A chemical and thermodynamic model of aluminous dioctahedral 2:1 layer clay minerals in diagenetic processes; regular solution representation of interlayer dehydration in smectite

1994 ◽  
Vol 294 (4) ◽  
pp. 449-484 ◽  
Author(s):  
B. Ransom ◽  
H. C. Helgeson
Keyword(s):  
Clay Minerals ◽  
Regular Solution ◽  
Thermodynamic Model ◽  
Diagenetic Processes ◽  
Solution Representation

scholarly journals Gale crater: the Mars Science Laboratory/Curiosity Rover Landing Site

2012 ◽  
Vol 12 (1) ◽  
pp. 25-38 ◽  
Author(s):  
James J. Wray
Keyword(s):  
Clay Minerals ◽  
Environmental Conditions ◽  
Spectral Properties ◽  
Landing Site ◽  
Science Laboratory ◽  
Deep Lakes ◽  
Mars Science Laboratory ◽  
Gale Crater ◽  
Diagenetic Processes ◽  
Curiosity Rover

AbstractGale crater formed from an impact on Mars ∼3.6 billion years ago. It hosts a central mound nearly 100 km wide and ∼5 km high, consisting of layered rocks with a variety of textures and spectral properties. The oldest exposed layers contain variably hydrated sulphates and smectite clay minerals, implying an aqueous origin, whereas the younger layers higher on the mound are covered by a mantle of dust. Fluvial channels carved into the crater walls and the lower mound indicate that surface liquids were present during and after deposition of the mound material. Numerous hypotheses have been advocated for the origin of some or all minerals and layers in the mound, ranging from deep lakes to playas to mostly dry dune fields to airfall dust or ash subjected to only minor alteration driven by snowmelt. The complexity of the mound suggests that multiple depositional and diagenetic processes are represented in the materials exposed today. Beginning in August 2012, the Mars Science Laboratory rover Curiosity will explore Gale crater by ascending the mound's northwestern flank, providing unprecedented new detail on the evolution of environmental conditions and habitability over many millions of years during which the mound strata accumulated.

scholarly journals Evolution with depth from detrital to authigenic smectites in sediments from AND-2A drill core (McMurdo Sound, Antarctica)

Clay Minerals ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 481-498 ◽  
Author(s):  
F. Iacoviello ◽  
G. Giorgetti ◽  
F. Nieto ◽  
I. T. Memmi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Clay Minerals ◽  
Clay Fraction ◽  
Drill Core ◽  
Mcmurdo Sound ◽  
Volcanic Material ◽  
The Core ◽  
Diagenetic Processes ◽  
Scanning Electron

AbstractWe have examined the nature and origin of smectites in glaciomarine sediments of the AND-2A drill core (McMurdo Sound, Antarctica) by means of X-ray diffraction (XRD) analyses on the clay fraction, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. Relying on the smectite variation throughout the drill core it was possible to split the sequence into three units. Smectites throughout the core are either detrital or authigenic. Detrital smectites are close to montmorillonite-beidellite in composition while newly-formed smectites frequently have higher Fe-Mg contents and intermediate compositions between the saponite and nontronite field, with lower amounts in the montmorillonite-beidellite field. In the upper sedimentary sections (Unit I, and Unit II, 36-440 mbsf, 0.7-16.5 Ma) smectites are interpreted to be predominantly detrital, whereas in the lower portion of the core (Unit III, 440-1123.20 mbsf, 16.5-20.2 Ma) authigenic smectites are the most common feature. The predominance of mica, the abundance of chlorite, and the nature of smectites in the upper units indicate physical weathering under cold and dry climate, and a dominant provenance for the clay minerals from the Transantarctic Mountains. Smectites in the lower unit are considered mostly authigenic and they are most likely to be the result of early diagenetic processes, being formed from the alteration of volcanic material (glass, pyroxenes and feldspars) and/or through precipitation from fluids of a possible hydrothermal origin. Our survey attests to the importance of discriminating between a detrital and authigenic nature of smectites as the occurrence of authigenic clay minerals in ancient sedimentary successions might lead to incorrect palaeoclimatic interpretations, since they can be affected by diagenetic processes, thus obliterating the climatic signal.

