Academic literature on the topic 'Barberton Greenstone belt'
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Journal articles on the topic "Barberton Greenstone belt"
Anhaeusser, C. R. "The geology and tectonic evolution of the northwest part of the Barberton Greenstone Belt, South Africa: A review." South African Journal of Geology 122, no. 4 (December 1, 2019): 421–54. http://dx.doi.org/10.25131/sajg.122.0033.
Full textHofmann, A., C. R. Anhaeusser, and X.-H. Li. "Layered ultramafic complexes of the Barberton Greenstone Belt – age constraints and tectonic implications." South African Journal of Geology 124, no. 1 (March 1, 2021): 7–16. http://dx.doi.org/10.25131/sajg.124.0002.
Full textDiener, J. F. A., and A. Dziggel. "Can mineral equilibrium modelling provide additional details on metamorphism of the Barberton garnet amphibolites?" South African Journal of Geology 124, no. 1 (March 1, 2021): 211–24. http://dx.doi.org/10.25131/sajg.124.0003.
Full textWard, J. H. W. "Geology and metallogeny of the Barberton greenstone belt: a survey." Journal of African Earth Sciences 21, no. 2 (August 1995): 213–40. http://dx.doi.org/10.1016/0899-5362(95)00067-4.
Full textDziggel, A., R. A. Armstrong, G. Stevens, and L. Nasdala. "Growth of zircon and titanite during metamorphism in the granitoid-gneiss terrane south of the Barberton greenstone belt, South Africa." Mineralogical Magazine 69, no. 6 (December 2005): 1019–36. http://dx.doi.org/10.1180/0026461056960305.
Full textVan Kranendonk, Martin J. "Cool greenstone drips and the role of partial convective overturn in Barberton greenstone belt evolution." Journal of African Earth Sciences 60, no. 5 (July 2011): 346–52. http://dx.doi.org/10.1016/j.jafrearsci.2011.03.012.
Full textFurnes, Harald, Maarten J. de Wit, Brian Robins, and Nils Rune Sandstå. "Volcanic evolution of the upper Onverwacht Suite, Barberton Greenstone Belt, South Africa." Precambrian Research 186, no. 1-4 (April 2011): 28–50. http://dx.doi.org/10.1016/j.precamres.2010.11.002.
Full textde Wit, Maarten J., Harald Furnes, and Brian Robins. "Geology and tectonostratigraphy of the Onverwacht Suite, Barberton Greenstone Belt, South Africa." Precambrian Research 186, no. 1-4 (April 2011): 1–27. http://dx.doi.org/10.1016/j.precamres.2010.12.007.
Full textByerly, Benjamin L., Donald R. Lowe, Nadja Drabon, Matthew A. Coble, Dale H. Burns, and Gary R. Byerly. "Hadean zircon from a 3.3 Ga sandstone, Barberton greenstone belt, South Africa." Geology 46, no. 11 (September 27, 2018): 967–70. http://dx.doi.org/10.1130/g45276.1.
Full textHomann, Martin. "Earliest life on Earth: Evidence from the Barberton Greenstone Belt, South Africa." Earth-Science Reviews 196 (September 2019): 102888. http://dx.doi.org/10.1016/j.earscirev.2019.102888.
Full textDissertations / Theses on the topic "Barberton Greenstone belt"
Diergaardt, Byron Nico. "Rhyolitic volcanism in the Onverwacht Group, Barberton Greenstone Belt." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80255.
