Secondary-mineral formation during natural weathering of pyroxene; review and thermodynamic approach

1993 ◽  
Vol 293 (2) ◽  
pp. 111-134 ◽  
Author(s):  
Y. Noack ◽  
F. Colin ◽  
D. Nahon ◽  
J. Delvigne ◽  
L. Michaux
Keyword(s):  
Natural Weathering ◽  
Thermodynamic Approach ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Secondary Mineral Formation

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.

scholarly journals Influence of Calcium Ion and pH on Oxidation Rates and Secondary Mineral Formation on Pyrite Surface

2020 ◽  
Author(s):  
Jifeng Xue ◽  
Sana Ishida ◽  
Tatsuya Kato ◽  
Shigeshi Fuchida ◽  
Shigeto Kuroiwa ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Pyrite Surface ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Oxidation Rates ◽  
Secondary Mineral Formation

scholarly journals The Influence of Weathering, Water Sources, and Hydrological Cycles on Lithium Isotopic Compositions in River Water and Groundwater of the Ganges–Brahmaputra–Meghna River System in Bangladesh

2021 ◽  
Vol 9 ◽  
Author(s):  
Toshihiro Yoshimura ◽  
Daisuke Araoka ◽  
Hodaka Kawahata ◽  
H. M. Zakir Hossain ◽  
Naohiko Ohkouchi
Keyword(s):  
River Water ◽  
Rainy Season ◽  
Global Climate ◽  
River System ◽  
Mineral Formation ◽  
Ganges River ◽  
Secondary Mineral ◽  
Li Isotope ◽  
Secondary Mineral Formation ◽  
The Ganges

The silicate weathering of continental rocks plays a vital role in determining ocean chemistry and global climate. Spatiotemporal variations in the Li isotope ratio (δ7Li) of terrestrial waters can be used to identify regimes of current and past weathering processes. Here we examine: 1) monthly dissolved δ7Li variation in the Ganges River’s lower reaches; and 2) the spatiotemporal variation of river water of the Brahmaputra, Meghna rivers, and groundwater in Bangladesh. From the beginning to maximum flood discharges of the rainy season (i.e., from June to September), Li concentrations and δ7Li in the Ganges River show remarkable changes, with a large influence from Himalayan sources. However, most Li discharge across the rainy season is at steady-state and strongly influenced by the secondary mineral formation in the low-altitude floodplain. Secondary mineral formation strongly influences the Meghna River’s Li isotopic composition along with fractionation lines similar to the Ganges River. A geothermal input is an additional Li source for the Brahmaputra River. For groundwater samples shallower than ∼60 m depth, both δ7Li and Li/Na are highly scattered regardless of the sampling region, suggesting the variable extent of fractionation. For deep groundwater (70–310 m) with a longer residence time (3,000 to 20,000 years), the lower δ7Li values indicate more congruent weathering. These results suggest that Li isotope fractionation in rivers and groundwater depends on the timescale of water-mineral interaction, which plays an essential role in determining the isotopic signature of terrestrial Li inputs to the ocean.

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