Karstification without carbonic acid: Bedrock dissolution by gypsum- driven dedolomitization

Geology
By: , and 

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Abstract

Aggressive karstification can take place where dolomite and gypsum are in contact with the same aquifer. Gypsum dissolution drives the precipitation of calcite, thus consuming carbonate ions released by dolomite. Lake Banyoles, in northeastern Spain, is a karst lake supplied by sublacustrine springs, and karstic collapse is occurring in the immediate vicinity of the lake. Lake water is dominated by Mg-Ca and SO4-HCO3, and is supersaturated with calcite that is actively accumulating in lake sediments. Water chemistry, sulfur isotope composition, local stratigraphy, and mass-balance modelling suggest that the primary karst-forming process at at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. Gypsum-driven dedolomitization may be responsible for other karstic systems heretofore attributed to soil-generated carbonic acid.

Publication type Article
Publication Subtype Journal Article
Title Karstification without carbonic acid: Bedrock dissolution by gypsum- driven dedolomitization
Series title Geology
DOI 10.1130/0091-7613(1994)022<0995:KWCABD>2.3.CO;2
Volume 22
Issue 11
Year Published 1994
Language English
Publisher Geological Society of America
Description 4 p.
First page 995
Last page 998
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