Terra rossa samples were taken from the B horizons of soil profiles and from cracks within limestone in Italy. The average annual temperature (AAT) of the sites ranged from 8.4 to 20.3°C and the average annual precipitation (AAP) from 511 to 3113 mm, with either a 5–6 month water deficit or a large water surplus. Goethite and hematite were identified in all the samples. Under a moist (> 1700 mm AAP) and cool (13°C AAT) climate, a xeric, hematitic pedoenvironment was preserved by the well-litified carbonate rock. Hematite occurred in trace amounts, even with an AAT of 8.4°C and an AAP of 3300 mm, confirming the specific role of the hard limestone on the pedoclimate of terra rossa. The lowest mean crystallite dimension of goethite and hematite was found in the samples from the wettest sites, and in these samples hematite was nearly free of Al substitution. Rubification in terra rossa appeared to be due to the specific pedoenvironment. The hematite cannot be considered a relict phase formed under another climate. Illite and kaolinite were the main clay minerals in samples from xeric sites whereas more weathered clays, such as Al-interlayered vermiculite, occurred in cool, moist sites. We postulate that the processes of rubification and vermiculitization could have taken place at the same time. The effects of layer charge magnitude and location on expansion were represented by an energy change (expansion energy: ΔEr) during the hydration and solvation processes. Plots of basal spacings versus ΔEr show a reasonable relationship; the spacings generally decrease stepwise as the value of ΔEr increases. The basal spacings of K-samples with glycerol solvation, Na-saturated and K-saturated samples at 100% RH are apt to contract stepwise with increasing value of ΔEr. For these samples, the figures showing the relationship between each expanded phase and the charge characteristics are obtained from the isoquants of ΔEr, given the boundary of the expanded phases. A behavior test using these figures may be combined with the Greene-Kelly test to estimate the amount and the location of the layer charge of common smectites.

Effects of Layer Charge, Charge Location, and Energy Change on Expansion Properties of Dioctahedral Smectites

Formation of clay minerals under hydrothermal influence is the result of rock alteration by circulating hot water in the Earth’s crust. A pre-existing rock-forming mineral assemblage is altered to a new set of minerals which are more stable under the hydrothermal conditions of temperature, pressure, and fluid composition. The interaction of hot water and rocks forms a spatially and temporally regular zonal pattern of new clay minerals, as the fluid with cooling temperature moves through the surrounding rock mass. This chapter discusses the formation of clay minerals in such dynamic processes of hydrothermal alteration. The approach is one of clay-mineral facies formed under conditions of massive alteration in the rocks. The chemical and mineralogical changes which occur on the scale of a rock or rock mass are considered to have been dealt with in the preceding chapter. The exact process of change via local, vein-influenced exchange processes is ignored for simplicity (see Chap. 6).

Formation of Clay Minerals in Hydrothermal Environments

Batch reactor experiments were performed at 150°C, 175°C, and 200°C to determine the effect of high pH NaOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25°C, solution composition, and mineralogy were monitored as a function of time for up to ≈40 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5–5.0 g of the 80–200 mesh size fraction of Opalinus shale, and 25 ml of solution (0.1 and 0.01 M NaOH). The general sequence of reaction products observed under these high pH conditions include first the formation of analcime, followed by vermiculite, and finally Na-rectorite formation.

LOW TEMPERATURE EXPERIMENTAL INVESTIGATION OF THE EFFECT OF HIGH pH NaOH SOLUTIONS ON THE OPALINUS SHALE, SWITZERLAND

Temporal changes in the chemistry of lake water within Yugama Crater, Kusatsu-Shirane Volcano, Japan: Implications for the evolution of the magmatic hydrothermal system

Geothermometry, geochronology, and mass transfer associated with hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy

Mineralogical study on regularly interstratified dioctahedral mica-smectites

Phyllosilicates were present in the volcanic ashes from several 1982-1983 eruptions of Kusatsu-Shirane Volcano . Pyrophyllite, kaolin and smectite were present as major clay minerals. Hydrothermally altered rocks collected from the western flank showed that, the basement rocks of this volcano were altered to form silica minerals, alunite and various clay minerals such as pyrophyllite, kaolin and smectite. The presence of pyrophyllite in the volcanic ashes indicates that the explosions probably have taken at a depth corresponding to the basement rocks. On the other hand, samples of air-fall tephra from 1897 and 1925 eruptions contained little or no pyrophyllite suggesting that these explosions likely occurred in the volcanic rocks of Kusatsu-Shirane Volcano. Based on the distribution and amounts of clay minerals in the volcanic ejectas, the depth of explosions during repeated eruptions may be inferred.

https://www.jstage.jst.go.jp/article/gkk1952/19/Special/19_Special_87/_pdf

Toshihiko Matsuda

Papers

Mineralogical study on regularly interstratified dioctahedral mica-smectites

Clay minerals in the volcanic ejectas from Kusatsu-Shirane Volcano and the style of eruption.

Hydrothermal behaviors of an interstratified mineral from the Mine of Ebara, Hyogo Prefecture, Japan

Beidellite from the sano mine, nagano prefecture, japan

Syntheses of interstratified minerals from kaolin with addition of various cations