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1.
N. VANDENBERGHE 《Sedimentology》1975,22(4):615-622
Grain-size data of Boom clay (Belgium) are represented on CM, AM, LM diagrams as suggested by Passega. They show a typical ‘uniform suspension’ pattern. It is argued that a ‘uniform suspension’ pattern can be due simply to the clay-rich nature of the sediments. As these sediments are not deposited by a single transport mechanism, the ‘uniform suspension’pattern does not necessarily indicate a specific transport mechanism. 相似文献
2.
何瑞霞 金会军 蒋观利 张泽 陈雪梅 Raul David SERBAN Mihaela SERBAN Jef VANDENBERGHE Valentin V.SPEKTOR Hugh M.FRENCH 《冰川冻土》2021,43(1):263-273
冰缘遗迹（特别是冷生楔形构造及融冻褶皱）是重建古气候及第四纪晚期多年冻土环境的重要证据。内蒙古鄂尔多斯高原是我国北方地区冰缘现象最为发育的地区之一。为准确了解鄂尔多斯高原冰缘遗迹类型及其分布特征、区域冻土演化历史等,中国科学院西北生态环境资源研究院和荷兰自由大学共同组成科研小组,于2018年5—6月组织了“鄂尔多斯高原冰缘遗迹科学考察”。考察区域涉及靖边—城川—乌审旗—鄂尔多斯东胜区一带约12 000 km2的范围。考察内容主要包括鄂尔多斯高原冰缘遗迹类型及特征、分布区域、各类型冰缘遗迹所指示的气候条件的初步推断等。结果表明：冻融褶皱和冷生楔体构造是鄂尔多斯高原主要存在的两大类冰缘遗迹。基于本次考察中关于冰缘遗迹的分布与特征等新发现,并综合前人研究成果,初步推断：在气温极低、多年冻土非常发育的时段,有利于形成各类冷生楔状构造,如冰楔假形和大型原生砂楔等;在气候转暖、多年冻土退化,但还没有全部融化完阶段,可能形成融冻褶皱;区域性大面积分布和成群出现的融冻褶皱一般反映较暖气候环境下,多年冻土层上部已退化到一定程度。基于光释光（OSL）年代测试结果,结合冰缘遗迹的特征及其所指示的古气候环境,初步重建了鄂尔多斯5万年以来的冻土环境变化序列。区内多年冻土在多年冻土最大期（LPM,25~19 ka BP）时最发育,以大面积连续多年冻土为主;之后,随气温转暖,总趋势呈退化状态,多年冻土分布逐渐变为片状→岛状→零星斑状,直至现今全部融完变为深季节冻土区。 相似文献
3.
C. VAN CROMPHAUT V. G. DE RESENDE E. DE GRAVE R. E. VANDENBERGHE 《Meteoritics & planetary science》2007,42(12):2119-2123
Abstract— –Meridiani Planum is the first iron meteorite found on Mars. It was discovered in 2005 by the Mars Exploration Rover Opportunity (MER‐B). Mössbauer spectra (MS) of the unbrushed and brushed meteorite species were acquired in 10 degrees temperature windows in the range of 210–260 K. Earlier examinations of these MS have led to the conclusion that the meteorite, which contains ～～7 wt% Ni, belongs to the IAB meteorite group. Here, making use of a recently developed calibration/folding procedure for MER MS, we report the results of the MS analyses for the single temperature windows m5 (210–220 K), m6 (220–230 K), m7 (230–240 K), and m89 (240–260 K). All spectra consist of a sextet and a ferric doublet. The hyperfine field of the sextet, extrapolated to room temperature, is ～～34.5 T, which is, based on Mössbauer studies of meteorites found on Earth, indeed consistent with the presence of kamacite. The fractional spectral area of the sextet is ～～0.96 of the total spectrum. The ferric doublet has an average quadrupole splitting of 0.70 mm/s and is not diagnostic of any specific Fe mineral. 相似文献
4.
