IDENTIFICATION OF PEDOGENIC CARBONATE MINERALS USING STABLE CARBON AND OXYGEN ISOTOPES, X-RAY DIFFRACTION AND SEM ANALYSES

1987 ◽  
Vol 67 (4) ◽  
pp. 953-958 ◽  
Author(s):  
J. J. MILLER ◽  
M. J. DUDAS ◽  
F. J. LONGSTAFFE
Keyword(s):  
Stable Carbon Isotope ◽  
Soil Samples ◽  
Bulk Soil ◽  
Stable Carbon ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
Carbon And Oxygen Isotopes ◽  
Pedogenic Carbonate ◽  
X Ray ◽  
O Isotope

A Cca and Ck horizon of an Orthic Regosol in Alberta were investigated using 13C/12C and 18O/16O isotope ratios, X-ray diffraction and the scanning electron microscope as a possible basis for differentiating pedogenic and lithogenic carbonate minerals Using the stable carbon-isotope method, the abundance of newly-formed pedogenic carbonate minerals in bulk soil samples of the Cca and Ck horizon was estimated to be 48 and 33% respectively. The δ18O values of carbonate minerals in bulk soil samples of the Cca and Ck horizon were −13.1 and −12.0‰, respectively. The presence of Mg-bearing pedogenic calcite in the sand and fine silt (2–10 μm) fractions of the Cca horizon were associated with soluble Mg2+/Ca2+ ratios of about two. Pedogenic carbonate minerals were visible as tiny equidimensional crystals about 0.1–0.6 μm in diameter, and as surface coatings on the sand-size, primary carbonate minerals in both horizons. These results may have a practical application in the use of ca and k suffixes in horizon designation. Key words: Pedogenic carbonate minerals, stable isotopes, Mg-bearing calcite, surface morphology

scholarly journals Comparative Study on Thermodynamic and Geochemical Characteristics between Cemented and Clotted Parts of Thrombolite

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1017
Author(s):  
Dingxiang Zhuang ◽  
Yan Guo ◽  
Song Chen
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Carbon Isotope ◽  
Carbonate Rocks ◽  
Oil And Gas ◽  
Stable Carbon Isotope ◽  
Geochemical Characteristics ◽  
Stable Carbon ◽  
X Ray Diffraction ◽  
X Ray

Carbonate rocks are widely distributed in nature and are one of the main reservoir rocks for oil and gas. Microbes play an important role in the formation of carbonate rocks. Compared with the cemented part with fewer microorganisms (abiotic minerals), the nucleation and growth of the clotted part with more microorganisms (biotic minerals) are affected by the metabolic activities of microorganisms, so it has a unique morphology and crystal structure. However, there are still some confusing questions such as ones regarding the unique thermal decomposition characteristics and geochemical characteristics, which have rarely been studied. Here, X-ray diffraction (XRD) was used to determine the mineral composition of the cemented and clotted part in the same thrombolite. Then, thermal analysis and stable isotope geochemistry were used to explore the thermal stability and stable carbon isotope. The results of X-ray diffraction (XRD) show that the mineral components of the cemented and clotted part in the thrombolite are calcites, but their crystallinity is different. The crystallinity of the clotted part in the thrombolite is higher than that of the cemented part. Thermal analysis results show that the activation energy and the thermal stability of the clotted part in the thrombolite are relatively higher. In addition, the stable carbon isotope results show that, compared with the chemical precipitated calcite in the cemented part, the microorganisms in the clotted part absorb more 12C through photosynthesis, which results in more 13C in the clotted part, and the carbon isotope δ13C value is higher. This study helps to distinguish the crystallographic, thermodynamic and geochemical characteristics of cemented and clotted parts in thrombolite, and may be helpful to deepen our understanding of abiotic and biotic minerals.

scholarly journals Biomineralization of Carbonate Minerals Induced by The Moderate Halophile Staphylococcus Warneri YXY2

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 58 ◽  
Author(s):  
Yu Han ◽  
Bin Sun ◽  
Huaxiao Yan ◽  
Maurice E. Tucker ◽  
Yanhong Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Isotope ◽  
Stable Carbon Isotope ◽  
Preferred Orientation ◽  
Dynamics Simulation ◽  
Stable Carbon ◽  
Carbonate Minerals ◽  
Moderate Halophile ◽  
X Ray ◽  
Staphylococcus Warneri

