Marine clay maturation induces systematic silicon isotope decrease in authigenic clays and pore fluids

Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)

Published: Oct. 9, 2024

Marine silicate alteration exerts a major influence on marine carbon and cation cycles, but has proven difficult to quantify. In this context, silicon isotopes of pore fluids became an important tracer. However, poorly constrained isotope signatures precipitates produced during (i.e. authigenic clays) remain source uncertainty. Here we present in situ analyses clays (intergrown iron-smectites iron-glauconites) occurring within recent sediments from the Oregon margin, eastern North Pacific. We identify trend lower (from −2.24‰ −3.17‰), accompanied by decreasing aluminum/silicon ratios increasing potassium oxide contents, which interpret as isotopic shift caused progressive clay maturation via dissolution-reprecipitation reactions. Our modelling suggests that pathway, together with mixing other fluid sources, may induce shifts up −1.7‰, if sufficient newly precipitated are re-dissolved. This could potentially produce values significantly than seawater implies conventional isotope-based approaches underestimate prevalence alteration. findings highlight must be considered when interpreting terms upscaling global element cycles. authigenesis governs cycling geochemical according in-situ analysis sedimentary glauconite.

Language: Английский

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Tracing Water–Rock–Gas Reactions in Shallow Productive Mud Chambers of Active Mud Volcanoes in the Caspian Sea Region (Azerbaijan)

Minerals, Journal Year: 2023, Volume and Issue: 13(5), P. 696 - 696

Published: May 19, 2023

We present geochemical and mineralogical datasets for five new mud volcanoes in continental Azerbaijan (Hamamdagh Bendovan) the adjacent Caspian Sea (Khara-Zire, Garasu Sangi-Mughan). The fluid ejects have a Na–Cl-type composition are generated by mixing of evaporated seawater low- to high-salinity pore waters, as indicated Br–B Cl–B systematics Na–K SiO2 geo-thermometers. fluids contain high concentrations As, Ba, Cu, Si, Li, Sr Zn (60 26,300 ppm), which caused surface evaporation, pyrite oxidation, ion exchange reactions hydrocarbon maturation Oligocene-Miocene ‘Maykop’ shales. solid comprise liquid, oily brecciated mud, mud/claystones sandstones. heterogeneity is related geological age different sedimentological strata host rocks that pass through during their ascent. All show evidence chemical alterations via water–rock–gas reactions, such feldspar weathering, smectite illitization precipitation Fe-(hydr)oxides, calcite, calcian dolomite, kaolinite smectite. studied localities petrographic similarities northern extending volcano systems located on Bahar Zenbil islands, suggests region sourced from giant shallow chambers (~1–4 km depth) Productive Series strata. Our results document complex architecture South Basin—the most prolific world.

Language: Английский

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Authigenic clay mineral constraints on spatiotemporal evolution of restricted, evaporitic conditions during deposition of the Ediacaran Doushantuo Formation

Earth and Planetary Science Letters, Journal Year: 2023, Volume and Issue: 626, P. 118524 - 118524

Published: Dec. 12, 2023

The carbonate-rich shelf facies of the Ediacaran Doushantuo Formation (South China) have produced a broad array microfossil and isotope proxy records which underpin much our understanding environmental change biospheric evolution during this key time period. Recent reports locally abundant authigenic, Mg-rich saponite clay in Yangtze Gorges Area hint at potentially widespread evaporitic conditions lagoonal setting. Despite implications for interpretation setting early metazoans, spatiotemporal extent restricted, across Block remains largely unexplored. Here we use mineralogical petrographic techniques to document spatial stratigraphic distribution authigenic minerals seven sites, representing transect from shallow proximal deep basinal settings. Our results demonstrate persistent occurrence settings, whereas talc is identified more distal consistent with Mg-clay authigenesis an lagoon spatially variable detrital aluminosilicate input. Slope sites contain no Mg-clays are instead characterized by illite, open marine Stratigraphically, illite was found basal cap carbonate uppermost Formation, only present interval in-between, suggesting gradual development extensive rimmed over that restricted seawater exchange, followed stronger influence due erosion rim subsequent transgression. We conclude were expansive than previously assumed, providing favorable Biota. Further, presence clays supports case enhanced reverse weathering before advent biosilicification.

Language: Английский

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Investigating the use of two-dimensional OSL laser scanning instruments and energy-dispersive x-ray spectroscopy for OSL exposure dating

Radiation Measurements, Journal Year: 2023, Volume and Issue: 167, P. 106999 - 106999

Published: Aug. 25, 2023

Language: Английский

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Geochemistry of pore water

Elsevier eBooks, Journal Year: 2024, Volume and Issue: unknown, P. 631 - 682

Published: May 1, 2024

Language: Английский

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