Nitrogen isotopic composition of the MORB mantle: A reevaluation

Triple oxygen isotopic composition of the high-He/He mantle

Measurements of Xe isotope ratios in ocean island basalts (OIB) suggest that Earth’s mantle accreted heterogeneously, and that compositional remnants of accretion are sampled by modern, high-He/He OIB associated with the Icelandic and Samoan plumes. If so, the high-He/He source may also have a distinct oxygen isotopic composition from the rest of the mantle. Here, we test if the major elements ...

Major and Trace Element Composition of the Depleted MORB Mantle (DMM)

We derive an estimate for the chemical composition of the depleted MORB mantle (DMM), the source reservoir to mid-ocean ridge basalts (MORBs), which represents at least 30% the mass of the whole silicate Earth. A database for the chemical and physical properties of abyssal peridotites has become robust and complete enough to truly access a reference DMM. Using trace element depletion trends fro...

Stable nitrogen isotopic composition of amino acids reveals

New Insights on Saturn’s Formation from Its Nitrogen Isotopic Composition

The recent derivation of a lower limit for the 14N/15N ratio in Saturn’s ammonia, which is found to be consistent with the Jovian value, prompted us to revise models of Saturn’s formation using as constraints the supersolar abundances of heavy elements measured in its atmosphere. Here we find that it is possible to account for both Saturn’s chemical and isotopic compositions if one assumes the ...

The prevalence of kilometer-scale heterogeneity in the source region of MORB upper mantle

The source regions of mid-ocean ridge basalts (MORB) are heterogeneous, consisting of chemically and lithologically distinct domains of variable size. Partial melting of such heterogeneous mantle sources gives rise to diverse isotopic compositions of MORB and abyssal peridotites. Variations in radiogenic isotope ratios in MORB are attributed to mixing of melts derived from enriched and depleted...