Pb/Pb, SmNd and RbSr geochronology in the Archean Craton of Zimbabwe

Taylor, Paul N.; Kramersb, J.D.; Moorbatha, S.; Wilson, J. F.; Orpen, J.L.; Martín, Alexis

doi:10.1016/0168-9622(91)90020-w

Cited by 58 publications

(61 citation statements)

References 28 publications

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“…[Robertson and Du Toit, 1981] and [Fripp, 1983]). Geochemical fractionations ( [Rollinson, 1993], [Luais and Hawkesworth, 1994] and ), Nd model ages ( [Taylor et al, 1991] and ) and Pb isotope systematics ( [Taylor et al, 1991] and [Berger and Rollinson, 1997]) strongly support this assertion. In contrast to the SMZ it consists of predominantly charno-enderbites and charnockites with subordinate ultramafic-mafic enclaves, minor banded iron formations and exceedingly rare metapelitic lithologies.…”

Section: The Northern Marginal Zonesupporting

confidence: 66%

A review of the pressure–temperature–time evolution of the Limpopo Belt: Constraints for a tectonic model

Rigby

Mouri

Brandl

2008

Journal of African Earth Sciences

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Published literature argues that the Limpopo Belt can be subdivided into three zones, each with a distinctive geological character and tectono-metamorphic fingerprint. There are currently two contrasting schools of thought regarding the tectono-metamorphic evolution of the CZ. One camp argues that geochronological, structural and prograde pressure-temperature (P-T) evidence collectively indicate that the CZ underwent tectono-metamorphism at ca. 2.0 Ga which followed a clockwise P-T evolution during a transpressive orogeny that was initiated by the collision of the Kaapvaal and Zimbabwe cratons. Deformation and metamorphism consistent with this scenario are observed in the southern part of the NMZ but are curiously absent from the whole of the SMZ. The opposing view argues that the peak metamorphism associated with the collision of the Kaapvaal and Zimbabwe cratons occurred at ca. 2.6 Ga and the later metamorphic event is an overprint associated with reactivation along Archean shear zones. Post-peakmetamorphic conditions, which at present cannot be convincingly related to either a ca. 2.6 or 2.0 Ga event in the CZ reveal contrasting retrograde paths implying either nearisothermal decompression and isobaric cooling associated with a 'pop-up' style of exhumation or steady decompression-cooling linked to exhumation controlled by erosion. Recent data argue that the prograde evolution of the ca. 2.0 Ga event is characterised by isobaric heating prior to decompression-cooling. Contrasting P-T paths indicate that either different units exist within the CZ that underwent different P-T evolutions or that some P-T work is erroneous due to the application of equilibrium thermobarometry to mineral assemblages that are not in equilibrium. The morphology of the P-T path(s) for the ca. 2.6-2.52 Ga event are also a matter of dispute. Some workers have postulated an anticlockwise P-T evolution during this period whilst others regard this metamorphic event as following a clockwise evolution. Granitoid magmatism is broadly contemporaneous in all three zones at ca. 2.7-2.5 suggesting a possible causal geodynamic link. P-T contrasts between and within the respective zones prevent, at present, the construction of a coherent and inter-related tectonic model that can account for all of the available evidence. Detailed and fully-integrated petrological and geochronological studies are required to produce reliable P-T-t paths that may resolve some of these pertinent issues.

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Section: The Northern Marginal Zonesupporting

confidence: 66%

A review of the pressure–temperature–time evolution of the Limpopo Belt: Constraints for a tectonic model

Rigby

Mouri

Brandl

2008

Journal of African Earth Sciences

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“…Horstwood et al 1999). Gneisses from the Tokwe segment have Sm-Nd T DM ages between 3.65 and 3.51 Ga (Horstwood et al, 1999;Taylor et al, 1991) and low initial Sr ratios (0.700-0.701; Hawkesworth et al, 1975;Moorbath et al, 1977), suggesting that they were derived from depleted or chondritic mantle sources. Numerous infolded greenstone remnants (several kilometres long) have been assigned to the undated Sebakwian Group.…”

Section: Geology Of the Zimbabwe Cratonmentioning

confidence: 99%

“…Numerous infolded greenstone remnants (several kilometres long) have been assigned to the undated Sebakwian Group. The gneisses are intruded by the 3.38 Ga (U-Pb SIMS, Dodson et al 1988) Mushandike granite and the c. 3.35 Ga (Pb-Pb, Taylor et al, 1991) Mont d'Or 'granite', both of which are foliated but not banded (Fig. 1).…”

Section: Geology Of the Zimbabwe Cratonmentioning

confidence: 99%

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Juvenile crust formation in the Zimbabwe Craton deduced from the O-Hf isotopic record of 3.8–3.1 Ga detrital zircons

Bolhar

Hofmann

Kemp

et al. 2017

Geochimica et Cosmochimica Acta

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“…less than 150 Ma from beginning of accretion) mantle degassing and, therefore, even the earliest Archaean mantle seems to have been strongly degassed; (2) the TTG and GGM studied here span emplacement over 400 Ma and, compared with the preceding >1,000 Ma of Earth history, this time span is short for such a variation in H 2 O content of the mantle; and (3) the occurrence of TTG and GGM on different Archaean cratons is diachronous. For instance, GGM in the BML pre-date TTG in parts of the Zimbabwe craton (Taylor et al 1991).…”

Section: Mode and Efficiency Of Water Release From Archaean Subductiomentioning

confidence: 99%

Importance of water for Archaean granitoid petrology: a comparative study of TTG and potassic granitoids from Barberton Mountain Land, South Africa

Kleinhanns

Kramers

Kamber

2003

Contributions to Mineralogy and Petrology

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A new model for Archaean granitoid magmatism is presented which reconciles the most important geochemical similarities and differences between tonalite-trondhjemite-granodiorite (TTG) and potassic granitoids. Trace element abundances reveal a strong arc magmatism signature in all studied granitoids from Barberton Mountain Land. Characteristic features include HFSE depletion as well as distinct enrichment peaks of fluid-sensitive trace elements such as Pb in N-MORB normalisation, clearly indicating that all studied granitoids are derived from refertilised mantle above subduction zones. We envisage hydrous basaltic (s.l.) melts as parental liquids, which underwent extensive fractional crystallisation. Distinctive residual cumulates evolved depending on initial water content. High-H 2 O melts crystallised garnet/amphibole together with pyroxenes and minor plagioclase, but no olivine. This fractionation path ultimately led to TTG-like melts. Less hydrous basaltic melts also crystallised garnet/ amphibole, but the lower compatible element content indicates that olivine was also a liquidus phase. Pronounced negative Eu-anomalies of the granitic melts, correlating with Na, Ca and Al, indicate plagioclase to be of major importance. In the context of our model, the post-Archaean disappearance of TTG and concomitant preponderance of granites (s.l.), therefore, is explained with secular decrease of aqueous fluid transport into subduction zones and/or efficiency of deep fluid release from slabs.

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Pb/Pb, SmNd and RbSr geochronology in the Archean Craton of Zimbabwe

Cited by 58 publications

References 28 publications

A review of the pressure–temperature–time evolution of the Limpopo Belt: Constraints for a tectonic model

A review of the pressure–temperature–time evolution of the Limpopo Belt: Constraints for a tectonic model

Juvenile crust formation in the Zimbabwe Craton deduced from the O-Hf isotopic record of 3.8–3.1 Ga detrital zircons

Importance of water for Archaean granitoid petrology: a comparative study of TTG and potassic granitoids from Barberton Mountain Land, South Africa

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