Cambrian sea water preserved as inclusions in marine low-magnesium calcite cement

Article Abstract:

Calcite cements collected from marine truncation surfaces which bracket the Cambrian/Ordovician boundary at Wilberns Formation, TX, were analyzed for the composition of their primary, one-phase fluid inclusions. These inclusions represent samples of water of Early Palaeozoic oceans. The results showed that these cements have a low magnesium content, unlike the high magnesium calcites and argonites of the present carbonate precipitates. These findings indicate that the chemistry of oceans have undergone changes between the Cambrian and the present time.

Analysis, Cambrian period, Marine sediments, Sea-water, Seawater, Calcite

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Vanadium partitioning and the oxidation state of Archaean komatiite magmas

Article Abstract:

Komatiite lava formation temperatures in the Archaean mantle are determined by their MgO content. The oxidation state is characterized by the oxygen fugacity (fosub2), which remains poorly constrained for such lavas. An estimate of the fosub2 for komatiite flows is presented, based on vanadium partitioning between komatiitic liquid and olivine in komatiite flows. Results show that the oxidation state of several of the flows was the same, or more oxidizing than, that of current oceanic basalts.

Oxidation-reduction reaction, Oxidation-reduction reactions, Archean Eon

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Extreme damping in composite materials with negative-stiffness inclusions

Article Abstract:

Negative-stiffness inclusions of ferroelastic vanadium dioxide were embedded in a pure tin matrix to study extreme mechanical damping.

Damping (Mechanics), Damping (Physics)

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