<正>The Huang Shui River,a main tributary of the Yellow River,crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation.The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping.Three terraces in the Haiyan Basin,four terraces in the Huangyuan Basin,19 terraces in the Xi'ning Basin(the four high terraces may belong to another river),nine terraces in the Ping'an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized.Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River,which is located at the margin of Tibet,are different from that of the rivers at other regions.The formation process of the terrace is more complicated at the Huang Shui catchment:both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins,indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins.A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper.First,the equilibrium state of the river is broken because of climatic change and/or tectonic movement,and the river incises in all basins in the whole catchment until reaching a new equilibrium state.Then,the downstream basin subsides quickly and the equilibrium state is broken again,and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again.Finally,the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins.The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment.These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin.Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau. 相似文献
5.
JEF VANDENBERGHE PETER VAN DEN BROEK 《Boreas: An International Journal of Quaternary Research》1982,11(4):299-315
In three excavations in the southern Netherlands and northern Belgium, the Weichselian convolutions in fine sand, silt and clay deposits were investigated, and an attempt was made towards a semi-quantitative approach to some sediment parameters. This, together with a detailed field survey, enabled interpretation of the deformations as forms of periglacial loadcasting. They originated from the time of permafrost degradation when large quantites of water were available. The amplitude of the involutions can be related to the depth of the permafrost table at that time. During the weichselian, two periods occurred in which this involution process could have been active 相似文献
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7.
Comparison of laser grain size analysis with pipette and sieve analysis: a solution for the underestimation of the clay fraction 总被引：54，自引：1，他引：54
Classically, the grain size of soil and sediment samples is determined by the sieve method for the coarse fractions and by the pipette method, based on the ‘Stokes’ sedimentation rates, for the fine fractions. Results from the two methods are compared with results from laser diffraction size analysis, which is based on the forward scattering of monochromatic coherent light. From a point of view of laboratory efficiency, the laser sizing technique is far superior. Accuracy and reproducibility are shown by measurements on certified materials. It appears that laser grain size measurements of certified materials correspond very well with the certificated measurements. Tests were also done on a set of randomly selected sediments of fluvial, aeolian and lacustrine origin. Except for the (<2 μm) clay fraction, there is a coarsening of the mean diameter of one to two size classes (0.25 ?), caused by the non-sphericity of the particles. The platy form of the clay particles induces considerable differences (eight size classes) between pipette and laser measurements: the <2 μm grain size, defined by the pipette method corresponds with a grain size of 8 μm defined by the Laser Particle Sizer for the studied sediments. Using a higher grain size level for the clay fraction, when laser analysis is applied, enables workers in the geological and environmental field to compare classical pipette analysis with a laser sizing technique. 相似文献
8.
DAMASCENO DIMITRI; SCOATES JAMES S.; WEIS DOMINIQUE; FREY FREDERICK A.; GIRET ANDRE 《Journal of Petrology》2002,43(7):1389-1413
Phenocryst compositions and mineral–melt equilibria inthe mildly alkalic basalts from the 25 Ma Mont Crozier sectionon the Kerguelen Archipelago are used to estimate the depthsat which magmas stalled and crystallized and to constrain therole of crustal structure in the evolution of magmas producedby the Kerguelen mantle plume. The Crozier section, of nearly1000 m height, consists of variably porphyritic flows (up to21 vol. % phenocrysts), dominated by plagioclase ± clinopyroxene± olivine ± Fe–Ti oxides. Feldspars showan extreme range of compositions from high-Ca plagioclase (An88)to sanidine and variable textures that are related to extensivefractionation, degassing, and mixing in relatively low-pressure(sub-volcanic) magma chambers. Although clinopyroxene is a minorphenocryst type (0–3 vol. %), its non-quadrilateral components,principally Al (1·9–8·6 wt % Al2O3), varywidely. The results of clinopyroxene–liquid thermobarometryand clinopyroxene structural barometry indicate that the Croziermagmas crystallized at pressures ranging from 相似文献
9.