Although biomineralization of minerals induced by microorganisms has been widely reported, the mechanisms of biomineralization and the characteristics of the biominerals precipitated needs to be studied further. In this study, Staphylococcus warneri YXY2, a moderate halophile, was used to induce the precipitation of carbonate minerals at various Mg/Ca molar ratios. To investigate the biomineralization mechanism, the growth curve, pH changes, ammonia test, the concentration of bicarbonate and carbonate ions, and the activity of carbonic anhydrase (CA) and alkaline phosphatase (ALP) were determined. X-ray powder diffraction (XRD), scanning electron microscopy - energy disperse spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and stable carbon isotope analyses were used to characterize the minerals. The obtained biotic minerals were calcite, vaterite, Mg-rich calcite, and aragonite crystals. The crystallinity of aragonite decreased with increasing Mg/Ca ratios. The preferred orientation, diverse morphologies, organic substances, and more negative stable carbon isotope values proved the biogenesis of these carbonate minerals. The presence of Mg in the biotic aragonite crystals was likely related to the acidic amino acids which also facilitated the nucleation of minerals on/in the extracellular polymeric substances (EPS). Mg2+ and Ca2+ ions were able to enter into the YXY2 bacteria to induce intracellular biomineralization. Dynamics simulation using Material Studio software proved that different adsorption energies of Glutamic acid (Glu) adsorbed onto different crystal planes of aragonite led to the preferred orientation of aragonite. This study helps to deepen our understanding of biomineralization mechanisms and may be helpful to distinguish biotic minerals from abiotic minerals.

scholarly journals The crystal structures and mechanical properties of the uranyl carbonate minerals roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite

2020 ◽  
Vol 7 (21) ◽  
pp. 4197-4221 ◽  
Author(s):  
Francisco Colmenero ◽  
Jakub Plášil ◽  
Jiří Sejkora
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Diffraction Pattern ◽  
Crystal Structures ◽  
First Principles ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
X Ray ◽  
Uranyl Carbonate

The structure, hydrogen bonding, X-ray diffraction pattern and mechanical properties of six important uranyl carbonate minerals, roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite, are determined using first principles methods.

Characterization of mineral phases of agricultural soil samples of Colombian coffee using Mössbauer spectroscopy and X-ray diffraction

ICAME 2011 ◽  
2012 ◽  
pp. 593-598
Author(s):  
Humberto Bustos Rodríguez ◽  
Dagoberto Oyola Lozano ◽  
Yebrayl Antonio Rojas Martínez ◽  
Marlene Rivera Pinilla ◽  
German Antonio Pérez Alcázar
Keyword(s):  
Mössbauer Spectroscopy ◽  
Agricultural Soil ◽  
Mossbauer Spectroscopy ◽  
Soil Samples ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mößbauer Spectroscopy ◽  
Mineral Phases

scholarly journals Evidence for solum recarbonation following forest invasion of a grassland soil

1999 ◽  
Vol 79 (3) ◽  
pp. 443-448 ◽  
Author(s):  
L. G. Fuller ◽  
D. Wang ◽  
D. W. Anderson
Keyword(s):  
Populus Tremuloides ◽  
Calcareous Soil ◽  
Stable Carbon Isotopes ◽  
Stable Carbon ◽  
Carbonate Minerals ◽  
Fine Silt ◽  
Pedogenic Carbonate ◽  
Secondary Enrichment ◽  
High Concentrations ◽  
Forest Invasion

Calcareous organic-matter-rich Black Chernozemic soils often persist under poplar forests in Saskatchewan, not acquiring the Ae horizons and related properties more characteristic of Gray Luvisol soils. These are Rego Black Chernozems, locally termed "Wooded Calcareous" because of the occurrence of a dark, calcareous horizon (AC) at depths of 10 to 30 cm. We hypothesize that dark, calcareous horizons are former Bm horizons that have been recarbonated because of intense biocycling of Ca by aspen (Populus tremuloides). The comparatively small amounts of carbonate occur mainly in the fine silt and clay fractions, and are dominantly calcite, indicating secondary origin, in comparison to the carbonate minerals of the Ck horizons where both calcite and dolomite occur, the latter more common in coarse fractions. The δ13C values of the carbonate minerals indicate that virtually all the carbonate in fine fractions of the upper horizons of the Wooded Calcareous soil is pedogenic. The dominance of pedogenic carbonate in the Ahk and AC horizons of the Wooded Calcareous soil is consistent with a secondary enrichment, a probable result of increased biocycling of Ca where aspen grows on sites with large amounts of soluble Ca in the subsoil. High concentrations of soluble Ca2+ and SO42− in the LFH of the Wooded Calcareous are consistent with increasing biocycling of these ions, from a gypsum-rich subsoil. Key words: Pedogenic carbonate, prairie-forest transition, stable carbon isotopes, biocycling, δ13C values