Full textENGLISH ABSTRACT: The source of the K2O in the K2O-rich ~3.45 Ga felsic intrusive rocks of the H6 unit in the Hooggenoeg Formation of the Onverwacht Group in the Barberton Granite Greenstone Terrain (BGGT) is examined in this study. This is of particular research interest because the Paleoarchaean rock record is considered to lack K2O-rich magmatic rocks. Previous studies on the felsic igneous rocks of the H6 unit have proposed that these rhyolites are K-metasomatised eruptive equivalents of the sodium-rich ~3.45 Ga TTGs of the BGGT and that the K-feldspar crystals in the rocks formed as a consequence of subsolidus replacement of plagioclase by K-feldspar. Furthermore, the timing of K-metasomatism has previously been related to the formation of the Buck Ridge Chert (BRC), which overlies the H6 unit. However, it has recently been demonstrated from granitic clasts in the conglomerate layer at the base of the Moodies sucession that K2O-rich magmatic rocks formed concurrently with TTG magmas during each of three episodes of TTG magmatism observed in the BGGT. Consequently, the hypothesis of a metasomatic origin for the K2O-rich character of the felsic rocks of the H6 unit requires further examination. Previous studies of the chemistsry of felsic volcanic rocks within the H6 unit were based on relatively low numbers of samples. This study has examined a substantial set of the freshest material available. Two varieties of felsic volcanic rocks were identified; K2O-rich, CaO-poor, Na2O-poor rhyolites and Na2O-rich, CaO-poor, K2O-poor Na-rhyolites. The K2O- rich rhyolite variety is dominant. Consequently, it is possible that the K2O-rich character of these rocks represents a primary magmatic signature. However, this judgment is complicated by the presence of a greenschist-facies metamorphic overprint at 3.2 Ga, which has resulted in complete replacement of micrystalline groundmass and partial replacement of the phenocryst assemblages by greenschist- and sub-greenschist-facies mineral assemblages, which undoubtedly allowed possible shifts in chemical compositions In this thesis, I test the source of K2O in these rocks by using the porphyritic textures of the rocks as an indication of the primary composition of the magmas they were formed from. These textures are typically defined by K-feldspar or albite and quartz phenocrysts within a microcrystalline groundmass. The rocks containing albite are Na-rich (Na-rhyolites) whereas the rocks defined by K-feldspar phenocrysts are rhyolites. XRD study of the structural state of the K-feldspar phenocrysts in the rhyolites indicates that these crystals are orthoclase and intermediate microcline, i.e. medium temperature K-feldspar polymorphs. The modal proportions of K-feldspar, quartz and microcrystalline groundmass in the rhyolites were calculated by using image analysis software. The compositions of the feldspar minerals were determined by electron beam analysis. Minimum bulk rock K2O content of the rhyolites were calculated from the proportions of K-feldspar crystals and their compositions. Even where the proportion of K-feldspar phenocrysts is relatively low (~ 30%), the calculated minimum bulk-rock K2O content is still above 5 wt%. The HREE slope (GdN/LuN) of the felsic porphyritic rocks of the H6 rhyolites is similar to that of ~3.45 Ga TTG plutons and steeper than that of granitic clasts of identical age contained in the basal conglomerate of the Moodies Group. Hence this study has illustrated that the rhyolites of the H6 unit were primary K-feldspar-rich, K2O-rich magmas that formed contemporarily with the ~3.45 Ga TTGs. This implicitly means that rhyolitic volcanism was more wide spread than previously thought in the Paleoarchaean and that it occurred together with the intrusion of the ~3.45 Ga TTGs in the BGGT.
AFRIKAANSE OPSOMMING: Die bron van die K2O in die K2O-ryk ~ 3,45 Ga felsiese vulkaniese rotse van die H6-eenheid in die Hooggenoeg formasie van die Onverwacht Groep in die Barberton Graniet Groensteen Terrein (BGGT) is in hierdie studie ondersoek. Dit is van besondere navorsingsbelang omdat die Paleoargeïse gesteenterekord beskou word as vry van magmatiese K2O ryke gesteentes. Vorige studies oor die felsiese vulkaniese rotse van die H6 eenheid het voorgestel dat hierdie rioliete K-gemetasomatiese eruptiewe ekwivalente van die natrium-ryke ~ 3,45 Ga TTGs van die BGGT is en dat die K-veldspaat kristalle in die gesteentes gevorm is as gevolg van subsolidus vervanging van plagioklaas deur K-veldspaat. Verder is die tydsberekening van K-metasomatisme voorheen gekoppel aan die vorming van die Buck Ridge Chert (BRC) wat die felsiese H6 eenheid bedek. Dit is egter onlangs aangetoon dat K2O-ryke magmatiese rotse gelyktydig met TTG magmas gevorm is tydens elk van drie