Stevns Klint Fish Clay (FC-1): Preparation of, and Preliminary Results for, a Candidate Reference Material     

Rajmund Gwozdz  Hans J. Hansen  Kaare L. Rasmussen 《Geostandards and Geoanalytical Research》2001,25(1):159-166

The collapse of a section of the cliff at Stevns Klint, Denmark in 1986 provided a unique opportunity to collect about 50 kg of Fish Clay representing the Cretaceous-Tertiary (K-T) boundary layer. In this paper, details of the preparation of this sample are presented, together with preliminary analytical results to support the development of this sample as a reference material, particularly for the determination of iridium and the other platinum-group elements in clays and sediments associated with K-T boundary studies and in other environmental samples collected to study the effects of automobile exhaust catalysts.  相似文献   

Distribution of clay minerals in surface sediments from the eastern Barents and south-western Kara seas   总被引：2，自引：0，他引：2  

D. Nürnberg  M. A. Levitan  J. A. Pavlidis  E. S. Shelekhova 《International Journal of Earth Sciences》1995,84(3):665-682

Surface samples from the eastern Barents and south-western Kara seas have been analysed for clay mineralogy. Transport paths, the role of regional sources and local bedrock outcrops and the influence of hydrodynamic and glacigenous processes for clay distribution on the shelves are discussed in relation to central Arctic Ocean deep sea and sea ice sediments. Franz Josef Land and Novaya Zemlya show significantly different clay mineral associations. Although smectite concentrations are fairly high, Franz Josef Land can be excluded as a source for central Arctic sea ice sediments, which are relatively rich in smectite. In the Kara Sea, smectite concentrations in coastal sediments surpass even the Franz Josef Land concentrations. The large cyclonic gyre in the eastern Barents Sea between Novaya Zemlya and Franz Josef Land, which serves as a mixing zone between Arctic and North Atlantic water, is apparently reflected within the smectite distribution pattern. With the exception of Franz Josef Land, the area of investigation is typically low in kaolinite. In particular, coastal areas and areas north of Novaya Zemlya, influenced by the inflow of Arctic waters, show the lowest kaolinite concentrations. A high kaolinite occurrence within the Nansen Basin is most probably related to Franz Josef Land and emphasizes the importance of long-range downslope transport of sediments across the continental slope. The surface water circulation pattern in close interaction with local outcrops onshore Novaya Zemlya and locally restricted occurrences within the eastern Barents Sea significantly alter the illite dispersal pattern. Illite concentrations are lowest around Franz Josef Land. Chlorite is generally low in the area of investigation. Submarine outcrops and important chlorite occurrences onshore Novaya Zemlya bias its distribution pattern.  相似文献   

Neoformation of montmorillonite by post-depositional subsurface weathering in a slope deposit in central France     

J. Sevink  J. M. Verstraten 《地球表面变化过程与地形》1978,3(1):23-29

Observations on an Early Quaternary slope deposit in the Massif Central indicated that the texture and mineralogy of this deposit have been seriously altered by post-depositional subsurface weathering. Analyses of clay fractions and water samples show that the montmorillonite present is a stable mineral in this environment and is, and has been, newly formed. As shown by water analyses from nearby sites, the chemical environment is strongly dependent on local factors. Consequently it can be seen that great care should be taken firstly in correlating different slope deposits on the basis of texture and clay mineralogy and secondly in using these parameters as (paleo) climatic indicators.  相似文献   

The Austin Chalk-Taylor Clay succession in Texas and the Santonian-Campanian boundary     

P. Marks  B. Stam 《Cretaceous Research》1983,4(3):271-279

Re-evaluation of samples from several Texas localities over the Austin Chalk-Taylor Clay boundary for planktic Foraminifera, and comparison with recent work on European and North African successions confirms the general correlation of the Texan formations with the European Stage succession. The sedimentary hiatus indicated by Pessagno (1967) does not appear to be present: the Late Santonian-Early Campanian zonal marker Globigerinita elevata (Brotzen) occurs in the Lower Taylor Clay associated with late representatives of Marginotruncana. The Lower Taylor Clay may belong to the Late Santonian in some localities.  相似文献   

Authigenic clays in East Africa: Regional trends and paleolimnology at the Plio–Pleistocene boundary, Olduvai Gorge, Tanzania     

