Some aspects of the genesis of an alpine humus soil

An alpine humus soil profile has been examined in the field, in thin section and by X-ray diffraction. The presence of a stone line and the sudden change in characteristics across the stone line, including particle size distribution, degree of exfoliation of the micas, major mineral composition, and clay mineralogy suggest that this is a polygenetic profile consisting of two soil stratigraphic units. There has been little pedological reorganization within either unit, soil formation consisting essentially of in situ weathering, removal of soluble constituents, and accumulation of organic matter, with some biological activity, in the upper unit. It is shown that gibbsite derived from weathering of feldspar is a major component of the clay fraction, especially in the lower unit. The clay mineralogy is considered in relation to proposed mineral weathering sequences and weathering in a yellow podzolic soil.

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Provenance and Sedimentary Context of Clay Mineralogy in an Evolving Forearc Basin, Upper Cretaceous-Paleogene and Eocene Mudstones, San Joaquin Valley, California

Minerals ◽

10.3390/min11010071 ◽

2021 ◽

Vol 11 (1) ◽

pp. 71

Author(s):

Andrew Hurst ◽

Michael Wilson ◽

Antonio Grippa ◽

Lyudmyla Wilson ◽

Giuseppe Palladino ◽

...

Keyword(s):

Phase Transitions ◽

Upper Cretaceous ◽

Clay Fraction ◽

Clay Mineralogy ◽

Bulk Rock ◽

X Ray Diffraction ◽

Arc Volcanism ◽

X Ray ◽

Magmatic Arc ◽

Tropical Weathering

Mudstone samples from the Moreno (Upper Cretaceous-Paleocene) and Kreyenhagen (Eocene) formations are analysed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) to determine their mineralogy. Smectite (Reichweite R0) is the predominant phyllosilicate present, 48% to 71.7% bulk rock mineralogy (excluding carbonate cemented and highly bio siliceous samples) and 70% to 98% of the <2 μm clay fraction. Opal CT and less so cristobalite concentrations cause the main deviations from smectite dominance. Opal A is common only in the Upper Kreyenhagen. In the <2 μm fraction, the Moreno Fm is significantly more smectite-rich than the Kreyenhagen Fm. Smectite in the Moreno Fm was derived from the alteration of volcaniclastic debris from contemporaneous rhyolitic-dacitic magmatic arc volcanism. No tuff is preserved. Smectite in the Kreyenhagen Fm was derived from intense sub-tropical weathering of granitoid-dioritic terrane during the hypothermal period in the early to mid-Eocene; the derivation from local volcanism is unlikely. All samples had chemical indices of alteration (CIA) indicative of intense weathering of source terrane. Ferriferous enrichment and the occurrence of locally common kaolinite are contributory evidence for the intensity of weathering. Low concentration (max. 7.5%) of clinoptilolite in the Lower Kreyenhagen is possibly indicative of more open marine conditions than in the Upper Kreyenhagen. There is no evidence of volumetrically significant silicate diagenesis. The main diagenetic mineralisation is restricted to low-temperature silica phase transitions.

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THE OCCURRENCE OF CHLORITE AND VERMICULITE IN THE CLAY FRACTION OF THREE BRITISH COLUMBIA SOILS

Canadian Journal of Soil Science ◽

10.4141/cjss59-030 ◽

1959 ◽

Vol 39 (2) ◽

pp. 246-253

Author(s):

A. A. Theisen ◽

G. R. Webster ◽

M. E. Harward

Keyword(s):

British Columbia ◽

Clay Fraction ◽

Clay Mineralogy ◽

Vancouver Island ◽

X Ray Diffraction ◽

X Ray ◽

The Past ◽

Surface Samples

The clay mineralogy of surface samples from three soils on Vancouver Island which had been used in fertility experiments was determined by X-ray diffraction. Chlorite was identified as the predominant mineral in all three soils. Vermiculite was present in discrete units in the Chemainus soil and interstratified with chlorite in the Fairbridge and Merville soils. Kaolinite may also have been a constituent; this could not be determined since the use of certain criteria, proposed in the past for the identification of kaolinite in the presence of chlorite, proved unsuccessful. It was concluded that no universal criterion, which holds true in all cases, exists for distinguishing kaolinite in the presence of chlorite.

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Clay minerals in the agricultural surface soils in the Central United States

Clay Minerals ◽

10.1180/000985501750539391 ◽

2001 ◽

Vol 36 (3) ◽

pp. 277-294 ◽

Cited By ~ 38

Author(s):

B. Velde

Keyword(s):

United States ◽

Clay Minerals ◽

Agricultural Soils ◽

Clay Fraction ◽

Clay Mineralogy ◽

Parent Material ◽

X Ray Diffraction ◽

Charge Site ◽

X Ray ◽

Central United States

AbstractA survey of the clay fraction at the surface of 86 loam and silt loam agricultural soils from the Central United States was undertaken to observe the possible influences of climate and parent material (dominantly phyllosilicates in this study) on the clay mineralogy of the upper portions of the soils, for the most part in Mollisol–Alfisol order soils.Decomposed X-ray diffraction spectra show that the most abundant clay minerals are two disordered illite-smectite (I-S) minerals, one with ∼50% smectite layers and another, less abundant, disordered I-S phase with 20% smectite. These minerals usually co-exist in the same samples. The charge site in both of these I-S minerals is both beidellitic and montmorillonitic in the expanding layers. A relatively large proportion of these smectite layers (up to 20%) are of high charge.There seems to be a convergence in mineralogy towards mixed-layer phases formed under a range of mid-Continent climates from a range of phyllosilicate parent materials.

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Micromorphology and mineralogy of a layered red-brown earth profile

Soil Research ◽

10.1071/sr9750101 ◽

1975 ◽

Vol 13 (2) ◽

pp. 101 ◽

Cited By ~ 5

Author(s):

JR Sleeman

Keyword(s):

Surface Layer ◽

Iron Oxides ◽

Manganese Oxides ◽

Lower Layer ◽

Clay Fraction ◽

Clay Mineralogy ◽

Parent Material ◽

The Third ◽

In Situ Weathering

The micromorphology and non-clay mineralogy of a red-brown earth profile from Pyramid Hill, Vic., have been examined in order to test Butler's postulated genesis based on field criteria. The profile includes four separate parent material layers. The lowest layer appears to have been derived mainly from in situ weathering of granite. The upper three layers have been derived mainly from a source other than the local granite and have microscopic characteristics comparable to those of altered parna, viz. a non-clay fraction which shows a marked peak in the 30-60 �m range, which consists of quartz and felspar with magnetite, ilmenite, leucoxene and titanite and which has a zircon/tourmaline ratio of about 0.5. As well as a solum developed in the upper two parna layers, there appears to be a buried truncated soil associated with the third parna layer. In both soils there has been significant translocation and deposition of carbonates, iron oxides and hydroxides, manganese oxides and hydroxides and clay, with somewhat more material segregated in the lower solum. Weathering and water-table effects at some depth below a prior surface appear to have been responsible for segregations within the lower layer derived from granite. The data support the concepts of Butler, and in addition indicate contamination of the surface layer by reasonably fresh minerals.

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The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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