Relative Abundance Of Clay Minerals Research Articles

Clay-mineral distribution in recent deep-sea sediments around Taiwan: Implications for sediment dispersal processes

Clay-mineralogy study of Taiwanese river-mouth sediments, recent deep-water seafloor sediments around Taiwan, along with sediments collected from the Tainan shelf edge, have been investigated to access the source and transport of detrital fine-grained sediments. We determined the clay mineralogy in both hemipelagites and turbidites in the top 50 cm of the deep-sea sediment cores to infer how sediments are dispersed through river-fed turbidity currents, hypopycnal plumes, and oceanic currents. Our results show that the clay mineral assemblages in both hemipelagites and turbidites of different provinces change gradually between two major end-members: illite+chlorite and smectite. They are predominantly sourced from Taiwan and Luzon, respectively. The relative abundances of clay minerals in turbidites and hemipelagites are quite similar in most of the cores. Therefore, we argue that the adjacent turbidites and hemipelagites of a core share common detrital clay sources. We found that smectite is relatively abundant around Taiwan, indicating that the Kuroshio Current is an important transportation system, which brings smectite from Luzon. Besides, the river-related canyon systems consist dominantly of illite and chlorite, and less smectite, indicating that the smectite brought about by the Kuroshio Current is diluted by river-fed hyperpycnal and hypopycnal flows. This also implies that flood-induced turbidity currents are efficient agents for transporting Taiwan-derived sediments into the neighboring deep-sea basins.

Maastrichtian oil shale deposition on the southern Tethys margin, Egypt: Insights into greenhouse climate and paleoceanography

A comprehensive set of organic and inorganic geochemical proxies, clay mineralogy, and molecular fossils are presented from two biostratigraphically well-dated oil shale horizons of Egypt, within the Upper Cretaceous Duwi and Dakhla formations. The studied oil shales were deposited within intracratonic sedimentary basins in a broad northern African epeiric sea. Calcareous nannofossil biostratigraphy indicates that the oil shales range from early to late Maastrichtian in age, covering nannofossil zones UC18, UC19, and UC20. The oil shales contain smectite and kaolinite as the main clay minerals that formed by weathering of precursor basement rocks. The relative abundances of clay minerals and several geochemical proxies (e.g. C-value, CIA, Ga/Rb, Rb/Sr and Sr/Cu), along with the occurrence of warm-water nannofossil taxa, demonstrate that the Maastrichtian oil shales accumulated under a warm, arid to humid greenhouse climate during a general Maastrichtian cooling trend. This episode of oil shale deposition in Egypt coincided with the first potential imprint of the global warming, that has been recorded during early-to-late Maastrichtian times (~70.6–67.7 Ma). Elevated eolian terrigenous input was recorded within the Duwi Formation oil shales, shown by high Ti/Al, Si/Al, Zr/Al and low La/Lu ratios. The Duwi Formation environment was characterized by enhanced salinity and a stratified water column, compared to that of the Dakhla Formation, shown by elevated values of the gammacerane index, tetracyclic terpane, β‑carotene and Sr/Ba ratio. The CaCO3 content and carbonate/siliciclastic ratio indicate that the Dakhla Formation oil shales were deposited during a relative sea-level rise in a deeper marine setting than the Duwi Formation oil shales. The data further imply a wind-driven upwelling scenario of nutrient inputs that simulated primary production and increased organic matter fluxes. Thus, paleoclimate and paleoceanography had a considerable impact on organic matter enrichment.

Characterizing clay mineralogy in Lake Towuti, Indonesia, with reflectance spectroscopy

