Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8913529 | Journal of African Earth Sciences | 2018 | 18 Pages |
Abstract
As a step in evaluating the quality of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, their mineralogical characteristics were determined. The X-ray diffractometry technique was used to identify and quantify the mineral phases present in bulk and <2â¯Î¼m fractions. Scanning electron microscopy was used to determine the micromorphology of <2â¯Î¼m fractions kaolins. Thermal analyses (derivative thermal gravimetric analysis, thermal gravimetric analysis, and heat flow) were conducted to further characterise the kaolins. The main mineral phases present in the studied Cretaceous-Tertiary kaolins of the Douala Sub-Basin were kaoliniteâ¯>â¯smectiteâ¯>â¯illite, with mean values of 33.01â¯>â¯11.20 > 4.41â¯wt %; and 72.23â¯>â¯10.69 > 4.69â¯wt %, in bulk and <2â¯Î¼m fractions, respectively. The kaolins, micromorphologically, consisted of pseudo-hexagonal and thin platy particles; swirl-textured particles; and books or stacks of kaolinite particles. Three main reactions occurred during heating of the kaolins: a low temperature endothermic reaction, observed between 48 and 109â¯Â°C; a second low temperature peak, observed between 223 and 285â¯Â°C; and a third endothermic peak was found between 469 and 531â¯Â°C. In addition, an exothermic reaction also occurred between 943 and 988â¯Â°C in some of the samples. The absence of primary minerals such as feldspars and micas in most of these kaolins is an indication of intensive weathering, probably due to the humid tropical climate of the region. The different morphologies suggested that these kaolins might have been transported. Therefore, a humid tropical climate was responsible for the formation of Cretaceous-Tertiary kaolins of the Douala Sub-Basin through intense weathering of surrounding volcanic and metamorphic rocks.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Nenita N. Bukalo, Georges-Ivo E. Ekosse, John O. Odiyo, Jason S. Ogola,