Characteristics Of Clay Minerals Research Articles

Assemblage characteristics of clay minerals and its implications to evolution of eolian dust input to the Parece Vela Basin since 1.95 Ma

To understand the provenance and evolution of eolian input in the last 1.95 Ma in the Parece Vela Basin in the eastern Philippine Sea, the clay mineral assemblage of a gravity core PV090510 from the basin was investigated using paleogeomagnetic dating and X-ray diffraction. The assemblage of the core mainly consisted of smectite (46%) and illite (40%), with some chlorite (10%) and kaolinite (4%). Analysis of the provenance of these minerals suggested that smectite was mainly derived from volcanic rocks of the Mariana Arc, while illite, chlorite, and kaolinite were mainly transported as eolian dust by the East Asian monsoon from central Asia. We used the ratio of (illite+chlorite+kaolinite)/smectite as a proxy for Asian eolian input to the Parece Vela Basin since 1.95 Ma. This ratio followed glacial and interglacial cycles and was consistent with the intensity of the East Asian monsoon and aridity of central Asia since 1.95 Ma. The changes of the ratio reflected three different stages of the East Asian monsoon and provenance climate.

Chemico-mineralogical attributes of clays from the late Cretaceous–early Palaeogene succession of the Um Sohryngkew river section of Meghalaya, India: Palaeoenvironmental inferences and the K/Pg boundary

A continuous shallow marine 10 m thick succession within the Langpar Formation in the Um Sohryngkew river section of Meghalaya, containing late Maastrichtian through early Danian planktonic foraminiferal zones – CF4, CF3, CF2, CF1, P0, Pα and P1a and the K/Pg boundary (between CF1 and P0) that makes unique of its kind. The section has been re-studied and sampled for clay mineralogy to understand the palaeoenvironmental conditions prevalent in the region and to assess the K/Pg transition. The relative abundances of the clay mineral phases permitted a threefold sub-division of the studied section with a illite, illite/ smectite dominated lower part, illite, kaolinite and abundance of montmorillonite dominated middle part and kaolinite–montmorillonite dominated upper part. Enriched HREEs in the lower part of the succession suggest variations in the pH of alteration solutions. Most of the samples show positive cerium (δCe) and europium (δEu) anomalies, the former reflecting oxidizing conditions at the time of clay formation. Illite dominated clays present a positive Eu anomaly, formed at relatively higher temperatures than the clays with less illite and without Eu anomalies, whereas clays occurring in the lower and upper parts exhibit a prominent negative Eu anomaly. Shifts in the redox condition found in this section are more or less similar to the foraminiferal changes and Au, Pt, Pd anomalies. Clay mineralogical attributes and REE patterns, comparable to those of the known K/Pg boundaries, appeared within the CF3 and CF2 zones in the Um Sohryngkew river section. The sample at the boundary between CF3 and CF2 is marked by a negative <delta>Ce anomaly, high La/Yb and TOC values, suggesting that sea level rise during the upper part of CF3 was caused by tectonism rather than warming. The similar characteristics of clay minerals and REE patterns, attributed to the initiation of tectonic events during the CF3 zone, indicate environmental changes that affected the shelf area and the provenance of these sediments.

Spectral characteristics of clay minerals in the 2.5–14 μm wavelength region

Identification and quantification of clay minerals, particularly those that are responsible for susceptibility of soils to expansion and shrinkage, is a constant focus of research in geotechnical engineering. The visible, near infrared and short wave infrared wavelength regions are well explored. However, little is understood about the spectral characteristics of such clay minerals in the wavelength longer than 2.5 μm. The objective in this study was to explore the potential of laboratory spectroscopy in the 2.5–14 μm wavelength region for characterizing clay minerals. Montmorillonite, illite and kaolinite were investigated, for these clay minerals are key indicators of soil expansion and shrinkage potential. Characteristic absorption bands and their changes for mixtures of clay minerals were determined. Partial least squares (PLS) regressions in combination with continuum removal analyses were used to determine wavelength regions that best discriminate differences in mineralogical contents. Spectral contrast was high in the 3–5 μm wavelength region but overall low in the 8–14 μm. The clay minerals were characterized by strong, diagnostic absorption bands. Much of the variation in compositions of the mixtures was explained by the PLS models (coefficients of correlations of > 0.90). Thus, spectroscopy in the 2.5–14 μm wavelength region is a useful technique for characterizing clay minerals.

Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, i.e., from the Jurassic and Paleogene–Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals. Illite is the most widely spread clay mineral in this area. Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene–Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions, diagenesis transformation, tectonic and terrain conditions.

Clay minerals in the major Chinese coastal estuaries and their provenance implications

A sea-survey was carried out along the Chinese coast from the Bohai Sea to South China Sea, and 15 surficial samples were taken from major coastal estuaries, i.e., from north to south, the Yellow, abandoned Yellow, Yangtze, Qiantang, Ou, Min, Han, and Pearl River estuaries. On the basis of clay mineral analysis and published data collection, this paper discusses the characteristics of clay minerals of each coastal river and potentials of implications of sediment sources. The results show that the change of diagnostic clay minerals from smectite to kaolinite from the Yellow to the Pearl River estuaries is southward, as clearly shown by the ratios of smectite to chlorite (S/Ch) and kaolinite to illite (K/I). S/Ch decreases southward, while K/I moves reversely, implying change in climate setting from cool/dry to humid/hot with intensified weathering processes. Besides, these two indicators in the estuaries are also linked with the derivation of parent-rock of each river-basin and coastal hydrodynamics. The disproportional higher ratio of K/I in the Yellow and abandoned Yellow River estuaries is ascribed to their sediment sources with abundant loess component in the north-central China. The K/I decrease offshore from the Pearl River estuary is primarily due to hydrodynamic sorting. Therefore, the S/Ch and K/I of the present study comprehensively reflect the controls of climate, parent-rock, and sediment transport along the coast.

Clay mineral assemblages as indicators of hydrothermalism in the basal part of the CRP-3 core (Victoria Land Basin, Antarctica)

AbstractThe CRP-3 drilling project collected sediments from 3 to 939 mbsf (metres below sea floor) in the Victoria Land Basin in Antarctica. The upper sequence (down to ~790 m bsf) is of Cenozoic age and made up of detrital glaciogenic sediments; the characteristics of clay minerals in this part have been reported elsewhere. Here, the compositional features of clay minerals in the lower sequence such as conglomerates, Devonian sandstones and dolerites are described and genetic processes clarified. Clay minerals in the deepest part of the sequence derive from the alteration of different lithologies that mostly make up the sedimentary basin.Two clay mineral assemblages were characterized through analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). From 790 to 823 mbsf, samples consist of authigenic smectite of variable chemical composition forming imbricated texture of plates or flakes. The smectites probably result from hydrothermal/diagenetic transformation of earlier minerals. The primary smectite cement underwent reorganization during shearing and cataclasis. The lowest part of the sequence (below 823 mbsf) is characterized by an assemblage of kaolinite, mixed-layer illite-smectite, Fe oxyhydroxide, sporadic smectite and poorly crystallized illite. It reflects a stronger alteration process than that recorded in the upper units of core CRP-3, related to hydrothermalism connected with the intrusion of an igneous body. Both assemblages show clear differences in particle morphology, texture and smectite composition to the clay assemblages found in the Cenozoic glaciomarine sediments in the upper sequence. The different phases of alteration appear related to the processes of rifting, exhumation and faulting that characterized this region since the Mesozoic.

