Mineralogy, geochemistry and diagenesis of kaolin minerals in the Wadi Araba Area : Jordan

الملخص EN

Kaolinite and dickite have been recognized within the Disi Sandstone Formation in the Wadi Araba area.

Scanning Electron (SEM) and Transmission Electron Microscopic (TEM) data indicated that both kaolinite and dickite are characterised by a high degree of crystallinity with pseudohexagonal forms, such features indicate an autochthonous genesis (diagenetic) primary-type.

Dickite crystals were concentrated in the coarse silt size (up to 60 microns), and were mostly formed during late diagenesis by transformation of pre-existing kaolinite or fine dickite minerals, and are considered as secondary-type minerals (sedimentary origin).

The genesis of kaolin deposits within the Disi sandstone in the Wadi Araba area can be considered as a combination of the residual and sedimentary processes.

The residual (primary-type) kaolin is the most dominant within the sandstones of the investigated area.

The quantitative results of the Disi sandstone indicated that -20 microns and-63 microns size fractions comprise 80 % and 60 % kaolin minerals.

Kaolin forms about 10 % of the exposed rocks of Disi sandstone in the Wadi Araba area.

The quantity and quality of the kaolin minerals as well as the geological and geomorphological setting of the source rock suggest a possible economic value.