Halloysite in some soils from north-east Scotland

Clay Minerals ◽  
1977 ◽  
Vol 12 (1) ◽  
pp. 59-66 ◽  
Author(s):  
M. J. Wilson ◽  
J. M. Tait
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Soil Samples ◽  
X Ray Diffraction ◽  
X Ray ◽  
Drainage Class ◽  
North East ◽  
Parent Rocks ◽  
Diffraction Patterns

AbstractX-ray diffraction and electron microscopy show that halloysite occurs widely in soils derived from a variety of parent rocks (granite, gabbro, schist and slate) in north-east Scotland. Both tubular and non-tubular forms are observed, the latter being characterized by electron diffraction patterns with 001 reflection either absent or very weak and diffuse. Clay fractions from a poorly drained profile separated without prior drying of the soil samples contain essentially dehydrated halloysite at the surface, this becoming progressively more hydrated with depth. Since halloysite occurs extensively in soils of widely varying drainage class the mineral is probably not the result of recent soilforming processes but may have originated during Tertiary or interglacial weathering.

A precise and accurate method for the quantitative determination of carbonate minerals by X-Ray diffraction using a spiking technique

1971 ◽  
Vol 38 (296) ◽  
pp. 481-487 ◽  
Author(s):  
H. A. Gunatilaka ◽  
Roger Till
Keyword(s):  
Diffraction Method ◽  
Accurate Method ◽  
X Ray Diffraction ◽  
Carbonate Minerals ◽  
X Ray ◽  
Low Magnesium ◽  
Coefficients Of Variation ◽  
Magnesium Calcite ◽  
Peak Areas ◽  
High Magnesium Calcite

SummaryA precise and accurate X-ray diffraction method has been developed whereby the weight percentages of aragonite and low- and high-magnesium calcite are determined from the integrated peak areas of spiked and unspiked samples. The spike mixture was prepared from organisms extracted from the samples to be analysed. Use of a spiking method also avoided the preparation of working curves from artificial mixtures of carbonate minerals, which may not have the same diffraction behaviour as the unknowns. A test of the precision of the method indicates the following coefficients of variation: aragonite, 1·4 %; low-magnesium calcite, 1·5 %; high-magnesium calcite, 7·8 %. A test of the accuracy of the method indicates no significant bias in any of the carbonate results, except in samples where high-magnesium calcite values are below 10 %. Quartz may also be determined by this method (coefficient of variation 23·9 %; positive bias in values greater than 10 %).

A STUDY OF MACROCRYSTALLINE PEDOGENIC CARBONATES USING SUBMICROSCOPIC TECHNIQUES

1981 ◽  
Vol 61 (2) ◽  
pp. 261-272 ◽  
Author(s):  
A. R. MERMUT ◽  
R. J. ST. ARNAUD
Keyword(s):  
Electron Probe ◽  
Size Range ◽  
X Ray Diffraction ◽  
Pedogenic Carbonate ◽  
X Ray ◽  
Pedogenic Carbonates ◽  
Layered Crystals ◽  
Magnesium Calcite ◽  
Sem Analyses

Calcitic plasmic fabric, grain calcans, neocalcitans and carbonatic glaebules with diffuse boundary were studied in situ, in soils by electron probe and SEM analyses. The occurrence of pedogenic magnesium-bearing calcite, previously detected by a shift of X-ray diffraction spacing on bulk samples, was verified by electron probes analyses on purely pedogenic carbonatic sites. This made it possible to understand further the nature of carbonates and to differentiate pure calcite from magnesium-bearing calcite. Common types of microcrystalline pedogenic carbonates included elongated, equidimensional, rod-shaped, and layered crystals. Equidimensional crystals were common in calcite, whereas elongated and rod types occurring sometimes as bundles of coalescing fibres were found to be magnesium calcite. Most visible pedogenic carbonate crystals in the soils studies had a diameter of 0.3–1.0 μm. This size range may be important in establishing relative levels of secondary carbonates in soils. Phosphorus values for studied features were higher than in the entire soil and arc evidence of precipitation of this element with pedogenic carbonates.

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