Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa

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dc.contributor.advisorRichardson, Steveen_ZA
dc.contributor.authorGrosch, Eugene Geralden_ZA
dc.date.accessioned2014-11-05T17:30:47Z
dc.date.available2014-11-05T17:30:47Z
dc.date.issued2011en_ZA
dc.descriptionIncludes bibliographical references (leaves 146-162).en_ZA
dc.description.abstractLow-grade metabasites and hydrothermally altered ultramafic rocks comprise most of the ca. 3.5-3.2 Ga, Paleoarchean Barberton Greenstone Belt (BGB) of South Africa. However, PT-constraints and detailed petrological information on the variably altered mafic-ultramafic rocks are sparse and the nature of greenschist facies metamorphism is poorly characterized. In addition, alteration and silicification associated with distinct emerald green, fuchsite-(Crmica)- carbonate-quartz alteration zones is commonly found beneath chert horizons in the mafic-ultramafic rocks of the Onverwacht Group of the BGB. The origin of this silicification is highly debated and has important bearing on the nature of Paleoarchean geodynamic models, crustal geothermal gradients, hydrothermal oceanic regimes, as well as potential early life-sustaining environments. Over the past four decades, widely varying interpretations have been reported for the origin of these silica-rich fuchsitic alteration zones in the BGB, ranging from very low temperature (less than 60oC) atmospheric weathering of komatiites (Lowe and Byerly, 1986; 1999); low-temperature (less than 125oC) seafloor alteration (Hofmann and Harris, 2008); to bedding-parallel ‘flaser-banded gneissesschists’ in oceanic ‘extensionaloverthrust glide planes’ (de Wit, 1982a; 1986a,b; de Wit et al., 1982b; 1987b; 2011). Consequently, these fuchsitic-alteration zones have been at the centre of much debate surrounding stratigraphy models and the possible operation of early Paleoarchean platetectonic processes in the BGB.en_ZA
dc.identifier.apacitationGrosch, E. G. (2011). <i>Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/9239en_ZA
dc.identifier.chicagocitationGrosch, Eugene Gerald. <i>"Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2011. http://hdl.handle.net/11427/9239en_ZA
dc.identifier.citationGrosch, E. 2011. Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Grosch, Eugene Gerald AB - Low-grade metabasites and hydrothermally altered ultramafic rocks comprise most of the ca. 3.5-3.2 Ga, Paleoarchean Barberton Greenstone Belt (BGB) of South Africa. However, PT-constraints and detailed petrological information on the variably altered mafic-ultramafic rocks are sparse and the nature of greenschist facies metamorphism is poorly characterized. In addition, alteration and silicification associated with distinct emerald green, fuchsite-(Crmica)- carbonate-quartz alteration zones is commonly found beneath chert horizons in the mafic-ultramafic rocks of the Onverwacht Group of the BGB. The origin of this silicification is highly debated and has important bearing on the nature of Paleoarchean geodynamic models, crustal geothermal gradients, hydrothermal oceanic regimes, as well as potential early life-sustaining environments. Over the past four decades, widely varying interpretations have been reported for the origin of these silica-rich fuchsitic alteration zones in the BGB, ranging from very low temperature (less than 60oC) atmospheric weathering of komatiites (Lowe and Byerly, 1986; 1999); low-temperature (less than 125oC) seafloor alteration (Hofmann and Harris, 2008); to bedding-parallel ‘flaser-banded gneissesschists’ in oceanic ‘extensionaloverthrust glide planes’ (de Wit, 1982a; 1986a,b; de Wit et al., 1982b; 1987b; 2011). Consequently, these fuchsitic-alteration zones have been at the centre of much debate surrounding stratigraphy models and the possible operation of early Paleoarchean platetectonic processes in the BGB. DA - 2011 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa TI - Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa UR - http://hdl.handle.net/11427/9239 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9239
dc.identifier.vancouvercitationGrosch EG. Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2011 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9239en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Geological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherGeological Sciencesen_ZA
dc.titleDetermining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africaen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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