A primary consequence of plate tectonics is that basaltic oceanic crust subducts with lithospheric slabs into the mantle. Seismological studies extend this process to the lower mantle, and geochemical observations indicate return of oceanic crust to the upper mantle in plumes. There has been no direct petrologic evidence, however, of the return of subducted oceanic crustal components from the lower mantle. We analyzed superdeep diamonds from Juina-5 kimberlite, Brazil, which host inclusions with compositions comprising the entire phase assemblage expected to crystallize from basalt under lower-mantle conditions. The inclusion mineralogies require exhumation from the lower to upper mantle. Because the diamond hosts have carbon isotope signatures consistent with surface-derived carbon, we conclude that the deep carbon cycle extends into the lower mantle.

interpreted as evidence of diamond growth from abiotic organic carbon added to the oceanic crust during hydrothermal alteration. The bulk isotopic composition of the oceanic crust, carbonates plus organics, is equal to the composition of mantle carbon (−5 ‰), and we suggest that recycling/mixing of subducted material will replenish this reservoir over geological time. Several exposed, syngenetic inclusions have bulk compositions consistent with former eclogitic magnesium silicate perovskite, calcium silicate perovskite and NAL or CF phases that have reequilibrated during their exhumation to the surface. There are multiple occurrences of majoritic garnet with pyroxene exsolution, coesite with and without kyanite exsolution, clinopyroxene, Fe or Fe-carbide and sulphide minerals alongside single occurrences of olivine and ferropericlase. As a group, the inclusions have eclogitic affinity and provide evidence for diamond formation at pressures extending to Earth's deep transition zone and possibly the lower mantle. It is observed that the major element composition of inclusions and isotopic compositions of host Juina-5 diamonds are not correlated. The diamond and inclusion compositions are intimately related to subducted material and record a polybaric growth history across a depth interval stretching from the lower mantle to the base of the lithosphere. It is suggested that the interaction of slabderived melts and mantle material combined with subsequent upward transport in channelised networks or a buoyant diapir explains the formation of Juina-5 diamonds. We conclude that these samples, despite originating at great mantle depths, do not provide direct information about the ambient mantle, instead, providing a snapshot of the Earth's deep carbon cycle. Keywords Diamonds · Sub-lithospheric mantle · Carbon cycle · SubductionAbstract Forty-one diamonds sourced from the Juina-5 kimberlite pipe in Southern Brazil, which contain optically identifiable inclusions, have been studied using an integrated approach. The diamonds contain <20 ppm nitrogen (N) that is fully aggregated as B centres. Internal structures in several diamonds revealed using cathodoluminescence (CL) are unlike those normally observed in lithospheric samples. The majority of the diamonds are composed of isotopically light carbon, and the collection has a unimodal distribution heavily skewed towards δ 13 C ~ −25 ‰. Individual diamonds can display large carbon isotope heterogeneity of up to ~15 ‰ and predominantly have isotopically lighter cores displaying blue CL, and heavier rims with green CL. The light carbon isotopic compositions are Communicated by O. Müntener. Electronic supplementary materialThe online version of this article

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Precise and accurate δ 66/64 Zn data for environmental reference materials (RMs) including rocks, sediments, soils and plants are presented in order to improve the metrological traceability and analytical control of Zn isotope ratio determinations in future environmental studies. Previously developed ion exchange chromatography protocols were adjusted to enable faster sample throughput and instrumental mass bias processes were investigated. The improved chromatographic protocol yielded precise and quantitative recoveries (99 ± 7%, σ, n = 16), while the mass bias correction using Cu as external dopant provided precisions better than 0.02‰, 2σ, n = 7. Investigations into spectral and non-spectral interferences identified significant formation of Cr and Ti oxides and hydroxide ionic species. Analysis of six RMs (BHVO-2 basalt (USGS), BCR-2 basalt (USGS), AGV-2 andesite (USGS), 2709 San Joaquin soil (NIST), 1646a estuarine sediment (NIST) and 1573a tomato leaves (NIST)) showed good reproducibility (< 0.01‰, 2σ, 5 ≤ n ≥ 1).

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-Objective: To investigate the effect of three months of low-frequency repetitive transcranial magnetic stimulation (rTMS) treatment in intractable epilepsy. Methods: Five patients (four males, one female; ages 6 to 50 years), were enrolled in the study; their epilepsy could not be controlled by medical treatment and surgery was not indicated. rTMS was performed twice a week for three months; patients kept records of seizure frequency for an equal period of time before, during, and after rTMS sessions. rTMS was delivered to the vertex with a round coil, at an intensity 5 % below motor threshold. During rTMS sessions, 100 stimuli (five series of 20 stimuli, with one-minute intervals between series) were delivered at a frequency of 0.3 Hz. Results: Mean daily number of seizures (MDNS) decreased in three patients and increased in two during rTMS-one of these was treated for only one month; the best result was achieved in a patient with focal cortical dysplasia (reduction of 43.09 % in MDNS). In the whole patient group, there was a significant (p<0.01) decrease in MDNS of 22.8 %. Conclusions: Although prolonged rTMS treatment is safe and moderately decreases MDNS in a group of patients with intractable epilepsy, individual patient responses were mostly subtle and clinical relevance of this method is probably low. Our data suggest, however, that patients with focal cortical lesions may indeed benefit from this novel treatment. Further studies should concentrate on that patient subgroup.KEY WORDS: transcranial magnetic stimulation, rTMS, epilepsy.Terapia experimental da epilepsia com estimulação magnética transcraniana: ausência de melhora adicional com tratamento prolongado RESUMO -Objetivo: investigar o efeito de três meses de estimulação magnética transcraniana repetitiva (EMTr) de baixa freqüência, na epilepsia de difícil controle. Método: Cinco pacientes (quatro homens, uma mulher, idades entre 6 e 50 anos), participaram do estudo; suas crises epilépticas não puderam ser controlados por tratamento medicamentoso e não tinham indicação cirúrgica; a EMTr foi realizada duas vezes por semana durante três meses, sendo que os pacientes anotaram o número diário de crises neste perío-do, assim como nos três meses anteriores e posteriores ao tratamento. A aplicação da EMTr foi feita no vértex com bobina circular, com intensidade 5% abaixo do limiar motor. Durante as sessões de EMTr, 100 estímulos (5 séries de 20 estímulos, com um minuto de intervalo entre as séries) foram realizadas na freqüência de 0,3 Hz. Resultados: A média diária de crises (MDC) decresceu em três pacientes e aumentou em dois durante o uso da EMTr; um destes casos foi tratado somente por um mês; o melhor resultado foi encontrado em um paciente com displasia cortical focal (redução de 43,09% na MDC). Em todo o grupo de pacientes, houve decréscimo significativo na MDC de 22,8% (p<0,01). Conclusão: Embora o tratamento prolongado com a EMTr seja seguro e tenha sido registrado decréscimo moderado da MDC em um grupo de pacientes com epilepsia de difí...