TY - JOUR
T1 - A mössbauer and Mineralogical Investigation of Soils from Central Sudan
AU - Ahmed, M. M.O.
AU - Aldahan, A. A.
AU - Ericsson, T.
N1 - Funding Information:
This work was carried out mainly at the Institutes of Physics and Geology at the University of Uppsala. M. M. O. Ahmed thanks the International Science Programs, University of Uppsala, for a scholarship making this joint project possible. Thanks are also extended to the Soil Survey Administration, Wad Medani, Sudan, for providing the samples and El Hadi M. Ibrahim (Geological Research Corporation, Khartoum, Sudan) for comments.
PY - 1991/1
Y1 - 1991/1
N2 - Quaternary soil samples from four localities (El Gezira, El Gunaid, El Mukabrab, and El Gash) in central Sudan were examined by Mössbauer spectroscopy, x-ray diffraction, transmitted light microscopy, and chemical analyses. Quartz, feldspars, and rock fragments are the main components of the detrital portions together with clay minerals, Fe and Ti oxides, and traces of pyroxene and amphibole. The main sources of these materials are the basic igneous and metamorphic rocks of the Abyssinian plateau as well as the eolian sands to the east of the Nile River (particularly for El Mukabrab soil). The less than 2-μm fraction contains smectite and chlorite as the dominant clay minerals with subordinate amounts of kaolinite. Mössbauerdata indicate that about 95% of the iron is in the ferric state which is mainly (up to 85%) located in the structure of smectite and chlorite. Variable amounts (15 to 30%c) of the ferric iron occur in hematite and goethite with roughly equal proportions. A substantial part of these iron oxides have minute grain size (less than a few hundred angstroms), thus showing superparamagnetic behavior in the Mössbauer spectra. Pedogenic-diagenetic effects on these soils are reflected by (1) precipitation of calcite mottles and nodules and gypsum aggregates, (2) relatively homogeneous distribution of hematite and goethite with depth, and (3) alteration of some smectite and chlorite into kaolinite.
AB - Quaternary soil samples from four localities (El Gezira, El Gunaid, El Mukabrab, and El Gash) in central Sudan were examined by Mössbauer spectroscopy, x-ray diffraction, transmitted light microscopy, and chemical analyses. Quartz, feldspars, and rock fragments are the main components of the detrital portions together with clay minerals, Fe and Ti oxides, and traces of pyroxene and amphibole. The main sources of these materials are the basic igneous and metamorphic rocks of the Abyssinian plateau as well as the eolian sands to the east of the Nile River (particularly for El Mukabrab soil). The less than 2-μm fraction contains smectite and chlorite as the dominant clay minerals with subordinate amounts of kaolinite. Mössbauerdata indicate that about 95% of the iron is in the ferric state which is mainly (up to 85%) located in the structure of smectite and chlorite. Variable amounts (15 to 30%c) of the ferric iron occur in hematite and goethite with roughly equal proportions. A substantial part of these iron oxides have minute grain size (less than a few hundred angstroms), thus showing superparamagnetic behavior in the Mössbauer spectra. Pedogenic-diagenetic effects on these soils are reflected by (1) precipitation of calcite mottles and nodules and gypsum aggregates, (2) relatively homogeneous distribution of hematite and goethite with depth, and (3) alteration of some smectite and chlorite into kaolinite.
KW - Day minerals
KW - Mössbauer spectroscopy
KW - Quaternary soils
UR - http://www.scopus.com/inward/record.url?scp=0025950542&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0025950542&partnerID=8YFLogxK
U2 - 10.1080/15324989109381266
DO - 10.1080/15324989109381266
M3 - Article
AN - SCOPUS:0025950542
SN - 1532-4982
VL - 5
SP - 55
EP - 75
JO - Arid Land Research and Management
JF - Arid Land Research and Management
IS - 1
ER -