Iron isotopic composition of iron-silica layers along a profile in a single = 2, 9 Ga old BIF from Dhawar Craton, southern India

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Lead isotopic analysis of infant bone tissue dating from the Roman Era via multi-collector ICP – mass spectrometry.

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The Red Beds series in the Erta Ale segment, North Afar. Evidence for a 6 Ma-old post-rift basin prior to continental rupturing

The Erta Ale rift segment, North Afar, is regarded as the most mature rift part within the entire Afar rift system. Very little is known about its deformation history because of limited exposures of geological records in its inner floor, except volcanics of the Erta Ale chain, and the poorly-known Red Beds series along the flanks of the depression. An integrated study, combining sedimentological, geochemical, 40Ar-39Ar radiometric and tectonic approaches, has been devoted to Red Beds series flanking the depression to the SW. Our new results allow to argue that (1) the >300 m-thick Red Beds exposed section comprises alluvial deposits that enclose (2) basaltic lavas and related sill intrusions that both yield ~6 Ma 40Ar-39Ar ages and display similar geochemical affinities, (3) the Red Beds series locally overlap unconformably basement bounding terrains, and (4) are involved in a limited number of low-displacement normal faults that recorded a modest amount of extension (<6%), (5) isotope contents of Red Beds volcanics indicate crustal contamination, without any contribution of the Afar plume, by contrast to the younger Erta Ale magmatism which represents the more recent Afar-plume related event in the Erta Ale segment. Combining these results leads us to regard the Red Beds series as part of an alluvial basin that post-dated a major rift event to which are attributed to (1) the present-day Ethiopian fault-scarp, (2) a concealed sedimentary depocenter at depth in its hanging wall, and (3) prominent crustal thinning. Riftward migration and axial focusing of strain during Miocene-Present times is also argued, while later flexuring of the entire Red Beds basin is assigned to magmatic loading during the axial emplacement of the Erta Ale volcanic chain. Lastly, emphasis is put on the large-scale segmentation of the Afar system into the tectonically-accreted Erta Ale rift segment to the north, and the magmatically-accreted Central segment to the south

Magnesium isotope heterogeneity of the isotopic standard SRM980 and new reference materials for magnesium-isotope-ratio measurements

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Variation in the isotopic composition of zinc in the natural environment and the use of zinc isotopes in biogeosciences : a review

Zinc (Zn) is a trace element that is, as a building block in various enzymes, of vital importance for all living organisms. Zn concentrations are widely determined in dietary, biological and environmental studies. Recent papers report on the first efforts to use stable Zn isotopes in environmental studies, and initial results point to significant Zn isotope fractionation during various biological and chemical processes, and thus highlight their potential as valuable biogeochemical tracers. In this article, we discuss the state-of-the-art analytical methods for isotopic analysis of Zn and the procedures used to obtain accurate Zn isotope ratio results. We then review recent applications of Zn isotope measurements in environmental and life sciences, emphasizing the mechanisms and causes responsible for observed natural variation in the isotopic composition of Zn. We first discuss the Zn isotope variability in extraterrestrial and geological samples. We then focus on biological processes inducing Zn isotope fractionation in plants, animals and humans, and we assess the potential of Zn isotope ratio determination for elucidating sources of atmospheric particles and contamination. Finally, we discuss possible impediments and limitations of the application of Zn isotopes in (geo-) environmental studies and provide an outlook regarding future directions of Zn isotope research