We tested the use of visible to near-infrared (VNIR) reflectance spectroscopy to characterize the relative abundances of clay minerals in sediments from Lake Towuti, a large tectonic lake in Sulawesi, Indonesia. We measured VNIR spectra of lake and river sediments from Lake Towuti and its catchment to identify clay minerals, fit major VNIR absorption features with a modified Gaussian model to estimate relative abundances of these minerals, and compared these absorptions to the samples’ chemistry to test the utility of VNIR spectroscopy to characterize sediment compositional variations. We found that major absorptions are caused by vibrations of Al–OH in kaolinite (2.21 μm), Fe–OH in nontronite (2.29 μm), Mg–OH in saponite and serpentine (2.31 μm), and Mg–OH in serpentine (2.34 μm). This was confirmed with X-ray diffraction data. The correlations between absorption band areas for Fe–OH, Al–OH, and Mg–OH vibrations and Fe, Al and Mg concentrations, respectively, are statistically significant, varying between r = 0.51 and r = 0.90, and spatial variations in inferred clay mineralogy within the lake are consistent with variations in the geology of the catchment. We conclude that VNIR spectroscopy is an effective way to characterize the clay mineralogy of lake sediments, and can be used to investigate changes in mineral inputs to lake deposits.

Clays and bodies for ceramic tiles: Reappraisal and technological classification

The ceramic tile industry is a dynamic sector whose technological innovation and market trends have drawn a complex picture of products and processes. Raw materials have been deeply involved in such an evolution: the flexibility of current manufacturing cycles enables the use of a very wide range of clays, whose chemical and mineralogical composition, particle size distribution and ceramic properties were reappraised. The classical reference schemes are no longer able to properly describe and predict the role of clays in tilemaking. In order to fill this gap, an industry-oriented, technological classification of clay raw materials is proposed on the basis of chemical (Fe2O3 content) and mineralogical parameters (amount of phyllosilicates and carbonates) together with particle size (fractions <2μm and >63μm) and plasticity (methylene blue index and Atterberg plastic index). It firstly discriminates light-firing and dark-firing clays according to an iron oxide threshold of 3%. Light-firing clays are distinguished by the amount of kaolinite group minerals and plasticity in “kaolins” (high-grade, low-grade, and raw kaolins, kaolinitic loams) and “plastic clays” (ball clays, pyrophyllitic clays, white bentonites); the distinction of three classes of ball clays with increasing plasticity is envisaged. Dark-firing clays are classified according to coarse-grained fraction and amount of carbonates in carbonate-rich types (marly and carbonatic clays), red loams and red clays; these latter are furtherly differentiated by the relative abundance of clay minerals. Such a classification is essential to draw the guidelines for body formulation and to explain the criteria followed in the industrial practice for each category of ceramic tiles. Key properties are discussed to design batches for porous tiles, vitrified and semi-vitrified red stoneware, and vitrified light-firing bodies. Both the clay classification and the guidelines to body formulation are intended to provide up-to-date tools to assess the ceramic potential and correct use in tilemaking of clay materials, but they cannot substitute a throroughful technological characterization, adequately simulating the industrial processing.

Analysis of rock samples collected from rock hewn churches of Lalibela, Ethiopia using laser-induced breakdown spectroscopy

With the aim to study alteration processes of the rock hewn churches from Lalibela (Ethiopia), we applied Laser Induced Breakdown Spectroscopy (LIBS) technique to measure the elemental composition both of the bulk rock materials and their external layers, exposed to the environmental factors. The analytical plasma was generated by nanosecond pulses of an Nd: YAG laser emitting at 1064 nm. Different major and minor sample constituents were detected, including Ca, Mg, Na, Fe, Ti, Al and K. The detected O emission originates both from air surrounding and the sample, while the intensity of N lines, coming exclusively from air, was used for the LIBS signal normalization. By depth profiling of the weathered basalt rock, we observed a lower presence of K in the external layers, corresponding to the first 5 laser shots. The emission from this element is anti-correlated with the line intensities from O, and this was attributed to the variations in relative abundances of clay minerals and K-feldspar. The analogue measurements were performed on the tuff rock, and compared to the spectra from powder samples containing only the external soft material, scratched from the rocks. These analyses show an abundance of H in the weathered, wetted layers and suggest that cations are lost from the constituent primary minerals and replaced by H+; this process disrupts the lattice structure and causes a marked loss of strength. The studies presented here demonstrate that LIBS is a useful technique for studying the alteration processes in the rocks, caused by environmental factors.

