Results 11 to 20 of about 313 (146)
Mineralogical Appraisal of Sediments of Duricrust Suites and Pans around Jwaneng Area, Botswana
Journal of Applied Sciences and Environmental Management, 2009 A mineralogical investigation of duricrust suites in Letlhakeng valley, and five pans around Jwaneng in Botswana was undertaken in order to know the mineral assemblages and infer on their landscape formation. In Letlhakeng, duricrusts comprised calcretes,
JR Atlhopheng, G-I E Ekosse
doaj +5 more sources
Heat treatment as a universal technical solution for silcrete use? A comparison between silcrete from the Western Cape (South Africa) and the Kalahari (Botswana). [PDF]
PLoS One, 2017 Heat treatment was one of the first transformative technologies in the southern African Middle Stone Age (MSA), with many studies in the Cape coastal zone of South Africa identifying it as an essential step in the preparation of silcrete prior to its use in stone tool manufacture. To date, however, no studies have investigated whether heat treatment is
Schmidt P +4 more
europepmc +5 more sources
Sedimentology, 2000 Four regressive sequences are present in the opaline rocks and related deposits of the Miocene Intermediate Unit of the Madrid Basin. The sequences consist of silty mudstones and argillaceous opals, separated by transitional facies.
Bustillo, M.A. +1 more
exaly +2 more sources
Earth Surface Processes and Landforms, 2004 This paper presents the first intensive integrated field and laboratory study of an area of typical silcrete occurrence in the UK, and enables parallels to be drawn with in situ silcretes in the neighbouring Paris Basin and other parts of northern Europe.
David J Nash, Rory N Mortimore
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Cap structures as diagnostic indicators of silcrete origin [PDF]
Sedimentary Geology, 2015 Cap structureswithin silcretes have long been used as a diagnostic indicator of pedogenic silicification. However, a growing number of studies of the micromorphology of non-pedogenic silcretes indicate that this may no longer be appropriate.
Nash, David; id_orcid +2 more
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Boletín de la Sociedad Española de Cerámica y Vidrio, 2003 Mineralogy, chemical composition and textures of silcretes, calcretes/palustrine limestones and argillaceous beds are studied to consider the features and the genesis of fibrous-clay minerals.
Bustillo, M. A., García Romero, E.
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Tertiary paleoweatherings and silcretes in the southern Paris Basin
CATENA, 1996 Abstract The southern border of the Paris Basin has undergone successive weathering events during the Tertiary. Fluviatile and lacustrine deposits are scattered, being mainly confined to several North-South trending grabens. These are generally devoid of fossils which would allow them to he dated. A discontinuous blanket of weathering products is the
Médard Thiry, Régine Simon-Coinçon
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ChemEngineering, 2022 After subjecting Zamora building stones to accelerated ageing tests, colour changes were studied, namely: (a) freezing/thawing and thermal shock (gelifraction and thermoclasty), and (b) combination of freezing/thawing plus thermal shock and salt ...
Jacinta García-Talegón +3 more
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Gem-quality chrysoprase from Haneti-Itiso area, Central Tanzania [PDF]
Bulletin of the Geological Society of Finland, 1990 Gem-quality, apple-green, Ni-bearing chalcedonic quartz occurs as near-surface veins in silicified serpentinite in the Haneti-Itiso area, Central Tanzania.
K.A. Kinnunen, E.J. Malisa
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Geosphere, 2022 Silcretes have long been recognized as modern and ancient duricrusts, but more recently also as silicified layers precipitated at groundwater tables, termed groundwater silcrete. However, the silica sources, transport mechanisms, and precipitation processes of groundwater silcrete are not well understood, and models are limited to the near-surface ...
David G. Lowe +3 more
openaire +1 more source