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Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal
Thesis (PhD)--University of Pretoria, 1986.
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| _version_ | 1867613670319587328 |
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| access_status_str | Open Access |
| author2 | Engelbrecht, Johann Pieter |
| author_browse | Engelbrecht, Johann Pieter |
| author_facet | Engelbrecht, Johann Pieter |
| collection | Thesis |
| dc_rights_str_mv | © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 1986. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/68491 |
| institution | University of Pretoria (South Africa) |
| language | Afrikaans |
| last_indexed | 2026-06-10T12:39:50.247Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2019 |
| publishDateRange | 2019 |
| publishDateSort | 2019 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/68491 Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal Engelbrecht, Johann Pieter UCTD Thesis (PhD)--University of Pretoria, 1986. Afrikaans: 'n Dagsoomkaart <skaal 1:100 000) en 'n struktuurkaart <skaal ongeveer 1:225 OQO> van die geologie van die Maricodistrik, is saamgestel. 'n Verskeidenheid van afsettings- gesteentes van die Transvaal Opeenvolging vorm die vloer van die Bosveld Kompleks. 'n Toename van grofklastiese afsettingsgesteentes in die noord-weste getuig van 'n aanvoerrigting van die afsettings vanuit hierdie rigting. Die groat diktes van meta- pelitiese gesteentes ten ooste van Enzelsberg wys op diepwater- afsettings in hierdie gebied. Getyvlakte-afsettings en lokale magnetietkwartsiete in die noord-weste~ getuig van klein afgeskermde sub-komme. Plooistrukture in die vloer en verskuiwings- dekblaaie het ontstaan deur gravitasieglyding van die ongekonsolideerde sedimente~ v~n wes na oos. Meerveranderlike statistiese tegnieke soos hoofkomponenteontleding, trosontleding en diskriminantontleding, word algemeen toegepas op die chemiese data. Die Hekpoortlawas van die Wes- en Des-Transvaal asook die Ongeluklawas van die Noord-Kaap~ word chemies onderling vergelyk. Hulle word geklassifiseer as intrakratoniese andesiete. Tussen- gelaagde tuwwe en graderingsgelaagde cherte dui op die onderwaterse afsetting van die lawa in die Wes-Transvaal. Die paleogrond wat deurgaans hierdie lawa oorle, het gevorm deur die chemiese uitloging van die onderliggende vulkaniese gesteentes. Die Marice Hipabissale Suite bestaan hoofsaaklik uit dun amfibolitiese en noritiese plate wat tussengelaagd met die Transvaal Opeenvolging voorkom. Die noriete is jonger, en kom nader aan die Bosveld Kompleks voor, as die amfiboliete. Die amfiboliete het gevorm deur hidrasie tydens metamorfisme van die noriete. Die randsone van die Rustenburg Gelaagde Suite is 814 m dik in die Nietverdiendomgewing, en bestaan uit sikliese eenhede met oliviennoriet, noriet en gabbroiese noriet. In hierdie omge~ing word geen hipabissale ekwivalent van die randsone aangetref nie. Die sikliese eenhede van die daaropvolgende laer sone en kritieke sone bestaan uit duniet, harzburgiet, chromitiet en bronsitiet. In die laer sone is dik lae van duniet en harzburgiet ontwikkel~ terwyl chromitiete tipies is van die kritieke sone. Volgens definisie begin die kritieke sone aan die basis van die LG-1 chromitietlaag. Die LG-1 tot LG-5 chromitietlaag word uitgeken in die gebied. Die siklisiteit, saam met die patroon van die chemiese veranderlikes langs die boorgatprofiel word verklaar aan die hand van 'n proses van progressiewe reaksie, gevolg deur 'n proses van progressiewe kristallisasie. Die "omgekeerde" differensiasieneiging van die randsone en 'n gedeelte van die laer sone word deur hierdie meganisme verklaar. Op hierdie wyse word daar deurgaans geintegreer onder die samestellings- en die temperatuurkurwe. 'n Kinetiese kristallisasiemodel vir die onstaan van die chromietkonsentrasies, word aan die hand gedoen. Hiervolgens het die chromiet voortdurend uitgesak, terwyl die olivien en ortopirokseen teen wisselende tempo's gekristalliseer het. 