Specific features of postmagmatic and hypergene kimberlite rock alteration research

2021 ◽  
pp. 26-42
Author(s):  
N. ZINCHUK
Keyword(s):  
Wide Temperature Range ◽  
Formation Processes ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Secondary Minerals ◽  
Temperature Range ◽  
Secondary Mineral Formation ◽  
Rock Alteration

Methods of studying postmagmatic and hypergene kimberlite rock alteration, as well as identifying secondary minerals and their associations are characterized. It is shown that secondary mineral formation processes took place in a wide temperature range and they are caused by their downward change of medium reaction from alkaline to acidic followed by neutralization, which resulted in dissolution, additional growth and emergence of new secondary mineral generations.

Low-temperature, hydrothermal garnet associated with zeolites, from basalt lavas near Beith, Ayrshire

1989 ◽  
Vol 53 (369) ◽  
pp. 125-129 ◽  
Author(s):  
A. Livingstone
Keyword(s):  
Close Association ◽  
Salient Feature ◽  
Contact Metamorphism ◽  
Alteration Zone ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Secondary Minerals ◽  
Close Proximity ◽  
Secondary Mineral Formation

A Working quarry, at Loanhead (NS363557) within the Clyde Plateau Carboniferous lavas, is traversed by a tholeiitic Tertiary dyke some 25-30 m wide. Throughout the quarry the lavas are extensively altered and the most prominent secondary minerals are calcite and prehnite. Adjacent to the dyke is an indefinite alteration zone within which garnet has developed in close association with analcime and thomsonite. Contact metamorphism is not apparent. Secondary minerals in the quarried lavas and from the alteration zone have been described by Meikle (1989). The most salient feature of secondary mineral formation central to this paper is that grossular and andradite occur, in situ, in close proximity to the dyke, and only in the amygdales.

scholarly journals Effects of Fe(III) Oxide Mineralogy and Phosphate on Fe(II) Secondary Mineral Formation during Microbial Iron Reduction

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 149
Author(s):  
Edward J. O’Loughlin ◽  
Maxim I. Boyanov ◽  
Christopher A. Gorski ◽  
Michelle M. Scherer ◽  
Kenneth M. Kemner
Keyword(s):  
Iron Reduction ◽  
Phosphate Concentration ◽  
Green Rust ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
X Ray Diffraction ◽  
Secondary Minerals ◽  
Iron Reducing Bacteria ◽  
Secondary Mineral Formation ◽  
Reducing Bacteria

The bioreduction of Fe(III) oxides by dissimilatory iron-reducing bacteria may result in the formation of a suite of Fe(II)-bearing secondary minerals, including magnetite (a mixed Fe(II)/Fe(III) oxide), siderite (Fe(II) carbonate), vivianite (Fe(II) phosphate), chukanovite (ferrous hydroxy carbonate), and green rusts (mixed Fe(II)/Fe(III) hydroxides). In an effort to better understand the factors controlling the formation of specific Fe(II)-bearing secondary minerals, we examined the effects of Fe(III) oxide mineralogy, phosphate concentration, and the availability of an electron shuttle (9,10-anthraquinone-2,6-disulfonate, AQDS) on the bioreduction of a series of Fe(III) oxides (akaganeite, feroxyhyte, ferric green rust, ferrihydrite, goethite, hematite, and lepidocrocite) by Shewanella putrefaciens CN32, and the resulting formation of secondary minerals, as determined by X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy. The overall extent of Fe(II) production was highly dependent on the type of Fe(III) oxide provided. With the exception of hematite, AQDS enhanced the rate of Fe(II) production; however, the presence of AQDS did not always lead to an increase in the overall extent of Fe(II) production and did not affect the types of Fe(II)-bearing secondary minerals that formed. The effects of the presence of phosphate on the rate and extent of Fe(II) production were variable among the Fe(III) oxides, but in general, the highest loadings of phosphate resulted in decreased rates of Fe(II) production, but ultimately higher levels of Fe(II) than in the absence of phosphate. In addition, phosphate concentration had a pronounced effect on the types of secondary minerals that formed; magnetite and chukanovite formed at phosphate concentrations of ≤1 mM (ferrihydrite), <~100 µM (lepidocrocite), 500 µM (feroxyhyte and ferric green rust), while green rust, or green rust and vivianite, formed at phosphate concentrations of 10 mM (ferrihydrite), ≥100 µM (lepidocrocite), and 5 mM (feroxyhyte and ferric green rust). These results further demonstrate that the bioreduction of Fe(III) oxides, and accompanying Fe(II)-bearing secondary mineral formation, is controlled by a complex interplay of mineralogical, geochemical, and microbiological factors.