episodes van TTG magmatisme waargeneem in die BGGT. Gevolglik vereis die hipotese van 'n metasomatiese oorsprong vir die K2O-ryke karakter van die felsiese gesteentes van die H6 eenheid verdere ondersoek. Vorige studies van die felsiese vulkaniese gesteentechemie in die H6 eenheid is gebaseer op 'n relatief klein getal monsters. Hierdie studie het 'n aansienlike stel van die varsste materiaal beskikbaar vir analise ondersoek. Twee variëteite van peralumineuse felsiese vulkaniese gesteentes naamlik 'n K2O-ryk, CaO-arm, Na2O-arm rioliet en Na2O-ryk, CaO-arm, K2O-arm Na-rioliet. Die K2O-ryke rioliet variëteit is meer oorheersend as die Na-rioliete. Dit is dus moontlik dat die K2O-ryk karakter van hierdie rotse 'n primêre magmatiese kenmerke verteenwoordig. Hierdie uitspraak is egter bemoeilik deur die teenwoordigheid van 'n groenskisfasies metamorfe oorprint op 3,2 Ga, wat gelei het tot die volledige vervanging van mikrokrisstalyne grondmassa en gedeeltelike vervanging van fenokrist samestellings deur groenskis en sub-groenskisfasies minerale samestellings en wat ongetwyfeld toegelaat het vir 'n moontlike verskuiwing in chemiese samestelling. In hierdie tesis toets ek die bron van K2O in hierdie gesteentes deur gebruik te maak van die vulkaniese teksture van die gesteentes as 'n aanduiding van die primêre samestelling van die magmas waaruit hulle gevorm het. Hierdie teksture word gewoonlik gedefinieer deur K-veldspaat of albiet en kwarts fenokriste binne 'n grondmassa van wat vroeërglasoorblyfsels was. Die rotse wat albiet bevat is Na-ryk (Na-rioliete) terwyl die rotse gedefinieer deur K-veldspaat fenokriste rioliete is. XRD studie van die strukturele toestand van die K-veldspaat fenokriste in die rioliete dui aan dat hierdie kristalle ortoklaas en intermediêre mikroklien is, dit wil sê die hoër temperatuur K-veldspaat polimorfe. Die modale proporsies van K-veldspaat, kwarts en glasoorblyfsels in die rioliete is akkuraat bereken deur gebruik te maak van beeld analise sagteware. Verder is die samestellings van die veldspaat minerale bepaal deur die elektronstraal analise. Minimum grootmaat rots K2O inhoud van die rioliet is berekén vanaf die fase verhouding van K-veldspaat en hul komposisies. Resultate dui daarop dat selfs waar die verhouding van K-veldspaat phenocrysts is relatief laag (~ 30%), die berekende minimum K2O grootmaat rots samestelling is nog steeds bo 5 wt%. Die REE-helling (GDN / Lun) van felsiese porphyritic rotse van die H6 is soortgelyke relatief tot die REE helling van ~ 3,45 Ga TTGs en steiler REE helling relatief tot granitiese klaste vervat in die basale konglomeraat van die Moodies-groep. Dus het hierdie studie getoon dat die rioliete van die H6-eenheid primêre K-veldspaat-ryke, K2O-ryke en peralumineuse magmas was wat gevorm is terselfdertyd met die ~3,45 Ga TTGs. Dit beteken implisiet dat riolitiese vulkanisme meer wyd verspreid was as wat voorheen gedink is in die Paleoargeïkum en dat dit tesame met die indringing van die ~ 3,45 Ga TTGs in die BGGT plaasgevind het.
MacLennan, Scott Angus. "Structural, geophysical and geochemical characterisation of a Mesoarchean paleosuture zone, Barberton Greenstone Belt, South Africa." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/10949.
Full textImages of the electrical conductivity of the subsurface below the Barberton Greenstone Belt (BGB) reveal two electrically conductive zones that extend to a depth of at least 5km. These high conductivity zones correlate well with regional shear zones geologically mapped at surface. The serpentinised Stolzburg Layered Ultramatic Body (SLUB) occurs along one of these shear zones, the Saddleback-Inyoka Shear Zone (SISZ). In an attempt to identify the conductive rocks or phases responsible for the observed electrical conductivity anomalies, impedance spectroscopy measurements on samples collected from regional rock types and shear zone related lithologies were undertaken, and show that the rocks from the BGB are generally very resistive. Sulphide rich greenschists and greywackes collected at depth from the northern extension of the SISZ have elevated conductivities, but are not comparable to the anomalies observed in inversions of the magnetotelluric data. Magnetite veins from the SLUB were the only materials that had electrical resistivities low enough to be comparable with the conductivity anomalies. In order to better understand the structural evolution of the western extent of the greenstone belt, a field investigation was undertaken in the SLUB.
Kemp, Jacobus Nicholas, H. L. Zietsman, and G. Stevens. "Evaluating image classification techniques on ASTER data for lithological discrimination in the Barberton Greenstone Belt, Mpumalanga, South Africa." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/4933.
