Aluminium under the spotlight

Article Abstract:

Research showing the importance of the presence of aluminium in the Earth's lower mantle could change the understanding of the mantle's dynamics. Scientists agree that between depths of 670 km and 2,900 km, the lower mantle comprises an aggregation of crystals of iron and magnesium, with sodium chloride structure, and a perovskite structured assemblage of iron and magnesium silicate. Aluminium is a minor element in the lower mantle. Research shows that the iron content of perovskite is controlled by aluminium, present as FE3+, which may influence the electrical conductivity of the lower mantle.

Observations, Composition, Perovskite, Aluminum compounds, Geophysical research

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Oxygen isotope evidence for recycled crust in the source of EM-type ocean island basalts

Article Abstract:

Ocean island basalts were studied to determine whether these were subducted into the mantle and recycled to the surface after hundreds of millions of years. It appears that subducted crustal components were essential in the oxygen isotope compositions of fresh volcanic glasses obtained from submarine volcanoes of enriched mantle type. Thus, previous theories based on trace elements and radiogenic isotopes have been confirmed by these new data. The new information could also be crucial in determining the proportion of subducted material which rises to the region of ocean island basalts.

Basalt, Inclusions

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Sulphur isotope evidence for an oxic Archaean atmosphere

Article Abstract:

Sedimentary rocks and marine shales in the Pilbara Craton, Western Australia are analyzed to detect whether they contain mass-independently fractionated sulphur isotopes (MIF-S). It is found that these rocks in Western Australia show no presence of MIF-S which may be due to the level of atmospheric oxygen fluctuation during the Archaean era and MIF-S in rocks was mostly created by non-photochemical reactions during sediment diagenesis and thus is not linked to atmospheric chemistry.

Australia, Science & research, Natural history, Isotope separation, Rocks, Sedimentary, Sedimentary rocks, Diagenesis, Diagenesis (Geology)

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