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The geology of the area surrounding the Venetia kimberlite pipes, Limpopo Belt, South Africa; a complex interplay of nappe tectonics and granitoid magmatism

Jay M. Barton, W. P. Barnett, E. S. Barton, M. Barnett, A. Doorgapershad, C. Twiggs, R. Klemd, J. Martin, L. Mellonig and R. Zenglein
The geology of the area surrounding the Venetia kimberlite pipes, Limpopo Belt, South Africa; a complex interplay of nappe tectonics and granitoid magmatism (in Recent studies of geology in and around the Venetia kimberlite pipes, Limpopo Belt, South Africa, Jay M. Barton (editor), Reiner Klemd (editor) and Fred Brown (editor))
South African Journal of Geology (September 2003) 106 (2-3): 109-128

Abstract

The area surrounding the approximately 530 to approximately 519 Ma Venetia kimberlite pipes in the Central Zone of the Limpopo Belt, South Africa, consists of four tectonic units intruded by Proterozoic dolerite dykes and sills. The structurally lowest Krone metamorphic terrane is composed primarily of quartzofeldspathic gneisses, gently folded along approximately north-south trending axes. The ages of these rocks have not been determined but they are assumed to be Archean. Zones of mylonite separate the Krone metamorphic terrane from the Venetia and Endora klippen. The Venetia klippe, which includes a synclinal remnant of a nappe, is composed of four mappable units. The lowest consists of interlayered 3.2 Ga quartzofeldspathic gneisses and approximately 3.1 Ga orthoamphibolite. The next highest unit consists of thin, discontinuous layers of quartzofeldspathic gneisses, ortho- and para-amphibolite, carbonate and calc-silicate rocks, magnetite-quartzite and quartzite. Over lying this is a metasedimentary unit composed primarily of quartzite and carbonate and calc-silicate rocks. U-Pb ages for detrital zircons from within the quartzite indicate that this unit is younger than approximately 2.67 Ga. The upper most unit consists of granitic orthogneisses derived from an approximately 2.45 Ga precursor. Most of the contacts within and between these units in the Venetia klippe have been tectonically deformed into mylonite or biotite-schist although some sedimentary contacts may be preserved. The klippe is a doubly folded synform with a strong east-west trending, approximately 2.04 Ga D1 fold axis locally refolded long approximately 2.03 Ga north-south trending fold axes. Sedimentary structures preserved in the metasedimentary unit indicate that the synform is a syncline. The Endore klippe comprises a synform of quartzite and magnetite-quartzite of uncertain age. Intruding the Krone metamorphic terrane and probably the Venetia klippe is the Gotha granitic complex consisting of granite, granodiorite and tonalite of possible approximately 1.9 to approximately 2.0 Ga age. Igneous rocks composing this terrane are characterized by large U and Th contents. The emplacement of the Venetia kimberlite pipes into this area was largely controlled by faults related to the Dowe-Tokwe system. It is argued that rocks of both Archean and Proterozoic age are found in this portion of the Central Zone and that their juxtaposition was the result of largely horizontal tectonism and possible magmatism at approximately 2.04 Ga. The Proterozoic rocks have compositional similarities to and are possibly coeval with the rocks of the Transvaal Supergroup on the Kaapvaal Craton but it is unlikely that they were derived from that source.


ISSN: 1012-0750
EISSN: 1996-8590
Coden: TGSAA3
Serial Title: South African Journal of Geology
Serial Volume: 106
Serial Issue: 2-3
Title: The geology of the area surrounding the Venetia kimberlite pipes, Limpopo Belt, South Africa; a complex interplay of nappe tectonics and granitoid magmatism
Title: Recent studies of geology in and around the Venetia kimberlite pipes, Limpopo Belt, South Africa
Author(s): Barton, Jay M., Jr.Barnett, W. P.Barton, E. S.Barnett, M.Doorgapershad, A.Twiggs, C.Klemd, R.Martin, J.Mellonig, L.Zenglein, R.
Author(s): Barton, Jay M., Jr.editor
Author(s): Klemd, Reinereditor
Author(s): Brown, Frededitor
Affiliation: Rand Afrikaans University, Department of Geology, Auckland Park, South Africa
Affiliation: RAU, Department of Geology, Auckland Park, South Africa
Pages: 109-128
Published: 20030901
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 45
Accession Number: 2006-005993
Categories: Areal geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 3 tables, sketch map
S24°00'00" - S20°00'00", E26°00'00" - E32°00'00"
Secondary Affiliation: University of Wuerzburg, DEU, Federal Republic of GermanyDeBeers Consolidated Mines, ZAF, South AfricaPremier Mine, ZAF, South AfricaDeBeers Geoscience Center, ZAF, South AfricaUniversity of Wuerzburg, DEU, Federal Republic of Germany
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200603
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