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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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01 Jan 1971
TL;DR: In this paper, the Stafford Clay marker bed from the Middle Coal Measures of North Staffordshire and the Woolhope Bentonite from the Silurian, Wool-hop Limestone near Woolhop in Herefordshire are described.
Abstract: Two clay deposits, the Stafford Clay marker bed from the Middle Coal Measures of North Staffordshire and the Woolhope Bentonite from the Silurian, Woolhope Limestone near Woolhope in Herefordshire are described. These clays contain mixed-layer clay minerals which have been separated by sedimentation for mineralogical and chemical analysis. Both minerals are shown to be mica-montmorillo- nites with MacEwan stacking parameters P,~ = 0.59, PAA = 0.44 and PA = 0-56, PaA = 0'70 respectively. In both cases the average layer charge (1"22 and 1"46) is intermediate between that of montmorillonites and micas but the exchangeable cation layer charge (1'07 and 1"27/montmorillonite layer) and fixed cation layer charge (1"32 and 1-63/mica layer) of the component layers are higher and lower respectively than the normal range of montmorillonites and micas. Some chemical data are given for the raw material which yielded these minerals and for associated and related rocks. In particular K, U and Th determinations permit a discussion of the natural gamma-ray flux which is sufficiently more intense than that of the associ~.ted sediments to permit its detection by scintillation counter in the field.
6 citations
TL;DR: The high organic C content in the clay fractions could be due to biological activity in the fissural filling or to organic acids transported from the topographic surface by the percolating water.
Abstract: The clayey fissural fillings ( 18 O data obtained from the quartz vein and the 2 ++ phosphate precipitation. The high organic C content in the clay fractions could be due to present biological activity in the clayey fissural filling or to organic acids transported from the topographic surface by the percolating water. In this last case, organie-clay complexes would probbly be formed.
6 citations
01 Mar 1985
TL;DR: Chennaux et al. as mentioned in this paper studied the vertical and lateral variation and evolution of the sedimentation at the DSDP sites and pointed out three main breaks in the general evolution of sedimentation: the first, corresponding to the lower/middle Eocene boundary, is marked by the increase of carbonates and associated elements; the second, corresponding with a major decrease of the smectite/(illite + chlorite) ratio at all sites and by a massive appearance of quartz at Site 548; and the third, which occurred toward the late Pliocene, is
Abstract: Cenozoic sediments recovered from Sites 548, 549, and 550 were the objects of mineralogical (bulk sample and <2-μm fraction) and geochemical (HCl extract) studies. Thin sections of rock pebbles embedded in sediments (upper levels at Site 548, particularly) were examined on a polarizing microscope. This study outlines the vertical and lateral variation and evolution of the sedimentation. In the Paleocene and lower Eocene, the clay fraction is abundant and smectite is practically the sole existing clay mineral. High Mn, Al, Fe, Mg, and K contents were measured in HCl extracts. Through the middle Eocene, carbonates become more abundant—highly dominant at Site 548. Metal contents in HCl extracts are very low. The clay fraction, although dominated at all sites by smectites, becomes richer in illite and poorly crystallized chlorite. At the middle/upper Miocene boundary, a significant decrease in the smectite/(illite + chlorite) ratio occurs at all sites, and this decrease continues into the middle Pliocene. This decrease is marked by an abrupt increase of quartz at Site 548. At the two other sites, carbonates remain highly predominant; HCl extracts reflect the relative abundance of the clay and carbonate fractions. After a brief recurrence of smectite in a high-metal-content interval, illite and chlorite become the dominant clay minerals in the upper Pliocene and the Pleistocene, where numerous variations in mineralogical composition occur in the clay fraction (Sites 548 and 549) or in non-clay components (Site 548). Several pebbles of various nature and origin, encountered in different levels of this interval at Site 548, appear to have an ice-rafting origin. This study points out three main breaks in the general evolution of the sedimentation: the first, corresponding to the lower/middle Eocene boundary, is marked by the increase of carbonates and associated elements; the second, corresponding to the middle/upper Miocene boundary, is marked by a major decrease of the smectite/(illite + chlorite) ratio at all sites and by a massive appearance of quartz at Site 548; and the third, which occurred toward the late Pliocene, is marked by the dominance of primary clay minerals and the arrival of ice-rafted pebbles. Our interpretation of results considers paleohydrological and paleoclimatic phenomena. It is suggested that the major middle/late Miocene break was associated with an increase of the deep bottom-water circulation