Daniel M. Deocampo 《Journal of Paleolimnology》2004,31(1):1-9

Ultrafine clays (<0.1 m) from six East African basins show wide chemical variability that can be conveniently described as the octahedral cation index (OCI), calculated as octahedral element ratio Mg/(Al+Fe). Values range from dioctahedral clays with OCI < 0.1 (upland soils/detrital sources) to trioctahedral clays with OCI > 4 (saline, alkaline lake deposits). The association of Mg-rich clays with saline, alkaline conditions provides a paleochemical proxy in sedimentary contexts. The octahedral chemistry of central-basin clays from paleolake Olduvai (1.79 Ma) records two lake expansions, with an intervening lake contraction, over 18,000 years. The initial lake expansion correlates well with the marine record of increased African humidity, but the subsequent drying episode does not, suggesting that some high-frequency environmental oscillations in East Africa may occur independent of obliquity and precession control. The clay record correlates well with the fossiliferous and archaeologically rich stratigraphy of the lake margin, and suggests that fossils and artifacts accumulated on the exposed lake margin over <4000 years. The chemistry of clays is a potentially powerful tool to add to multi-proxy studies in basins with alkaline waters, particularly in stratigraphic intervals that lack pollen, calcareous, or siliceous microfossils.  相似文献   

Geomorphologic evidence of phased uplift of the northeastern Qinghai-Tibet Plateau since 14 million years ago   总被引：11，自引：0，他引：11  

LU Huayu  WANG Xiaoyong  AN Zhisheng  MIAO Xiaodong  ZHU Rixiang  MA Haizhou  LI Zhen  TAN Hongbing & WANG Xianyan . State Key Laboratory of Loess  Quaternary Geology  Institute of Earth Environment  Chinese Academy of Sciences  Xi''''an China  . Qinghai Institute of Salt Lakes  Chinese Academy of Sciences. Xining  China  . Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China  . Department of Geography  Qinghai Normal University  Xining  Chi 《中国科学D辑(英文版)》2004,47(9)

~~Geomorphologic evidence of phased uplift of the northeastern Qinghai-Tibet Plateau since 14 million years ago~~  相似文献   

A new species of Kimmeridgian pliosaur (Reptilia; Sauropterygia) and its bearing on the nomenclature of Liopleurodon macromerus     

L.F. Noè  D.T.J. Smith 《Proceedings of the Geologists' Association. Geologists' Association》2004,115(1):13-24

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Effects of clay mineral turbidity on dissolved organic carbon and bacterial production     

Todd Tietjen  Anssi V. Vähätalo  Robert G. Wetzel 《Aquatic Sciences - Research Across Boundaries》2005,67(1):51-60

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准噶尔盆地南缘新生界粘土矿物分布及影响因素   总被引：10，自引：8，他引：10       下载免费PDF全文

张立强  罗晓容  刘楼军  何登发  向宝力 《地质科学》2005,40(3):363-375

根据粘土矿物的相对含量研究了准噶尔盆地南缘新生界砂岩粘土矿物类型、组合特征及纵、横向分布规律及其主要影响因素。划分出无序伊/蒙混层型、部分有序伊/蒙混层型、伊利石+伊/蒙混层型、蒙皂石型以及含坡缕石型等5类粘土矿物组合。按照伊/蒙混层相对含量的变化,粘土矿物纵向上演化呈正常转化型(伊/蒙混层相对含量降低)、反向转化型(伊/蒙混层相对含量增加)和“S”型(伊/蒙混层相对含量呈曲线变化)3种形式。平面上,伊/蒙混层和伊利石这两类主要粘土矿物从湖盆的边缘向中心分别呈现减少和增多的趋势,湖盆边缘相带以无序伊/蒙混层型、蒙皂石型和含坡缕石型为主,湖盆中心则为部分有序伊/蒙混层型和伊利石+伊/蒙混层型组合等类型。上述分布规律的控制因素主要有沉积环境、构造运动及层序发育等。  相似文献   

Experimental study of migration of potassium ion through a two-layer soil system     

Yan Jun Du  Shigenori Hayashi  Song Yu Liu 《Environmental Geology》2005,48(8):1096-1106

A barrier system based on the hydraulic trap design concept for a landfill was proposed. To study the field scenario in which a clay liner is underlain by a granular layer functioning as a secondary leachate drain layer, a laboratory advection–diffusion test was performed to investigate factors controlling the transport of contaminants in a two-layer soil system. The soils used for this study were Ariake clay and, the underlying layer, Shirasu soil from the Kyushu region of Japan. Potassium (K⁺) was selected as the target chemical species with an initial concentration of 905 mg L⁻¹. The effective diffusion coefficients (D _e) of K⁺ for Ariake clay and Shirasu soil were back-calculated using an available computer program, Pollute V 6.3. Values of D _e derived from this experiment are consistent with previously published ones. The Ariake clay has lower D _e than the Shirasu soil. The hypothesis that mechanical dispersion can be considered negligible is reasonable based on both the observation that the predicted values well fit the experimental data and the analyses of two dimensionless parameters. Parametric analyses show that transport of K⁺ through soils is controlled by advection–diffusion rather than diffusion only, whereas at low Darcy velocity (i.e., ≤10⁻⁹ m s⁻¹), transport of K⁺ will be controlled by diffusion. Applications of the test results and parametric analysis results in practical situations were reviewed.  相似文献