The periglaciation of Great Britain. Colin K. Ballantyne and Charles Harris. Publisher Cambridge University Press,Cambridge 1994 (330 pp) £50.00/37.50 to QRA and BGRG Members (hardback) ISBN 0-521-32459-9 (also available in paperback)     

Eduard Koster 《第四纪科学杂志》1995,10(1):91-91

  相似文献   

A 6000-year record of ecological and hydrological changes from Laguna de la Leche, north coastal Cuba     

Matthew C. Peros  Eduard G. Reinhardt 《Quaternary Research》2007,67(1):69-82

Laguna de la Leche, north coastal Cuba, is a shallow (≤ 3 m), oligohaline (∼ 2.0-4.5‰) coastal lake surrounded by mangroves and cattail stands. A 227-cm core was studied using loss-on-ignition, pollen, calcareous microfossils, and plant macrofossils. From ∼6200 to ∼ 4800 cal yr BP, the area was an oligohaline lake. The period from ∼ 4800 to ∼ 4200 cal yr BP saw higher water levels and a freshened system; these changes are indicated by an increase in the regional pollen rain, as well as by the presence of charophyte oogonia and an increase in freshwater gastropods (Hydrobiidae). By ∼ 4000 cal yr BP, an open mesohaline lagoon had formed; an increase in salt-tolerant foraminifers suggests that water level increase was driven by relative sea level rise. The initiation of Laguna de la Leche correlates with a shift to wetter conditions as indicated in pollen records from the southeastern United States (e.g., Lake Tulane). This synchronicity suggests that sea level rise caused middle Holocene environmental change region-wide. Two other cores sampled from mangrove swamps in the vicinity of Laguna de la Leche indicate that a major expansion of mangroves was underway by ∼ 1700 cal yr BP.  相似文献   

Comparison of in-situ Field Measurements of Soil Magnetic Susceptibility with Laboratory Data   总被引：1，自引：0，他引：1  

Kapička  Aleš  Petrovský  Eduard  Jordanova  Neli 《Studia Geophysica et Geodaetica》1997,41(4):391-395

Results of magnetic susceptibility mapping around a coal-burning power plant were used to verify the field in situ measurements with data acquired in laboratory on soil samples collected at approximately the same measurement grid sites at different distance from the source. This comparison enables quantifying the field data obtained using the Bartington MS2 meter and to relate them, at least approximately, to mass specific values. Moreover, it is shown that certain diversity in the grid points of field measurements and soil sampling can slightly bias the field measurements. However, this shift is of minor significance and Bartington field readings can be considered as reliable.  相似文献   

Implications for Deglaciation Chronology from New AMS Age Determinations in Central West Greenland     

Frank G.M. van Tatenhove  Jaap J.M. van der Meer  Eduard A. Koster 《Quaternary Research》1996,45(3):245-253

  相似文献   

Permafrost response to climate change in the Northern Tien Shan     

Eduard Severskiy 《寒旱区科学》2017,9(4):398-403

This paper presents the results of long-term studies on the response of mountain permafrost in the Northern Tien Shan to changes in climate. Significant warming has been observed in the region over the past 70 years. Records from the high-elevation weather stations Tuyuksu-1(3,450 m a.s.l.) and Mynzhylki(3,017 m a.s.l.) indicate a warming trend of 0.02 °C/a in the mean annual air temperature during this period. Permafrost temperatures have increased at a rate of about 0.01 °C/a over the 40-year observation period. The effects of local factors, including slope aspect, tectonic faulting, snow cover, and human activities, on the distribution of temperature and thickness of permafrost are discussed in the paper.  相似文献   

Volatiles in pillows of the Mid-Ocean-Ridge-Basalt (MORB) and vitreous basaltic rims     

