Li-isotope exchange during low-temperature alteration of the upper oceanic crust at DSDP Sites 417 and 418

Neutron powder diffraction has been carried out on a congruent LiNbO 3 sample containing 7 Li isotope ( C 7 LN ) and a near stoichiometric Mg doped LiNbO 3 sample ( Mg : NSLN ) in the temperature range of 4 K and 90 K. Large anisotropic displacement parameters (ADPs) of the Li ions have shown evidence of large disorder along the c-axis for both samples. The results have shown no evidence for the existence of anomalous structural behavior for both samples at low temperatures, although abnormal structural features at 55 K and 100 K for a LiNbO 3 crystal having different Li content as the samples used in the present studies have been observed by Fernandez-Ruiz et al. [Phys. Rev. B72 (2005) 184108].

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New isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation

Nature Communications ◽

10.1038/s41467-019-13514-6 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 5

Author(s):

Netta Shalev ◽

Tomaso R. R. Bontognali ◽

C. Geoffrey Wheat ◽

Derek Vance

Keyword(s):

Low Temperature ◽

Carbon Cycle ◽

Oceanic Crust ◽

Isotope Fractionation ◽

Hydrothermal Fluids ◽

Carbonate Precipitation ◽

Magnesium Isotopes ◽

Conventional View ◽

The Past ◽

Dolomite Formation

AbstractThe oceanic magnesium budget is important to our understanding of Earth’s carbon cycle, because similar processes control both (e.g., weathering, volcanism, and carbonate precipitation). However, dolomite sedimentation and low-temperature hydrothermal circulation remain enigmatic oceanic Mg sinks. In recent years, magnesium isotopes (δ26Mg) have provided new constraints on the Mg cycle, but the lack of data for the low-temperature hydrothermal isotope fractionation has hindered this approach. Here we present new δ26Mg data for low-temperature hydrothermal fluids, demonstrating preferential 26Mg incorporation into the oceanic crust, on average by εsolid-fluid ≈ 1.6‰. These new data, along with the constant seawater δ26Mg over the past ~20 Myr, require a significant dolomitic sink (estimated to be 1.5–2.9 Tmol yr−1; 40–60% of the oceanic Mg outputs). This estimate argues strongly against the conventional view that dolomite formation has been negligible in the Neogene and points to the existence of significant hidden dolomite formation.

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Stable-isotope evidence for low-temperature kaolinitic weathering and post-formational hydrogen-isotope exchange in permian kaolinites

Chemical Geology Isotope Geoscience section ◽

10.1016/0168-9622(88)90028-0 ◽

1988 ◽

Vol 72 (3) ◽

pp. 249-265 ◽

Cited By ~ 33

Author(s):

Michael I. Bird ◽

Allan R. Chivas

Keyword(s):

Stable Isotope ◽

Low Temperature ◽

Hydrogen Isotope ◽

Isotope Exchange ◽

Hydrogen Isotope Exchange ◽

Isotope Evidence

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Microorganisms Isolated from Deep Sea Low-temperature Influenced Oceanic Crust Basalts and Sediment Samples Collected along the Mid-Atlantic Ridge

Geomicrobiology Journal ◽

10.1080/01490450902892456 ◽

2009 ◽

Vol 26 (4) ◽

pp. 264-274 ◽

Cited By ~ 13

Author(s):

Kristina Rathsack ◽

Erko Stackebrandt ◽

Joachim Reitner ◽

Gabriela Schumann

Keyword(s):

Low Temperature ◽

Oceanic Crust ◽

Deep Sea ◽

Sediment Samples ◽

Mid Atlantic Ridge

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Nitrogen Isotope Exchange between Liquid N2O3 and NO at Low Temperature and Elevated Pressure

Zeitschrift für Naturforschung A ◽

10.1515/zna-1963-0222 ◽

1963 ◽

Vol 18 (2) ◽

pp. 235-241 ◽

Cited By ~ 2

Author(s):

E. U. Monse ◽

Lois Nash Kauder ◽

W. Spindel

Keyword(s):

Low Temperature ◽

Separation Factor ◽

Isotope Exchange ◽

Spectroscopic Data ◽

Room Temperature ◽

Nitrogen Isotopes ◽

Nitrogen Isotope ◽

Elevated Pressure ◽

Single Stage ◽

Stage Separation

The single stage separation factor, a, for nitrogen isotope exchange between liquid N2O3—N2O4-mixtures and their vapor has been measured at temperatures ranging from — 76°C to room temperature and pressures between 1 atm. and 7.4 atm.At —76°C and 1 atm., α = 1.061 ± 0.003;at —23°C and 1 atm., α=1.034 ± 0.002;at +23°C and 2.1 atm., α=1.017 ± 0.002;at +23°C and 7.4 atm., α=1.030 ± 0.002.The results are compared with values, calculated from spectroscopic data for N2O3, N2O4, NO and NO2. The value of α = 1.030 found at room temperature and 7.4 atm. pressure enhances the usefulness of the N2O3—NO-system for separating the nitrogen isotopes, since it eliminates the need of refrigeration.

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