Paucity of sulfide in a large slab of Esquel: New perspectives on pallasite formation

Abstract— The 0.7 ton Esquel meteorite, found in Patagonia before 1951, is a typical main-group pallasite in most respects. We examined petrographically a slab ～1 m long having an area of 3000 cm² that shows the typical pallasitic texture with fragmental olivine. Phase abundances (in vol%) are olivine (66%), metal (32%), schreibersite (0.76%), troilite (0.46%) and chromite (0.31%). Esquel can be divided into four lithologies: (1) “pallasitic” matrix consisting of olivine fragments embedded in metal (81%); (2) large (>5 cm) olivine nodules having low metal contents (18%); (3) massive metal (0.3%); and (4) zones dominated by FeS and fine olivine (0.7%). Main-group pallasites appear to have formed by the intrusion of a highly evolved (low Ir, high Ni, Au and S) metallic magma into fragmented olivine. This model implies that FeS should be abundant in main-group pallasites, and we had speculated that examination of an exceptionally large slab might reveal a high troilite content. We found instead an exceptionally low FeS content. New compositional data confirm that Esquel has a lower Au content than other main-group pallasites having similar Ir contents. Literature data (based, however, on relatively small sections) suggest that high-Au pallasites have higher S contents than Esquel but have lower S contents than expected from a trapped-melt model. We conclude that a relatively complex model is required to explain the origin of main-group pallasites. After intrusion, the degree of crystallization of the metallic magma varied from location to location but, in almost all cases, an FeS-rich liquid either escaped or formed FeS-rich pallasitic rocks that are underrepresented in the meteorite inventory.     

Temporal population dynamics of dinoflagellate Prorocentrum minimum in a semi-enclosed mariculture pond and its relationship to environmental factors and protozoan grazers

The ecological processes and interrelationships between protists,either autotrophic or heterotrophic,and environmental factors in mariculture ponds are largely unknown.This study investigated the temporal dynamics of potentially harmful dinoflagellate,Prorocentrum minimum (Pavillard) Schiller,and its relationship to physico-chemical factors and protozoan grazers over a complete cycle in a semi-enclosed shrimp-farming pond near Qingdao,Northern China.P.minimum occurred frequently in low numbers from June to ...     

集合同化方法在黄海海域海表面温度同化中的应用

The effects of sea surface temperature(SST) data assimilation in two regional ocean modeling systems were examined for the Yellow Sea(YS). The SST data from the Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA) were assimilated. The National Marine Environmental Forecasting Center(NMEFC) modeling system uses the ensemble optimal interpolation method for ocean data assimilation and the Kunsan National University(KNU) modeling system uses the ensemble Kalman filter. Without data assimilation, the NMEFC modeling system was better in simulating the subsurface temperature while the KNU modeling system was better in simulating SST. The disparity between both modeling systems might be related to differences in calculating the surface heat flux, horizontal grid spacing, and atmospheric forcing data. The data assimilation reduced the root mean square error(RMSE) of the SST from 1.78°C(1.46°C) to 1.30°C(1.21°C) for the NMEFC(KNU) modeling system when the simulated temperature was compared to Optimum Interpolation Sea Surface Temperature(OISST) SST dataset. A comparison with the buoy SST data indicated a 41%(31%) decrease in the SST error for the NMEFC(KNU) modeling system by the data assimilation. In both data assimilative systems, the RMSE of the temperature was less than 1.5°C in the upper 20 m and approximately 3.1°C in the lower layer in October. In contrast, it was less than 1.0°C throughout the water column in February. This study suggests that assimilations of the observed temperature profiles are necessary in order to correct the lower layer temperature during the stratified season and an ocean modeling system with small grid spacing and optimal data assimilation method is preferable to ensure accurate predictions of the coastal ocean in the YS.     

中韩河流沉积物微量元素地球化学研究

长江和黄河以及韩国的Keum和Yeongsan江，具有不同的微量元素地球化学特征。韩国河流沉积物中微量元素含量多介于长江和黄河之间，以Li、Rb和Th较高为特征，粒级效应明显。长江富铁族和铜族元素，黄河则Sr最高，其他元素均低于其他3条河流；韩国河流中Sr主要赋存于长石中，而长江和黄河中则主要赋存于碳酸盐矿物中。根据沉积物中元素的赋存相态及含量，我们认为Ti、Cr/Th、Ti/Nb和Zr/Nb等可以作为判剐西太平洋边缘海，尤其是黄海中长江、黄河与韩国河流物质贡献的可靠地球化学参数，但在运用中必须注意粒级效应影响。     

Two climate factors in May that affect Korean rainfall in September

This study revealed a high positive correlation between rainfall in Korea during September and the trade wind (TW)/Arctic Oscillation (AO) index in May that combines two climate factors, low-level TWs and the AO. This correlation was identified on the basis of the difference in the 850 hPa streamline analysis between the positive and negative phases selected using the combined TW/AO index. In May, the spatial pattern of the anomalous pressure systems is similar to that in the positive AO phase. These anomalous pressure systems continue in June to August (JJA) and September, but the overall spatial distribution shifts a little to the south. Particularly in September, a huge anomalous anticyclone centered over the southeast seas of Japan strengthens in most of the western north Pacific region and supplies a large volume of warm and humid air to the region near Korea. This characteristic is confirmed by the facts that during the positive TW/AO phase, the subtropical western north Pacific high (SWNPH) is more developed to the north and that the continuous positioning of the upper troposphere jet over Korea from May to September strengthens the anomalous upward flow, bringing warm and humid air to all layers. These factors contribute to increasing September rainfall in Korea during the positive TW/AO phase. Because the SWNPH develops more to the north in the positive phase, tropical cyclones tend to make landfall in Korea frequently, which also plays a positive role in increasing September rainfall in Korea.The above features are also reflected by the differences in average rainfall between the six years that had the highest May Ni o 3.4 indices (El Ni o phase) and the six years that had the lowest May Ni o 3.4 indices (La Ni a phase).     