between the Norwegian Sea and the North Atlantic Ocean, and/or a climatic evolution: humidification and cooling of climate. The changes toward the late Pliocene appear to have been the first effects of the glaciations at the end of Cenozoic. INTRODUCTION Previous mineralogical studies of sediments recovered at DSDP sites have provided numerous data on the evolution of the northeastern Atlantic deposits since the Mesozoic (Fan and Zemmels, 1972; Chamley et al., 1979; Latouche and Maillet, 1979; Cassat, 1979). Major modifications in mineralogical assemblages have been recognized in the Cenozoic, particularly between sediments deposited before and after the important hiatuses that often interrupt the stratigraphic series in the vicinity of the Paleogene/Neogene boundary (van Andel, 1975). These mineralogical changes have been interpreted by Latouche and Maillet (1978, 1980, 1982) as regional consequences of the general paleoclimatic and paleohydrological evolution of the North Atlantic Ocean (Berg1 Graciansky, P. C. de, Poag, C. W., et al., Init. Repts. DSDP, 80: Washington (U.S. Govt. Printing Office). 2 Addresses: (Chennaux and Esquevin) Société Nationale Elf-Aquitaine (Production) 64000 Pau, France; (Jourdan) Compagnie Française des Pétroles, 218-228 Avenue du HautLevèque, 33605 Pessac Cédex, France; (Latouche and Maillet) Institut de Géologie du Bassin d'Aquitaine, Université de Bordeaux I, 351 Cours de la Liberation, 33405 Talence Cedex, France. gren and Holister, 1974). The exact stratigraphic intervals in which these changes occurred have nevertheless not been well established. Leg 80 provides an opportunity to fill out previous data and interpretations as a consequence of fairly good recovery and of the critical location of the leg's drill sites with respect to the tropical-to-arctic climatic gradient. Cenozoic sediments recovered at Sites 548, 549, and 550 were the objects of mineralogical and geochemical studies. X-ray diffraction was used in the mineralogical analysis of 103 bulk-sediment samples and later of 167 samples of fine-grained fractions (< 2 μm). Titration of HCl extracts was used in the geochemical analysis of three drilling-site samples. Rock pebbles occurring in the upper sediment levels of the three sites were examined on a polarizing microscope (13 samples). Both mineralogical and geochemical studies were carried out in the three collaborating laboratories with which the authors are affiliated: (1) Compagnie Française des Pétroles: Paleocene, Eocene, and Oligocene; clay minerals and pebble petrographic determination; (2) Institut de Géologie du Bassin d'Aquitaine: Miocene, Pliocene, and Pleistocene; clay minerals; (3) Société Nationale Elf-Aquitaine: total-sediment and geochemistry analyses.
6 citations
Cites background from "The x-ray identification and crysta..."
...Minerals were identified on the basis of their typical reactions to classical treatment (Brown, 1961; Thorez, 1975)....
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05 Feb 1965-The Journal of the Japanese Association of Mineralogists,Petrologists and Economic Geologists
TL;DR: In this paper, it has been confirmed that a variety of sepiolite exhibiting a very low crystallinity and giving an irregularity of the structure on the X-ray patterns as compared to that of typical one, further, it would being considered also to be an incipient stage of the crystallization process from β-sepiolite to α-speniolite described in the literature, judging from microscopical observation, electron micrographs, chemical analysis data, thermobalance curve, differential thermal analysis curve and X-rays data.
Abstract: Sepiolite is a very rare mineral in Japan and only one occurrence has been reported hitherto. The sepiolite from the Oeyama nickel mine would be speculated to attribute its formation to the reaction between serpentine rock and supergene water descending along fissures in the rock, considering from its occurrence; and it has been confirmed to be a variety of sepiolite exhibiting a very low crystallinity and giving an irregularity of the structure on the X-ray patterns as compared to that of typical one, further it would being considered also to be an incipient stage of the crystallization process from β-sepiolite to α-sepiolite described in the literature, judging from microscopical observation, electron micrographs, chemical analysis data, thermobalance curve, differential thermal analysis curve and X-ray data.
6 citations
TL;DR: In this paper, natural bentonite clay was treated in order to remove impurities to increase the cation exchange capacity of the montmorillonite and to obtain a more effective radioactive cesium sorption.
Abstract: Natural bentonite clay was treated in order to remove impurities to increase the cation exchange capacity of the montmorillonite and to obtain a more effective radioactive cesium sorption. It was found that the treatment of the clay determines the amount of sorbed cesium. On the other hand it was shown that montmorillonites may retain cesium through several mechanisms which provide strongly retained cations occupying cationic sites into the clay structure or sorbed cesium which may be lost by purification treatments.
6 citations