Involvement of fluids in the metamorphic processes within different zones of the Southern Marginal Zone of the Limpopo complex, South Africa: An oxygen isotope perspective

Дубинина, Е. О.; Aranovich, L. Ya.; Reenen, Dirk D. van; Avdeenko, A. S.; Варламов, Д. А.; Shaposhnikov, V. V.; Kurdyukov, E. B.

doi:10.1016/j.precamres.2014.10.019

Cited by 16 publications

(7 citation statements)

References 61 publications

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“…The post-peak decompressional path recorded in sample RC35-2 could be related to rapid weathering and exhumation as inferred in previous studies (Kreissig et al, 2001;Miyano et al, 1992;Perchuk et al, 2000;Smit et al, 2014;van Reenen et al, 2014), although it could also be related ing SMZ granulites (Smit et al, 2014;van Reenen et al, 2011van Reenen et al, , 2014van Reenen & Hollister, 1988). This scenario is supported by available oxygen isotope data (Dubinina et al, 2015;Hoernes et al, 1995) that reported the formation of leucocratic rocks as the result of in situ partial melting of metapelitic rocks in the presence of external saline -8, together with the metamorphic P-T path of the SMZ (after Perchuk et al, 2000). P1 and P2: Peak metamorphic conditions obtained in this study.…”

Section: Prograde and Peak Conditionssupporting

confidence: 80%

Fluid migration along deep‐crustal shear zone: A case study of the Rhenosterkoppies Greenstone Belt in the northern Kaapvaal Craton, South Africa

et al. 2023

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The north‐dipping Hout River Shear Zone (HRSZ), which marks the boundary between the high‐grade Limpopo Complex in its hanging wall and the low‐grade granite‐greenstone terrane of the Kaapvaal Craton in South Africa in its footwall, is a deep‐crustal shear zone that controlled emplacement of hot Limpopo Complex granulites over and against low‐grade granite‐greenstones during exhumation at ~2.72–2.62 Ga. This major shear zone controlled migration of large volumes of hydrous fluids released during devolatilization of underthrusted greenstones that infiltrated into hot overlying granulites, establishing a retrograde anthophyllite‐in isograd and associated zone of retrograde rehydrated granulite that bounds the Limpopo Complex in the south. Here, we report new petrological data based on mineral equilibrium modelling of amphibolites from the Rhenosterkoppies Greenstone Belt (RGB) located in the immediate footwall of the HRSZ and discuss evidence that these rocks also interacted with high‐temperature fluids that infiltrated along the HRSZ. This study provides an important perspective of the interaction of hot granulites with underthrusted relatively cold greenschist‐facies rocks along the steeply north‐dipping section of the HRSZ, and shows that evidence for such interaction is restricted to a relatively narrow zone in the footwall of the HRSZ termed a hot‐iron‐zone. The peak mineral assemblage of a garnet‐free amphibolite from the RGB (magnesio‐hornblende + plagioclase + quartz + clinopyroxene + titanite + ilmenite) yielded the peak P–T condition of 7–8 kbar and 640–680°C with H2O content of 3.5–3.8 mol%. Clinopyroxene is replaced by actinolite + quartz and epidote + quartz symplectites by a post‐peak hydration event at <5 kbar and <590°C caused by elevated H2O content in the rock (>4.0 mol%), possibly related to fluid infiltration along the HRSZ. Mineral equilibria in a garnet‐bearing amphibolite records a prograde path from 5 to 7 kbar and 540–630°C to the peak conditions at 7.6–8.7 kbar and 620–650°C. A clockwise P–T path suggesting rapid compression and decompression has been inferred for the amphibolites from the RGB, possibly because of pressure increase related to overthrusting of the high‐grade terrane (Southern Marginal Zone of the Limpopo Complex) onto the low‐grade granite‐greenstone terrane, followed by rapid exhumation. The quantity of H2O associated with the amphibolite‐facies metamorphism in the RGB was elevated from the peak stage (M(H2O) = 3.5–3.8 mol%) to the retrograde stage (M(H2O) = 4.0–4.5 mol%) of metamorphism in the RGB, possibly suggesting fluid infiltration not only from internal sources but also from external sources. The results of this study indicate that a H2O‐bearing fluid, which infiltrated along the HRSZ, affected both the footwall and the hanging wall sections of the shear zone, although the effect on the footwall section was limited.

