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Fate of silicate minerals in a peat bog

Geology

By:
, , , and
https://doi.org/10.1130/0091-7613(1991)​019<0328:FOSMIA>​2.3.CO;2

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Abstract

An investigation of silicate weathering in a Minnesota mire indicates that quartz and aluminosilicates rapidly dissolve in anoxic, organic-rich, neutral- pH environments. Vertical profiles of pH, dissolved silicon, and major cations were obtained at a raised bog and a spring fen and compared. Profiles of readily extractable silicon, diatom abundance, ash mineralogy, and silicate surface texture were determined from peat cores collected at each site.

In the bog, normally a recharge mound, dissolved silicon increases with depth as pH increases, exceeding the background silicon concentration by a factor of two. Silicate grain surfaces, including quartz, are chemically etched at this location, despite being in contact with pore water at neutral pH with dissolved silicon well above the equilibrium solubility of quartz. The increasing silica concentrations at circum-neutral pH are consistent with a system where silicate solubility is influenced by silica-organic-acid complexes. Silica-organic-acid complexes therefore may be the cause of the almost complete absence of diatoms in decomposed peat and contribute to the formation of silica-depleted underclays commonly found beneath coal.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Fate of silicate minerals in a peat bog
Series title:
Geology
DOI:
10.1130/0091-7613(1991)​019<0328:FOSMIA>​2.3.CO;2
Volume:
19
Issue:
4
Year Published:
1991
Language:
English
Publisher:
Geological Society of America
Contributing office(s):
Toxic Substances Hydrology Program
Description:
4 p.
First page:
328
Last page:
331