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Progressive chemical modification of clastic sediments with burial

Conference · · AIP Conf. Proc.; (United States)
OSTI ID:6801246
The porosity of clastic sediments at deposition varies very approximately between about 45% (sands) and 85% (muds). With burial, consolidation takes place as pore water is progressively eliminated. It would be misleading, however, to attribute alterations in sediment bulk properties to physical processes alone. Very significant mineralogical changes occur and these start soon after burial, especially in mudrocks. Striking heterogeneities such as thin, laterally continuous cemented horizons or discrete concretions are commonly introduced. These shallow burial processes are predominently the result of microbial activity. Thermodynamically unstable mixtures of organic matter and various oxidants (dissolved oxygen, sulphate, nitrate, particulate Fe(III) and Mn(IV)) provide both substrate and energy source for a variety of different microbial ecosystems. Mineralogical consequences include both leaching and the precipitation of carbonate, sulphide, phosphate and silica cements. The type and extent of mineral modification depends strongly on depositional environment variables such as rate of sedimentation and water composition.
Research Organization:
Department of Geology, University of Sheffield, Sheffield S3 7HF, England
OSTI ID:
6801246
Report Number(s):
CONF-8610148-
Conference Information:
Journal Name: AIP Conf. Proc.; (United States) Journal Volume: 154:1
Country of Publication:
United States
Language:
English