TY - JOUR
T1 - Characterization and origin of two Fe-rich bentonites from Westerwald (Germany)
AU - Fontaine, François
AU - Christidis, Gerorge E.
AU - Yans, Johan
AU - Hollanders, Sofie
AU - Hoffman, Andreas
AU - Fagel, Nathalie
PY - 2020/3/15
Y1 - 2020/3/15
N2 - The Westerwald region is one of the major ceramic clay mining areas of Germany. The mined clays were deposited on the weathered Rhenish massif during Eocene and Oligocene and were protected from erosion by a large alkaline basalt cover. Two Fe-rich bentonite layers exposed in quarries of the Eastern part of the Westerwald were investigated with X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, optical microscopy, scanning electron microscopy, chemical analyses and cation exchange capacity (CEC). In both bentonite layers, the main mineral is a high-charge Fe-rich beidellite containing exchangeable Ca and Mg. Even if they both derive from mafic volcanic rocks, the difference in accessory minerals and trace element content leads to the conclusion that they have a different precursor. The lower bentonite layer also contains talc, saponite, halloysite, goethite and anatase. It is part of the Paleozoic bedrock and results from the weathering of a Lower Carboniferous metabasalt. The upper bentonite layer has Upper Oligocene age and has been derived from the alteration of tuffite with a composition ranging from alkali basalt to trachyte. This bentonite is linked to the first eruptions of the intraplate Cenozoic volcanic activity of the Westerwald.
AB - The Westerwald region is one of the major ceramic clay mining areas of Germany. The mined clays were deposited on the weathered Rhenish massif during Eocene and Oligocene and were protected from erosion by a large alkaline basalt cover. Two Fe-rich bentonite layers exposed in quarries of the Eastern part of the Westerwald were investigated with X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, optical microscopy, scanning electron microscopy, chemical analyses and cation exchange capacity (CEC). In both bentonite layers, the main mineral is a high-charge Fe-rich beidellite containing exchangeable Ca and Mg. Even if they both derive from mafic volcanic rocks, the difference in accessory minerals and trace element content leads to the conclusion that they have a different precursor. The lower bentonite layer also contains talc, saponite, halloysite, goethite and anatase. It is part of the Paleozoic bedrock and results from the weathering of a Lower Carboniferous metabasalt. The upper bentonite layer has Upper Oligocene age and has been derived from the alteration of tuffite with a composition ranging from alkali basalt to trachyte. This bentonite is linked to the first eruptions of the intraplate Cenozoic volcanic activity of the Westerwald.
KW - Anatase
KW - Bentonite
KW - Fe-rich smectite
KW - Genesis
KW - Geochemistry
KW - Westerwald
UR - http://www.scopus.com/inward/record.url?scp=85078669450&partnerID=8YFLogxK
U2 - 10.1016/j.clay.2020.105444
DO - 10.1016/j.clay.2020.105444
M3 - Article
AN - SCOPUS:85078669450
SN - 0169-1317
VL - 187
JO - Applied Clay Science
JF - Applied Clay Science
M1 - 105444
ER -