Three-Dimensional Numerical Model for Tsunami Propagation Passing Through An Obstacle

1 .Introduction In the present numerical analysis of a tsunami ,atwo-dimensional numerical model based on non-linear shallowwater theoryis mainly used (Aburaya and Imamura ,2002 ;Imamura ,1995 ; Goto andOgawa ,1992) .Thoughthis model representstsunami hei…     

Geochemistry of peridotite xenoliths in alkali basalts from Jeju Island, Korea

Abstract   Ultramafic xenoliths in alkali basalts from Jeju Island, Korea, are mostly spinel lherzolites with subordinate amounts of spinel harzburgites and pyroxenites. The compositions of major oxides and compatible to moderately incompatible elements of the Jeju peridotite xenoliths suggest that they are residues after various extents of melting. The estimated degrees of partial melting from compositionally homogeneous and unfractionated mantle to form the residual xenoliths reach 30%. However, their complex patterns of chondrite-normalized rare earth element, from light rare earth element (LREE)-depleted through spoon-shaped to LREE-enriched, reflect an additional process. Metasomatism by a small amount of melt/fluid enriched in LREE followed the former melt removal, which resulted in the enrichment of the incompatible trace elements. Sr and Nd isotopic ratios of the Jeju xenoliths display a wide scatter from depleted mid-oceanic ridge basalt (MORB)-like to near bulk-earth estimates along the MORB–oceanic island basalt (OIB) mantle array. The varieties in modal proportions of minerals, (La/Yb)_N ratio and Sr-Nd isotopes for the xenoliths demonstrate that the lithospheric mantle beneath Jeju Island is heterogeneous. The heterogeneity is a probable result of its long-term growth and enrichment history.     

Physiological differences in the growth and maturation of Eisenia bicyclis and Ecklonia cava gametophytes in Korea

The objective of this study was to examine the ef fects of temperature and light intensity on growth of female gametophytes of Eisenia bicyclis and Ecklonia cava and responses of these female gametophytes to Fe addition and daylength. Female gametophytes of each species were cultured at four temperatures(10, 15, 20, and 25°C) and under a combination of four light intensities(10, 20, 40, and80 μmol photons/(m 2 ·s)) with two temperatures(15 and 20°C for E i. bicyclis; 20 and 25°C for E c. cava) to clarify their optimal growth conditions. Growth and maturation of female gametophytes of these two species under a combination of five Fe-EDTA concentrations(0, 1, 2, 4, and 8 μmol/L) and three daylengths(10,12, and 14 h) were also examined. The growth of E i. bicyclis gametophyte was maximal at approximately15–20°C, 20 μmol photons/(m 2 ·s), Fe-EDTA concentration of 8 μmol/L and daylengths of 12–14 h. While E c. c ava gametophytes showed optimal growth at approximately 20–25°C, 20 μmol photons/(m 2 ·s), FeEDTA concentration of 8 μmol/L and daylength of 14 h. Maturation of gametophytes was enhanced at Fe-EDTA concentration of 4 μmol/L for E i. bicyclis and at 2 μmol/L for E c. c ava. In conclusion, optimal growth temperatures and Fe-EDTA concentrations for maturation of E i. bicyclis and E c. c ava gametophytes were dif ferent. Higher optimal growth temperature for E c. c ava gametophytes may contribute to its wider geographical distribution compared to E i. bicyclis which has restricted habitats in Korea. This suggests that addition of Fe ion could be used to recover beds of these two species in barren grounds of Korea.     

日本海西部大陆坡自生碳酸盐的特征与成因

对日本海西部大陆坡沉积物柱状样中的自生碳酸盐样品进行了X射线衍射、扫描电镜、地球化学和碳氧同位素组成的系统研究。X射线衍射和扫描电镜分析结果表明,碳酸盐主要组成矿物为颗粒状自生高镁方解石微晶,放射状自生文石微晶仅在一个层位出现。结合碳酸盐的地球化学组成,认为研究区碳酸盐来自于富Ca2+、Mg2+和HCO3-流体的沉淀。中度亏损的13C (-33.85‰~-39.53‰)表明碳来自于甲烷的厌氧氧化,同时,这也是研究区海底存在甲烷冷泉的重要证据。重氧同位素比值(5.28‰~5.31‰)则指示着富18O流体来源,而该流体应源于天然气水合物的分解。综上可知,研究区碳酸盐来自于研究区甲烷冷泉上升流的沉淀,指示着海底更深处天然气水合物的存在与分解。     

Preliminary Results of the Ground-Based Orographic Snow Enhancement Experiment for the Easterly Cold Fog （Cloud） at Daegwallyeong during the 2006 Winter

The snow enhancement experiments, carried out by injecting AgI and water vapor into orographically enhanced clouds (fog), have been conducted to confirm Li and Pitter’s forced condensation process in a natural situation. Nine ground-based experiments have been conducted at Daegwallyeong in the Taebaek Mountains for the easterly foggy days from January–February 2006. We then obtained the optimized condi- tions for the Daegwallyeong region as follows: the small seeding rate (1.04 g min-1) of AgI for the easte...