Full text81 Leaves printed on single pages i-xi, preliminary pages and numbered pages 1- 70. Includes bibliography, list of tables and list of figures.
Digitized at 300 dpi color PDF format (OCR), using KODAK i 1220 PLUS scanner.
ENGLISH ABSTRACT: Geological field mapping is often limited by logistical and cost constraints as well as the scope and extent of observations possible using ground-based mapping. Remote sensing offers, among others, the advantages of an increased spectral range for observations and a regional perspective of areas under observation. This study aimed to determine the accuracy of a collection of image classification techniques when applied to ASTER reflectance data. Band rationing, the Crosta Technique, Constrained Energy Minimization, Spectral Correlation Mapping and the Maximum Likelihood Classifier were evaluated for their efficiency in detecting and discriminating between greenstone and granitoid material. The study area was the Archaean Barberton Greenstone Belt in the eastern Mpumalanga Province, South Africa. ASTER reflectance imagery was acquired and pre-processed. Training and reference data was extracted from the image through visual inspection and expert knowledge. The training data was used in conjunction with USGS mineral spectra to train the five classification algorithms using the ERDAS's software package. This resulted in abundance images for the target materials specified by the training data. The Maximum Likelihood Classifier produced a classified thematic map. The reference data was used to perform a rigorous classification accuracy assessment procedure. All abundance images were thresholded to varying levels, obtaining accuracy statistics at every level. In so doing, threshold levels could be defined for every abundance image in such a way that the reliability of the classification was optimized. For each abundance image, as well as for the output map of the Maximum Likelihood Classifier, user's- and producer's accuracies as well as kappa statistics were derived and used as comparative measures of efficiency between the five techniques. This information was also used to assess the spectral separability of the target materials. The Maximum Likelihood Classifier outperformed the other techniques significantly, achieving an overall classification accuracy of 81.1% and an overall kappa value of 0.748. Greenstone rocks were accurately discriminated from granitoid rocks with accuracies between 72.9% and 98.5%, while granitoid rocks showed very poor ability to be accurately distinguished from each other. The main recommendations from this study are that thermal infrared and gamma-ray data be considered, together with better vegetation masking and an investigation into object orientated techniques.
AFRIKAANSE OPSOMMING: Geologiese veldkartering word algemeen beperk deur logistiese en koste-verwante faktore, sowel as die beperkte bestek waartoe waarnemings met veld-gebasseerde tegnieke gemaak kan word. Afstandswaarneming bied, onder andere, 'n vergrote spekrale omvang vir waarnemings en 'n regionale perspektief van die area wat bestudeer word. Hierdie studie was gemik daarop om die akkuraatheid van 'n versameling beeld-klassifikasie tegnieke, toegepas op ASTER data, te bepaal. Bandverhoudings, die Crosta Tegniek, "Constrained Energy Minimization", Spektrale Korrellasie Kartering, en Maksimum Waarskynlikheid Klassifikasie is evalueer op grond van hul vermoë om groensteen en granitoied-rotse op te spoor en tussen hulle te onderskei. Die studiegebied was die Argalese Barberton Groensteengordel in die oostelike Mpumalanga Provinsie in Suid Afrika. 'n ASTER refleksie beeld is verkry, waarop voorverwerking uitgevoer is. Opleidings- en verwysingsdata is van die beeld verkry deur visuele inspeksie en vakkundige kennis. Die opleidingsdata is saam met VSGO mineraalspektra gebruik om die vyf klassifikasie algoritmes met behulp van die ERDAS sagteware pakket op te lei. Die resultaat was volopheidsbeelde vir die teikenmateriale gespesifiseer in die opleidingsdata. Die Maksimum Waarskynlikheid algoritme het 'n geklassifiseerde tematiese beeld gelewer. Met behulp van die verwysingsdata is 'n streng akkuraatheidstoetsing prosedure uitgevoer. Vir alle volopheidsbeelde is 'n reeks drempelwaardes gestel, en by elke drempelwaarde is akkuraatheidsstatistieke afgelei. Op hierdie manier kon 'n drempelwaarde vir elke volopheidsbeeld vasgestel word sodat die drempelwaarde die betroubaarheid van die klassifikasie optimeer. Vir elke volopheidsbeeld, asook vir die tematiese kaart verkry van die Maksimum Waarskynlikheid klassifikasie, is gebruikers- en produsent-akkuraathede en kappa statistieke bereken. Hierdie waardes is gebruik as vergelykende maatstawwe van akkuraatheid tussen die vyf tegnieke, asook van die spektrale skeibaarheid van die onderskeie teikenmateriale. Die Maksimum Waarskynlikheid klassifikasie het die beste resultate gelewer, met 'n algehele klassifikasie akkuraatheid van 81.1%, en 'n gemiddelde kappa waarde van 0.748. Groensteenrotse kon met hoë akkuraathede van tussen 72.9% en 98.5% van granitoiedrotse onderskei word, terwyl granitoiedrotse 'n swak vermoë getoon het om van mekaar onderskei te word. Die belangrikste aanbevelings vanuit hierdie studie is dat termiese uitstralingdata asook gamma-straal data geimplimenteer word. Beter verwydering van plantegroei en 'n studie na die lewensvatbaarheid van objekgeorienteerde metodes word ook aanbeveel.
