Geochemistry and tectonic setting of mafic rocks from the Othris Ophiolite, Greece

Barth, Matthias; Gluhak, Tatjana M.

doi:10.1007/s00410-008-0318-9

Cited by 40 publications

(43 citation statements)

References 61 publications

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“…However, the current observed differences can be attributed to different degrees of partial melting and melt impregnation of the mantle in the two areas, suggesting the occurrence of a large mantle inhomogeneity. This interpretation is consistent with previous works, which have shown that the west Othrys ophiolite is related with an extension regime (back-arc basin or MORB; [23,24,30]), while the east Othrys ophiolite is strongly associated with a supra-subduction zone setting (SSZ; [24,31]). …”

Section: Petrogenetic Implicationssupporting

confidence: 93%

“…It is structurally overlain by the Kournovon Dolerite unit (approximately 150 m thick), which is comprised of vertical sheeted dolerite penetrating minor cumulate gabbro. The higher structural members comprise dismembered oceanic mantle rocks dominated by medium-to coarse-grained, variably serpentinised harzburgite with minor lherzolite, plagioclase lherzolite and dunite (e.g., [22][23][24][25]). Chromitite deposits occur in two major parts of the Othrys complex.…”

Section: Geological Settingmentioning

confidence: 99%

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Investigation of Platinum-Group Minerals (PGM) from Othrys Chromitites (Greece) Using Superpanning Concentrates

et al. 2016

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Platinum-group minerals were concentrated using superpanning from two composite chromitite samples, which were collected from two old mines within the Othrys ophiolite. This method allows for the recovery of a broad spectrum of these rare and fine-grained minerals, and helps to better identify them and interpret their origin. Major differences between the east and west Othrys ophiolites were determined, probably as a result of their different origin and evolution. Primary Os-, Ir-, and Ru-bearing platinum-group minerals (IPGM)-alloys and the Rh-, Pt-and Pd-bearing platinum-group minerals (PPGM) occur only in the east Othrys chromitite, indicating an evolution from initially low f S2 conditions at shallower mantle levels with the subsequent implication of a S-saturated ascending fluid. In contrast, the absence of primary IPGM-alloys in west Othrys chromitite indicates that S saturation had been attained. The presence of erlichmanite suggests that sulphur fugacity eventually increased significantly in both suites. Substantial fluctuations of a fluid phase, likely related to serpentinising fluids, modified the platinum-group minerals (PGM) assemblage of west Othrys, and resulted in a large diversity of secondary PGM minerals. The limited number of secondary species developed in the east Othrys indicate that secondary processes were also different in the two suites.

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Section: Petrogenetic Implicationssupporting

confidence: 93%

Section: Geological Settingmentioning

confidence: 99%

Investigation of Platinum-Group Minerals (PGM) from Othrys Chromitites (Greece) Using Superpanning Concentrates

et al. 2016

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“…The ophiolite is thought to have formed near a transform fault at a slowspreading ridge (Barth, 2003;Dijkstra, 2001) or above an intraoceanic subduction zone at a mid-oceanic ridge (Barth and Gluhak, 2009;Barth et al, 2008;Rassios and Smith, 2000). It consists mainly of spinel-harzburgites and plagioclase-lherzolites with minor amounts of spinel-lherzolites and dunites (Dijkstra, 2001;Dijkstra et al, 2002b;Menzies and Allen, 1974).…”

Section: Othrismentioning

confidence: 97%

Small quantity but large effect — How minor phases control strain localization in upper mantle shear zones

2015

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“…Fields of MORB, IAT, and Bon (boninites) are from Pearce (2003) and Dilek et al (2007). Groups (I) and (II) gabbroic rock fields from Koutsovitis (2012), Eretria basalts field from Migiros et al (1997), low-Mg mafic volcanic and subvolcanic rocks in West Othris from Barth and Gluhak (2009) Ford et al (1983), based on compositionally corrected olivinemelt KDs for FeO and MgO. In this diagram (Figure 10), boninites EX11/AER, 272/AER, and 64/VRI are the most undifferentiated since they have the highest [Mg] values, whereas the low-Mg lavas seem to have been formed after moderate fractionation of olivine, spinel, and/or clinopyroxene/plagioclase.…”

Section: Mantle Source and Differentiation Processesmentioning

confidence: 99%

Boninitic and tholeiitic basaltic lavas and dikes from dispersed Jurassic East Othris ophiolitic units, Greece: petrogenesis and geodynamic implications

Koutsovitis

Magganas

2016

International Geology Review

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Pillow lavas, massive lava flows, and sub-volcanic dikes of tholeiitic basaltic composition are found to be members of the Vrinena, Aerino, Eretria, and Velestino dispersed Middle-Upper Jurassic ophiolitic units in East Othris. The Vrinena and Eretria ophiolitic units appear to have been emplaced onto the Pelagonian continental margin during the Upper Jurassic-Lower Cretaceous, whereas the Aerino and Velestino units seem to have been finally emplaced during postPalaeocene times. Geochemically these are divided into two groups: Group I includes subduction-related boninites and low-Ti basalts from the Vrinena and Aerino units, and Group II high-Ti basalts show spreading-type characteristics occurring in the Eretria and Velestino units. Primary magma of the Group I volcanics appears to have been formed after high partial melting degrees (~18%) of a highly depleted harzburgitic mantle source, under relatively high temperatures (mantle potential temperature~1372°C). Petrogenetic modelling also suggests that the primary magma of the Group II volcanics were formed after lower partial melting degrees (~7%) of a moderately depleted mantle source. The petrological and geochemical data from the East Othris dispersed and diversely emplaced ophiolitic units provide evidence of a common intra-oceanic supra-subduction zone (SSZ) origin within the Pindos oceanic strand of the Western Tethys. Specifically, Group I lavas and dikes from Vrinena seem to represent the extrusive part of an almost complete fore-to island-arc ophiolitic sequence. Dikes of Aerino most likely correspond to fore-arc magmatic material that intruded within exhumed serpentinized ultramafic rocks through a subduction channel that developed close to the slab and towards the fore-arc and the accretionary prism. The Group II volcanics either corresponded to a fore-arc magmatic expression, which extruded earlier than Group I volcanics and prior to the establishment of a mature subduction zone, or represent back-arc to island-arc magmatism that was contemporaneous to the fore-arc magmatic activity during rollback subduction. ARTICLE HISTORY

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Geochemistry and tectonic setting of mafic rocks from the Othris Ophiolite, Greece

Cited by 40 publications

References 61 publications

Investigation of Platinum-Group Minerals (PGM) from Othrys Chromitites (Greece) Using Superpanning Concentrates

Investigation of Platinum-Group Minerals (PGM) from Othrys Chromitites (Greece) Using Superpanning Concentrates

Small quantity but large effect — How minor phases control strain localization in upper mantle shear zones

Boninitic and tholeiitic basaltic lavas and dikes from dispersed Jurassic East Othris ophiolitic units, Greece: petrogenesis and geodynamic implications

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