Aspects of climatic influence on the clay mineralogy and geochemistry of soils, Palaeosols and clastic sedimentary rocks

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doi: 10.1144/gsjgs.147.2.0351
Authors:Curtis, C. D.
Author Affiliations:Primary:
Univ. Manchester, Dep. Geol., Manchester, United Kingdom
Volume Title:Palaeoclimates
Source:Journal of the Geological Society of London, 147(2), p.351-357; Third Lyell meeting of the Geological Society of London, London, United Kingdom, Feb. 23, 1989. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:1990
Note:In English. 20 refs.; illus. incl. 3 tables, sketch maps
Summary:In humid climates chemical weathering is at its most intense and virutally all 'primary' bedrock minerals undergo complete breakdown. They are replaced by authigenic hydrated oxides of Fe and Al together with halloysite and kaolinite in deep profiles; these minerals develop where the residence time of water is slight. Longer residence times lead to higher solute concentrations and the stabilization of smectite. Authigenic palygorskite and sepiolite may form in highly saline, alkaline soils. The stability of these precipitated minerals is problematical; they may be metastable or even unstable. All other clays found in soils are unstable, being incomplete, solid-state hydrolysis products of substrate minerals. Bedrock influence is greatest in conditions of low to moderate precipitation where unstable minerals persist. Local topography, however, also strongly influences both the rate and products of chemical weathering. The sediments delivered to major basins today do not reflect global soil distribution patterns. The bulk composition of suspended sediment entering the Indian Ocean, for example, is rather similar to that entering the Arctic Ocean. Sediment dispersal patterns can also confuse climatic signals, a problem not encountered with palaeosols. Climatic signals are likely to survive best in bulk compositional data and in the distribution of more stable yet climatically sensitive minerals (kaolinite as opposed to illite, chlorite). [R.A.H.]
Subjects:Authigenic minerals; Basins; Bedrock; Chemical composition; Chemical weathering; Chlorite; Chlorite group; Clastic rocks; Clay mineralogy; Clay minerals; Controls; Geochemistry; Halloysite; Humid environment; Illite; Indicators; Kaolinite; Lithostratigraphy; Paleoclimatology; Paleosols; Palygorskite; Pedogenesis; Precipitation; Sedimentary basins; Sedimentary rocks; Sepiolite; Sheet silicates; Silicates; Smectite; Soil profiles; Soils; Terrestrial environment; Weathering; Zoning
Abstract Numbers:90M/2643
Record ID:1990036335
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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