Multi-proxy evidences of Mid-Pleistocene dry climates observed on calcretes in Central Turkey

Palaeosols are very important in reconstructing palaeoclimate studies, since they are accepted as useful climate markers and as potential providers of proxy data. The study of the palaeosols of the Plio-Pleistocene rock sequences around Ankara revealed evidence for a reconstruction of the Quaternary palaeoclimate of the region. The study area is located in Bala, south-east of Ankara, which contains Middle Pleistocene red palaeosols with powdery to nodular calcrete developments, alternating with channel deposits. During this warm and arid period in the Pleistocene, the limited water available in the soil led to the accumulation of low magnesian carbonates, forming calcretes. The clay fractions of the samples were X-rayed using air-drying, ethylene-glycol solvation and heating treatments. The clay mineral contents were determined as smectite, kaolinite, illite and chlorite. Palygorskite was also identified. In the relative abundances of clay minerals, smectite, the most abundant clay mineral, is depleted towards the upper part of the section while the amount of palygorskite increases. Since palygorskite is the only pedogenic mineral formed during the Pleistocene, its presence can be accepted as evidence of the dominant arid climatic conditions. The isotopic composition of carbonates in the Bala section exhibits a slightly wider range in \delta^{13}C composition from -5.98%o to -9.22%o and a narrower range in \delta^{18}O composition from -7.19%o to -8.66%o. The carbon isotope values clearly imply that arid to semiarid flora C4 is dominant, with C3:C4 mixed vegetation. This study suggests that the Middle Pleistocene is the time of the Mid-Brunhes Event when the dominantly warm climatic temperatures led to the development of calcretes in Bala, Ankara, as with all Quaternary Mediterranean-type calcretes.

Impact of long-term wastewater irrigation on variability of soil attributes along a landscape in semi-arid region of Iran

Twelve soil profiles and 62 soil cores were described from two neighboring landscapes in the northwest of Iran to understand whether long-term wastewater irrigation has caused variations in morphological, physicochemical, and DTPA-heavy metals contents in soils. Along a gradual slope, different positions reflected heterogeneous response to flooding wastewater irrigation. Upper slope and mainly midslope were subject to gradual soil loss as characterized by thin Ap-horizons and shallow soil depth, whereas periodic cycles of soil accumulation and sediment along with local reducing condition were highlighted in lower slope. Compared to different positions of control land, wastewater irrigation increased significantly (P ≤ 0.05) soil fertility attributes (N, P, K, and organic matter) along with electrical conductivity. Significant correlations were observed between soil fine particles fraction and available P and also with available K, indicating that spatial distribution pattern of these elements is mainly dependent on distribution of the <0.002 mm fractions along the landscape as it is affected by wastewater irrigation. Midslope position was found to be more degraded compared to the other position regarding soil loss and available nutrients (N, P, and K) as a result of the processes of soil redistribution and soil transport in wastewater irrigation system. Mean concentrations of DTPA-extractable Zn, Cu, Cd, and Pb in the different geomorphological positions were 3.8–7.8, 2.5–3, 3–4, and 1.7–3.5 times greater, respectively, when compared to the adjacent control soil. With the exception of lower slope position, which indicated a remarkable increasing pattern of smectite in response to wastewater irrigation and unfavorable drainage condition, the relative abundances of clay minerals in view of the peak position and intensity followed almost the same pattern in both wastewater-irrigated and control landscape.

Weathering of Coastal Dunes in Northern KwaZulu-Natal, South Africa

Abstract This paper identifies and quantifies the clay assemblage within coastal dunes of northern KwaZulu-Natal, South Africa, and proposes a model for clay distribution and abundance. Distinct dune units identified by previous authors on the basis of the sand fraction are redefined on the basis of the composition of the clay fraction. The most mature dune unit is classified as Unit 0 (250–350? ka) and is characterised by a clay assemblage rich in kaolinite and goethite. Units 1 and 2 (19–250 ka) are of intermediate maturity and comprise kaolinite, interstratified clays, quartz, and goethite. The relatively immature Units 3 and 4 (Recent to 19 ka) are characterised by calcite, quartz, vermiculite, and montmorillonite. The relative abundance of clay minerals in dune units allows weathering and postdeposition alteration processes within the dunes to be investigated. From these, a simplified weathering sequence with increasing maturity can be summarised as follows: quartz + feldspars + calcite + heavy miner...

