N2-Ar-He compositions in fluid inclusions: Indicators of fluid source

Norman, David I.; Musgrave, John

doi:10.1016/0016-7037(94)90576-2

Cited by 80 publications

(51 citation statements)

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“…3A) by approximately five times relative to air-saturated water. The N 2 /Ar ratio for ASW is 38 (Norman & Musgrave, 1994). However, only one crush yielded an ASW-equivalent value whereas most N 2 /Ar ratios approximate to atmospheric values and higher.…”

Section: Discussionmentioning

confidence: 93%

“…In some cases, oxygen levels within inclusions were enriched above air-saturated water levels and in contrast, other samples showed oxygen depletion. High nitrogen in the Red Stream samples indicates either breakdown of nitrogenous organic matter or nitrate to produce excess nitrogen, or it may confirm an influx elevated helium from deeper sources (Norman and Musgrave, 1994). However, determining the length of such a flow path in a hydrologically intermittent environment where dye tracing is not possible is a tricky calculation and poorly constrained.…”

Section: Discussionmentioning

confidence: 99%

“…A definite correlation of gases within the cave with gas data from the El Chichón Volcano (Spilde et al, 2004) has shown that there must be some physical connection between the two geological features (Rosales Lagarde et al 2007) and thus we suggest that volcanic gases are plausibly involved in the fluid inclusion results shown here. Finally, magmatic gases typically have high N 2 /Ar ratios (Norman & Musgrave, 1994;Blamey, 2012) and the analyses of the Red Stream samples have N 2 /Ar ratios that exceed 100. Fluctuating contributions of atmosphere and volcanic volatiles can explain the spread within the data.…”

Section: Spainmentioning

confidence: 99%

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High-resolution signatures of oxygenation and microbiological activity in speleothem fluid inclusions

Blamey

Boston²,

Rosales-Lagarde³

2016

IJS

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Abstract:Speleothems frequently host "fossil" fluids that were trapped in small inclusions during growth. Such fluids may provide valuable clues to past microbial, geochemical, and climatic processes during their formation. However, one difficulty is to understand which gases represent background atmosphere and fluids within a given cave system at a particular time, and which may be the product of post-trapping residual microbial activity or abiotic chemical reactions? Do we have any hope of sorting out these differences?The success depends on a quantitative understanding of the gas composition trapped in the inclusions and an understanding of the interactions of cave mineralogy, air and water chemistry, and microbiological processes that may interfere with climatic or geochemical interpretations. Our proof-of-concept project uses time synchronous samples from several sites. We report here on this pilot investigation of speleothem inclusions using a methodology for quantitatively analyzing gases dissolved in inclusion fluids. We use incremental crushing of highly spatially resolved samples by mass spectrometry. Here, we report primarily on CH 4 , CO 2 , O 2 , and N 2 , but have included other detectable gases. The detection limit for He within aqueous fluid inclusions is ~0.2 ppm and gas ratios have ~5% precision using natural standards. We used chemically inert argon as a tracer gas to normalize results to air or air-saturated water. This enables interpretation of gas data despite variability in hydrological and geological cave histories. Results are variable. For example, in one case oxygen was depleted while nitrogen was increased, which may be attributable to the breakdown of nitrate or nitrogen-containing biomolecules. In other cases, oxygen is enriched which may be attributed to several factors both geochemical and biological. We suggest potential interpretations between the competing hypotheses with larger future data sets. This first attempt tackles the complex and intertwined speleological questions using the inclusion gas method.fluid inclusions, fluid inclusion gases, microbial activity, speleothems

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Spainmentioning

confidence: 99%

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High-resolution signatures of oxygenation and microbiological activity in speleothem fluid inclusions

Blamey

Boston²,

Rosales-Lagarde³

2016

IJS

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“…Our recent study (Lutz et al, 1999) uses quadrupole-mass spectrometric analyses of fluid-inclusion gases trapped in vein and alteration minerals (Norman and Musgrave, 1995) to characterize the fluids that have circulated through the geothermal system through time.…”

Section: Projectbackgroundandstatusmentioning

confidence: 99%

Federal Geothermal Geoscience Research Fiscal Year 1998

1999

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“…Also, those inclusions may trap traces of the gases that existed during diagenesis. The relative concentrations of these gases reveal significant information about the nature of the diagenetic fluid (e.g., basinal vs. magmatic) and environment to provide an additional verification tool of the conditions that dominated during the sediment burial history (e.g., Norman and Musgrave, 1994).…”

Section: Introductionmentioning

confidence: 99%

Source of diagenetic fluids from fluid-inclusion gas ratios

Azmy

Blamey

2013

Chemical Geology

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Alteration of marine carbonates, such as those from the Mesoproterozoic and Lower Ordovician, during burial history is carried out by diagenetic fluids that could potentially have different sources. During precipitation diagenetic minerals may trap tiny amounts of those solutions in fluid inclusions, thus providing fossil archives and aliquots that offer valuable record about the origin of fluids. The analysis of various fluid-inclusion gases (e.g., CH 4 , CO 2 , N 2 , He and Ar) may provide reliable information which allows the discrimination among different fluid sources. Generally speaking, the meteoric cements should have N 2 /Ar ratio around 38 (the value for air-saturated water). However, the gases in inclusions of the current study, trapped by diagenetic carbonates (cements), from independent depositional basins of different ages (Mesoproterozoic, Early Ordovician, and Modern) and locations (Canada, USA, Brazil and Java Sea), have N 2 /Ar ratios (~92) which match non-magmatic (modified marine or meteoric) fluids. Also, the Ar/He ratios (~3) in the studied fluid inclusions are significantly lower than those of calc-alkaline magmatic fluids (≥20), thus excluding magmatic fluids as a potential source. On the other hand, some N 2 /Ar and Ar/He ratios of the studied samples approach values reported for basinal fluids from the Hansonburg MVT deposit in New Mexico (68 and 1, respectively), suggesting that both meteoric/mixed marine-meteoric (evolved meteoric) and basinal fluids may be involved during carbonate diagenesis.

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N2-Ar-He compositions in fluid inclusions: Indicators of fluid source

Cited by 80 publications

References 45 publications

High-resolution signatures of oxygenation and microbiological activity in speleothem fluid inclusions

High-resolution signatures of oxygenation and microbiological activity in speleothem fluid inclusions

Federal Geothermal Geoscience Research Fiscal Year 1998

Source of diagenetic fluids from fluid-inclusion gas ratios

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