1 and Group 2, an isolated station with independent metal sources located in Jangsaengpo harbor, where a number of ship repairing and building companies operate, and a less contaminated station near a small fishing village. Metal accumulation rates (%·day^-1) in mussels were estimated to be between 8% (Cr) and 281% (Pb), based on accumulated metal concentrations over 21 days. The active biomonitoring technique using M. galloprovincialis demonstrated here is a useful monitoring method because it reflects the present status of seawaters; furthermore, physiological factors can be standardized, and bioavailable and time-integrated metal concentrations can be obtained. Furthermore, this method can be applied even in coastal seawaters so heavily contaminated that living organisms would not normally survive.     

Genesis and Mineralogy of Serpentinite Deposits,West of South Korea

The serpentinite deposits derived from ultramafic rockswithin the South Korea mainly occur in the west ofChungcheongnam - Do,the south of South Korea,Ulsan andAndong area,and in the middle of South Korea,Gapyeongarea. The present study is on the genesis and m ineral compo-sitions of the serpentinite deposits consisting of abouteighteenmasses in the west of Chungcheongnam- Do. The ultramaficrocks mainly occur as discontinuously isolated lenticular or el-liptical bodies and extend to NNE d…     

Distribution patterns of macrobenthic fauna communities in Deukryang Bay,one of the environment conservation areas of Korea

Macrobenthic fauna were collected seasonally at 44 sites in Deukryang Bay from February to November, 2012. The species number of macrobenthic fauna was in the range of 140 to 181, and polychaetes comprised 41.4% of them. The average density of the whole study area changed seasonally from 755 to 1,507 ind. m^?2, and the most abundant fauna group was crustaceans which accounted for 55.1% of total abundance. An amphipod species Nippopisella nagatai was the most dominant species and a decapod species Xenophthalmus pinnotheroides, an amphipod species Photis longicaudata, and a polychaete species Paralacydonia paradoxa were also dominant in all seasons. The mean seasonal values of Shannon’s diversity index (H′) were in the range of 2.2–2.4, and those values for the evenness index and richness index were 0.7–0.7 and 4.6–5.7, respectively. From the cluster analysis, Deukryang Bay could be divided into 3 or 4 station groups with its specific fauna composition. The cluster analysis and an nMDS ordination revealed that local environmental factors such as water depth were related to the spatial delineation of macrobenthic fauna communities in Deukryang Bay.     

A new approach to interpreting Rock-Eval S2 and TOC data for kerogen quality assessment

A simple method for application in source potential mapping is used to assess the original oil and gas potentials in source rock horizons based upon Rock-Eval potential (S₂) and total organic carbon (TOC) values. The method assumes that kerogens consist of mixtures of end-members with assigned hydrogen index values. Based on suggested algorithms, the average amounts of oil-prone, gas-prone and inert organic material over source rock intervals are determined in TOC units. The method uses regression lines from plots of remaining hydrocarbon potentials (S₂) versus total organic carbon (TOC), and “quick-look” transparent overlays are used to read the appropriate kerogen mixture.Mineral matrix effects during pyrolysis, when strong, can cause erroneous results. This effect which occurs for oil-prone kerogens and adsorptive minerals can cause problems particularly for lean samples (S₂ = 0–3 mg HC/g rock) whilst the errors for richer samples are less.The method is applied on three sections of Upper Jurassic organic-rich rocks from the Danish North Sea sector, which are at different maturity stages. One of these sections is dominated by gas-prone material, one is dominated by oil-prone material and the third section contains a mixture of oil- and gas-prone material.The method has been compared with other methods that split kerogens in oil and gas generating potential and has given reasonable results.Experience using the method and a presented example suggest that sedimentological, system tract information may be derived from S₂ to TOC cross-plots. A constructed modelling example suggests that the end-member concept used in this approach may be used in forward type source rock prediction models when combined with sedimentological models. The resulting S₂–TOC plots can be used in order to check the forward modelling results against observed values.     

Inverse relationship between the equatorial eastern Pacific annual-cycle and ENSO amplitudes in a coupled general circulation model

We propose a dynamical interpretation of the inverse relationship between the tropical eastern Pacific annual-cycle (AC) amplitude and the El Niño-Southern Oscillation (ENSO) amplitude, based on a pre-industrial simulation of Geophysical Fluid Dynamics Laboratory Couple climate model 2.0 with a fixed concentration of greenhouse gases spanning approximately 500 years. The slowly varying background conditions over more than a decade alternately provided favorable conditions for two opposite regimes, namely the ‘strong AC—weak ENSO regime’ and the ‘weak AC—strong ENSO regime’. For the weak AC—strong ENSO regime, the tropical eastern Pacific shows meridional-asymmetric surface warming with an emphasis on the southern part, leading to weakening of both the zonal trade wind and the cross equatorial southerly wind, as well as deepening of both the thermocline and mixed layer. The deeper mixed layer, weaker southerly wind, and reduced zonal gradient of the mean sea surface temperature due to tropical eastern Pacific warming all acts to reduce the AC. Conversely, the ENSO was intensified by the deeper mixed layer and deeper thermocline depth (thermocline feedback), but suppressed by the deeper thermocline depth (Ekman feedback) and the reduced zonal temperature gradient. We also computed the coupling strengths of the ENSO and AC, defined as the linear regression coefficients of the zonal and meridional wind stresses against the eastern Pacific SST, respectively. The coupling strengths of both the AC and ENSO are larger when they are intensified, and vice versa. All processes for the weak AC—strong ENSO regime operate in the opposite manner for the strong AC—weak ENSO regime.     

