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121.
The Shilu iron ore deposit, located in the western Hainan Province, South China, is one of the most important iron-ore mining districts in China not only for its huge reserves of hematite- rich ores, but also for its potentially economic significance of associated metals of copper, cobalt, nickel, silver, lead and zinc, and of non-metals of dolomite, quartzite,barite,gypsum and sulfur. 相似文献
122.
Jan Feranec Monika Kopecka Rumiana Vatseva Anton Stoimenov Jan Otahel Juraj Betak Karol Husar 《Central European Journal of Geosciences》2009,1(1):106-119
Landscape change assessment was conducted in selected areas of Slovakia and Bulgaria in 1990–2000 using CORINE land cover (CLC) data layer analysis. Assessment of causes that led to these changes was undertaken, with an emphasis on those that determined the extensification of agriculture. The LC data were obtained under the CLC90 and I&CLC2000 projects, jointly managed by the European Environment Agency in Copenhagen, Denmark and the Joint Research Centre of the European Commission in Ispra, Italy. The CLC1990-2000-changes data layer was generated by overlaying the CLC90 and CLC2000 data layers for change in areas of a minimum 5 ha. The analysed causes of changes (driving forces) were then classified. Land cover (LC) changes characterizing urbanization processes occurred only in the Trnava and Tatras areas. Intensification of agriculture was also higher in these two areas. LC changes characterizing the extensification of agriculture were dominant in Plovdiv and Trnava. Deforestation and forestation were identified in all areas (Trnava, Tatras, Plovdiv, and Burgas). The basic reasons of these changes were related to the transformation of national economies from being centrally planned to market controlled, following the fall of socialism and before the countries joined the European Union. 相似文献
123.
Artur Sobczyk Ryszard K. Borówka Janusz Badura Renata Stachowicz-Rybka Julita Tomkowiak Anna Hrynowiecka Joanna Sławińska Michał Tomczak Mateusz Pitura Mariusz Lamentowicz Piotr Kołaczek Monika Karpińska-Kołaczek Dariusz Tarnawski Marcin Kadej Piotr Moska Marek Krąpiec Krzysztof Stachowicz Bartosz Bieniek Krzysztof Siedlik Małgorzata Bąk Jan van der Made Adam Kotowski Krzysztof Stefaniak 《第四纪科学杂志》2020,35(4):539-558
The sedimentary succession exposed in the Gorzów Wielkopolski area includes Eemian Interglacial (MIS 5e) or Early Weichselian (MIS 5d–e) deposits. The sedimentary sequence has been the object of intense interdisciplinary study, which has resulted in the identification of at least two palaeolake horizons. Both yielded fossil remains of large mammals, alongside pollen and plant macrofossils. All these proxies have been used to reconstruct the environmental conditions prevailing at the time of deposition, as well as to define the geological context and the biochronological position of the fauna. Optically stimulated luminescence dating of the glaciofluvial layers of the GS3 succession to 123.6 ± 10.1 (below the lower palaeolake) and 72.0 ± 5.2 ka (above the upper palaeolake) indicate that the site formed during the Middle–Late Pleistocene (MIS 6 – MIS 5). Radiocarbon-dating of the lacustrine organic matter revealed a tight cluster of Middle Pleniglacial Period (MIS 3) ages in the range of ~41–32 ka cal bp (Hengelo – Denekamp Interstadials). Holocene organic layers have also been found, with 14C ages within a range of 4330–4280 cal bp (Neolithic). Pollen and plant macrofossil records, together with sedimentological and geochemical data, confirm the dating to the Eemian Interglacial. 相似文献
124.