Clay mineral anomalies in the fault zone of the Chelungpu Fault, Taiwan, and their implications

The Taiwan Chelungpu‐fault Drilling Project (TCDP) Hole‐A recovered continuous core samples across the rupture zone of the 1999 Chi‐Chi earthquake (Mw7.6). Studying in‐situ chemical properties sequentially from fresh‐fault‐zone materials of the Chelungpu fault provides insight into possible faulting mechanisms. Distinct anomalies of mineral assemblages at the 1111‐m fault zone of TCDP Hole‐A are found to be: (1) A decrease in clay content within the primary slip zone (PSZ); and (2) A significant decline of illite, disappearance of chlorite and kaolinite, and spike in smectite within the PSZ. Meanwhile, features relating to melting or amorphous material in the PSZ have been observed by SEM and TEM. The results suggest that the PSZ might have experienced generation of glassy materials such as pseudotachylyte by the expense of clay minerals due to strong shear heating, then prompt alteration of pseudotachylyte into smectite. Characteristics of clay minerals and images obtained from electronic microscopes in the PSZ thus imply that pseudotachylyte possibly developed during the 1999 Chi‐Chi earthquake, but quickly altered into smectite. This particular phenomenon may explain why pseudotachylyte is rarely found in exhumed hydrated fault zones.

Mineralogia e cristalografia da fração argila de horizontes coesos de solos nos tabuleiros costeiros

A coesão de horizontes de solos do Brasil vem sendo associada, principalmente, a fatores físicos e químicos inter-relacionados, mas a influência das propriedades mineralógicas e cristalográficas dos minerais da fração argila também foi aventada por alguns pesquisadores. Neste trabalho, testou-se a hipótese de que a fração argila de horizontes coesos de solos do Sedimento Barreiras da faixa dos Tabuleiros Costeiros é dominantemente caulinítica e apresenta elevado grau de cristalinidade e ordenamento, o que pode favorecer o ajuste face a face dos cristais. O objetivo deste trabalho foi avaliar as características mineralógicas e cristalográficas dos minerais da fração argila de horizontes coesos provenientes de solos de sedimentos do Grupo Barreiras e uma possível contribuição para a ocorrência do caráter coeso. Para isso, foram analisados cinco horizontes coesos e um não-coeso de solos distribuídos ao longo da faixa dos Tabuleiros Costeiros. Também foi incluída, como referência, uma caulinita com elevado grau de cristalinidade. Todos os perfis foram analisados para classificação taxonômica e localização dos horizontes de interesse. Nas amostras dos horizontes selecionados, foram removidos a matéria orgânica e os óxidos. Após a dispersão de partículas, a fração argila foi individualizada, tratada e analisada por difração de raios X (DRX) para determinar os minerais e o grau de ordem/desordem estrutural, segundo o Método Especialista de Plançon &amp; Zacharie (1990). Todos os horizontes coesos apresentaram caulinitas com grau de ordenamento estrutural similar ao do horizonte não-coeso e inferior à caulinita de referência, o que não permitiu associar o empacotamento da fração argila com a manifestação do caráter coeso nos horizontes estudados, a partir das avalioações obtidas pelo método utilizado.

Formation of clay minerals and exhumation of lower‐crustal rocks at Atlantis Massif, Mid‐Atlantic Ridge

