Fossil diatom assemblages as paleoecological indicators of paleo-water environmental change in the Ulleung Basin,East Sea,Republic of Korea

The fossil diatom assemblage record from two sediment cores obtained from the Ulleung Basin, East Sea, Republic of Korea, revealed changes in the diatom assemblage zones in PG1 and PD3 core samples. The two sediment cores were δC¹⁴ dated and approximately represented the late Pleistocene–Holocene. The analysis of age zones in the PG1 core and PD3 core was assessed based on the frequency of variations, and occurrences of biostratigraphical fossil diatom species. During the Last Glacial Maximum (LGM), the sea level was lower than that at present and the Ulleung Basin became isolated from the Pacific Ocean. As a result, there would have been a limited Tsushima Warm Current (TWC) influence, and salinity would have decreased resulting in increased freshwater and coastal diatoms. The distribution pattern of diatoms presented in the cores was associated with changes in water temperature and salinity and the adding of terrigenous material brought about by the input of freshwater. Changes in the abundance of a tychopelagic diatom, Paralia sulcata, reflected the effect of the water currents. Diatom temperature (Td) values and the ratio of centric/pennate diatoms provided evidence of limited influences of the TWC and freshwater inflow. It is thought that all assemblage zones were influenced by the TWC, which had an important effect on the distribution and composition of fossil diatoms.     

Role of debris flow on the change of <Superscript>10</Superscript>Be concentration in rapidly eroding watersheds: a case study on the Seti River,central Nepal

The concentration of cosmogenic ¹⁰Be in riverine sediments has been widely used as a proxy for catchment-wide denudation rate (CWDR). One of the key assumptions of this approach is that sediments originating from sub-basins with different erosional histories are well mixed. A tragic debris flow occurred in the Seti River watershed, central Nepal, on May 5, 2012. This catastrophic debris flow was triggered by slope failure on the peak of Annapurna IV and resulted in many casualties in the lower Seti Khola. However, it provided an opportunity to test the assumption of equal mixing of sediments in an understudied rapidly eroding watershed. This study documents the CWDR of ¹⁰Be to evaluate the extent of the influence of episodic erosional processes such as debris flow on the spatio-temporal redistribution of 10Be concentrations. Our data show that the debris flow caused little change in CWDR across the debris flow event. In addition to isotopic measurement, we calculated denudation rates by using the modeled concentrations in pre- and post-landslide sediments based on the local 10Be production rate. The modeled result showed little change across the event, indicating that the debris flow in May 2012 played a minor role in sediment evacuation, despite the rapid erosion in the catchment. Our study concludes that although the 2012 event caused many casualties and severe damage, it was a low-magnitude, high frequency event.     

黄河、长江与韩国Keum、Yeongsan江沉积物常量元素地球化学特征

运用同样的样品采集和测试方法比较分析了我国的长江和黄河以及韩国的Keum和Yeongsan江的常量元素地球化学特征。韩国河流沉积物中Ca及碳酸盐含量显著低于长江和黄河,而其他元素含量则在二者之间;黄河沉积物以总无机碳(TIC)、Na和Ca含量高为特征,而长江沉积物则显著富集Ti和P。Keum和Yeongsan江沉积物中P、Ca、Fe和Mg在酸溶相中比例可达30％～66％,而K、Al和Ti则富集在残渣相中。韩国河流沉积物极低的Ca含量同流域缺乏碳酸盐源岩密切相关,其沉积物主要由侏罗一晚白垩纪的花岗岩经过中等程度的化学风化而成。虽然Ca在中韩河流沉积物之间含量差异显著,但必须谨慎运用全钙含量来识别海区物源。而沉积物中非碳酸盐态钙(Ca^*)及相应的K／Ca^*和Al／Ca^*比更适合用来示踪黄河及Keum和Yeongsan江沉积物;Ti则可以用来区分长江与其他河流沉积物。     

Three‐dimensional dynamic response of underground openings in saturated rock masses

In this paper a three‐dimensional dynamic analysis program for saturated porous rocks and soils is presented. The theoretical formulations incorporated in the proposed computer program are the extension of Biot's two‐phase theory to non‐linear region. Numerical study using the program is carried out to demonstrate the three‐dimensional features of the program and to show the effects of pore water on the dynamic response of underground openings in saturated rock masses. It is shown that underground openings in saturated porous media could be significantly more vulnerable to the potential damages associated with high motions and shear failure than those in dry media. Copyright © 2001 John Wiley & Sons, Ltd.     