Impact of Climate and Parent Material on Chemical Weathering in Loess‐derived Soils of the Mississippi River Valley

Peoria Loess‐derived soils on uplands east of the Mississippi River valley were studied from Louisiana to Iowa, along a south‐to‐north gradient of decreasing precipitation and temperature. Major element analyses of deep loess in Mississippi and Illinois show that the composition of the parent material is similar in the northern and southern parts of the valley. We hypothesized that in the warmer, wetter parts of the transect, mineral weathering should be greater than in the cooler, drier parts of the transect. Profile average values of CaO/TiO2, MgO/TiO2, K2O/TiO2 and Na2O/TiO2, Sr/Zr, Ba/Zr, and Rb/Zr represent proxies for depletion of loess minerals such as calcite, dolomite, hornblende, mica, and plagioclase. All ratios show increases from south to north, supporting the hypothesis of greater chemical weathering in the southern part of the valley. An unexpected result is that profile average values of Al2O3/TiO2 and Fe2O3/TiO2 (proxies for the relative abundance of clay minerals) show increases from south to north. This finding, while contrary to the evidence of greater chemical weathering in the southern part of the transect, is consistent with an earlier study which showed higher clay contents in Bt horizons of loess‐derived soils in the northern part of the transect. We hypothesize that soils in the northern part of the valley received fine‐grained loess from sources to the west of the Mississippi River valley either late in the last glacial period, during the Holocene or both. In contrast, soils in the southern part of the valley were unaffected by such additions.

Clay Diagenesis in the Sandstone Reservoir of the Ellon Field (Alwyn, North Sea)

AbstractThe nature, composition, and relative abundance of clay minerals in the sandstones of the Brent Group reservoir were studied between 3200–3300 m in a well of the Ellon Field (Alwyn area, North Sea). The sandstones have a heterogeneous calcite cement which occurred during early-diagenesis. Clay diagenesis of the cemented and uncemented sandstones was investigated using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction analyses (XRD), and infrared spectroscopy (IR). The influence of cementation on clay neoformation is demonstrated in this study. Detrital illite and authigenic kaolinite are present in both the calcite-cemented and uncemented sandstones suggesting that kaolinite precipitated before calcite cementation. In the uncemented sandstones, blocky dickite replaces vermiform kaolinite with increasing depth. At 3205 m, authigenic illite begins to replace kaolinite and shows progressive morphological changes (fibrous to lath-shape transition). At 3260 m, all sandstones are not cemented by calcite. Illite is the only clay mineral and shows a platelet morphology.In the cemented samples, vermiform kaolinite is preserved at all depths, suggesting that dickite transformation was inhibited by the presence of the calcite cement. This observation suggests that calcite cement would prevent fluid circulation and dissolution-precipitation reactions.

Terrigenous sediment supply along the Chilean continental margin: modern regional patterns of texture and composition

The regional patterns of texture and composition of modern continental slope and pelagic sediments off Chile between 25°S and 43°S reflect the latitudinal segmentation of geological, morphological, and climatic features of the continental hinterland. Grain-size characteristics are controlled by the grain-size of source rocks, the weathering regime, and mode of sediment input (eolian off northern Chile vs fluvial further south). Bulk-mineral assemblages reveal a low grade of maturity. Regional variations are governed by the source-rock composition of the different geological terranes and the relative source-rock contribution of the Coastal Range and Andes, as controlled by the continental hydrology. The relative abundance of clay minerals is also predominantly influenced by the source-rock composition and partly by continental smectite neoformation. Latitudinal variations of illite crystallinities along the Chilean continental slope (and west of the Peru–Chile trench) clearly reflect modifications of the weathering regime which correspond to the strong climatic zonation of Chile.

Clay minerals and trace metal association in the Gangolli estuarine Sediments, West Coast of India

X-ray diffraction analysis of the clay fraction of surficial sediments of Gangolli estuary reveals that smectite is the dominant clay mineral followed by kaolinitechlorite and illite. The distribution of clay minerals is almost uniform throughout the estuary. Most of the trace elements, except Cu, Pb, Zn and Ti, do not show any association with clay minerals. This may be due to the desorption of trace elements which normally takes place in high saline estuarine environment. Organic matter and calcium do not show any significant effect on the abundance and distribution of clay minerals. It appears that the detrital source is the dominating factor in influencing the relative abundance of clay minerals in the estuary.

