scholarly journals A Newly Designed Analytical Line to Examine Fluid Inclusion Isotopic Compositions in a Variety of Carbonate Samples

2018 ◽  
Vol 19 (4) ◽  
pp. 1107-1122 ◽  
Author(s):  
Emilie P. Dassié ◽  
Dominique Genty ◽  
Aurélie Noret ◽  
Xavier Mangenot ◽  
Marc Massault ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Analytical Line ◽  
Isotopic Compositions

Fluid inclusion and stable isotope constraints on the origin of Wernecke Breccia and associated iron oxide – copper – gold mineralization, Yukon

2011 ◽  
Vol 48 (10) ◽  
pp. 1425-1445 ◽  
Author(s):  
Julie A. Hunt ◽  
Tim Baker ◽  
James Cleverley ◽  
Garry J. Davidson ◽  
Anthony E. Fallick ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Fluid Inclusion ◽  
Gold Mineralization ◽  
Fluid Pressure ◽  
Yukon Territory ◽  
Metasedimentary Rocks ◽  
Isotopic Compositions ◽  
Copper Gold ◽  
Oxygen Isotopic ◽  
Hydrothermal Sulfides

Iron oxide – Cu ± Au ± U ± Co (IOCG) mineralization is associated with numerous Proterozoic breccia bodies, collectively known as Wernecke Breccia, in Yukon Territory, Canada. Multiphase breccia zones occur in areas underlain by Paleoproterozoic Wernecke Supergroup metasedimentary rocks and are associated with widespread sodic, potassic, and carbonate alteration assemblages. Fluid inclusion data indicate syn-breccia fluids were hot (185–350 °C) saline (24–42 wt.% NaCl equivalent) NaCl–CaCl2–H2O brines. Estimates of fluid pressure vary from 0.4 to 2.4 kbar (1 kbar = 100 MPa). Carbon and oxygen isotopic compositions of breccia-related carbonates range from ~–11‰ to +1.5‰ (Pee Dee belemnite (PDB)) and –2‰ to 20‰ (Vienna standard mean ocean water (V-SMOW); δ18Owater ~–8‰ to +15‰), respectively. δ13C and δ18O values for host Wernecke Supergroup limestone/dolostone vary from ~–2‰ to 1.6‰ and 12‰ to 25‰, respectively. Sulfur isotopic compositions of hydrothermal sulfides and sulfate vary from ~–12‰ to +13‰ and +8‰ to +17‰ (Cañon Diablo Troilite (CDT)), respectively. Syn-breccia biotite, muscovite, and actinolite have δD and δ18O values of ~–141‰ to –18‰ and +7‰ to +12‰ (V-SMOW; δ18Owater ~7‰ to 11‰), respectively. The Wernecke Breccias and the associated IOCG mineralization appear to have formed from largely nonmagmatic fluids — based on isotopic, fluid inclusion, and geological data. The emerging hypothesis is that periodic overpressuring of dominantly formational/metamorphic water led to repeated brecciation and mineral precipitation. The weight of overlying sedimentary rocks led to elevated fluid temperatures and pressures; fluid flow may have been driven by tectonics and (or) gravity with metals scavenged from host strata.

scholarly journals Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems

2020 ◽  
Vol 16 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Ryu Uemura ◽  
Yudai Kina ◽  
Chuan-Chou Shen ◽  
Kanako Omine
Keyword(s):  
Fluid Inclusion ◽  
Isotope Ratio ◽  
Isotopic Exchange ◽  
Quantitative Estimation ◽  
Depth Interval ◽  
Exchange Effect ◽  
Fractionation Factor ◽  
The Past ◽  
Isotopic Compositions ◽  
Quaternary Climate

Abstract. The oxygen and hydrogen isotopic compositions of water in fluid inclusions in speleothems are important hydroclimate proxies because they provide information on the isotopic compositions of rainwater in the past. Moreover, because isotopic differences between fluid inclusion water and the host calcite provide information on the past isotopic fractionation factor, they are also useful for quantitative estimation of past temperature changes. The oxygen isotope ratio of inclusion water (δ18Ofi), however, may be affected by isotopic exchange between the water and the host carbonate. Thus, it is necessary to estimate the bias caused by this postdepositional effect for precise reconstruction of paleotemperatures. Here, we evaluate the isotopic exchange reaction between inclusion water and host calcite based on a laboratory experiment involving a natural stalagmite. Multiple stalagmite samples cut from the same depth interval were heated at 105 ∘C in the laboratory from 0 to 80 h. Then, the isotopic compositions of the inclusion water were measured. In the 105 ∘C heating experiments, the δ18Ofi values increased from the initial value by 0.7 ‰ and then remained stable after ca. 20 h. The hydrogen isotope ratio of water showed no trend in response to the heating experiments, suggesting that the hydrogen isotopic composition of fluid inclusion water effectively reflects the composition of past drip water. We then evaluated the process behind the observed isotopic variations using a partial equilibration model. The experimental results are best explained by the assumption that a thin CaCO3 layer surrounding the inclusion reacted with the water. The amount of CaCO3 that reacted with the water is equivalent to 2 % of the water inclusions in molar terms. These results suggest that the magnitude of the isotopic exchange effect has a minor influence on paleotemperature estimates for Quaternary climate reconstructions.