Klaus Heide  Eduard Woermann† 《Chemie der Erde / Geochemistry》2008,68(4):353-368

Temperature-resolved analyses of volatiles from Mid-Ocean-Ridge-Basalt (MORB) and vitreous basaltic rims were carried out to investigate the total volatile contents of basaltic melts and the influence of magma contamination on the degassing behaviour of volcanic rocks.With respect to the sources of methane evolution from the MORB the investigations are taken into consideration, the hydrocarbon (HC) release especially from the melt.The current paper presents data for H₂O, CO₂, SO₂, He, H₂, HF, HCl, CO, N₂, O₂, and HC degassing profiles of samples from the MORB sampling cruise 02.10.1983-11.11.1983 with FS Sonne 28 during the GEMINO-1 project near the Carlsberg Ridge (CR) and the Mid-Indian-Ocean-Ridge (MIOR).It aims to estimate the magnitude and nature of source magma volatiles and contamination (crustal material, seawater, atmospheric gases).The degassing of H₂O, CO₂, HCs as well as sulphur and chlorine species, or O₂ from vitreous specimens shows characteristic differences associated with sample position with respect to the lava surface.From the water release by bubbling and diffusion above 700 °C it must be concluded that any assimilation of sea water in vitreous rim is very low. The water content in the vitreous rim is about 0.1-0.2 wt%. The low interaction of melt with sea water is supported by the missing of a significant release of chlorine species during the heat treatment of the sample up to 1450 °C.Mixed H₂O/CO₂ bubbles escape between 700 and 800 °C from the vitreous rim. The CO₂ release in the temperature range of 1060-1170 °C from the basalt and the vitreous rim is interpreted as an indication for the primary carbon-dioxide content in the melt.Above 1100 °C CO₂ and SO₂ are evolved by both diffusion and small bubbles. The quantities of CO₂ in the vitreous rim and the basalt are similar (between 0.05 and 0.15 wt%), whereas the quantities of SO₂ escaping both from the vitreous rim and the crystalline basalt are between 0.013 and 0.024 wt%.Simultaneous with the CO₂ release by bubbling, HC species, especially CH fragments, were observed. The fact that the temperature of release maxima are above 1050 °C in both the vitreous rim and in the basalt is an indication for a geogenetic origin of HCs, e.g. methane.A low temperature of release for methane, which is consistent with biogenetic HC, was observed from the gas-release profiles of the basalts only. The maxima of the low-temperature gas releases are between 80 and 200 °C with a high correlation between the fragments m/z 13 and m/z 15. This correlation is a significant indication for a methane release.The oxygen release profiles of vitreous and crystalline basalts give significant indications for oxygen fugacity below the (QMF) of basaltic magma.Secondary minerals, generated by alteration of basaltic rocks, can be characterized by gas release profiles (GRPs) due to their decomposition in the temperature range below 800 °C. Only in the basalt were there observed indications of alteration processes. Small traces of carbonates (<0.0001 wt%) were detected by the gas release during the decomposition.Processes of degassing at temperatures higher than 800 °C are correlated to volatiles in the melt and to fluid inclusions of the minerals. There are no obvious correlations in the degassing characteristics between H₂O, CO₂ and SO₂. The different maxima of the degassing velocity, especially of CO₂, and SO₂, are indications of the different bonding forces of the site occupancy of the volatiles in the melt and in the glass. A micelle model for bonding sites in the basaltic glass for dissolved volatiles is discussed.  相似文献   

Iron titanium oxides in equilibrium with metallic iron     

Bruno Simons  Eduard Woermann 《Contributions to Mineralogy and Petrology》1978,66(1):81-89

The iron titanium oxide phases ulvite, ilmenite and ferropseudobrookite were synthesized in equilibrium with metallic iron at 1000 ° C, 1130 ° C and 1300 ° C in CO₂/H₂ gas mixtures.The composition of the phases were determined by wet chemical and electron microprobe analyses and by direct oxygen determination.The chemical composition of the Fe-Ti oxide phases in equilibrium with metallic iron is sensitively influenced by temperature and by bulk composition.Ulvite in equilibrium with wüstite does not contrivalent titanium in the whole temperature range up to the eutectic temperature at 1312 °C.Ulvite+ilmenite phase assemblages contain trivalent titanium only at temperatures above 1200 ° C.A ferropseudobrookite phase is stable under the given conditions at temperatures above 1068 °C (Ender and Woermann, 1977).Ferropseudobrookite in equilibrium with metallic iron always contains trivalent titanium.Deviations from stoichiometric compositions of the solid solution phases are generally small. Thus recalculation of microprobe data to stoichiometric solid solutions does not involve a major error.From: Bruno Simons, Diplomarbeit Aachen, October 1974  相似文献   

The effect of syndepositional deformation within the Upper Permian Capitan Platform on the speleogenesis and geomorphology of the Guadalupe Mountains, New Mexico, USA     