Scroggs, Elizabeth E. "An Examination of the Carbonaceous Materials in the S3 Bed of the Barberton Greenstone Belt, South Africa." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/120292.
Full textM.S.
Carbonaceous materials found in Archean rocks have been the source of study and controversy for the last two decades due to questions of the biogenecity of these particles. One of the key locations for these studies is the Barberton Greenstone Belt (BGB), in South Africa which contains some of the oldest known rocks on Earth, ranging in age from 3.5 to 3.2 billion years old. Preserved within the Onverwacht and Fig Tree Groups of the BGB are spherules that formed by the condensation of an impact-produced global vapor plume. The spherules are distal deposits that would have been deposited globally, but are only preserved at this location and in western parts of Australia. Like several other sediments in the BGB, there is evidence of minor amounts of carbonaceous particles contained within the spherule beds. Four individual impact events are preserved in distinct beds designated as S1, S2, S3, and S4. Due to the wide distribution of this bed in a variety of depositional settings, including both protected shallow and deep water depositional settings where there is little evidence of reworking, the S3 bed is an ideal choice for mineralogical, geochemical, and petrographic studies of impact spherules. This research examines samples from four different locations of the S3 spherule bed layer, the Barite Syncline, Maid-of-the-Mist, Sheba Mine, and Loop Road locations, in order to determine the origin of carbonaceous particles contained within the bed. Several geologic processes could account for the presence of the carbonaceous materials within the S3 spherule bed layer. These processes include: (1) Diagenetic processes, (2) Fisher-Tropsch Synthesis, (3) Microbial activity, and (4) Primary condensates from the impact plume. In order to distinguish between these processes, the spatial distribution of the carbonaceous matter was mapped, noting the mineral associations with these grains. Petrographic and electron microanalytical studies of the S3 samples reveal the presence of carbonaceous material in the sections with highly concentrated spherules, Barite Syncline, Loop Road, and Sheba Mine locations, but not in the samples from the Maid-of-the-Mist location, where there is a low concentration of spherules and abundant admixed volcanic detritus. Only Fischer-Tropsch Synthesis can be excluded as a process responsible for the origin of carbonaceous materials in the S3 beds. Though there is no direct evidence of the biogenecity of the observed carbonaceous materials, other textual observations within the S3 spherule bed are consistent with microbial activity, including Ambient Inclusion Trails and an unusual feature with a cyanobacteria-like morphology. While microbial activity cannot be ruled out as a process responsible for the origins of the carbonaceous materials, the findings of this study indicate that the carbon was mobilized from within the spherules during diagenesis. The location of carbon along spherule rims and microfractures within the spherules can also be attributed to diagenetic processes, such as fracture flow, dissolution, and replacement. A plausible explanation is that the carbon was a primary condensate from the impact plume, but has been diagenetically remobilized locally into microfractures and along the rims of the spherules.
Temple University--Theses
Kütter, Sissy [Verfasser], Michael H. [Akademischer Betreuer] Weber, and Ute [Akademischer Betreuer] Weckmann. "Magnetotelluric measurements across the southern Barberton Greenstone Belt, South Africa / Sissy Kütter ; Michael H. Weber, Ute Weckmann." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218399805/34.
Full textKütter, Sissy Verfasser], Michael [Akademischer Betreuer] [Weber, and Ute [Akademischer Betreuer] Weckmann. "Magnetotelluric measurements across the southern Barberton Greenstone Belt, South Africa / Sissy Kütter ; Michael H. Weber, Ute Weckmann." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218399805/34.
