of Technology Prof. Jean Hertzberg, University of Colorado Dr. M. Hertzberg, Lock Haven University Dr. Gunnar Heskestad, Factory Mutual Research...Univ Catholique de Louvain Prof. Uri Vandsburger, Virginia Polytechnic Institute Dr. Jean -Pierre Vantelon, Universite de Poitiers Dr. Philip...Scientific Pub- lishing Co., Singapore, 1994. 22. a) Ionov, S., Bruckner, G. A., Jacques , C, Valachovic, L., and Wittig, C, J. Chem. Phys. 97:9486-9489
Ageev, V. N.; Kuznetsov, Yu. A.; Potekhina, N. D.
After a brief discussion of the main result of the research initiated by N.I. Ionov in his laboratory using electron-stimulated desorption for studying the surface layers of tungsten, we consider in greater detail recent results on layered coatings formed on the tungsten surface upon simultaneous adsorption of sodium (or cesium) and gold atoms on this surface, as well as the effect of sputtering of samarium atoms on the (Cs + Au)/W(100) surface that has already been formed at 300 K.
Yakob, J. L.; Feineman, M. D.; Penniston-Dorland, S. C.; Eggler, D. H.
Measured 7Li/6Li of mineral separates from mantle xenoliths from diverse localities show unexpectedly large differences between olivines and pyroxenes, often with lighter Li found in the pyroxenes (Jeffcoate et al., 2007; Rudnick and Ionov, 2007; Ionov and Seitz, 2008). Although changes in isotopic fractionation with temperature could explain the differences, a kinetic isotope effect is as likely. Because 6Li diffuses faster than 7Li, bulk lithium exchange between two phases could result in dynamic isotopic fractionation, with the receiving phase becoming lighter and the donating phase becoming heavier. Thus if Li becomes more compatible in cpx upon cooling, that is, if DLiol/cpx is temperature-dependent, the diffusive exchange of Li will generate temporary 6Li enrichment in cpx and depletion in olivine. Experiments were conducted using a piston cylinder apparatus at 1100°C and 1.4 GPa (1-5 days) to determine DLiol/cpx. San Carlos olivine and Dekalb diopside were finely ground for starting materials. A mixture of olivine (52 wt%), diopside (34 wt%), albite (7 wt%), and quartz (7 wt%) powders (0.0145 g) was loaded into a Pt capsule inside of a Ni crucible. Milli-Q water with 100 ppm Li and 500 ppm Ba (obtained through dilution of stock solutions) was added (0.1100 g) to serve as the lithium source. Lithium concentrations in olivine and diopside from experiments held for 1, 3, and 5 days were determined by laser ablation ICP-MS. Partition coefficients DLiol/cpx from runs at 3 and 5 days are, within error, the same, 1.9 (0.3). These fall in the lower portion of the range, D = 2-7, of limited previous measurements (Brenan et al., 1998b, Blundy and Dalton, 2000; Caciagli-Warman 2010). Partitioning experiments at 700 and 900°C are ongoing. References Blundy, J. and Dalton, J. (2000) Experimental comparison of trace element partitioning between clinopyroxene and melt in carbonate and silicate systems, and implications for mantle metasomatism. Contrib. Mineral. Petrol
, major and trace element and isotope compositions of fertile lherzolites and thus cannot provide viable alternatives to the concept of melt extraction from pristine mantle as the major mechanism of CLM formation. Published data on xenoliths from andesitic volcanoes and on supra-subduction oceanic peridotites  show that the most common rocks in mantle wedge lithosphere are highly refractory harzburgites characterized by a combination of variable but generally high modal opx (18-30%) with very low modal cpx (1.5-3%). At a given olivine (or MgO) content, they have higher opx and silica, and lower cpx, Al and Ca contents than normal refractory peridotite xenoliths in continental basalts; the Mg-Si and Al-Si trends in those rocks resemble those in cratonic peridotites. These features may indicate either fluid fluxing during melting in the mantle wedge or selective post-melting metasomatic enrichments in silica to transform some olivine to opx. High oxygen fugacities and radiogenic Os-isotope compositions in those rocks may be related to enrichments by slab-derived fluids, but these features are not always coupled with trace element enrichments or patterns commonly attributed to "subduction zone metasomatism" deduced from studies of arc volcanic rocks and experiments. The valuable insights provided by experimental work and xenolith case studies are difficult to apply to many natural peridotite series because late-stage processes commonly overlap the evidence for initial melting. References:  Herzberg C., J. Petrol. 45: 2507 (2004).  Ionov D. & Sobolev A., GCA 72 (S1): A410 (2008).  Ionov D., Contrib. Miner. Petrol. (2007)  Ionov D., J. Petrol. doi: 10.1093/petrology/egp090 (2010)
Krause, J.; Brügmann, G. E.; Pushkarev, E. V.
