Comparative petrology and metamorphic evolution of the Limpopo (South Africa) and Lapland (Fennoscandia) high-grade terrains

Perchuk, L. L.; Gerya, Taras; Reenen, Dirk D. van; Krotov, A. V.; Сафонов, О. Г.; Smit, C. A.; Shur, M. Yu.

doi:10.1007/s007100050019

Cited by 55 publications

(68 citation statements)

References 28 publications

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“…6A-D) are consistent with the modes, compositions and zonations in the observed mineral assemblages, which define a P-T path that traverses from peak conditions of 8-9 kbar and 840 +/À 10°C along a decompression cooling path to 4.5-5.5 kbar and $650°C. The peak P-T conditions from this study are in agreement with those determined by Watkeys et al (1983), Windley et al (1984), Droop (1989), Hisada and Miyano (1996) and Perchuk et al (2000). The retrograde path, characterized by decompression cooling, is in agreement with the paths defined by Zeh et al (2004), Van Reenen et al (2004), and Boshoff et al (2006) and the DC1 path of Perchuk et al (2008).…”

Section: P-t Pathsupporting

confidence: 91%

“…The peak metamorphic P-T conditions agree well with the peak P-T estimates obtained by Droop (1989) and Hisada and Miyano (1996). However, the retrograde path, defined by matrix assemblages, garnet resorption textures, mineral zoning and diffusion patterns (Zeh et al, 2004) requires a simultaneous P-T decrease, in agreement with the DC paths defined by Perchuk et al (2000), Van Reenen et al (2004), Hisada et al (2005) and Rigby et al (2008b) but in stark contrast to retrograde paths defined by ITD (e.g. Droop, 1989;Hisada and Miyano, 1996) and subsequent IBC (Hisada and Miyano, 1996).…”

Section: P-t-t Evolution Of the Central Zonesupporting

confidence: 79%

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Conflicting P–T paths within the Central Zone of the Limpopo Belt: A consequence of different thermobarometric methods?

Rigby

2009

Journal of African Earth Sciences

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a b s t r a c tA single metapelitic sample from the Verbaard locality, near Messina was investigated in order to construct a P-T path and moreover, highlight pertinent contradictions in the current P-T database. Interpretations based on P-T pseudosections, garnet isopleth thermobarometry and mineral mode/isopleth modelling indicate that the mineral assemblages, textures and zonations developed in the metapelite formed along a single clockwise P-T path. The metamorphic evolution is characterized by an early high-pressure phase at 10-11 kbar/800°C, followed by a simultaneous pressure decrease and temperature increase to $8/850°C and subsequent retrogression via decompression-cooling to 4-5 kbar at T < 650°C. Growth zoning in garnet provides evidence for an earlier, prograde history, however, as potential melt-loss was not accounted for this must be deemed speculative. The results of this study agree entirely with that of [Zeh, A., Klemd, R., Buhlmann, S., Barton, J.M. 2004. Pro-and retrograde P-T evolution of granulites of the Beit Bridge Complex (Limpopo Belt, South Africa); constraints from quantitative phase diagrams and geotectonic implications. Journal of Metamorphic Geology 22, 79-95], who adopted a similar approach to thermobarometry i.e. pseudosections. The results are, however, inconsistent with recent publications that argue for a twofold, metamorphic history defined by two decompression-cooling paths (DC1 $2.6 Ga and DC2 $2.0 Ga) that are separated by an isobaric heating path ($2.0 Ga). The disparity in the results obtained from different workers can be explained by an examination of the thermobarometric methods employed. The methodology employed to derive the twofold, polymetamorphic P-T path appears to be erroneous. At present, the most reliable and robust method for determining P-T paths is the pseudosection approach to thermobarometry. Future modelling of Limpopo Belt granulites should adopt this strategy and ensure potential melt-loss is taken into account. Alternatively, this potential problem can be avoided altogether by investigating rocks of mafic composition.

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Section: P-t Pathsupporting

confidence: 91%

Section: P-t-t Evolution Of the Central Zonesupporting

confidence: 79%

Conflicting P–T paths within the Central Zone of the Limpopo Belt: A consequence of different thermobarometric methods?