scholarly journals Surface properties and wetting behavior of liquid Ag-Sb-Sn alloys

2012 ◽  
Vol 48 (3) ◽  
pp. 443-448 ◽  
Author(s):  
V. Sklyarchuk ◽  
Yu. Plevachuka ◽  
I. Kaban ◽  
R. Novakovic
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Surface Properties ◽  
Regular Solution ◽  
Wide Temperature Range ◽  
Thermodynamic Model ◽  
Sessile Drop ◽  
Sessile Drop Method ◽  
Experimental Results ◽  
Density Measurements

Surface tension and density measurements of liquid Ag-Sb-Sn alloys were carried out over a wide temperature range by using the sessile drop method. The surface tension experimental data were analyzed by the Butler thermodynamic model in the regular solution approximation. The wetting characteristics of these alloys on Cu and Ni substrates have been also determined. The new experimental results were compared with the calculated values as well as with data available in the literature.

Preservation of organic compounds and constraints on diagenetic processes by reactive iron phases on Mars

2021 ◽  
Author(s):  
Christian Schröder ◽  
Emily Bonsall
Keyword(s):  
Clay Minerals ◽  
Organic Compounds ◽  
Compositional Analysis ◽  
Landing Site ◽  
Earth Planet ◽  
X Ray ◽  
Gale Crater ◽  
Reactive Iron ◽  
Diagenetic Processes ◽  
Fe Species

<p>Over 20% of organic carbon in sediments on Earth are bound to reactive Fe mineral phases [1]. These reactive Fe phases are generally Fe (oxyhydr)oxides, often associated with clay minerals. It is important to note that they occur as nanoparticulate and X-ray amorphous phases that are challenging to identify. On Earth, proxy methods such as chemical sequential extractions are often used but they can produce misleading results when used for mineral identification [2,3]. We develop and use Mössbauer spectroscopy applications to identify these phase [2-4] and compare these to Raman spectroscopy because the Mars 2020 Perseverance rover and the ExoMars 2022 Rosalind Franklin rover use Raman spectrometers for mineralogical identification.</p> <p>Reactive Fe phases are abundant on Mars. It is important to note that they are not the well-crystalline expression of Fe (oxyhydr)oxides such as hematite and goethite that have been observed from orbit and with a variety of rover-based instruments. Instead, reactive Fe phases are represented by as yet unidentified Fe phases: Aqueously altered rocks and soils in Gusev crater and at Meridiani Planum (including the Burns formation) contain large amounts of nanophase iron oxides (npOx and Fe3D3) [5]; and 20-60 wt% of minerals in fluvio-lacustrine deposits in Gale crater are X-ray amorphous and this amorphous phase is rich in iron [6]. Mineralogical interpretation of CRISM data of Rosalind Franklin's landing site at Oxia Planum also suggest the presence of these phase. These reactive Fe phases can be any combination of a number of minerals including ferrihydrite, lepidocrocite, akaganèite, hissingerite, schwertmannite, and superparamagnetic (i.e. nanoparticulate) hematite and goethite [5].</p> <p>The preservation of organic compounds by reactive Fe species is effective over hundreds of thousands of years in Earth sediments [1]. In return, organic compounds slow down the transformation of reactive Fe species such as ferrihydrite into the more crystalline and thermodynamically stable Fe (oxyhydr)oxides hematite or goethite during diagenetic processes. With temperature and pressure rising further during diagenesis, however, organic compounds are oxidized and destroyed through the reduction of Fe (resulting in the diagenetic formation of the Fe carbonate siderite, for example), and the non-reduced Fe species are transformed into thermodynamically stable minerals. Thus, the presence of reactive Fe species in Martian sediments/sedimentary rocks indicates only little diagenetic overprinting and therefore a high preservation potential of organic compounds. Such samples will be of high priority for analysis with MOMA. However, the presence of Fe species during pyrolysis can reduce the detectability of certain organic compounds. This effect depends on the specific Fe species present and is mitigated in the presence of clay minerals [7,8].</p> <p>We will present Mössbauer and Raman spectrocopy investigations of reactive Fe phases in various sedimenatry settings and compare these results into the context of rover landing sites on Mars.</p> <p>References:</p> <p>[1] Lalonde et al (2012) <em>Nature</em> 483, 198-200. [2] Schröder et al (2016) <em>Hyperfine Interact </em>237, 85<em>.</em> [3] Hebpburn et al (2020) <em>Chem Geol</em> 543, 119584. [4] Klingelhöfer et al (2003) <em>J Geophys Res</em> 108(E12), 8067. [5] Morris et al (2019) in <em>Remote Compositional Analysis: Techniques for Understanding Spectroscopy, Mineralogy, and Geochemistry of Planetary Surfaces</em>, pp. 538-554, Cambridge University Press. [6] Rampe et al (2017) <em>Earth Planet Sci Lett</em> 471, 172–185. [7] Tan et al (2021) <em>Astrobiology</em> 21, 199-218. [8] Royle et al (2021) <em>Astrobiology</em> in press. </p>

