Mineralogy of pliocene to pleistocene pelitic sediments of the Great Hungarian Plain
Mineralogical composition of pelitic sediments of the Great Hungarian Plain is reviewed in this paper. Published data and unpublished analyses made in the laboratories of the Geological Institute of Hungary a total of about 150 samples were collected. Determinations were made mainly by X-ray diffrac...
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Main Author: | |
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Format: | Article |
Published: |
Department of Mineralogy, Geochemistry and Petrology, University of Szeged
Szeged
2002
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Series: | Acta mineralogica-petrographica
43 |
Kulcsszavak: | Földtan, Kőzettan, Ásványtan |
Subjects: | |
Online Access: | http://acta.bibl.u-szeged.hu/25096 |
Summary: | Mineralogical composition of pelitic sediments of the Great Hungarian Plain is reviewed in this paper. Published data and unpublished analyses made in the laboratories of the Geological Institute of Hungary a total of about 150 samples were collected. Determinations were made mainly by X-ray diffraction, the data were systematically corrected by comparison with the results of thermal analysis and partly chemical analysis. All data were revised and recalculated in a uniform system in order to obtain comparable results. In the bulk composition dominant clay minerals are smectite, illite/smectite, illite and chlorite. In the <2 |im fraction the same minerals occur, however, expanded phases are more dominant. Triple mixed-layer i 11 ite/smectite/ch 1 orite and kaolinite of various degree of disorder may appear. Clay minerals are essentially detrital, derived from various areas of the surrounding Carpathians and Alps. Sub-basins may differ in degree of disorder and quantitative proportions of clay minerals and quantitative relations of other phases like calcite, dolomite, quartz and feldspars depending on relatively permanent source areas and transport directions. Smaller variations in the transport directions as shown by the micromineralogical composition are normally not reflected in the clay mineral record, neither climatic variations during the Pleistocene seem to have significant effect. In the South Tisza Basin and Maros Alluvial Fan well crystallised detrital phases prevail while in the Kóros Basin more mature sedimentary material of lesser crystallinity, higher kaolinite and very low carbonate contents can be found. The clay, carbonate, feldspar and iron minerals deposited may have been modified by flow systems of ground water. In the upper flow regime comprising Pleistocene and Pliocene horizons of the South Tisza Basin and Maros Alluvial Fan dissolution of carbonate minerals and albite and ion exchange on clay minerals may proceed. In the stagnant ground waters filling the Pleistocene and Pliocene beds of the Kóros Basin neoformation of pure smectite and kaolinite from dissolution of albite and dissolution of carbonates may be inferred from hydrogeochemical and mineralogical data. Amorphous iron hydroxides underwent crystallisation and reduction producing, in a downward sequence, amorphous "limonite", goethite and siderite. No diagenetic K-fixation and illitisation occurs in this level, however, some kind of palaeo-pedological illitisation may have occurred in those continental sediments. The first main step of burial diagenetic illitisation as well as of kerogen diagenesis starts in the lower groundwater regime which corresponds to the Upper Pannonian stratigraphic horizon, i. e. below the formations discussed in the present paper. |
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Physical Description: | 39-53 |
ISSN: | 0365-8066 |