A study of igneous rocks related to Zn–Pb mineralization in the Shinyemi and Gagok deposits of the Taebaeksan Basin,South Korea

The Shinyemi and Gagok deposits, located in the Taebaeksan Basin, South Korea, display Zn–Pb mineralization along a contact between Cretaceous granitoids and Cambrian–Ordovician carbonates of the Joseon Supergroup. The Shinyemi mine is one of the largest polymetallic skarn‐type magnetite deposits in South Korea and comprises Fe and Fe–Mo–Zn skarns, and Zn–Cu–Pb replacement deposits. Both deposits yield similar Cretaceous mineralization ages, and granitoids associated with the two deposits displaying similar mineral textures and compositions, are highly evolved, and were emplaced at a shallow depth. They are classified as calc‐alkaline, I‐type granites (magnetite series) and were formed in a volcanic arc. Compositional variation is less in the Shinyemi granites and aplites (e.g., SiO₂ = 74.4–76.6 wt% and 74.4–75.1 wt%, respectively) than in the Gagok granites and aplites (e.g., SiO₂ = 65.6–68.0 wt% and 74.9–76.5 wt%, respectively). Furthermore, SiO₂ vs K/Rb and SiO₂ vs Rb/Sr diagrams indicate that the Shinyemi granitoids are more evolved than the Gagok granitoids. Shinyemi granitoids had been already differentiated highly in deep depth and then intruded into shallow depth, so both granite and aplite show the highly evolved similar chemical compositions. Whereas, less differentiated Gagok granitoids were separated into two phases in the last stage at shallow depth, so granite and aplite show different compositions. The amounts of granites and aplite are similar in the Shinyemi deposit, whereas the aplite appears in an amount less than the granite in the Gagok deposit. For this reason, the Shinyemi granitoids caused not only Fe enrichment during formation of the dolomite‐hosted magnesian skarn but also was associated with Mo mineralization in the Shinyemi deposit. Zn mineralization of the Gagok deposit was mainly caused by granite rather than aplite. Our data suggest that the variation in mineralization displayed by the two deposits resulted from differences in the compositions of their associated igneous intrusions.     

Potassium–Argon Ages of the Epithermal Gold–Silver Mineralization in the Haenam–Jindo Area,Southwestern Korea

The Haenam–Jindo area, located on the southwestern margin of the Korean Peninsula, was the site of vigorous volcanic activity during the Late Cretaceous and Early Tertiary periods. Large parts of the area record strong hydrothermal alteration, and there exist many clay–alunite and gold–silver deposits. We undertook potassium–argon (K–Ar) age dating of five mineral samples (including adularia, sericite and alunite) from the Eunsan, Moisan and Gasado epithermal gold–silver deposits in this area. The purities of the samples were confirmed by X‐ray diffraction analysis. The K–Ar ages of adularia from the Eunsan deposit and adularia and sericite from the Moisan deposit (related to gold–silver mineralization) are 75.0 ± 1.6, 74.7 ± 1.6 and 75.1 ± 1.6 Ma, respectively. The similarity of these ages, combined with the close proximity and similar geochemical characteristics of the deposits, indicates that the mineralization occurred as part of a single hydrothermal system. The K–Ar ages of alunite at the surface and adularia at depth within the Gasado deposit are 82.2 ± 1.9 and 70.7 ± 1.9 Ma, respectively, revealing that the clay–alunite and gold–silver mineralization formed at different ages. K–Ar age data indicate that the gold–silver mineralization in this area occurred mainly at 75–70 Ma, resulting from hydrothermal activity in the Haenam–Jindo area (82–70 Ma). This is the first time that the mineralization of precious metals in Korea has been identified during this period.     

Palaeoclimatic and regional implications of Older Dryas and Younger Dryas local glacier activity in the low-Arctic valley Finnkongdalen,Andøya,northern Norway

Continuous glacier margin and equilibrium-line altitude fluctuations of a former glacier on central Andøya, northern Norway, are reconstructed during the Lateglacial based on moraines and AMS ¹⁴C-dated sediments from the distal glacier-fed lake Ner-Finnkongdalsvatnet. The results indicate that a valley glacier occupied the entire valley during the Last Glacial Maximum (before 21 970±620 cal. a BP). The glacier remained large throughout the early Lateglacial until a significant glacier retreat took place about 14 300±330 cal. a BP. Major advances occurred during the Older Dryas (OD) and during the Younger Dryas (YD), while minor advances are suggested to have taken place during the Intra Allerød Cold Period and the Late Allerød Cooling. Additionally, three smaller glacier retreats/re-advances within the YD are suggested to have taken place, the latter being the largest. The glacier re-formations/advances during the Lateglacial are consistent with increases in temperature, and they are thus suggested to be the result of increased winter precipitation. Comparing the results with relevant glacier and sea-surface temperature records, a south–north migration of storm tracks may have occurred between 12 100–11 810±220 cal. a BP. The high temporal resolution of local glacier activity in Finnkongdalen improves our understanding of the climate forcing of the regional glacier fluctuations of the northwestern sector of the Scandinavian Ice Sheet during the Skarpnes- (OD) and Tromsø-Lyngen (YD) re-advances.