Stress-induced proton disorder in hydrous ringwoodite 总被引:1,自引:1,他引:0
Monika Koch-Müller Sergio Speziale Fiorenza Deon Maria Mrosko Ulrich Schade 《Physics and Chemistry of Minerals》2011,38(1):65-73
We have measured in situ high-pressure IR absorption of synthetic hydrous (MgxFe1−x)2SiO4 ringwoodites (x = 0.00 to 0.61) up to a maximum pressure of 30 GPa. In our study, we combined the megabar-type diamond-anvil cell (DAC) with
conventional and synchrotron FTIR spectroscopy. The high-pressure measurements were performed in three different pressure-transmitting
environments: (1) CsI powder, (2) cryogenically loaded liquid argon, and (3) cryogenically loaded liquid argon annealed at
8.6 GPa at temperature of 120°C before further pressure increase. Between 10 and 12 GPa, all the samples loaded with methods
(1) and (2), independent on composition, showed a sudden disappearance of the prominent OH-stretching feature and simultaneous
discontinuities and/or changes in the pressure dependence of lattice vibrations compared with spectra of samples loaded with
method (3). In experiments performed with method (3) the OH-stretching vibrations as well as lattice vibrations could be observed
up to 30 GPa and their pressure behavior (dν/dP) can well be described by linear fits. Molecular vibrations, such as the OH stretching, are sensitive to non-hydrostatic
conditions, especially in minerals with highly symmetric structures. We interpret the disappearance of the OH bands using
methods (1) and (2) as a stress-induced proton disordering in hydrous ringwoodite. Our results confirm that argon pressure
medium produces strongly non-hydrostatic conditions comparable to CsI or KBr, if it is not thermally annealed at pressures
above 8 GPa. Our results suggest that the transition observed in hydrous Mg-ringwoodite end member is not present in compositions
containing Fe. By comparing the behavior of samples compressed in different environments, we suggest that sudden disappearance
of the OH-stretching band in hydrous ringwoodite could be driven by deterioration of the quasi-hydrostatic stress condition
instead of a pressure-induced effect. 相似文献
125.
Several samples of peat from 6 bogs located in southern Poland were investigated for occurrence and distribution types of biomarkers present in their extractable organic matter fraction. It was found that there are inputs from two different sources of organic compounds differing in their characteristics and origin: (1) recent immature peat organic matter deposited in situ which is the source of all polar functionalized compounds, most of n-alkanes, and acyclic isoprenoids, and (2) mature fossil fuels, most probably bituminous coals from the Upper Silesia Coal Basin of vitrinite reflectance equivalent values of 0.9–1.1%. The latter compounds were most probably transported with fly ash to bogs from nearby settlements utilizing such fuel in domestic ovens. This group includes pentacyclic triterpenoids (hopanes and moretanes), minor amounts of n-alkanes, and numerous alkyl naphthalenes and alkyl phenanthrenes. All these compounds show distributions and values of geochemical ratios characteristic for mature organic matter confirming there ex situ origin. 相似文献
126.
Manfred Wildner Gerald Giester Monika Kersten Klaus Langer 《Physics and Chemistry of Minerals》2014,41(9):669-680
Polarized electronic absorption spectra of colourless chalcocyanite, CuSO4, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm?1, which have been assigned to crystal field d–d transitions of Cu2+ cations in pseudo-tetragonally elongated CuO6 polyhedra with point symmetry C i ( \(\bar{1}\) ). The polarization behaviour is interpreted based on a D 2(C 2″) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a ‘classic’ pseudo-tetragonal crystal field approach yielding the parameters Dq (eq) = 910, Dt = 395, and Ds = 1,336 cm?1, corresponding to a cubically averaged Dq cub = 679 cm?1. A comparative survey on crystal fields in Cu2+ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu2+ minerals. The weak crystal field in CuSO4 can be related to the lower position of the SO4 2? anion compared to, e.g. the H2O molecule in the spectrochemical series of ligands. 相似文献
127.
Monika Arnez 《Singapore journal of tropical geography》2023,44(1):44-57
This article examines the ambivalent relationship between members of the Portuguese-Melakan Kristang minority and the state from the 1940s to the present day through the lens of ethnic politics. It reveals how ambivalent imaginaries of the future have shaped the politics of community members and what strategies they have used to assert their place. Moreover, it analyses how partly contradictory, partly converging imaginaries of the future of the Melaka coastline fuelled the failure of the Melaka Gateway land reclamation project. Grounded in ethnographic fieldwork in Melaka in 2018 and 2019, it focuses on the Melaka Gateway, a large-scale land reclamation project located in the Melaka Straits where three man-made islands and one natural island with high-rise buildings, a cruise terminal and a deep sea port have been planned. 相似文献
128.