Remote Detection of Anomalous Mineralogy Associated With Hydrocarbon Production, Lisbon Valley, Utah

Examination of a variety of remotely sensed data and geochemistry suggest that specific diagenetic mineral assemblages within the Wingate Formation are closely associated with hydrocarbon production at Lisbon Valley, Utah. The Wingate Formation, exposed along the southwestern flank of the anticline has a relatively uniform composition and appearance over the entire Colorado Plateau, except at isolated localities such as Lisbon Valley, where it is locally bleached. Previous workers have suggested that hydrocarbon microseepage may account for the bleaching of the Wingate Sandstone and the presence of uranium mineralization in rocks overlying the reservoir at Lisbon Valley. Broad-band Landsat Multispectral Scanner (MSS) and airborne Thematic Mapper Simulator (TMS) data were used to map the bleached facies on the basis of brightness and lack of ferric iron. The TMS data provided further discrimination of bleached facies based on the relative abundances of clay minerals detectable with this sensor. Analysis of high-resolution airborne spectroradiometric data, thin sections, and x-ray diffraction data suggests that bleached rocks overlying the reseNoir at Lisbon Valley contain abundant kaolinite and minor amounts of feldspar. Unbleach­ed exposures contain substantially less clay and abundant feldspar. This study shows a correlation between the abun­dance of clay minerals, particularly kaolinite, and hydrocarbon production at Lisbon Valley. Because one of the principal mineralogical differences between the bleached and unbleached rocks is the relative abundance of clay minerals, and the TMS (and Landsat Thematic Mapper) data are very sensitive to clays, areas of potential hydrocarbon induced diagenetic alteration may be mapped using broad-band sensors.

Remote Detection of Anomalous Mineralogy Associated with Hydrocarbon Production, Lisbon Valley, Utah: ABSTRACT

Diagenetic mineral assemblages within the Wingate formation are closely associated with hydrocarbon production at Lisbon Valley, Utah. The Wingate formation, exposed along the southwestern flank of the anticline, has a relatively uniform composition and appearance over the entire Colorado Plateau, except at isolated localities such as Lisbon Valley, where it is locally bleached. Previous workers have suggested that hydrocarbon microseepage may account for bleaching of the Wingate Sandstone and the presence of uranium mineralization in outcrops overlying the reservoir at Lisbon Valley. Using broad-band, Landsat Multispectral Scanner (MSS) and airborne Thematic Mapper Simulator (TMS) data, the bleached facies was mapped on the basis of brightness and lack of ferric iron. Ex mination of the TMS data provided further discrimination of bleached facies because relative abundances of clay minerals are detectable with this sensor. Analysis of high-resolution airborne spectroradiometric data, thin sections, and x-ray diffraction suggests that the bleached rocks overlying the reservoir at Lisbon Valley contain abundant kaolinite and minor amounts of feldspar. Unbleached exposures contain substantially less clay and abundant feldspar. This study shows a correlation between the abundance of clay minerals, particularly kaolinite, and hydrocarbon production at Lisbon Valley. Because one of the principal differences between the bleached and End_Page 305------------------------------ unbleached rocks is in the relative abundance of clay minerals (and the TMS is very sensitive to clays), areas of potential hydrocarbon-induced diagenetic alteration may be mapped using broad-bank sensors. End_of_Article - Last_Page 306------------

Mineralogical study of the core samples from the Indian Ocean, with special reference to the vertical distribution of clay minerals

The clay minerals in the 18 core samples collected from the northern, equatorial and southeastern Indian Ocean are illite, chlorite, montmorillonite and kaolinite. In the fraction finer than 2Μ in the surface layer (top to 5 cm deep) of each core, the relative abundance of clay minerals varies widely from area to area. Kaolinite possesses the maximum proportion of the clay mineral composition and chlorite has the minimum proportion.