The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

Plesovice zircon : A new natural reference material for U-Pb and Hf isotopic microanalysis

The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites

Major and trace element composition of the depleted MORB mantle (DMM)

Zircon chemistry and magma mixing, SE China: In-situ analysis of Hf isotopes, Tonglu and Pingtan igneous complexes

Luguet et al. (2019) applied the Re-Os and Pt-Os chronometers to date the Pt mineralisation of the Kondyor Zoned Ultramafic Complex (ZUC) and suggested this to be ∼250-240 Ma and related to the subduction of the Mongol-Okhotsk (MO) ocean seafloor under the Siberian craton. The discrepancy with the Early Cretaceous 190Pt-4He isochronal ages of Mochalov et al. (2016) led Luguet et al. (2019) to conclude that the 190Pt-4He chronometer was not robust due to the complex history of the Kondyor Pt mineralisation, thus not providing a meaningful insight into themineralisation age. Yakubovich et al. (2022) challenge these interpretations. There is however little controversy when the current Pt-Os (Luguet et al., 2019) and Pt-He (Mochalov et al., 2016) isotopic systems are considered together with regional geological history.

Reply to Comment on “190Pt-186Os geochronometer reveals open system behaviour of 190Pt-4He isotope system” by Yakubovich et al. (2022)

Paleozoic subduction into the deeper mantle recorded by superdeep diamonds

Our new, Equilibrated Major Element – Assimilation with Fractional Crystallisation (EME-AFC) approach simultaneously models the major element, trace element, and radiogenic and oxygen isotope compositions during such magmatic differentiation (including a new approach to oxygen modelling); addressing the lack of current AFC modelling approaches for felsic, amphiboleor biotite-bearing systems. We discuss the application of this model to granitic magmatism in SE Asia and Antarctica, with particular focus on the Mt Kinabalu granitic intrusion of Borneo. We discuss the background to the model, and explain how it can be freely accessed via GitHub [2], and applied to other scenarios of magmatic differentiation; not just granitic magmatism.

A new approach to modelling differentiation (with particular focus on granitic magmatism): Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC)

Corrigendum to “Establishing a strontium isotope baseline in New Zealand for future archaeological migration studies: A case study” [J. Archaeol. Sci. Rep. 32 (2020) 102412]

Abstract Mantle xenoliths from the Calatrava Volcanic District (CLV), central Spain, are characterized by a wide compositional range that includes lherzolites (prevalent), as well as minor amounts of wehrlite, olivine (ol)-websterite and rare dunites. They generally have a bulk-rock Mg# of less than 89, lower than any primordial mantle estimates. Intra-suite variations in modal proportions are inconsistent with those predicted by melting models irrespective of the starting composition; mineral and bulk-rock variation diagrams show inconsistencies between the CLV compositions (anomalously enriched in Fe–Ti) and those predicted from the partial melting of primordial mantle material. Processes other than pure melt extraction are confirmed by the whole-rock REE (rare earth element) budget, typically characterized by LREE enrichments, with LaN/YbN (up to 6.7), probably related to pervasive metasomatism. CLV mantle clinopyroxenes (cpx) generally display fractionated REE patterns with upwards-convex shapes, characterized by low HREE (Tm–Lu) concentrations (typically <6× chondrite) and enrichments in middle–light REE (MREE–LREE) (NdN/YbN up to 7, LaN/YbN up to 5). These ‘enriched’ cpx compositions either result from re-equilibration of primary mantle cpx with an incoming melt, or represent cpx crystallization directly from the metasomatic agent. The latter was plausibly generated at greater depths in the presence of residual garnet (from peridotite or eclogite starting materials). Separated cpx have homogeneous 87Sr/86Sr compositions between 0.7031 and 0.7032; 143Nd/144Nd ranges from 0.51288 to 0.51295 (ϵNd 4.74–6.07) and 176Hf/177Hf is in the range 0.28302–0.28265 (ϵHf −3.6 to 9.0). Unlike mantle xenoliths and alpine-type peridotites from other Iberian occurrences, which range in composition from the depleted mantle (DM) to the enriched mantle (EM), the CLV mantle cpx approach the composition of the HIMU mantle end member, the genesis of which is generally interpreted as the result of long-term recycling of oceanic basalts/gabbros (or their eclogitic equivalent) via ancient subduction. A model is proposed for the mantle evolution under central Iberia, where sublithospheric convective instabilities – possibly triggered by the neighbouring subduction along the Betic collisional belt – could have remobilized deep domains from the mantle ‘transition zone’ (410–660 km), which may include relicts of older subducted slabs. Within these remobilized domains, characterized by the coexistence of peridotite and eclogite and referred to as a ‘piclogite’ association, the eclogites melt preferentially generating Fe–Ti rich melts characterized by a HIMU isotopic signature that infiltrates and metasomatizes the shallower lithospheric mantle.

Geoff Nowell

Papers

Reply to Comment on “190Pt-186Os geochronometer reveals open system behaviour of 190Pt-4He isotope system” by Yakubovich et al. (2022)

Paleozoic subduction into the deeper mantle recorded by superdeep diamonds

A new approach to modelling differentiation (with particular focus on granitic magmatism): Equilibrated Major Element Assimilation with Fractional Crystallisation (EME-AFC)

Corrigendum to “Establishing a strontium isotope baseline in New Zealand for future archaeological migration studies: A case study” [J. Archaeol. Sci. Rep. 32 (2020) 102412]

Mantle metasomatism by melts of HIMU piclogite components: new insights from Fe-lherzolite xenoliths (Calatrava Volcanic District, Central Spain)