Stable Isotope Composition of Quartz-Calcite Veins in the Witwatersrand Basin, South Africa: Implication for Basin-Scale Fluid Circulation

Jaguin, Justine; Boulvais, Philippe; Poujol, Marc; Boiron, M.C.; Cathelineau, ‪Michel

doi:10.2113/gssajg.113.2.169

Cited by 7 publications

(3 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition to being older than the Lekkersmaak pluton, the Witwatersrand sediments display Sm-Nd signatures consistent with the signatures found for the Lekkersmaak pluton (εNd = -3 to 0 at 2.8 Ga, TDM = 3.35-3.12 Ga; Jahn and Condie, 1995). Besides, the δ 18 O values of the sediments (δ 18 O between 8 and 13‰) show a tendency to become lower as the grain size gets smaller (Barton et al, 1992;Vennemann et al, 1992;Jaguin et al, 2010), so that shales are expected to have quite low δ 18 O signatures, around 8‰ or slightly below. As a source, it would impose a comparable low δ 18 O value of any melt produced near 8‰ or slightly above, comparable to the one actually measured in the Lekkersmaak samples.…”

Section: Regional Correlationssupporting

confidence: 70%

Archaean S-Type granites: petrology, geochemistry and geochronology of the Lekkersmaak and Willie plutons, Kaapvaal Craton, South Africa

Poujol

Jaguin

Moyen

et al. 2021

South African Journal of Geology

Self Cite

View full text Add to dashboard Cite

S-type granites correspond to reworking of pre-existing continental material and form by partial melting of (meta)sediments. Early-to-mid Archaean S-type granites are rare and are more frequently found, usually as relatively small intrusions, during the Neoarchaean and the Archaean-Proterozoic transition. In the context of Archaean geology, their paucity is therefore significant, in that it matches the uncommon nature of processes during this period. In this study, we focus on the Late Mesoarchaean Willie pluton and Neoarchaean Lekkersmaak pluton, which crop out to the south of the Murchison Greenstone Belt in the Northern Kaapvaal Craton, South Africa. These intrusions represent the oldest S-type plutons known so far in the region. We constrain their petrogenesis by documenting their petrology, mineralogy (mineral composition), geochemistry (major and trace elements, Sr, Nd and O isotopes) and zircon U-Pb geochronology. The large Lekkersmaak and smaller Willie plutons represent two granites sharing many geochemical characteristics; they are both peraluminous, Ms-bearing S-type granites although they are more sodic and less potassic than typical S-type granites. The Willie granite was emplaced 2 816 ± 9 Ma ago while the Lekkersmaak yielded an emplacement age of 2 771 ± 2 Ma. Therefore, S-Type magmatism in the area occurred twice at 2.82 Ga and then 40 Myr later at 2.77 Ga, involving comparable immature metasedimentary sources and conditions of partial melting. Finally, a sample from the Lekkersmaak pluton devoid of S-type features as it is muscovite-free and aluminum poor was emplaced 2 734 ± 11 Ma ago. This confirms the episodic nature of magmatic activity south of the Murchison Greenstone Belt.

show abstract

Section: Regional Correlationssupporting

confidence: 70%

Archaean S-Type granites: petrology, geochemistry and geochronology of the Lekkersmaak and Willie plutons, Kaapvaal Craton, South Africa

Poujol

Jaguin

Moyen

et al. 2021

South African Journal of Geology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, these isotopic analyses provide a more direct representation of the paleofluid in the combined H and O isotopic space. Fluid inclusion isotope data are often used in the analysis of vein-type deposits to capture the circulation of subsurface fluids at a basin-scale [15], [16], [17]. The direct isotope analysis of fluid inclusions has a great potential to characterize fluid-host mineral systems, particularly nonequilibrium ones that are associated with rapid mineral precipitation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Novel crushing technique for measuring δ18O and δ2H values of fluid inclusions (H2O) in quartz mineral veins using Cavity Ring-Down Spectroscopy