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Section: Prograde and Peak Conditionssupporting

confidence: 80%

Fluid migration along deep‐crustal shear zone: A case study of the Rhenosterkoppies Greenstone Belt in the northern Kaapvaal Craton, South Africa

et al. 2023

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“…At the outcrop scale, fluid pathways may be localized (e.g., Aranovich et al, 2010;Dubinina et al, 2015;Kusebauch et al, 2015). This is also suggested in the SRM by localized distribution of post-peak Cl-rich veins in the outcrop scale in Brattnipene ( Comparison with other areas of the SRM The P-T-t conditions of Cl-rich aqueous fluid infiltration in the SRM have been previously determined from two other localities; the eastern part (Balchenfjella; Higashino et al, 2013a) and the central part (Brattnipene;Higashino et al, 2015a) (Fig.…”

Section: The Age Of Metamorphism and Cl-rich Fluid Infiltrationmentioning

confidence: 99%

Prograde infiltration of Cl-rich fluid into the granulitic continental crust from a collision zone in East Antarctica (Perlebandet, Sør Rondane Mountains)

Kawakami

Higashino

Skrzypek

et al. 2017

Lithos

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Utilizing microstructures of Cl-bearing biotite in pelitic and felsic metamorphic rocks, the timing of Cl-rich fluid infiltration is correlated with the pressure-temperature-time (P-T-t) path of upper amphibolite-to granulite-facies metamorphic rocks from Perlebandet, Sør Rondane Mountains (SRM), East Antarctica. Microstructural observation indicates that the stable Al2SiO5 polymorph changed from sillimanite to kyanite + andalusite + sillimanite, and P-T estimates from geothermobarometry point to a counterclockwise P-T path characteristic of the SW terrane of the SRM. In situ laser ablation inductively coupled plasma mass spectrometry for U-Pb dating of zircon inclusions in garnet yielded ca. 580 Ma, likely representing the age of garnet-forming metamorphism at Perlebandet. Inclusion-host relationships among garnet, sillimanite, and Cl-rich biotite (Cl > 0.4 wt%) reveal that formation of Cl-rich biotite took place during prograde metamorphism in the sillimanite stability field. This process probably predated partial melting consuming biotite (Cl = 0.1-0.3 wt%). This was followed by retrograde, moderately Cl-bearing biotite (Cl = 0.1-0.3 wt%) replacing garnet. Similar timings of Cl-rich biotite formation in different samples, and similar f(H2O)/f(HCl) values of coexisting fluid estimated for each stage can be best explained by prograde Cl-rich fluid infiltration. Fluid-present partial melting at the onset of prograde metamorphism probably contributed to elevate the Cl concentration (and possibly salinity) of the fluid, and consumption of the fluid resulted in the progress of dehydration melting. The retrograde fluid was released from crystallizing Cl-bearing partial melts or derived externally. The prograde Cl-rich fluid infiltration in Perlebandet presumably took place at the uppermost part of the footwall of the collision boundary. Localized distribution of Cl-rich biotite and hornblende along large-scale shear zones and detachments in the SRM supports external input of Cl-rich fluids through tectonic boundaries during continental collision.

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“…The results were calibrated relatively to VSMOW by the measurements of NBS 28 quartz and UWG 2 garnet [35]. The accuracy of δ 18 O determination was ±0.1‰ or better [36].…”

Section: Methodsmentioning

confidence: 99%

Influence of Host Marble Rocks on the Formation of Intrusive Alkaline Rocks and Carbonatites of Sangilen (E. Siberia, Russia)

et al. 2021

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The study of the O and C isotope composition of calcite from nepheline syenites, ijolites and carbonatites of the Chik intrusion and the intrusions of the Erzin–Tarbagatay group of Sangilen (Eastern Siberia, Russia) showed derivation from alkaline melts enriched with a carbonate component from the host marbleized sedimentary rocks. The calculations showed that about 40% of the initial mass of carbonates involved in the interaction with silicate melts have remained after decarbonation. During the assimilation of the carbonate, an oxygen isotope exchange took place between the residual carbonate material and the silicate phase. Crystallization products of such hybrid magmas are carbonatite veins, calcite-rich nepheline rocks and their pegmatites with a calcite core.

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Involvement of fluids in the metamorphic processes within different zones of the Southern Marginal Zone of the Limpopo complex, South Africa: An oxygen isotope perspective

Cited by 16 publications

References 61 publications

Fluid migration along deep‐crustal shear zone: A case study of the Rhenosterkoppies Greenstone Belt in the northern Kaapvaal Craton, South Africa

Fluid migration along deep‐crustal shear zone: A case study of the Rhenosterkoppies Greenstone Belt in the northern Kaapvaal Craton, South Africa

Prograde infiltration of Cl-rich fluid into the granulitic continental crust from a collision zone in East Antarctica (Perlebandet, Sør Rondane Mountains)

Influence of Host Marble Rocks on the Formation of Intrusive Alkaline Rocks and Carbonatites of Sangilen (E. Siberia, Russia)

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