Eduard Ko&#x;a  David W. Hunt 《Geomorphology》2006,78(3-4):279-308

The Guadalupe Mountains in New Mexico and Texas are home to more than 300 caves. Caves have been formed within the Upper Permian Capitan carbonate platform and are oriented along two structural trends, one of which is parallel to the platform margin and the other of which is roughly perpendicular to it. Our recent studies of the Capitan Platform have identified syndepositional faults associated with growth monoclines and synclines in Slaughter Canyon, New Mexico, and these are also parallel to the platform margin. In this study, we demonstrate that syndepositional faults and folds are also present in Rattlesnake and Walnut Canyons, as much as 19 km along strike, and that they have exerted control on karstification of the Guadalupe Mountains from the Upper Permian until present.Three distinctive episodes of karst formation have been recognised in outcrops on the basis of karst-filling deposits and crosscutting relationships. The syndepositional “Phase 1 karst” was formed along syndepositional faults and fractures and is filled by platform-derived sediments. The burial “Phase 2 karst” is filled by post-Permian siliciclastics and is limited to the youngest syndepositional faults and fractures that penetrate the platform in the proximity of its terminal margin. Connectivity of these youngest faults and fractures to the platform top and the overlying stratigraphy is inferred to have controlled the distribution of the Phase 2 karst. The “Phase 3 karst” includes the present cave systems, which were mainly formed by sulphuric acid produced by mixing of fossil and fresh underground waters in conjunction with the uplift of the Guadalupe Mountains in the Late Tertiary, and have since been modified by vadose karst processes. The Phase 3 karst caves are not solely developed along syndepositional faults and fractures as the earlier karst palaeocaverns are, but also follow another, uplift-related, structural trend.Syndepositional folds, faults, and fractures in the Capitan Platform have influenced the shaping of the modern surface geomorphology of the Guadalupe Mountains by controlling drainage and, hence, erosion. Trellis drainage parallel to the platform margin is developed where syndepositional folds, faults, and fractures occur. The morphology of the trellis drainage varies systematically across the range in response to the character of the deformation structures and karst features along which the drainage channels have developed.  相似文献   

Distribution of Al between coexisting micas in metamorphic rocks from the Central Alps     

Eduard Wenk 《Contributions to Mineralogy and Petrology》1970,26(1):50-61

In 61 pairs of coexisting biotites and muscovites from the Central Alps total Al scatters considerably, but in both series a gradual increase is noticed with increasing metamorphic grade. The ratio Al _Mu ^tot /Al _Bi ^tot remains virtually constant (1.61 average for greenschist facies, 1.57 for amphibolite facies). Tetrahedral Al varies little in biotites and increases in muscovites-phengites with rising metamorphic grade; accordingly the ratio Al _Mu ^IV /Al _Bi ^IV increases slightly with grade. Far the best control of metamorphism is evidenced by octahedral Al. In the muscovite series, and still more pronounced in the biotite series, Al^VI increases with increasing metamorphic grade. Consequently 1 $$K_D = \frac{{Al_{Mu}^{VI} }}{{Al_{Bl}^{VI} }}$$ decreases from 14 to 3. A map (Fig. 6) representing the regional distribution of the K_D values locates a 100 km long and 23 km broad central zone with low K_D. The outline of this central core almost coincides with the isograds anorthite-diopside-calcite and labradorite-pyroxene-hornblende of the Tertiary regional metamorphism; with some deviations this core also agrees with the zone in which phenomena of partial anatexis are observed. The K_D values of micas from anateotic pegmatites agree with those of associated gneisses and schists. The study demonstrates that in the course of progressive regional metamorphism equilibrium has been approached to an unexpected extent and that the two micas coexisted in a strict sense.  相似文献   

Fluctuations of electrical conductivity as a natural tracer for bank filtration in a losing stream     

Tobias Vogt  Eduard Hoehn  Philipp Schneider  Anja Freund  Mario Schirmer  Olaf A. Cirpka 《Advances in water resources》2010

A key parameter used in the assessment of bank filtration is the travel time of the infiltrated river water during the passage through groundwater. We analyze time series of electrical conductivity (EC) in the river and adjacent groundwater observation wells to investigate travel times of young hyporheic groundwater in adjoining channelized and restored sections of River Thur in North-East Switzerland. To quantify mixing ratios and mean residence times we perform cross-correlation analysis and non-parametric deconvolution of the EC time series. Measurements of radon-222 in the groundwater samples validate the calculated residence times. A simple relationship between travel time and distance to the river has not been observed. Therefore, we speculate that the lateral position and depth of the thalweg as well as the type of bank stabilization might control the infiltration processes in losing rivers. Diurnal oscillations of EC observed in the river and in nearby observation wells facilitate analyzing the temporal variation of infiltration. The diurnal oscillations are particularly pronounced in low flow situations, while the overall EC signal is dominated by individual high-flow events. Differences in travel times derived from diurnal and overall EC signals thus reflect different infiltration regimes.  相似文献