We calculate the amount of methane that may form via reactions catalyzed by metal-rich dust that condenses in the wake of large cometary impacts. Previous models of the gas-phase chemistry of impacts predicted that the terrestrial planets' atmospheres should be initially dominated by CO/CO2, N2, and H2O. CH4 was not predicted to form in impacts because gas-phase reactions in the explosion quench at temperatures ∼2000 K, at which point all of the carbon is locked in CO. We argue that the dust that condenses out in the wake of a large comet impact is likely to have very effective catalytic properties, opening up reaction pathways to convert CO and H2 to CH4 and CO2, at temperatures of a few hundred K. Together with CO2, CH4 is an important greenhouse gas that has been invoked to compensate for the lower luminosity of the Sun ∼4 Gyr ago. Here, we show that heterogeneous (gas-solid) reactions on freshly-recondensed dust in the impact cloud may provide a plausible nonbiological mechanism for reducing CO to CH4 before and during the emergence of life on Earth, and perhaps Mars as well. These encouraging results emphasize the importance of future research into the kinetics and catalytic properties of astrophysical condensates or “smokes” and also more detailed models to determine the conditions in impact-generated dust clouds. 相似文献
129.
Roland Pail Thomas Fecher Michael Murböck Moritz Rexer Monika Stetter Thomas Gruber Claudia Stummer 《Studia Geophysica et Geodaetica》2013,57(2):155-173
The reprocessing of Gravity field and steady-state Ocean Circulation Explorer (GOCE) Level 1b gradiometer and star tracker data applying upgraded processing methods leads to improved gravity gradient and attitude products. The impact of these enhanced products on GOCE-only and combined GOCE+GRACE (Gravity Recovery and Climate Experiment) gravity field models is analyzed in detail, based on a two-months data period of Nov. and Dec. 2009, and applying a rigorous gravity field solution of full normal equations. Gravity field models that are based only on GOCE gradiometer data benefit most, especially in the low to medium degree range of the harmonic spectrum, but also for specific groups of harmonic coefficients around order 16 and its integer multiples, related to the satellite’s revolution frequency. However, due to the fact that also (near-)sectorial coefficients are significantly improved up to high degrees (which is caused mainly by an enhanced second derivative in Y direction of the gravitational potential — VYY), also combined gravity field models, including either GOCE orbit information or GRACE data, show improvements of more than 10% compared to the use of original gravity gradient data. Finally, the resulting gradiometry-only, GOCE-only and GOCE+GRACE global gravity field models have been externally validated by independent GPS/levelling observations in selected regions. In conclusion, it can be expected that several applications will benefit from the better quality of data and resulting GOCE and combined gravity field models. 相似文献
130.
Abstract Visualization techniques have been developed to recreate natural landscapes, but little has been done to investigate their potential for illustrating land cover change using spatio‐temporal data. In this work, remote sensing, geographic information systems (GIS) and visualization techniques were applied to generate realistic computer visualizations depicting the dynamic nature of forested environments. High resolution digital imagery and aerial photography were classified using object‐oriented methods. The resulting classifications, along with preexisting land cover datasets, were used to drive the correct placement of vegetation in the visualized landscape, providing an accurate representation of reality at various points in time. 3D Nature's Visual Nature Studio was used to construct a variety of realistic images and animations depicting forest cover change in two distinct ecological settings. Visualizations from Yellowstone National Park focused on the dramatic impact of the 1988 fire upon the lodgepole pine forest. For a study area in Kansas, visualization techniques were used to explore the continuous human‐land interactions impacting the eastern deciduous forest and tallgrass prairie ecotone between 1941 and 2002. The resulting products demonstrate the flexibility and effectiveness of visualizations for representing spatio‐temporal patterns such as changing forest cover. These geographic visualizations allow users to communicate findings and explore new hypotheses in a clear, concise and effective manner. 相似文献