Mudstone (“shale”) depositional and diagenetic processes: Implications for seismic analyses of source-rock reservoirs

2013 ◽  
Vol 1 (1) ◽  
pp. B7-B26 ◽  
Author(s):  
Bruce S. Hart ◽  
Joe H. S. Macquaker ◽  
Kevin G. Taylor
Keyword(s):  
Hydraulic Fracturing ◽  
Clay Minerals ◽  
Elastic Properties ◽  
Source Rock ◽  
Conceptual Models ◽  
Source Rocks ◽  
Geomechanical Properties ◽  
Fine Grained ◽  
Diagenetic Processes ◽  
Seismic Methods

Source-rock reservoirs are fine-grained petroleum source rocks (“shales” or “mudstones”) having geomechanical properties that allow those rocks to produce hydrocarbons at economic rates after stimulation by hydraulic fracturing. Many of the assumptions commonly adopted by geophysicists to characterize shales cannot be applied to source-rock reservoirs. For example, the mineralogies of many source-rock reservoirs are not dominated by clay minerals and so mathematical and/or conceptual models developed for clay-dominated mudstones are not appropriate and cannot be applied to them. Instead, mudstones of shale plays are generally dominated by biogenic calcite and/or quartz. We use terminology of sedimentary geology to show that anisotropy is scale-dependent in source-rock reservoirs, and we discuss the depositional and diagenetic processes that control these and other geophysical properties of interest. The mudstones of source-rock reservoirs may or may not be anisotropic at the lamination scale (i.e., millimeters), the scale commonly used to measure anisotropic parameters via core plugs, but they are nearly always anisotropic at the bedset (centimeters to several meters) and member (tens of meters) scales. Because of the anisotropic nature of mudstones, elastic properties are not scalars at the length/thickness scales that can be defined using seismic methods. Properties of interest are likely to be different parallel to bedding compared to perpendicular to bedding. Because of the subseismic scale of much of this variability, thin-bed effects are likely to influence the AVO behavior of source-rock reservoirs.

Mineralogy and geochemistry of Miocene deposits at Alcubierre Sierra, central sector of the Ebro Basin, Spain

Clay Minerals ◽  
1994 ◽  
Vol 29 (3) ◽  
pp. 391-400 ◽  
Author(s):  
B. Bauluz Lazaro ◽  
C. Arenas Abad ◽  
C. Fernandez-Nieto ◽  
J. M. Gonzalez Lopez
Keyword(s):  
Clay Minerals ◽  
Source Area ◽  
Pore Waters ◽  
Ebro Basin ◽  
Authigenic Carbonates ◽  
Lacustrine Deposits ◽  
Diagenetic Processes ◽  
Activity Ratios ◽  
Ree Patterns ◽  
Significant Chemical