JEF VANDENBERGHE SJOERD BOHNCKE WIM LAMMERS LIESBETH ZILVERBERG 《Boreas: An International Journal of Quaternary Research》1987,16(1):55-67
Vandenberghe, Jef, Bohncke, Sjoerd, Lammers, Wim & Zilverberg, Liesbeth 1987 03 01: Geomorphology and palaeoecology of the Mark valley (southern Netherlands): geomorphological valley development during the Weichselian and Holocene. Boreas , Vol. 16, pp. 55–67. Oslo. ISSN 0300–9483.
The actual area of the Mark valley is limited by the borders of an Early Weichselian erosion phase. The subsequent accumulation has resulted in the formation of a Weichselian Pleniglacial terrace which has been deeply dissected by Late Glacial erosion. The present alluvial plain is formed by Late Glacial and Holocene infilling. The maximum incision of the Late Glacial fluvial phase was reached slightly before 11,780 B.P. and involved locally dry conditions which have given rise to aeolian activity during this period (Older Dryas). On the deepest parts of the Pleniglacial terrace, a backswamp environment was established until the end of the Alleröd. At the beginning of the Younger Dryas the river invaded the terrace but shortly afterwards aeolian activity progressively increased. At the climax of the Younger Dryas, deep seasonal frost or local permafrost characterized the Mark valley. 相似文献
The actual area of the Mark valley is limited by the borders of an Early Weichselian erosion phase. The subsequent accumulation has resulted in the formation of a Weichselian Pleniglacial terrace which has been deeply dissected by Late Glacial erosion. The present alluvial plain is formed by Late Glacial and Holocene infilling. The maximum incision of the Late Glacial fluvial phase was reached slightly before 11,780 B.P. and involved locally dry conditions which have given rise to aeolian activity during this period (Older Dryas). On the deepest parts of the Pleniglacial terrace, a backswamp environment was established until the end of the Alleröd. At the beginning of the Younger Dryas the river invaded the terrace but shortly afterwards aeolian activity progressively increased. At the climax of the Younger Dryas, deep seasonal frost or local permafrost characterized the Mark valley. 相似文献
10.
JAN-PIETER BUYLAERT GUNTHER GHYSELS REW S. MURRAY KRISTINA J. THOMSEN DIMITRI VANDENBERGHE FRANS DE CORTE IRENÉE HEYSE PETER VAN DEN HAUTE 《Boreas: An International Journal of Quaternary Research》2009,38(1):160-175
We report on quartz Optically Stimulated Luminescence (OSL) dating of the infill of 14 relict sand wedges and composite-wedge pseudomorphs at 5 different sites in Flanders, Belgium. A laboratory dose recovery test indicates that the single-aliquot regenerative-dose (SAR) procedure is suitable for our samples (measured to a given dose ratio 0.980 ± 0.005; n =139). Completeness of resetting of the wedge infill of two samples was confirmed by single-grain analyses. The suite of optical ages indicates that repeated thermal contraction cracking, degradation and infilling with wind-blown sediment appear to have been commonplace in Flanders during the Late Pleniglacial (Oxygen Isotope Stage 2; OIS2); more specifically, around the Last Glacial Maximum (LGM, ∼21 kyr ago) and the transition period between the LGM and the start of the Lateglacial (∼15 kyr ago). Optical dating at one site has revealed two significantly older wedge levels, the younger inset into the older; the younger wedge has an age of 36 ± 4 kyr (Middle Pleniglacial; OIS3), the older wedge 129 ± 11 kyr, which points to formation during the Late Saalian (OIS6). Our OSL ages of the wedges and host sediments bracket formation of the BGB (Beuningen Gravel Bed: a widespread deflation horizon in northwestern Europe) at between ∼15 and 18 kyr; this is in good agreement with previous OSL dating studies. We conclude that optical dating using quartz SAR OSL establishes an absolute chronology for these periglacial phenomena and allows secure palaeoenvironmental reconstructions to be made. 相似文献