Huseynov,

(Jeroen),

Verdegaal-Warmerdam

et al. 2024

Preprint

View full text Add to dashboard Cite

Fluid inclusions in mineralized fracture infillings (i.e. veins) could preserve information about sub-surface fluids like temperature and salinity. The isotopic composition of water in these fluid inclusions could provide direct evidence of the provenance of these fluids and indirectly about the temperatures and rate of vein formation. So far, the isotope compositions of fluid inclusions have been mainly derived from carbonate veins and other precipitates, like speleothems. The aim of this study is to analyse the δO and δH isotopic compositions of aqueous fluid inclusions of quartz veins using a Cavity Ring-Down Spectroscopy (CRDS) analyser in combination with a moisturized nitrogen background and mechanical stepwise crushing. For this study, we analysed δO and δH values of fluid inclusions in quartz veins from three north-western European locations formed during the Variscan orogeny. Prior to crushing, the fluid-rich quartz fraction was separated from the pure quartz fraction from other mineral phases and host rock by using conventional heavy liquids and magnet separation. Raman spectrometry detected some rare occurrences of hydrocarbon, methane and nitrogen in the fluid inclusions. The samples were sequentially crushed to understand the impact of different fluid inclusion assemblages (FIA) on δO and δH isotopic values. The results from single and stepwise mechanical crushing, together with interlaboratory comparisons, exhibit, reliable and consistent isotopic patterns across locations with high accuracy and precision (for δO 1SD<0.8 ‰; for δH 1SD< 1.5‰). The obtained data aligns with the existing Global Meteoric Water Line, providing evidence for the presence of meteoric fluids in the examined fold-and-thrust belt of the Variscan orogeny. These findings demonstrate that the CRDS approach can be successfully used in other geological research to investigate fluids pathways within the upper crust and the formation of minerals.

show abstract

“…Therefore, these isotopic analyses provide a more direct representation of the paleo-fluid in the combined H and O isotopic space. Fluid inclusion isotope data are often used in the analysis of vein-type deposits to capture the circulation of subsurface fluids at a basinscale (Jaguin et al, 2010;Beaudoin et al, 2014;De Graaf et al, 2019). The direct isotope analysis of fluid inclusions has a great potential to characterize fluid-host mineral systems, in particularly non-equilibrium ones that are associated with rapid mineral precipitation (e.g.…”

Section: Introductionmentioning

confidence: 99%

New crushing approach for δ 18 O and δ 2 H measurements of fluid inclusion water in quartz mineral veins using Cavity-Ring Down Spectroscopy

Huseynov,

(Jeroen),

Verdegaal-Warmerdam

et al. 2024

Preprint

View full text Add to dashboard Cite

Fluid-inclusions in mineralized fracture infillings (i.e. veins) could preserve information about sub-surface fluids like temperature and salinity. The isotopic composition of water in these fluid-inclusions could provide direct evidence of the provenance of these fluids and indirectly about the temperatures and rate of vein formation. So far, the isotope compositions of fluid-inclusion have been mainly derived from carbonate veins and other precipitates like speleothems. The aim of this study is to analyse the δ O and δ H isotopic compositions of water fluid inclusions of quartz vein using a Cavity Ring-Down Spectroscopy (CRDS) analyser in combination with a moisturized nitrogen background and mechanical stepwise crushing. For this study, we analysed δ O and δ H values of fluid inclusions quartz veins from three north-western European locations formed during the Variscan orogeny. Prior to crushing, the fluid-inclusions rich fraction was separated from the pure quartz fraction from other mineral phases and host rock by using conventional heavy liquid mineral and magnet separation technique to avoid from adsorbed atmospheric water contaminant or “bleeding” effect from intergranular or primary permeability water. Raman spectrometry detected some rare occurrences of hydrocarbon, methane and nitrogen. The samples were sequentially crushed to minimize the influence of (pseudo)secondary on the isotopic signal of the primary fluid-inclusion. The results from single and stepwise mechanical crushing, together with interlaboratory comparisons, exhibit, reliable and consistent isotopic patterns across locations with high accuracy and precision (for δ O 1SD<0.8‰; for δ H 1SD<1.5‰). The obtained data aligns with the existing Global Meteoric Water Line, providing evidence for the presence of meteoric fluids in the examined fold-and-thrust belt of the Variscan orogeny. These findings demonstrate that the CRDS approach can be successfully used in other geological research to investigate fluids pathways within the upper crust and the formation of minerals.

show abstract

Stable Isotope Composition of Quartz-Calcite Veins in the Witwatersrand Basin, South Africa: Implication for Basin-Scale Fluid Circulation

Cited by 7 publications

References 44 publications

Archaean S-Type granites: petrology, geochemistry and geochronology of the Lekkersmaak and Willie plutons, Kaapvaal Craton, South Africa

Archaean S-Type granites: petrology, geochemistry and geochronology of the Lekkersmaak and Willie plutons, Kaapvaal Craton, South Africa

Novel crushing technique for measuring δ18O and δ2H values of fluid inclusions (H2O) in quartz mineral veins using Cavity Ring-Down Spectroscopy

New crushing approach for δ 18 O and δ 2 H measurements of fluid inclusion water in quartz mineral veins using Cavity-Ring Down Spectroscopy

Contact Info

Product

Resources

About