The rare earth element compositions of the Changjiang (Yangtze) and Huanghe (Yellow) river sediments

Thirty-four samples from the Changjiang and Huanghe were analyzed to characterize their rare earth element (REE) compositions. Although REE concentrations in the Changjiang sediments are higher than those of the Huanghe sediments, the former are less variable. Bulk samples and acid-leachable fractions have convex REE patterns and middle REE enrichments relative to upper continental crust, whereas flat patterns are present in the residual fractions. Source rock composition is the primary control on REE composition, and weathering processes play a minor role. Grain size exerts some influence on REE composition, as demonstrated by the higher REE contents of clay minerals in sediments from both rivers. Heavy minerals contribute about 10-20% of the total REE in the sediments. Apatite is rare in the river sediments, and contributes less than 2% of the REE content, but other heavy minerals such as sphene, allanite and zircon are important reservoirs of residual REE fractions. The Fe-Mn oxides phase accounts for about 14% of bulk REE content in the Changjiang sediments, which could be one of the more important factors controlling REE fractionation in the leachable fraction.     

Untersuchungen am Tholeyit von Tholey (Saar)

Zusammenfassung Das Originalvorkommen des Tholeyits am Schaumberg bei Tholey (Saar) wurde auf seinen Mineralbestand und seine chemische Zusammensetzung hin untersucht. Dabei wurde festgestellt, daß nach der Intrusion in dem lagergang-förmigen Vorkommen eine gravitative Kristallisationsdifferentiation stattgefunden hat, deren Umfang von doleritischen Olivinbasalten über Tholeyite bis zu Latiten und Plagiapliten reicht. Die einzelnen Differentiationsprodukte wurden gegeneinander abgegrenzt und, gemäß ihrer Lage im System der magmatischen Gesteine, benannt. Dabei wurde der Original-Tholeyit definiert als ein hypabyssischer, leukokrater Vertreter der Mangeritfamilie. In seiner Nähe vorkommende Pigeonit-Tholeyite und intrusive doleritische Olivinbasalte wurden kurz mineralogisch und chemisch beschrieben. Die Unterschiede zu räumlich und systematisch benachbarten Gesteinen des Saar-Nahe-Pfalz-Gebietes, den Palatiniten und Naviten, wurden herausgestellt. Ein Vergleich mit anderen Tholeyiten und Abkömmlingen des tholeyitbasaltischen MagmasKennedys ergab, daß die Bezeichnung tholeyitbasaltisch irreführend ist, und daß in vielen Fällen auch Vertreter der Diorit- und Gabbrofamilie Tholeyit benannt wurden.     

Regional policy in the Federal Republic of Germany

Since the 1950s, regional policy in the Federal Republic of Germany has switched emphasis from assistance to specific locations with development problems to a systematic programme of development aid. Within the Common Task ‘Improvement of Regional Economic Structure’, which is undertaken jointly by the Federal and Laender governments, areas embracing 62% of the Federal Republic's total area have received aid for establishing new industries, expansion of existing manufacturing industry and rationalisation, and for developing tourism. Overall economic deterioration since the mid-'70s has been accompanied by increasing criticism of the inefficiency of this kind of regional policy directed towards the mobilisation of capital. More recent appraisals of methods improving development aid are aimed at achieving spatial concentration of the development areas, more selective aid for new establishments or expansion schemes which have sound future prospects, and increased encouragement to existing firms to innovate.     

Dynamic analysis of structures using modified Lanczos co‐ordinates

An efficient dynamic analysis method using the modified Lanczos co‐ordinates is presented. The proposed method is obtained by applying the modified Lanczos algorithm using Lanczos vectors that satisfy the stiffness‐orthonormality condition to the conventional Lanczos co‐ordinates method. The modified Lanczos co‐ordinates method is more efficient than the conventional method in the case of structures under multi‐input loads. The effectiveness of the modified Lanczos co‐ordinates method is verified by analysing a numerical example. Copyright © 2003 John Wiley & Sons, Ltd.