'n Maksimum metamorfe temperatuur van 610 °C en druk van 4.25 kb is bereken vir die granofelse ten ooste van Zelikatskop. Die druk tydens die inplasing van rand- laer en kritieke·sone was ongeveer 2 kb, maar het toegeneem met die inplasing van verdere magma van die Bosveld Kompleks. Die temperatuur van die vloergesteentes het gedurende hierdie tydperk nie gestyg het nie. English: An outcrop map (scale 1:100 000>, together with a structural map (scale approximately 1:225 000) of the geology of the Marico district, is presented. The floor of the Bushveld Complex is made up of a variety of rocks belonging to the Transvaal Sequence. An abundance of coarse-grained sedimentary rocks in the north-western part of the area is evidence of material transport from this direction. The presence of a significant thickness of metapelitic rocks to the east of Enzelsberg points to deep-water deposition in this area. Intertidal deposits and locally distributed magnetite quartzites, represent protected, small sub-basins. Fold structures and slides formed due to gravitation sliding of the soft sediments from west to east. The chemical data are subjected to multivariant statistical techniques such as principal components anal~sis, discriminant analysis, and cluster analysis. The chemical relationships between the Hekpoart volcanics of the western and eastern Transvaal, as well as the Ongeluk volcanics of the northern Cape, are investigated. All the lavas are classified as intracratonic andesites. Interlayered tuffs and graded cherts in the lavas of the western Transvaal favour a sub-aqueous extrusion. The paleo-soil which commonly overlies the lavas farmed by the chemical leaching thereof. The Marice Hypabyssal Suite is composed mainly of thin amphibolite and norite sills intrusive into the Transvaal Sequence. The amphibolites originated from the norites during metamorphism and hydration. The marginal zone of the Rustenburg Layered Suite is 814 m thick in the Nietverdiend area and is composed of cyclic units of olivine norite, norite and gabbroic norite. No hypabyssal equivalent of the marginal zone was found in this area. The cyclic units of the lower and critical zones are co~posed of dunites, harzburgites, chromitites and bronzitites. Thick layers of dunite and harzburgite are developed in the lower zone, while chromitite is typical of the critical zone. By definition, the critical zone commences at the base of the LG-1 chromitite layer, and the LG-1 to LG-5 chramitite layers are identified in the area. The cyclicity together with the chemical trends along the borehole profile is explained by a process of progressive reaction, followed by a process of progressive crystallization. The "reversed'' differentiation seen in the marginal zone and a part of the lower zone is explained by this mechanism. In this way there is a continual integration under the composition and temperature curves. A kinetic crystallization model for the origin of the chromite concentrations is proposed. According to this, the chromite was deposited at a constant speed, while the olivine and the orthopyroxene crystallized at fluctuating rates. A maximum metamorphic temperature of 610 °C and pressure of 4.25 kb was calculated for the ganolites to the east of Zelikatskop. During the formation of the marginal, lower and critical zones, the pressure was approximately 2 kb, but increased with the emplacement of the rest of the Bushveld Complex. The temperature in the floor-rocks did not increase during this time. Animal and Wildlife Sciences PhD Unrestricted 2019-02-20T12:31:38Z 2019-02-20T12:31:38Z 1986 1986 Thesis Engelbrecht, JP 1986, Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal, PhD Thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/68491> http://hdl.handle.net/2263/68491 Afrikaans © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title | Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title_full | Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title_fullStr | Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title_full_unstemmed | Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title_short | Die Bosveld kompleks en sy vloergesteentes in die omgewing van Nietverdiend, Wes-Transvaal |
| title_sort | die bosveld kompleks en sy vloergesteentes in die omgewing van nietverdiend wes transvaal |
| topic | UCTD |
| url | http://hdl.handle.net/2263/68491 |