scholarly journals A record of Neogene seawater <i>δ</i><sup>11</sup>B reconstructed from paired <i>δ</i><sup>11</sup>B analyses on benthic and planktic foraminifera

2017 ◽  
Vol 13 (2) ◽  
pp. 149-170 ◽  
Author(s):  
Rosanna Greenop ◽  
Mathis P. Hain ◽  
Sindia M. Sosdian ◽  
Kevin I. C. Oliver ◽  
Philip Goodwin ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Middle Miocene ◽  
Isotope Composition ◽  
Boron Isotope ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Cycle Model ◽  
Planktic Foraminifera ◽  
Carbon Cycle Model ◽  
Secondary Mineral Formation

Abstract. The boron isotope composition (δ11B) of foraminiferal calcite reflects the pH and the boron isotope composition of the seawater the foraminifer grew in. For pH reconstructions, the δ11B of seawater must therefore be known, but information on this parameter is limited. Here we reconstruct Neogene seawater δ11B based on the δ11B difference between paired measurements of planktic and benthic foraminifera and an estimate of the coeval water column pH gradient from their δ13C values. Carbon cycle model simulations underscore that the ΔpH–Δδ13C relationship is relatively insensitive to ocean and carbon cycle changes, validating our approach. Our reconstructions suggest that δ11Bsw was  ∼  37.5 ‰ during the early and middle Miocene (roughly 23–12 Ma) and rapidly increased during the late Miocene (between 12 and 5 Ma) towards the modern value of 39.61 ‰. Strikingly, this pattern is similar to the evolution of the seawater isotope composition of Mg, Li and Ca, suggesting a common forcing mechanism. Based on the observed direction of change, we hypothesize that an increase in secondary mineral formation during continental weathering affected the isotope composition of riverine input to the ocean since 14 Ma.

scholarly journals Raman spectroscopy of the minerals boléite，cumengéite， diaboléte and phosgenite — implications for the analysis of cosmetics of antiquity

2003 ◽  
Vol 67 (1) ◽  
pp. 103-111 ◽  
Author(s):  
R. L. Frost ◽  
P. A. Williams ◽  
W. Martens
Keyword(s):  
Molecular Structure ◽  
Raman Spectroscopy ◽  
Molecular Structures ◽  
Carbonate Mineral ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Secondary Mineral Formation ◽  
Bending Modes ◽  
Wavenumber Region ◽  
Deformation Modes

AbstractThe application of Raman spectroscopy to the study of the mixed cationic Pb-Cu and Pb-Cu-Ag minerals: boleite, cumengeite and diaboleite has enabled their molecular structures to be compared. Each of these three minerals shows different hydroxyl-stretching vibrational patterns, but some similarity exists in the Raman spectra of the hydroxyl-deformation modes. The low-wavenumber region is characterized by the bands assigned to the cation-chloride stretching and bending modes. Phosgenite is also a mixed chloride-carbonate mineral and a comparison is made with the molecular structure of the aforementioned minerals. Raman spectroscopy lends itself to the study of these types of minerals in complex mineral systems of secondary mineral formation.

The behaviour of Li and Mg isotopes during primary phase dissolution and secondary mineral formation in basalt

2010 ◽  
Vol 74 (18) ◽  
pp. 5259-5279 ◽  
Author(s):  
Josh Wimpenny ◽  
Sigurður R. Gíslason ◽  
Rachael H. James ◽  
Abdelmouhcine Gannoun ◽  
Philip A.E. Pogge Von Strandmann ◽  
...  
Keyword(s):  
Primary Phase ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Phase Dissolution ◽  
Mg Isotopes ◽  
Secondary Mineral Formation

Studies of secondary mineral formation in the PbO-H2O-HC1 system

1992 ◽  
Vol 56 (382) ◽  
pp. 53-65 ◽  
Author(s):  
R. Edwards ◽  
R. D. Gillard ◽  
P. A. Williams ◽  
A. M. Pollard
Keyword(s):  
Stability Constant ◽  
Metastable Phase ◽  
Metastable Phases ◽  
Corrosion Products ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Solid Phases ◽  
Secondary Mineral Formation

AbstractNew stability constant data are presented for the minerals blixite, mendipite and the compound Pb7O6Cl2.2H2O at 298.2 K and P = 105 Pa. Mendipite is in fact a metastable phase at this temperature, being thermodynamically stable under the appropriate conditions at temperatures above about 29°C Kinetic influences are of some significance with respect to the sequence of formation of solid phases in the PbO-HCl-HH2O system, and these have been elucidated for some important reactions. Penfieldite and fiedlerite appear to be metastable phases at all temperatures at 105 Pa. The results have been used to reassess the conditions of formation of the lead(II) oxy- and hydroxychloride phases that are known to form as minerals and as corrosion products of lead-containing artefacts. The effect of CO2 on the system is also described.

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