Low‐temperature alteration products in gabbros from the ocean floor have significant implications for incipient processes of seawater‐rock interaction and exhumation tectonics of the lower‐crustal rocks. In this paper we report mode of occurrence and mineralogical characteristics of clay minerals in gabbroic rocks recovered from Integrated Ocean Drilling Program (IODP) Hole U1309D at an oceanic core complex, Atlantis Massif, Mid‐Atlantic Ridge at 30°N. The clay minerals were identified by optical microscope, electron microprobe, Raman spectrometer, and transmission electron microscope as mainly composed of mixed‐layer saponite‐talc, saponite, and vermiculite. They are characteristically rich in iron that is significantly oxidized and distributed into the tetrahedral site, suggesting a relatively high‐temperature condition for oxidation. They are restricted to domains near the contacts between olivine and talc or form pseudomorphs after olivine near microcracks filled with zeolite or clay minerals. These facts suggest the infiltration of oxidative seawater and reactions to variable fluid/rock ratios at variable temperatures. Close association of vermiculite with microcracks radiated from serpentinized olivine suggests that the deep infiltration of seawater at an off‐axis region was caused by fracturing resulting from serpentinization and enhanced by relatively abundant olivine‐rich lithology at Atlantis Massif. Compared with gabbroic rocks of an oceanic core complex at ultraslow‐spreading ridge (ODP Hole 735B), those of Atlantis Massif substantially lack mixed‐layer smectite‐chlorite. Mixed‐layer smectite‐chlorite is a product of prehnite‐actinolite to greenschist facies alteration and looks to preserve a record of ambient thermal structure through which the massif passed on rising to a shallow level. The absence of pervasive formation of mixed‐layer smectite‐chlorite under relatively reducing conditions suggests low permeability and/or limited fluid‐rock reactions on the way to shallow levels. From the observation and consideration of the characteristics of clay minerals, sequence and distribution of static alteration related to fracturing, original lithology, and tectonic settings of the oceanic core complexes, we conclude that Atlantis Massif was more rapidly exhumed to the oxidative subseafloor environment than Atlantis Bank. The difference of exhumation rate possibly reflected either the disparity in spreading rate between the whole ridge systems or regional variation of exhumation tectonics between the two oceanic core complexes.

Characteristics of Clay Minerals in the Northern South China Sea and Its Implications for Evolution of East Asian Monsoon since Miocene

Clay mineral assemblages, crystallinity, chemistry, and micromorphology of clay particles in sediments from ODP Site 1146 in the northern South China Sea (SCS) were analyzed, and used to trace sediment sources and obtain proxy records of the past changes in the East Asian monsoon climate since the Miocene, based on a multi-approach, including X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive X-ray spectrometry (SEM-EDS). Clay minerals consist mainly of illite and smectite, with associated chlorite and kaolinite. The illite at ODP Site 1146 has very well-to-well crystallinity, and smectite has moderate-to-poor crystallinity. In SEM the smectite particles at ODP Site 1146 often appear cauliflower-like, a typical micromorphology of volcanic smecites. The smectite at ODP Site 1146 is relatively rich in Si element, but poor in Fe, very similar to the smectite from the West Philippine Sea. In contrast, the chemical composition of illite at ODP Site 1146 has no obvious differences from those of the Loess plateau, Yellow River, Yangtze River, and Pearl River. A further study on sediment source indicates that smectite originates mainly from Luzon, kaolinite from the Pearl River, and illite and chlorite from the Pearl River, Taiwan and/or the Yangtze River. The clay mineral assemblages at ODP Site 1146 were not only controlled by continental eathering regimes surrounding the SCS, but also by the changing strength of the transport processes. The ratios of (illite+chlorite)/smectite at ODP Site 1146 were adopted as proxies for the East Asian monsoon evolution. Relatively higher ratios reflect strongly intensified winter monsoon relative to summer monsoon, in contrast, lower ratios indicate a strengthened summer monsoon relative to winter monsoon. The consistent variation of this clay proxy from those of Loess plateau, eolian deposition in the North Pacific, planktonic, benthic foraminifera, and black carbon in the SCS since 20 Ma shows that three profound shifts of the East Asian winter monsoon intensity, and aridity in the Asian inland and the intensity of winter monsoon relative to summer monsoon, occurred at about 15 Ma, 8 Ma, and the younger at about 3 Ma. The phased uplift of the Himalaya-Tibetan plateau may have played a significant role in strengthening the Asian monsoon at 15 Ma, 8 Ma, and 3 Ma.

Characteristics of clay minerals in asian dust and their environmental significance

The objectives of this research were to characterise the clay minerals composition of soil-derived dust in Northern China and to set up a mineralogical signature to trace their origin. Mineral composition of aerosol particles was investigated at Aksu, Dunhuang, Yulin, Tongliao and Changwu during an intensive field campaign period of ACE-Asia. The results show that the kaolinite (K) to chlorite (C) ratio is sensitive to the regional origin of Asian dust. Western source areas (represented by Aksu) displayed the lowest K/C ratio of 0.3 (average), while it was found to increase up to 0.70 (average) upon moving towards northern source areas (represented by Yulin). By studying transported dust in a deposition area representative of the Chinese Loess Plateau, the usefulness of the K/C ratio, when associated with back air-mass trajectories, was found to lie in revealing the origin of the dust. Comparison of the mineralogical data between Asian dust and Sahara dust, shows that the K/C ratio is also an effective signature to identify the source areas on a hemisphere scale.

