Dual mechanisms for the formation of fluvial silcretes in the distal reaches of the Okavango Delta fan, Botswana

Auteurs :
SHAW, P.A.
NASH, D.J.

Description :
This paper describes the characteristics and possible origins of massive surface and sub-surface silcretes at Samedupe and Boro Junction, beyond the distal margin of the Okavango Delta. Morphological and petrological evidence from surface exposures and 3 sedimentary cores suggests that other modes of formation may also be applicable. A dual model of formation is proposed : surface silcretes are suggested to have developed by silica accumulation in seasonal pools remaining after the annual Okavango flood, whilst sub-surface horizons appear to have formed under conditions of varying pH associated with fluctuating groundwater levels beneath the channel floor.


Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 1998, vol. 23, n°. 8, p. 705-714, Collation : Illustration, Références bibliographiques : 49 ref.

Date :
1998

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley