Noble gases in South Indian carbonatites: Trapped and in situ components

Murty, S. V. S.; Basu, Sudeshna; Kumar, Anil

doi:10.1016/j.jseaes.2006.08.004

Cited by 8 publications

(2 citation statements)

References 46 publications

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“…The number of steps may be adjusted depending on the mineral type, e.g., for carbonates a sequence of three steps with 15, 300, and +300 strokes were used while for apatite 15, 500 and +500 strokes were used [88]. The first step is typically applied to release the gases from the larger inclusions with possibly a larger fraction of atmospheric gases; the second step delivers the main extraction while completion is achieved in the third step.…”

Section: Magnetic Crushing Systemsmentioning

confidence: 99%

Mineral Crushing Methods for Noble Gas Analyses of Fluid Inclusions

et al. 2023

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Noble gases are frequently probed for investigating fluid inclusions in minerals to unravel rock-forming processes through time. Over the last decades, heating and crushing have been the two main methods applied for noble gas extraction from fluid inclusions in ultrahigh vacuum (about 10-9 mBar). The heating of minerals or pieces of bulk rock causes the release of noble gases from both fluid inclusions and the mineral or rock matrix, the latter due to temperature-dependent mineral dehydration. Crushing of minerals only affects fluid inclusions and allows a release of noble gases at room temperature with minor contributions from the mineral matrix. This review describes different ultravacuum crushing techniques for noble gas analysis from fluid inclusions. It examines the technical details and operational conditions of each crushing system as well as methods to prepare samples prior to crushing. Crushing systems were found to have unique designs across the different laboratories reviewed; they include single or multiple sample loadings and manual, magnetic, or hydraulic operation of the crushing pistons. Due to the small amounts of noble gases released, the technology requires several mg to a few grams of rock material to achieve a measurement of all stable noble gas isotopes in a single fluid inclusion. While theoretically all stable noble gas isotopes are of interest, the elements and isotopes reported in different studies vary widely and reference materials as well as laboratory intercomparisons are lacking. The review includes applications on the origins of magmatic rocks and geochemical processes in the Earth’s mantle, the origin and chemical composition of deep crustal fluids and how these contribute to the formation of minerals of economic interest, and paleoclimate studies based on speleothems.

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Section: Magnetic Crushing Systemsmentioning

confidence: 99%

Mineral Crushing Methods for Noble Gas Analyses of Fluid Inclusions

et al. 2023

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“…Noble gas data for carbonatites are still rare, and the reservoirs which could be considered as sources of carbonatitic magmas are still to be revealed. Thus, in order to explain the noble gas isotope signatures in some carbonatite objects on Kola Peninsula, Cabo Verde, Brazil and Canada (Marty et al, 1998;Tolstikhin et al, 2002;Mata et al, 2010) it was necessary to involve deep mantle (plume) sources, while, for instance, for Indian carbonatites Basu and Murty (2006), Murty et al (2007) argue for an important role of subcontinental lithospheric mantle and recycled crustal components of noble gases. However, this is challenged by new data for some Indian carbonatites which strongly suggest contributions of a Deccan mantle plume component (Hopp and Viladkar, 2018).…”

Section: Introductionmentioning

confidence: 99%

The Sources and Evolution of Fluid Phases of Guli Massif Carbonatites (West Siberia): Summarizing of Noble Gases, N2, CO2, H2O Stepwise Crushing Data

et al. 2021

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Here we present summarizing of isotopic compositions and element ratios of noble gases, nitrogen, carbon and hydrogen in carbonatites of different generations of the Guli massif (West Siberia, Russia) obtained by stepwise crushing. The data point to the subcontinental lithospheric mantle (SCLM) as a primary source of the fluid phase in Guli carbonatites. However, the estimated 40 Ar/ 36 Ar ratio in the Guli mantle source of about 5400 is similar to the Kola plume value of 5000 ± 1000 (Marty et al., 1998). One explanation of such a low estimated 40 Ar/ 36 Ar ratio in the mantle end-member with SCLM type helium ( 4 Не/ 3 Не 120000) and neon ( 21 Nе/ 22 Nе mantle ~ 0.7) is an admixture of atmospheric argon to the local mantle source. This assumption is supported by the Ar-Ne systematics as well as by the data for hydrogen isotopic composition. Early carbonatite differs significantly from the later ones by the concentration of highly volatile components, as well as by the isotopic compositions of carbon (CO 2 ), argon, and hydrogen (H 2 O). The mantle component dominated in fluids at the early formation stages of the Guli massif rocks, whereas the late stages of carbonatite formation were characterized by an additional fluid source, which introduced atmospheric argon and neon, and most likely a high portion of CO 2 with isotopically heavy carbon. The argon-neon-hydrogen isotope systematics suggest that the most plausible source of these late stage fluids are high temperature paleometeoric waters. The absence of a plume signature could be explained in terms that Guli carbonatites have been formed at the waning stage of plume magmatic activity with an essential input of SCLM components.

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