The partitioning of trace elements between rock forming minerals in igneous rocks is largely controlled by physical and chemical parameters e.g. temperature, pressure and chemical composition of the minerals and the coexisting melt. In the present study partition coefficients for REE between hornblende, orthopyroxene, feldspars, apatite and clinopyroxene in a suite of co-genetic alkaline and tholeiitic mafic rocks from the Ural Mountains (Russia) were calculated. The results give insights to the influence of the chemical composition of the parental melt on the partitioning behaviour of the REE. Nepheline-bearing, alkaline melanogabbros (tilaites) are assumed to represent the most fractionated products of the melt that formed the ultramafic cumulates in zoned mafic-ultramafic complexes in the Ural Mountains. Co-genetic with the latter is a suite of olivine gabbros, gabbronorites and hornblende gabbros formed from a tholeiitic parental melt. Negative anomalies for the HFSE along with low Nb and Ta contents and a positive Sr anomaly indicate a subduction related origin of all parental melts. The nepheline gabbros consist predominantly of coarse-grained clinopyroxene phenocrysts in a matrix of fine grained clinopyroxene, olivine, plagioclase, K-feldspar and nepheline with accessory apatite. The tholeiitic gabbros have equigranular to porphyric textures with phenocrysts of olivine, pyroxene and hornblende in a plagioclase rich matrix with olivine hornblende, pyroxene and accessory apatite. Element concentrations of adjacent matrix grains and rims of phenochrysts were measured with LA-ICPMS. The distribution of REE between hornblende and clinopyroxene in the tholeiitic rocks is similar for most of the elements (DHblCpx(La-Tm) = 2.7-2.8, decreasing to 2.6 and 2.4 for Yb and Lu, respectively). These values are about two times higher than published data (e.g. Ionov et al. 1997). Partition coefficients for orthopyroxene/clinopyroxene systematically decrease from the HREE
Prikhodko, V.; Ashchepkov, I.; Ntaflos, T.; Barkar, A.; Vysotsky, S.; Esin, S.; Kutolin, V.; Prussevich, A.
-Koppy rivers and Mount Kurgan) show that in lava plateau stage Cpx in spinel facies have LREE Zr, Hf, Nb, Ta depleted patterns common for subduction related mantle melts. The Pliocene post erosion lava xenoliths's CPX reveal humped REE patterns, small depletions in Zr deeper in Ta corresponding to minor garnet in source. Clinopyroxenes from Amph- bearing websteritis are closer in TRE to to melts burn in garnet- bearing lherzolites (HFSE enriched U, Th spidergrams indication carbonatite metasomatism. Cpx in Podgelbanochny xenoliths (Ionov, 1995) reveal LREE - Th, U, Nb, Ta enriched content probably related to carbonatitic metasomatism or melts formed after decomposition of Amph - Phl measomaic association. The small Zr and Pb minima suppose sulfide and minor rutile precipitation. The host plume of Pliocene basalts are close to derived from primitive mantle source deviating in Sr (peak) small fluctuations in Zr- Hf. Reconstructed with KD parental liquids for websterites from MountKurgan are close to erupted lavas in La/Ybn . Melts parental for Cr- Di in the xenoliths from Podgelbanochny are more enriched. The sequence of xenolths show the sequent enrichment of the mantle columns beneath basaltic plateaus with the melts of subduction related to plume source. RBRF grant 11-05-00060.
Ishimaru, S.; Arai, S.; Tamura, A.; Okrugin, V. M.; Shcherbakov, V.; Plechov, P.
We have a large amount of data about petrological and geochemical features of upper mantle peridotites based on researches of mantle xenoliths, ophiolites or solid intrusions. But the nature of sub-arc mantle, especially beneath a volcanic front, has not been fully understood due to the scarcity of occurrences of mantle-derived materials there. Kamchatka Peninsula is one of the active volcanic arcs, having 29 active volcanoes, and 13 volcanoes of them contain cognate or mantle peridotite xenoliths (Erlich et al., 1979). Peridotite xenoliths derived from the upper mantle beneath the volcanic front are expected from 9 of them (Erlich et al., 1979). Avachinsky (Avacha) volcano is the most famous of them because of its easy accessibility and high xenolith production. Peridotite xenoliths from Avacha record high degree of melting and multiple stages of metasomatism (e.g., Ishimaru et al., 2007; Ionov, 2010). Formation of secondary orthopyroxenes replacing olivine is one of characteristics of arc-derived peridotite xenoliths (e.g., Arai & Kida, 2000; McInnes et al., 2001). In addition, we found peculiar metasomatisms, e.g., Ni enrichment (e.g., Ishimaru and Arai, 2008), in the Avacha peridotite xenolith suite. Here, we show petrological and geochemical features of ultramafic xenoliths from Bezymyanny volcano, central Kamchatka, to obtain a more generalized view of the sub-front mantle. We examined 2 harzburgite xenoliths from Bezymyanny. They are composed of fine-grained minerals (cf. Arai and Kida, 2000), and occasionally contain hornblende and/or phlogopite. Almost all orthopyroxenes show irregular shapes and replace olivine, indicating a secondary origin. At the boundary between the harzburgite and host andesite, we observed hornblende and secondary orthopyroxenes. At the xenoliths' interior, Fo content of olivine and Cr# (= Cr/(Cr + Al) atomic ratio) of chromian spinel are high, 91-92 and 0.43-0.69, respectively, and the Fo content decreases to 76 at the boundary