Full textRoberts, Artal Laura. "A palaeomagnetic study of 3.5 to 3.2 billion year old rocks from the Barberton Greenstone Belt, South Africa." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2014439/.
Full textDiener, Johann F. A. "The tectono-metamorphic evolution of the Theespruit Formation in the Tjakastad Schist Belt and surrounding areas of the Barberton Greenstone Belt, South Africa." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16309.
Full textENGLISH ABSTRACT: The southern portions of the Early- to Mid-Archaean Barberton granitoid-greenstone terrain of South Africa consists of a high-grade metamorphic granitoid-gneiss terrain that is juxtaposed against the low-grade metamorphic supracrustal sequence of the Barberton Greenstone Belt. The boundary of the two different crustal domains corresponds to the Theespruit Formation, an amphibolite-facies, highly tectonized mélange of metabasites, felsic volcanics and rare, aluminous clastic sediments that occurs along the granitoidgreenstone margins. Amphibolite-facies lithologies in the Theespruit Formation are characterized by strongly prolate mylonitic fabrics that formed in a constrictional tectonic regime. Away from the granitoid-greenstone margin and towards the central parts of the greenstone belt, these rocks grade to, and are overprinted by, greenschist-facies S-L mylonites that formed during non-coaxial deformation. Both peak and retrograde minerals define, and are aligned parallel to, the fabrics in these rocks, indicating that shearing was initiated under peak metamorphic conditions and continued during retrogression. S-C’ fabric relationships indicate that shearing occurred in an extensional tectonic regime and that, during deformation, the gneiss terrain was uplifted relative to the greenstone belt. Peak metamorphic assemblages of grt-st-bt-chl-pl-qtz and ky-st-btms- pl-qtz in metasediments and grt-ep-hbl-pl-qtz in amphibolite constrain peak metamorphic conditions of 7.4 ± 1.0 kbar and 560 ± 20 ºC that were attained during the main accretionary episode in the Barberton terrain at 3229 ± 25 Ma. Peak assemblages in all rocks are pre-tectonic and were deformed and re-equilibrated during retrogression, resulting in these being minimum estimates of peak metamorphic conditions. Petrographic evidence and retrograde pressure-temperature estimates indicate that retrogression involved near-isothermal decompression of ca. 4 kbar prior to cooling into the greenschist-facies. The style and timing of metamorphism in the Theespruit Formation is similar to that of the granitoid-gneiss terrain, suggesting that the Theespruit Formation shares a geological history with the gneiss terrain and that it is allochtonous to the greenstone belt. The main deformational and fabric-forming event exhibited in the Theespruit Formation occurred during the exhumation of the granitoid-gneiss terrain subsequent to peak metamorphism. Consequently, the juxtaposition of this terrain againstthe greenstone belt was achieved by tectonic underplating and core complex formation at ca. 3.23 Ga. The occurrence of high-grade constrictional mylonites that are overprinted by low-grade non-coaxial mylonites as well as extension in an overall compressional tectonic regime is consistent with exhumation by extensional orogenic collapse. Burial of the high-grade terrain to depths of 25 – 30 km is only possible in a relatively cold and rigid crustal environment, while the extremely low apparent geothermal gradients of ca. 20 ºC/km preserved in this terrain suggest that burial and exhumation occurred rapidly, within a time-span of ca. 15 – 20 Ma. These parameters strongly suggest that metamorphism occurred in response to a lateral plate tectonic process that was operational in the Barberton terrain at 3230 Ma.
