Titre du document / Document title
Secondary mineral zonation in the Drakensberg Basalt Formation, South Africa
Auteur(s) / Author(s)
DUNLEVEY J. N. (1) ;
RAMLUCKAN V. R. ;
MITCHELL A. A. ;
Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
(1) Univ. Durban-Westville, dep. geology, Durban 4000, AFRIQUE DU SUD
Résumé / Abstract
A distinct zonation of the secondary minerals has been identified in amygdales of the Karoo basaltic lavas of the Drakensberg Formation at the Sani Pass, on the Lesotho/Natal border. The basal 170 m of the lava sequence comprises a quartz and calcite zone, overlain by a zeolite-bearing zone. The zeolite zone is subdivised into a lower laumontite-rich and an upper mesolite-rich subzone. A comparison of the position of the Sani Pass laumontite zone with other similar zeolite successions indicates that the lava sequence (now 1400 m thick) was originally between 1600 and 1800 m thick, and that the goethermal gradient was approximately 110°C/km. The data support previous thickness estimates, and imply not only that 200 to 400 m of material has been removed from the top of the pile by erosion since the cessation of volcanic activity; but also that a thick succession of rhyolitic, units equivalent to the Lebombo Formation, were never extruded in the Lesotho portion of the Central Karoo Province
Revue / Journal Title
South African journal of geology
ISSN
1012-0750
Source / Source
1993, vol. 96, n
o4, pp. 215-220 (34 ref.)
Langue / Language
Anglais
Editeur / Publisher
Bureau for Scientific Publications, Pretoria, AFRIQUE DU SUD
(1987)
(Revue)
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Localisation / Location
INIST-CNRS, Cote INIST : 4128, 35400004707007.0060
Nº notice refdoc (ud4) : 4116460