Rigby

2009

Journal of African Earth Sciences

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“…Thermobarometric estimates and calculated mineral isopleths for the divariant equilibria define a decompression-cooling (DC) P-T path traversing from 780 °C at 5.7 kbar to 600 °C at 3.3 kbar. A DC retrograde path was proposed earlier by Perchuk et al (2000) who, on the basis of detailed microprobe profiling of garnet from a cordierite-bearing metapelite, defined a simultaneous P and T decrease from 800 °C at 9 kbar to 600 °C at 4-5 kbar. Furthermore, metapelites from the Mahalapye Complex (MC) in the extreme south-western part of the CZ record well-developed metasomatic reaction textures indicating that the retrograde evolution was strongly dependent on fluid infiltration (Hisada et al, 2005).…”

Section: The Central Zonementioning

confidence: 89%

“…Recent petrological studies (e.g. [Perchuk et al, 2000], [Klemd et al, 2003], [Van Reenen et al, 2004], [Zeh et al, 2004], [Zeh et al, 2005], [Hisada et al, 2005], and [Boshoff et al, 2006]) suggest that major parts of the CZ did not undergo a P-T path involving ITD and subsequent IBC (Fig. 2).…”

Section: The Central Zonementioning

confidence: 99%

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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“…These amphiboles are compared with hornblende from the Lapland granulite complex, which underwent metamorphism at a much higher pressure (up to 11-12 kbar). The petrology and mineralogy of rocks from the Lapland complex, including those used in this work, have been extensively treated by Perchuk et al (1999) and Skublov et al (2000). Metasomatic events in the Njurundukan rocks from the Sljudanka zone are difficult to distinguish from low-temperature regional metamorphic processes.…”

Section: Geological Setting and Metamorphismmentioning

confidence: 99%

Patterns of Trace-Element Distribution in Calcic Amphiboles as a Function of Metamorphic Grade

Скублов¹,

Drugova²

2003

The Canadian Mineralogist

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The distribution of the rare earths and other trace elements in calcic amphiboles from the Njurundukan mafic complex, northwestern Baikal region, in Russia, depends on metamorphic grade. Both total REE and La/Yb in amphiboles decrease with decreasing temperature of metamorphism. Consistent partition-coefficients for trace elements in amphibole and coexisting garnet, suggestive of equilibrium, are best developed in granulite-facies rocks. Such a consistent distribution of the REE is disturbed in amphibolite-facies rocks owing to incipient metasomatism. Amphiboles from metasomatic rocks show REE distributions that differ from those in amphiboles belonging to the metamorphic culmination, and commonly are inherited from precursor minerals. This property leads to the establishment of the sequence of mineral formation in metasomatically altered rocks. Comparison with amphiboles from the high-pressure Lapland granulite complex, Baltic Shield, suggests that pressure does not affect REE abundance and distribution in amphiboles.Keywords: trace elements, rare-earth elements, calcic amphibole, Njurundukan mafic complex, Baikal, Russia. SOMMAIRELa distribution des terres rares et autres éléments traces dans les amphiboles calciques du complexe mafique de Njurundukan, dans le nord-ouest de la région de Baïkal, en Russie, dépend du degré de métamorphisme. La teneur en terres rares et le rapport La/Yb des amphiboles diminuent à mesure que diminue la température du métamorphisme. Des coefficients de partage conséquents pour les éléments traces dans l'amphibole et le grenat coexistant, indications possible d'un équilibre, sont les mieux développés dans les roches sujettes à un métamorphisme dans le faciès granulite. Une telle distribution conséquente des terres rares est dérangée au cours d'épisodes de métamorphisme dans le faciès amphibolite à cause d'un début de métasomatose. Dans les amphiboles des roches métasomatiques, la distribution des terres rares diffère de celle des amphiboles développées menant à la culmination métamorphique; elle est apte à être héritée de minéraux précurseurs. Cette propriété mène à l'établissement d'une séquence de formation des minéraux dans des roches altérées par métasomatose. Une comparaison avec les amphiboles provenant du socle granulitique de haute pression en Lapponie, Bouclier Baltique, nous fait penser que la pression n'affecte pas l'abondance et la distribution des terres rares dans les amphiboles.(Traduit par la Rédaction)

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Comparative petrology and metamorphic evolution of the Limpopo (South Africa) and Lapland (Fennoscandia) high-grade terrains

Cited by 55 publications

References 28 publications

Conflicting P–T paths within the Central Zone of the Limpopo Belt: A consequence of different thermobarometric methods?

Conflicting P–T paths within the Central Zone of the Limpopo Belt: A consequence of different thermobarometric methods?

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

Patterns of Trace-Element Distribution in Calcic Amphiboles as a Function of Metamorphic Grade

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