Stratigraphic and sedimentological evidence bearing on structural repetition in early Archean rocks of the Barberton greenstone belt, South Africa

Lowe, Donald R.; Byerly, Gary R.; Ransom, Barbara; Nocita, Bruce W.

doi:10.1016/0301-9268(85)90011-7

Cited by 65 publications

(30 citation statements)

References 14 publications

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“…4;Lowe et al, 1985;Lowe et al, this volume, Chapter 2). The stratigraphy is more coherent along most of the east limb, and a complete section of the formation, 2,900 m thick, is present immediately north of the Msauli River (Figs.…”

Section: Southern Faciesmentioning

confidence: 95%

“…Our studies as well as those of Steyn (1965), Reimer (1967), Viljoen, R. P., and Viljoen (1969), and Paris (1985) have failed to establish either that these lithologies are part of a single, coherent stratigraphic succession or that they make up a mappable lithostratigraphic unit. In sections around the Onverwacht anticline, the Kromberg Formation of Viljoen, R. P., and Viljoen (1969) is succeeded directly by the Msauli Chert, regarded by previous investigators (Heinrichs, 1980;Stanistreet et al, 1981;Lowe et al, 1985; and others) as the basal unit of the Fig Tree Group. Our mapping has failed to disclose any Zwartkoppie rocks around the east end of the Stolzberg syncline ( Fig.…”

Section: Southern Faciesmentioning

confidence: 96%

“…At its top, M2v shows a 5-to 30-m-thick zone of greenish silicified and carbonated komatiite that contains silica pseudomorphs of pyroxene spinifex and cumulus textures (Lowe et al, 1985;Lowe and Byerly, 1986b;Duchac, 1986;Duchac and Hanor, 1987;Hanor and Duchac, 1990). The upper surface of this zone of silicification locally shows as much as 6 m of erosional relief (Figs.…”

Section: Southern Faciesmentioning

confidence: 96%

“…Paleocurrent indictors in the turbidites along the Komati River suggest general flow from north to south. The cherty turbidites at the top of the Komati River section have been correlated with the Buck Reef Chert on the west limb of the anticline (Viljoen, R. P., and Viljoen, 1969), but regional mapping indicates that these turbidites are a local facies of the felsic volcanic sequence in the type section of the Hooggenoeg Formation (Lowe et al, 1985).…”

Section: Southern Faciesmentioning

confidence: 97%

“…Ramsay (1963) pointed out that complex, polyphase deformation has affected Barberton rocks. De Wit (1982, Lamb (1984a, b), Lowe et al (1985), de Wit et al (1987b), Jackson et al (1987), Paris (1988), de Wit et al (1992), de Ronde and de Wit (1994), Heubeck and Lowe (1994a, b), Lowe (1994b), and Lowe et al (this volume,Chapter 2) have emphasized the existence of major thrust faults and fold nappes within the BGB that reflect major horizontal shortening of the belt and repeat major portions of the sequence. These authors differ, however, in their interpretation of which parts of the section are involved in this repetition.…”

Section: Introductionmentioning

confidence: 94%

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Stratigraphy of the west-central part of the Barberton Greenstone Belt, South Africa

Lowe¹,

Byerly²

1999

Geologic Evolution of the Barberton Greenstone Belt, South Africa

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The Swaziland Supergroup in the Barberton Greenstone Belt (BGB) consists of a lower, predominantly volcanic sequence, the Onverwacht Group; a middle volcaniclastic and quartz-poor clastic succession, the Fig Tree Group; and an upper quartzose terrigenous unit, the Moodies Group. In classic sections in the Onverwacht anticline, the Onverwacht Group includes 8 to 10 km of komatiitic, basaltic, and dacitic volcanic rocks and thin, silicified sedimentary layers that have been subdivided, from base to top, into the Komati, Hooggenoeg, and Kromberg Formations, and a new unit, the Mendon Formation. The ages and stratigraphic relationships of the highly altered Sandspruit and Theespruit Formations in the anticline are not fully resolved, but the latter includes felsic volcanic components that are in part older than the Komati Formation and in part correlative with dacitic volcanic units at the top of the Hooggenoeg Formation. However, in the Steynsdorp anticline, rocks assigned to the Theespruit Formation lie stratigraphically below the Komati Formation and include the oldest dated stratigraphic units in the Swaziland Supergroup. In the central part of the belt, north of the Granville Grove fault and south of the Inyoka fault, komatiitic volcanic rocks of the Onverwacht Group are younger than those of the Komati Formation and are here assigned to a new unit, the Mendon Formation. Exposed portions of the formation appear to young northward across a series of fault-bounded outcrop belts. North of the Inyoka fault, the Onverwacht Group includes a thick succession of komatiitic and basaltic volcanic rocks and tuffs, layered ultramafic intrusions, and thin cherty units. These rocks are here grouped into a new lithostratigraphic unit, the Weltevreden Formation. Age data suggest that the Weltevreden Formation is equivalent to at least the upper part of the Mendon Formation. The overlying Fig Tree Group consists of interstratified terrigenous clastic units and dacitic to rhyodacitic volcaniclastic and volcanic rocks. South of the Inyoka fault, these strata appear to include two formation-level units: the Mapepe and Auber Villiers Formations. The Mapepe Formation includes as much as 700 m of shale, chertgrit sandstone, and chert-clast conglomerate interstratified with fine-grained felsic pyroclastic and volcaniclastic rocks. Chert, jasper, and barite make up a minor part of most sections. Deposition took place in alluvial, fan-delta, and shallow to perhaps moderately deep subaqueous environments. Dacitic tuffs have yielded single-crystal zircon ages of 3,252 ± 6, 3,243 ± 4, and 3,226 ± 4 Ma. The Auber Villiers Formation includes 1,500 to 2,000 m of dacitic tuff; coarse volLowe, D. R.Downloaded from caniclastic sandstone, conglomerate, and breccia; and terrigenous chert-clast conglomerate, chert-grit sandstone, and shale. This sequence and the locally overlying Moodies strata form the hanging-wall succession above a thrust fault, named the 24-hour Camp fault. The footwall sequence includes rocks of the Mendon and Mapepe Formations...

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Section: Southern Faciesmentioning

confidence: 95%

Section: Southern Faciesmentioning

confidence: 96%