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

Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations

Arc magmas and the continental crust share many chemical features, but a major question remains as to whether these features are created by subduction or are recycled from subducting sediment. This question is explored here using Th/La, which is low in oceanic basalts ( 0·25) and varies in arc basalts and marine sediments (0·09–0·34). Volcanic arcs form linear mixing arrays between mantle and sediment in plots of Th/La vs Sm/La. The mantle end-member for different arcs varies between highly depleted and enriched compositions. The sedimentary end-member is typically the same as local trench sediment. Thus, arc magmas inherit their Th/La from subducting sediment and high Th/La is not newly created during subduction (or by intraplate, adakite or Archaean magmatism). Instead, there is a large fractionation in Th/La within the continental crust, caused by the preferential partitioning of La over Th in mafic and accessory minerals. These observations suggest a mechanism of ‘fractionation & foundering’, whereby continents differentiate into a granitic upper crust and restite-cumulate lower crust, which periodically founders into the mantle. The bulk continental crust can reach its current elevated Th/La if arc crust differentiates and loses 25–60% of its mafic residues to foundering.

http://www.mantleplumes.org/WebDocuments/Plank.Th-La.Jpet05.pdf

Constraints from Thorium/Lanthanum on Sediment Recycling at Subduction Zones and the Evolution of the Continents

http://www.geo.mtu.edu/EHaz/ConvergentPlatesClass/macpherson/macpherson_etal_2006.pdf

Adakites without slab melting: High pressure differentiation of island arc magma, Mindanao, the Philippines

We present new analytical data of major and trace elements for the geological MPI-DING glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, BM90/21-G, T1-G, and ATHO-G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA-ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties (at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Association of Geoanalysts (IAG). The reference values were derived from the results of 16 independent techniques, including definitive (isotope dilution) and comparative bulk (e.g., INAA, ICPMS, SSMS) and microanalytical (e.g., LA-ICPMS, SIMS, EPMA) methods. Agreement between two or more independent methods and the use of definitive methods provided traceability to the fullest extent possible. We also present new and recently published data for the isotopic compositions of H, B, Li, O, Ca, Sr, Nd, Hf, and Pb. The results were mainly obtained by high-precision bulk techniques, such as TIMS and MC-ICPMS. In addition, LA-ICPMS and SIMS isotope data of B, Li, and Pb are presented.

/pdf/mpi-ding-reference-glasses-for-in-situ-microanalysis-new-2gtmtexuej.pdf

MPI-DING reference glasses for in situ microanalysis: New reference values for element concentrations and isotope ratios

Pressure-temperature-time paths followed by arc magmas ascending through the lithosphere dictate the phase assemblage that crystallizes, and hence the compositions of liquid fractionates. Here we use La/Yb and Dy/Yb versus SiO2 relationships from selected volcanoes to show that amphibole is an important mineral during differentiation of arc magma. Production of intermediate and silicic arc magmas occurs as magmas stall and cool in the mid-lower crust, where amphibole is stable. Because amphibole is rarely a phenocryst phase, we term this “cryptic amphibole fractionation.” If this process is as widespread as our investigation suggests, then (1) amphibole cumulates may act as an effective filter for water dissolved in mantle-derived magmas; (2) amphibole cumulates may act as a fertile source of intracrustal melts and fluids; and (3) recycling of amphibole cumulates has the potential to return incompatible trace elements and water to the mantle.

Amphibole “sponge” in arc crust?

Oxygen isotope composition of mantle peridotite

Quaternary intraplate volcanism near Sana’a, western Yemen, INTRODUCTION produced a chemically and isotopically diverse volcanic field. The The ultimate source and reason(s) why continental inpredominantly mafic samples include alkali basalt, transitional traplate volcanism occurs remain unclear, despite combasalt, basanite and trachybasalt; rarer evolved compositions are mon links with continental rifting and regions of mantle typically trachyandesite. No samples represent primary magmas, upwelling. The extensive belt of late Cenozoic (<15 Ma) all having undergone fractionation of olivine+clinopyroxene± intraplate volcanic fields that crops out along the length plagioclase±Fe–Ti oxides±apatite. Sr–Nd–Pb–O isotopic variof the western margin of the Arabian peninsula in Jordan, ation ( Sr/Sr=0·7032–0·7046; Nd/Nd=0·51298– Israel, Saudi Arabia and Yemen forms one of the largest 0·51278; Pb/Pb=18·93–18·05; dO=+5·2 to intraplate volcanic provinces on Earth. These volcanic +5·5‰) is largely the result of mixing between a mantle component, rocks are generally more alkaline than older Eocene to with a composition intermediate between that of mid-ocean ridge Miocene flood volcanism erupted at the Afro-Arabian basalt (MORB) and the Afar plume, and 0–20% of an Early triple junction in Yemen, Ethiopia and Eritrea (Camp & Proterozoic or Late Archaean silicic lower-crustal component which Roobol, 1992). Intraplate volcanism in Yemen is clearly produced little change in dO values. Ratios of very to moderately incompatible trace elements vary widely (e.g. Ce/Y=0·9–3·7) and associated with both continental rifting, which produced independently of isotopic composition. Semi-quantitative modelling of the Red Sea and Gulf of Aden, and also a mantle plume, REE ratios requires this heterogeneity to be the product of mixing which produced Oligocene flood volcanism (Baker et al., between small melt fractions (<1%) from recently incompatible1996). Given the well-characterized crustal and mantle trace-element-enriched garnet peridotite facies mantle and relatively (asthenospheric, plume and lithospheric mantle) comlarger melt fractions (~5%) from spinel peridotite facies mantle, positions in this region, Yemen is an ideal setting in with samples containing 40–90% spinel-facies melt. Substantial which to attempt to identify the source of intraplate variations in Zr/Sm and Nb/La ratios also suggest that the spinelvolcanism and to speculate on why it occurred during facies mantle may be amphibole bearing. Intraplate volcanism in the Late Cenozoic. western Yemen appears to be the result of melting shallow mantle, Detailed chemical, but not isotopic, studies of some of perhaps in response to small amounts of lithospheric extension, that the Saudi Arabian volcanic fields have been published was metasomatized and hydrated by the Afar plume during, or (Camp & Roobol, 1989; Camp et al., 1991, 1992), highshortly after, Oligocene flood volcanism. lighting the role of fractional crystallization and variable degrees of partial melting in generating the diversity of predominantly mafic rock types present in these fields.

/pdf/petrogenesis-of-quaternary-intraplate-volcanism-sana-a-yemen-3z81g4b4n7.pdf

Petrogenesis of Quaternary Intraplate Volcanism, Sana'a, Yemen: Implications for Plume-Lithosphere Interaction and Polybaric Melt Hybridization

Resolution of the effects of crustal assimilation, sediment subduction, and fluid transport in island arc magmas: PbSrNdO isotope geochemistry of Grenada, Lesser Antilles

Colin G. Macpherson

Papers

Adakites without slab melting: High pressure differentiation of island arc magma, Mindanao, the Philippines

Amphibole “sponge” in arc crust?

Oxygen isotope composition of mantle peridotite

Petrogenesis of Quaternary Intraplate Volcanism, Sana'a, Yemen: Implications for Plume-Lithosphere Interaction and Polybaric Melt Hybridization

Resolution of the effects of crustal assimilation, sediment subduction, and fluid transport in island arc magmas: PbSrNdO isotope geochemistry of Grenada, Lesser Antilles