AFRIKAANSE OPSOMMING: Die suidelike dele van die Vroeg- tot Middel-Argaïese Barberton graniet-groensteen terrein van Suid-Afrika bestaan uit ‘n hoë-graad metamorfe graniet-gneiss terrein wat die lae-graad metamorfe groenstene van die Barberton Groensteen Gordel begrens. Die grens tussen die twee verskillende kors-domeine hang saam met die Theespruit Formasie, ‘n amfiboliet-fasies, getektoniseerde melange van metabasiete, felsiese vulkaniese gesteentes en skaars, alumineuse klastiese sedimente wat langs die graniet-groensteen kontakte voorkom. Amfiboliet-fasies gesteentes in die Theespruit Formasie word gekenmerk deur sterk prolaat milonitiese maaksels wat in ‘n vernouende tektoniese omgewing gevorm het. Hierdie rotse word weg van die graniet-groensteen kontak en na die sentrale dele van die groensteen gordel oordruk en vervang deur groenskis-fasies S-L miloniete wat tydens nie-koaksiale vervorming gevorm het. Beide piek en retrograad minerale definieer, en is georienteer parallel aan, die maaksel in die rotse, wat daarop dui dat skuifskeur onder piek metamorfe toestande begin het en volgehou het tydens retrogressie. S-C’ maaksels dui daarop dat skuifskeur in ‘n verlengende tektoniese omgewing plaasgevind het en dat die gneiss terrein opgehef is relatief tot die groensteengordel tydens vervorming. Piek metamorfe versamelings van grt-st-bt-chl-plqtz en ky-st-bt-ms-pl-qtz in metasedimente en grt-ep-hbl-pl-qtz in amfiboliet bepaal piek metamorfe toestande van 7.4 ± 1.0 kbar en 560 ± 20 ºC wat bereik is gedurende die hooffase van akkresie in die Barberton terrein teen 3229 ± 25 Ma. Die piek metamorfe versamelings in alle rotse is pre-tektonies en is vervorm en geherekwilibreer tydens retrogressie, wat maak dat die beramings minimum skattings van piek metamorfe toestande is. Petrografiese getuienis asook druk-temperatuur beramings dui daarop dat retrogressie gepaard gegaan het met byna-isotermiese drukverligting van naastenby 4 kbar voor afkoeling tot in die groenskis-fasies. Die styl en tydsberekening van metamorfose in die Theespruit Formasie is vergelykbaar met metamorfose in die granietgneiss terrein, wat daarop dui dat die Theespruit Formasie ‘n geologiese geskiedenis met die gneiss terrein deel en allochtoon is tot die groensteen gordel. Die hooffase van vervorming en maakselvorming in die Theespruit Formasie het plaasgevind gedurende die herontbloting van die graniet-gneiss terrein na piek metamorfose. Gevolglik is dieteenplasing van dié terrein teen die groensteen gordel vermag deur tektoniese onderplasing en kernkompleksvorming teen ongeveer 3.23 Ga. Die verskynsel van hoëgraadse vernoude miloniete wat oordruk word deur lae-graadse nie-koaksiale miloniete asook verlenging in ‘n algeheel saamdrukkende tektoniese omgewing dui daarop dat herontbloting plaasgevind het deur middel van verlengende orogenetiese ineenstorting. Die begrawing van die hoë-graadse terrein tot dieptes van 25 – 30 km is net moontlik in ‘n relatief koel en star kors-omgewing, terwyl die uitermate lae geotermiese gradiente van ongeveer 20 ºC/km wat in die terrein behoue gebly het daarop dui dat begrawing en herontbloting vinnig geskeid het, binne ‘n tydsverloop van ongeveer 15 – 20 Ma. Hierdie beperkings is ‘n sterk aanduiding dat metamorfose plaasgevind het as gevolg van ‘n laterale plaattektoniese proses wat werksaam was in die Barberton terrein teen 3230 Ma.
Homann, Martin [Verfasser]. "Depositional setting and metabolism of microbial mats in the Archean Moodies Group, Barberton Greenstone Belt, South Africa / Martin Homann." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1098185315/34.
Full textPesch, Katja [Verfasser], Franz Michael [Akademischer Betreuer] Meyer, and Peter A. [Akademischer Betreuer] Kukla. "Processes of seafloor hydrothermal alteration in the Archaean oceanic crust of the Barberton greenstone belt, South Africa / Katja Pesch ; Franz Michael Meyer, Peter A. Kukla." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1158599501/34.
Full textBooks on the topic "Barberton Greenstone belt"
1942-, Lowe Donald R., and Byerly Gary R. 1948-, eds. Geologic evolution of the Barberton Greenstone Belt, South Africa. Boulder, Colo: Geological Society of America, 1999.
Find full textLowe, Donald R., and Gary R. Byerly. Geologic Evolution of the Barberton Greenstone Belt, South Africa. Geological Society of America, 1999. http://dx.doi.org/10.1130/spe329.
Full textSpecial Paper 329: Geologic Evolution of the Barberton Greenstone Belt, South Africa. Geological Society of America, 1999. http://dx.doi.org/10.1130/0-8137-2329-9.
