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Boron isotope evidence for shallow fluid transfer across subduction zones by serpentinized mantle
No full textSerpentinites formed by alteration of oceanic and forearc mantle are major volatile and fl uid-mobile element reservoirs for arc magmatism, though direct proof of their dominance in the subduction-zone volatile cycles has been elusive. Boron isotopes are established markers of fl uid-mediated mass transfer during subduction. Altered oceanic crust and sediments have been shown to release in the subarc mantle 11B-depleted fl uids, which cannot explain 11B enrichment of many arcs. In contrast to these crustal reservoirs, we document high 11B values retained in subduction-zone Alpine serpentinites. No 11B fractionation occurs in these rocks with progressive burial: the released 11B-rich fl uids uniquely explain the elevated 11B of arc magmas. B, O-H, and Sr isotope systems indicate that serpentinization was driven by slab fl uids that infi ltrated the slab-mantle interface early in the subduction history
Serpentinites and Boron Isotope Evidence for Shallow Fluid Transfer Across Subduction Zones
No full textThe boron isotope composition of high-pressure subducted serpentinites: constraints on tectonic setting and implications for arc magmatism.
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Boron and Strontium isotope systematics in deeply subducted alpine-serpentinites: evidence of high-11B fluid flow
No full textGeodynamic evolution of the Aegean: constraints from the Plio-Pleistocene volcanism of the Volos-Evia area
No full textThe Plio-Pleistocene lava flows and domes of the Volos-Evia area were erupted between 3.4 and 0.5 Ma ago on the western continuation of the North Anatolian Fault, in a back-arc position with respect to the active arc. They are mainly high-K calc-alkaline trachyandesites. Based on their Sr-Nd-Pb isotopic compositions, the mantle source of the Volos-Evia area lavas is similar to that of a large volcanic belt that developed north of the Pelagonian-Attic-Cycladic-Menderes massifs, encompassing a 35 Ma timespan and widespread over a large area from NW Greece Macedonia to the Aegean western Anatolia. In contrast, southern Aegean arc rocks have a similar subduction fingerprint but distinctly lower Sr and higher Nd isotopic compositions. The geochemical and isotopic differences between southern and northern Aegean rocks may be ascribed to the different nature of the mantle wedge: depleted asthenosphere under the the southern Aegean, and lithosphere northward. The lack of an asthenospheric mantle wedge below the northern Aegean fits with the hypothesis of an almost horizontal subduction of the African slab. In the mantle reference frame the African slab is moving out of the mantle, and a slab-driven suction flow of the underlying mantle may be responsible for the recent development of a thin asthenospheric layer in the southern Aegean mantle wedge
B, Pb, Sr isotopic imprint of crustal and mantle rocks from the slab-mantle interface: The Cima di Gagnone example (Central Alps)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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