Geochemical and mineralogical approaches to assessing provenance and deposition of shales: a case study

AbstractMineralogical and geochemical studies of Cretaceous segments of Argille Varicolori and Flysch Rosso successions from the southern Apennines allow their provenance and history to be evaluated.The occurrence of detrital kaolinite and fine-grained Fe-oxyhydroxides, the strong depletion of Na2O, K2O and CaO, and the enrichment in the transition elements document severe alteration in the source areas. Nevertheless, mineralogical and geochemical features able to discriminate the shale families are still preserved. The presence/absence of rock fragments derived from a ‘crystalline’ source, the significant chemical differences as well as the characteristics of clay minerals, discriminate the studied shales. The absence of indications suggestive of mixing of the detrital components favour the hypothesis that the two shales were deposited in distinct basins which probably received contributions from continent-ocean convergent areas (Argille Varicolori) and from more stable areas (Flysch Rosso).

Characteristics of Clay Minerals in Gouges of the Dongrae Fault, Southeastern Korea, and Implications for Fault Activity

AbstractThe Dongrae fault within the Yangsan fault system is considered one of the major faults in the southeastern part of Korea, extending over 150 km. The results of K-Ar radiogenic dating of fault gouges collected from six localities show a relatively wide range in age from 57.5 million years ago (Ma) to 40.3 Ma. Fault gouges are composed of newly formed minerals, including smectite, illite, zeolite, kaolinite, K-rich feldspar, apatite, and pyrite. The occurrence of abundant smectite and illite-lMd with lesser quantities of zeolite suggests that the fault gouges experienced hydrothermal alteration at low temperatures. Smectite is probably unstable relative to other clay minerals, such as illite and zeolite. Considering that filiform mordenite is replacing the smectite, we suggest that mordenite formed by recrystallization involving a solid-state transformation. Under high fluid/rock ratios, smectite seems to have formed in the early stage of alteration. In contrast, zeolite minerals and authigenic K-rich feldspar progressively appeared with time as the fluid/rock ratio decreased with the changing chemistry of the hydrothermal fluids. The composition of clay minerals in the gouge materials probably was controlled by the chemistry and the amount of circulating fluids derived from adjacent granitic rocks.

Adsorption−Desorption of Simazine on Montmorillonite Coated by Hydroxy Aluminum Species

Adsorption−desorption of simazine on model systems which closely simulate those encountered in soils [i.e., pure montmorillonite and montmorillonite covered by different amounts of OH−Al species (chlorite-like complexes)] was investigated. The adsorption data were analyzed according to Langmuir and Freundlich equations. Results obtained indicate that the adsorption of simazine was strongly influenced by the charge characteristics of clay minerals and the pH of buffer (3.7 and 5.6). At pH 3.7, simazine was adsorbed in large amounts on montmorillonite, whereas adsorption significantly decreased with increasing amounts of Al(OH)x species on montmorillonite surfaces. When experiments were carried out at pH 5.6, the adsorption of the herbicide on montmorillonite drastically decreased, whereas no severe differences were observed with AM18 (a montmorillonite loading 18 mequiv g-1 M). Desorption tests showed that negligible and very little amounts of simazine were desorbed from montmorillonite and AM18, respectiv...