Full text(Editor), Donald R. Lowe, and Gary R. Byerly (Editor), eds. Geologic Evolution of the Barberton Greenstone Belt, South Africa (Special Papers (Geological Society of America), 329.). Geological Society of America, 1999.
Find full textCornel Edwin Jan.* de Ronde. Structural and geochronological relationships and fluid rock interaction in the central part of the ̃3.2-3.5 Ga Barberton greenstone belt, South Africa. 1991.
Find full textBook chapters on the topic "Barberton Greenstone belt"
Arndt, Nicholas. "Barberton Greenstone Belt." In Encyclopedia of Astrobiology, 143–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_148.
Full textArndt, Nicholas. "Barberton Greenstone Belt." In Encyclopedia of Astrobiology, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_148-3.
Full textArndt, Nicholas. "Barberton Greenstone Belt." In Encyclopedia of Astrobiology, 240–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_148.
Full textArndt, Nicholas. "Barberton Greenstone Belt." In Encyclopedia of Astrobiology, 1–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-642-27833-4_148-4.
Full textHofmann, Axel. "Barberton Greenstone Belt, Sedimentology." In Encyclopedia of Astrobiology, 146–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_149.
Full textHofmann, Axel. "Barberton Greenstone Belt, Sedimentology." In Encyclopedia of Astrobiology, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_149-3.
Full textHofmann, Axel. "Barberton Greenstone Belt, Sedimentology." In Encyclopedia of Astrobiology, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-642-27833-4_149-4.
Full textHofmann, Axel. "Barberton Greenstone Belt, Sedimentology." In Encyclopedia of Astrobiology, 244–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_149.
Full textWestall, Frances. "Barberton Greenstone Belt, Traces of Early Life." In Encyclopedia of Astrobiology, 147–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_150.
Full textWestall, Frances. "Barberton Greenstone Belt, Traces of Early Life." In Encyclopedia of Astrobiology, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_150-2.
Full textConference papers on the topic "Barberton Greenstone belt"
Nube, A., U. Weckmann, O. Ritter, X. Chen, J. Deacon, S. MacLennan, L. Moodley, et al. "Magnetotelluric Measurements Across the Southern Barberton Greenstone Belt: Data Analysis." In 11th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.241.nube_abstract.
Full textA. MacLennan, S., L. Moodley, U. Weckmann, O. Ritter, A. Nube, X. Chen, J. Deacon, et al. "Magnetotelluric Experiment Across Southern Barberton Greenstone Belt: a Students’ Perspective of the Field Work." In 11th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.241.maclennan_abstract.
Full textWeckmann, U., A. Nube, X. Chen, O. Ritter, and M. deWit. "Overview and Preliminary Results of a Magnetotelluric Experiment Across the Southern Barberton Greenstone Belt." In 11th SAGA Biennial Technical Meeting and Exhibition. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.241.weckmann_paper.
Full textReinhardt, Manuel, Volker Thiel, Henrik Drake, Walter Goetz, and Joachim Reitner. "Molecular Signatures from Kerogens Preserved in 3.42 Ga Microbial Mats (Buck Reef Chert, Barberton Greenstone Belt, South Africa)." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2185.
Full textFedo, Christopher M., Latisha Ashley Brengman, Martin J. Whitehouse, and Jeffrey S. Hanor. "SILICON ISOTOPE RECORD OF EARLY SILICIFIED PALEOARCHEAN (~3.3 GA) KOMATIITES FROM THE ONVERWACHT GROUP, BARBERTON GREENSTONE BELT, SOUTH AFRICA." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-303123.
Full textStoll, Emily J., and Donald R. Lowe. "CHARACTERIZATION OF BANDED FERRUGINOUS CHERT AND BANDED IRON FORMATION AND THEIR PROCESSES OF SEDIMENTATION IN THE FIG TREE GROUP, BARBERTON GREENSTONE BELT, SOUTH AFRICA." In GSA Annual Meeting in Phoenix, Arizona, USA - 2019. Geological Society of America, 2019. http://dx.doi.org/10.1130/abs/2019am-340421.
Full textWestall, Frances, and Dane Gerneke. "Electron microscope methods in the search for the earliest life forms on Earth (in 3.5-3.3 Ga cherts from the Barberton greenstone belt, South Africa): applications for extraterrestrial life studies." In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, edited by Richard B. Hoover. SPIE, 1998. http://dx.doi.org/10.1117/12.319833.
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