AbstractTwo profiles in Miocene fluvio-lacustrine deposits consist of sandy, marly, lutitic and carbonatic levels constituted by variable percentages of quartz, calcite and clay minerals as major components, and feldspars, dolomite and occasionally gypsum and anhydrite as minor ones. The clay minerals are inherited and consist mostly of micas, with minor quantities of chlorites, pyrophyllites and kaolinites. The crystallochemical parameters of the micas indicate muscovitic compositions and their uniformity through both the different rocks and their silt and clay fractions suggest the same provenance source area, possibly located northward.Clay minerals concentrate preferentially Li, Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Cs, Ba, Zr, Hf, Th, U and REE whereas the authigenic carbonates concentrate Mn and Sr. The Sc, Cr, Th, Y, Zr and REE values in clay minerals indicate that the provenance source area of these deposits was similar in composition to the average continental upper crust, probably as a result of sedimentary recycling processes.Zeolitic levels constituted by different proportions of analcime and smectite as major components outcrop at the top of the profiles. The analcimes show anhedral to euhedral morphologies, with grain-size ranging between 1 and 20 μm, and Si/Al ratios ranging from 2.2 to 2.5. The smectites are dioctahedral and beidellitic in composition. The zeolitic levels present significant chemical differences relative to the other ones, such as higher overall REE contents, more pronounced negative Eu anomalies and higher (La/Yb)n, Th/Sc and La/Sc ratios, suggesting a different provenance source area. Their chondrite-normalized REE patterns reflect the possibility that the starting materials were pyroclastic eruptive rocks originating from intracrustal partial melting. The variable analcime and smectite percentages are attributed to variations in H+/(Na+ + K+) and K+/(Na + Ca2+ + Mg2+) activity ratios and silica and water activities in the pore-waters during diagenetic processes.

Hydrated form of some clay minerals observed using a film sealed environmental cell

1978 ◽  
Vol 36 (1) ◽  
pp. 72-73
Author(s):  
N. Kohyama ◽  
K. Fukushima ◽  
A. Fukami
Keyword(s):  
Clay Minerals ◽  
Morphological Changes ◽  
Carbon Film ◽  
Electron Microscopic Observation ◽  
Adsorbed Water ◽  
Electron Microscopic ◽  
Hydrated Form ◽  
Thin Carbon ◽  
Environmental Cell ◽  
Thin Carbon Film

Since the interlayer or adsorbed water of some clay minerals are quite easily dehydrated in dried air, in vacuum, or at moderate temperatures even in the atmosphere, the hydrated forms have not been observed by a conventional electron microscope(TEM). Recently, specific specimen chambers, “environmental cells(E.C.),” have been developed and confirmed to be effective for electron microscopic observation of wet specimen without dehydration. we observed hydrated forms of some clay minerals and their morphological changes by dehydration using a TEM equipped with an E.C..The E.C., equipped with a single hole copper-microgrid sealed by thin carbon-film, attaches to a TEM(JEM 7A) with an accelerating voltage 100KV and both gas pressure (from 760 Torr to vacuum) and relative humidity can be controlled. The samples collected from various localities in Japan were; tubular halloysite (l0Å) from Gumma Prefecture, sperical halloysite (l0Å) from Tochigi Pref., and intermediate halloysite containing both tubular and spherical types from Fukushima Pref..

Colloidal systems in soils

1994 ◽  
Vol 52 ◽  
pp. 64-65
Author(s):  
J. Thieme ◽  
J. Niemeyer ◽  
P. Guttman
Keyword(s):  
Clay Minerals ◽  
Polymeric Materials ◽  
Spatial Arrangement ◽  
High Specific Surface Area ◽  
Turnover Rates ◽  
Colloidal Systems ◽  
Chemical Conditions ◽  
Aggregation Phenomena ◽  
Iron And Manganese ◽  
Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

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