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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, no4, pp. 215-220 (34 ref.)

Langue / Language

Anglais

Editeur / Publisher

Bureau for Scientific Publications, Pretoria, AFRIQUE DU SUD  (1987) (Revue)

Mots-clés anglais / English Keywords

South Africa

;

basalts

;

Karroo System

;

secondary minerals

;

zeolite group

;

zoning

;

laumontite

;

mesolite

;

stability

;

vesicular texture

;

calcite

;

chlorite

;

mordenite

;

heulandite

;

stellerite

;

stilbite

;

epistilbite

;

Southern Africa

;

volcanic rocks

;

igneous rocks

;

Mots-clés français / French Keywords

République Sud Africaine

;

Basalte

;

Karoo

;

Minéral secondaire

;

Zéolite

;

Zonalité

;

Laumontite

;

Mesolite

;

Stabilité

;

Formation Drakensberg

;

Amygdale

;

Texture vésiculaire

;

Calcite

;

Chlorite

;

Mordenite

;

Heulandite

;

Stellerite

;

Stilbite

;

Epistilbite

;

Afrique du Sud

;

Roche volcanique

;

Roche ignée

;

Mots-clés espagnols / Spanish Keywords

República de Sudáfrica

;

Basalto

;

Karoo

;

Mineral secundario

;

Zeolita

;

Zonalidad

;

Laumontita

;

Mesolita

;

Estabilidad

;

Textura vesicular

;

Calcita

;

Clorito

;

Mordenita

;

Heulendita

;

Stellerita

;

Estilbita

;

Epistilbita

;

África Sur

;

Roca volcánica

;

Roca ignea

;

Localisation / Location

INIST-CNRS, Cote INIST : 4128, 35400004707007.0060

Nº notice refdoc (ud4) : 4116460



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