Genesis of the Xishadegai Mo deposit in Inner Mongolia, North China: Constraints from geology, geochronology, fluid inclusion, and isotopic compositions

2018 ◽  
Vol 53 (6) ◽  
pp. 3110-3128 ◽  
Author(s):  
Yong-Mei Zhang ◽  
Xue-Xiang Gu ◽  
Xuan Sun ◽  
Wei Zhao ◽  
Zhong-Lin Xiang ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Inner Mongolia ◽  
North China ◽  
Isotopic Compositions

scholarly journals Experimental evaluation of oxygen isotopic exchange between inclusion water and host calcite in speleothems

2019 ◽  
Author(s):  
Ryu Uemura ◽  
Yudai Kina ◽  
Kanako Omine
Keyword(s):  
Fluid Inclusion ◽  
Isotope Ratio ◽  
Isotopic Exchange ◽  
Quantitative Estimation ◽  
Depth Interval ◽  
Exchange Effect ◽  
Fractionation Factor ◽  
The Past ◽  
Isotopic Compositions ◽  
Quaternary Climate

Abstract. The oxygen and hydrogen isotopic compositions of water in fluid inclusions in speleothems are important hydroclimate proxies because they provide information on the isotopic compositions of rainwater in the past. Moreover, because isotopic differences between fluid inclusion water and the host calcite provide information on the past isotopic fractionation factor, they are also useful for quantitative estimation of past temperature changes. The oxygen isotope ratio of inclusion water (δ18Ofi), however, may be affected by isotopic exchange between the water and the host carbonate. Thus, it is necessary to estimate the bias caused by this post-depositional effect for precise reconstruction of palaeo-temperatures. Here, we evaluate the isotopic exchange reaction between inclusion water and host calcite based on a laboratory experiment involving a natural stalagmite. Multiple stalagmite samples cut from the same depth interval were heated at 105 °C in the laboratory for 0–80 hours. Then, the isotopic compositions of the inclusion water were measured. In the 105 °C heating experiments, the δ18Ofi values increased from the initial value by 0.7 ‰ and then remained stable after ca. 20 hours. The hydrogen isotope ratio of water showed no trend in response to the heating experiments, suggesting that the hydrogen isotopic composition of fluid inclusion water effectively reflects the composition of past dripwater. We then evaluated the process behind the observed isotopic variations using a partial equilibration model. The experimental results are best explained when we assumed that a thin CaCO3 layer surrounding the inclusion reacted with the water. The amount of CaCO3 that reacted with the water is equivalent to 2 % of the water inclusions in molar terms. These results suggest that the magnitude of the isotopic exchange effect has a minor influence on palaeo-temperature estimates for the Quaternary climate reconstructions.

An improved interference correction for trace element analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1646-1647
Author(s):  
John J. Donovan ◽  
Donald A. Snyder ◽  
Mark L. Rivers
Keyword(s):  
Trace Element Analysis ◽  
Accurate Estimate ◽  
Simple Expression ◽  
Standard Reference Materials ◽  
Characteristic Line ◽  
Analytical Line ◽  
Element Analysis ◽  
Electron Probe Analysis ◽  
Calculated Concentration ◽  
X Ray

We present a simple expression for the quantitative treatment of interference corrections in x-ray analysis. WDS electron probe analysis of standard reference materials illustrate the success of the technique.For the analytical line of wavelength λ of any element A which lies near or on any characteristic line of another element B, the observed x-ray counts at We use to denote x-ray counts excited by element i in matrix j (u=unknown; s=analytical standard; ŝ=interference standard) at the wavelength of the analytical line of A, λA (Fig. 1). Quantitative analysis of A requires an accurate estimate of These counts can be estimated from the ZAF calculated concentration of B in the unknown C,Bu measured counts at λA in an interference standard of known concentration of B (and containing no A), and ZAF correction parameters for the matrices of both the unknown and the interference standard at It can be shown that:

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