Ashchepkov, Igor; Aseeva, Anna; Vysotsky, Sergei; Prikhodko, Valdimir; Kutolin, Valdislav
The trace element compositions were determined for 30 Cpx and some Cr spinels from the mantle xenoliths by LAM ICP using Finnigan ELEMENT with the YAG Nd 266 Laser Probe laser system (analyst S.V. Palessky) in Analytic centre of IGM SB RAS. Cpx from Kamku river show nearly flat or inclined REE patterns (La/Ybn ~2.5) with the depressions in Ta, Nb and less in Zr. Similar patterns show Cpx from volc. Medvezhy showing higher fluctuations in LREE 0.1>La/Ybn >1 with the depressions in HFSE. The Cpx from Tuttocha lava plateau show small depletion in LREE correspondent to 1-2% melting in Sp facie but one grain showing the spectrum with humped LREE probably refer to the interaction with basalt melt. CPx from the volc. Mount Kurgan show slightly humped in MREE convex upward patterns. Some of them reveal the depletion in LREE Zr, Hf, Nb, Ta which is common for the spinel peridotites subjected to the reactions with the oxidized melts crystallized oxides. Another one grain show La/Yb>1 correspondent to presence of small amount of Gar in the melting source and flattened incompatible part of TRE spectrum. The Cpx from Koppy reveal common REE slightly depleted LREE pattern and deeper Zr, Ta. minima. Podgelbanochny Cpx (Ionov et al., 1995) show stronger inclination referring to 2-5 % of Gar in melting source and progressively depleted incompatible part of the TRE spectrum as well as minima in Pb and smaller in Zr. The Cr spinels from Tuttocha show flattened patterns depleted LREE or U shaped patterns with peaks in Pb, Nb, U. But for Cr- Sp from Medvezhy the REE inclination is positive, the Pb dip is higher, and small Y depletion exists. So the mantle in the Southern part of Primorie and volcanoes of the latest activity show more inclines REE patterns with the garnet signatures and LREE enrichment and higher LA/Ybn rations corresponding to the lower melting degrees. In general there is now evidences for the support of the low crust and mantle lithosphere delamination which should
Pearson, D. G.; Canil, D.; Shirey, S. B.
, Sierra Leone ( Deines and Haggerty, 2000)91.6 (B): Non-cratonic xenoliths erupted by alkalic and potassic mafic magmas sensu latoa BI: Cr-diopside lherzolite groupVery widespread and common in a variety of tectonic settings, off-craton. Dominantly spinel-facies (Al or Cr-spinel) lherzolites but can be garnet-facies and garnet-spinel facies (e.g., Vitim). Coarse grained, commonly little deformed, sometimes show preferred orientation. Include harzburgites, orthopyroxenites, clinopyroxenites, websterites, and wehrlites. Pargasite and phlogopite may also be common. Both low TiO2 and high TiO2 amphiboles can occur at the same locality. Accessory apatite, can be common locally (e.g., Bullenmerri, Victoria). Interstitial silicate glass can be present. Garnet and spinel facies significantly more olivine-rich and orthopyroxene poor than peridotites from cratons such as Kaapvaal and Siberia. Bulk rocks less depleted in Ca, Al, Fe, and lower in Mg than cratonic peridotites. Minerals generally higher Mg# and Cr# and lower Na and Ti than those of the Al-Augite group. Can be subdivided into type IA (LREE depleted clinopyroxene) and type IB (LREE enriched clinopyroxene).Victoria, SE Australia (Frey and Green, 1974); Vitim ( Ionov et al., 1993a); San Carlos and other W. USA localities ( Frey and Prinz, 1978; Wilshire and Shervais, 1975); Eifel ( Stosch and Seck, 1980); Hawaii ( Jackson and Wright, 1970); Scotland ( Menzies and Halliday, 1988)Garnet facies: Thumb, Navajo field ( Ehrenberg, 1982a, b); Pali-Aike, Patagonia ( Stern et al., 1989); Vitim, S. Siberia ( Ionov, 1993a, b)>0.85, Avg. ˜90 BII: Al-augite wehrlite-pyroxenite groupWidespread and common. Frequently clinopyroxene-rich rocks but widely variable: wehrlites, clinopyroxenites, dunites, websterites, lherzolites, lherzites, gabbros. Al-spinel is the typical aluminous phase but may contain plagioclase. Kaersutite common along with apatite, Fe-Ti oxides, and phlogopite. Some igneous and metamorphic textures. Composite