Structure-related geochemical (REE) and isotopic (K-Ar, Rb-Sr, δ 18O) characteristics of clay minerals from Rotliegend sandstone reservoirs (Permian, northern Germany)

Euhedral illite cementing the gas-bearing sandstone reservoirs of the Rotliegend in the Niedersächsische rift system (northern Germany) was studied along a horst-to-graben cross-section to examine its chemical and isotopic characteristics. The data show that differentiated illite particles grew during a tectono-thermal event marked by distinct episodic hydrothermal activities along fault drains and in the poral space of sandstones at 210 Ma and at 195 to 190 Ma in horst positions, at 185 to 175 Ma in the nearby graben, and at 170 to 165 Ma in both the horst and graben. Varied REE distribution patterns and initial 87Sr/ 86Sr ratios (from 0.7124 to 0.7142) relative to illite-particle size outline a high chemical variability of the fluids during illite growth. The δ 18O values of illite range from +20.0 to +12.4‰ and those of chlorite from +12.0 to +6.9‰. The changing δ 18O values of the minerals most likely relate to varied δ 18O values of the fluids, or to different water/rock ratios during crystallization. Differences among the REE and 87Sr/ 86Sr tracers and the δ 18O values of different generations of illite also suggest a changing fluid chemistry relative to time. Significant positive Eu anomalies and negative Ce anomalies in the REE distributions of illite suggest feldspar alteration by the migrating fluids in oxidizing environments.

Textural and geochemical micro-analysis in the interpretation of clay mineral characteristics: lessons from sandstone hydrocarbon reservoirs

AbstractBack-scattered electron images of clay minerals from sandstones are used, together with complementary micro-analytical methods, to identify and quantify mineral microporosity and geochemistry. Clay minerals typically have a range of microporosity from 10 to &gt;90% dependent on texture and paragenesis. Fibrous clays are highly microporous; detrital clays have low microporosity but specific clay minerals have broad ranges of microporosity. The often quoted mineral-chemical association between thorium (Th) and kaolinite cannot be substantiated by micro-analysis. The Th content of clay minerals is associated with micro-inclusions within the kaolinite which form diagenetically or are derived from precursor minerals.

Textural and Geochemical Micro-Analysis in the Interpretation of Clay Mineral Characteristics: Lessons from Sandstone Hydrocarbon Reservoirs

Textural and Geochemical Micro-Analysis in the Interpretation of Clay Mineral Characteristics: Lessons from Sandstone Hydrocarbon Reservoirs

Chemical characteristics of clay minerals in the sediments from the Yellow River and the Changjiang River

1. Based on the result analyzed by means of ATEM, the chemical characteristics of main clay minerals from the Yellow River are rich in K, Ca, while the main clay minerals from the Changjiang River are characterized by being poor in K and rich in Fe, Mg. 2. The differences of chemical characteristics between the clay minerals of the Yellow River and those of the Changjiang River could be looked on as an indicator for studying the source of sediments in the given area.

Depletion of non-exchangeable NH 4-N in the soil—root interface in relation to clay mineral composition and plant species

Experiments were carried out with 10 soils with different clay contents and different clay composition to investigate the dynamics of non-exchangeable NH + 4 and 1 M HCl extractable NH + 4, respectively, in the vicinity of the roots. The experimental plant was rape ( Brassica napus). In addition the influence of plant species on the mobilization of non-exchangeable NH + 4 was investigated with ryegrass ( Lolium multiforum) and red clover ( Trifolium pratense) on a soil with a higher proportion of smectites and vermiculite. The depletion zone of non-exchangeable NH + 4 as well as 1 M HCl extractable NH + 4 extended to about 3 mm from the root zone in soils with a higher proportion of smectites and vermiculite, while in soils with mainly illites the depletion of both N fractions in the root vicinity was negligible. The depletion was less pronounced for red clover. It is suggested that the release of ammonium from the interlayers depends on clay mineral characteristics as well as on plant species.

Construction and Application of Clay-Swelling Diagrams by Use of XRD Methods

Clay swelling is one of the major causes of formation damage in hydrocarbon reservoirs and also can cause many drilling operations problems in shaly formations. Clay swelling is controlled primarily by the compositions of aqueous solutions with which the clay comes into contact. This paper presents a method to construct clay-swelling diagrams that can be used to determine the compatibility between swelling clays and aqueous fluids