Noble gas elemental abundances in polymorphs of silica

Mitchell, J. G.; Ineson, P. R.; Davison, M.; Lawley, Russell

doi:10.1016/0009-2541(92)90153-v

Cited by 4 publications

(2 citation statements)

References 15 publications

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“…These spherical particles are usually full of fluid (gas and water, etc.) [12] that can be maintained for a long period of geological time [13,14] . Studying the rare gas in silica can be helpful to understanding the origin and evolution of the volatile components in fluid when it was formed [15] .…”

Section: The Origin Of Armentioning

confidence: 99%

The noble gas isotope geochemical composition of chert at the bottom of Cambrian in Tarim Basin, China

Sun

Chen²,

Zheng

et al. 2009

Sci. China Ser. D-Earth Sci.

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In the Tarim Basin, black shale series at the bottom of Cambrian is one of the important marine facies hydrocarbon source rocks. This research focuses on the analysis of the isotope of noble gas of 11 cherts. The R/R a ratio of chert in the Keping area is 0.032-0.319, and 40 Ar/ 36 Ar is 338-430. In Quruqtagh the R/R a ratio is 0.44-10.21, and 40 Ar/ 36 Ar is 360-765. The R/R a ratio of chert increases with 40 Ar/ 36 Ar from the west to the east accordingly. They have evolved from the crust source area to the mantle source area in a direct proportion. Surplus argon 40 Ar E in chert is in direct proportion to the R/R a ratio, indicating that it has the same origin of excess argon as in fluid and mantle source helium. Comparison of the R/R a ratios between the west and the east shows that the chert in the eastern part formed from the activity system of the bottom hydrothermal venting driven by the mantle source, where the material and energy of crust and mantle had a strong interaction in exchange; whereas in the western part, chert deposited from the floating of hydrothermal plume undersea bottom, which is far away from the centre of activities of the hydrothermal fluid of ocean bottom. In addition, from noble gas isotope composition of chert, it is suggested that the ocean anoxia incident happened at the black shale of the Cambrian bottom probably because of the large-scaled ocean volcanoes and the following hydrothermal activities.Tarim Basin, Cambrian, chert, rare gas isotope Chert is widely spread in a long time span. It may appear under various circumstances from the Archean to modern ocean bottom hydrothermal venting area and the terrestrial hot spring area. It seems that from the formation cause, the older the chert is, the more advantageous the chemical cause of formation would be. However, the biological cause of formation gradually gained advantage since Mesozoic [1] . The cause of formation of marine facies black shale is always being concerned by geologists, but opinions differ, such as the cause of the accident of anoxia. Silica is one of the important rock of black shales [2][3][4][5][6] . It can reflect the ancient environment, the ancient structure, the source of mineralization and other information, etc., because it had a strong resistance against later reconstruction and formed under certain geochemical conditions. So it attracts a wide range of attention from geologists. This paper tries to probe into the construction activities and the interaction between crust and mantle at that time through the research on the rare gas isotope of chert from the black shale at the bottom of Cambrian in the Tarim Basin.

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Section: The Origin Of Armentioning

confidence: 99%

The noble gas isotope geochemical composition of chert at the bottom of Cambrian in Tarim Basin, China

Sun

Chen²,

Zheng

et al. 2009

Sci. China Ser. D-Earth Sci.

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“…Note that biogenic chert is also characterized with F(Ne) ∼ 1. Matusubara et al 29 and Mitchell et al 30 found that the noble gas concentrations in biogenic chert are not influenced by different environments. Because the observed Ne concentration is consistent with 3−10% contribution of air-saturated seawater, Ne retention is not affected by the precursor of amorphous silica.…”

Section: ■ Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Noble Gas Fractionation during Diffusion through Silica Nanopores

Ding

Qiu

et al. 2018

ACS Earth Space Chem.

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Ne retention and slight enrichment of Kr−Xe relative to atmospheric levels have been found in biogenic chert samples. Previous studies suggested that the incorporation of noble gas atoms is dependent upon the structure rather than the environment. In this study, we perform molecular dynamics simulations of dissolved noble gas atomic diffusion through 1−4 nm diameter silica pores. Bulk-liquidlike water does not exist in the 1 nm diameter nanopores, which hinder noble gas diffusion into or out of the pores. In ≥2 nm diameter nanopores, noble gas atoms transport with bulk-liquid-like water into the center of the pores but sizecontrolled diffusive separation occurs at the layer of surface water and in the interior of the silica structure. The motion of large atoms (Kr and Xe) in surface water is governed by significant adsorption. Relatively small Ne atoms are able to cross the surface water layer and diffuse into the crystal interior. As a result of its moderate size and the negligible interaction with the interfacial surface, Ar lies beyond the adsorption and silica structure diffusion regimes. Therefore, our simulation results indicate that noble gas entrapment is expected to occur in nanoscale fluid circulation during sediment-to-chert lithification.

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