Chromitites from the Vavdos ophiolite (Chalkidiki, Greece): Petrogenesis and geotectonic settings; constrains from spinel, olivine composition, PGE mineralogy and geochemistry

Sideridis, Alkiviadis; Zaccarini, Federica; Koutsovitis, Petros; Grammatikopoulos, Tassos; Tsikouras, Basilios; Garuti, Giorgio; Hatzipanagiotou, Konstantin

doi:10.1016/j.oregeorev.2021.104289

Cited by 10 publications

(11 citation statements)

References 82 publications

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“…Replicate analyses of laboratory standards were conducted to check reproducibility and accuracy. These include δ 13 C values of +1.95‰ to NBS19 and -46.6‰ to LSVEC and δ 18 O values of -2.20‰ to NBS19 and -23.2‰ to NBS18.…”

Section: Methodsmentioning

confidence: 99%

“…The isotopic δ 13 C-δ 18 O composition of carbonate minerals is linked with the temperature, as well as with the isotopic composition and CO 2 , H 2 CO 3 , and HCO 3 proportions of the fluid sources [73]. The isotopic inhomogeneous composition of RAB calcite suggests that 13 C- 18 O may have been derived from variable sources and/or mixing processes, whereas the low δ 13 C values are associated with C-depletions resulting from serpentinization related-fluids [74]. Thus, the extremely negative δ 13 C value of fracture-filling calcite observed in RCAB (sample EROD1Mc; δ 13 C = −14:40‰) is highly comparable with the compositional range of methane in hydrothermal fluids (δ 13 C = −14 to − 9‰; [75]).…”

Section: C-o Isotopementioning

confidence: 98%

“…Serpentinites that host the studied rodingites are members of the Evia ophiolitic sequence, which was emplaced on the Pelagonian isopic zone during the Hellenides orogen [13]. The Pelagonian zone is suggested to represent either a detached microcontinent from the northeastern margin of the Gondwana during Late Paleozoic-Middle Triassic forming in-between the Neotethyan strand of the Pindos Ocean [14][15][16] or the western passive margin of Vardar Ocean (also a Neotethyan strand) that separated Gondwana from Eurasia [17].…”

Section: Geological Settingmentioning

confidence: 99%

“…The δ 13 C and δ 18 Ο compositions of calcite veins from the studied ophicalcites are 0.27‰-0.29‰ and 18.24‰-23.89‰, respectively. The two analyzed calcite samples from the pelagic limestones of Kimi flysch are characterized by isotopic homogeneity regarding their δ 13 C and δ 18 Ο contents (2.16‰-2.18‰ and 22.78-23.97‰ for δ 13 C and δ 18 Ο, respectively).…”

Section: 2mentioning

confidence: 99%

“…Methane oxidation can be derived from the anaerobic microbial activity during serpentinization [78], a process that is usually associated with low δ 13 C values [80]. In a similar context, the slightly negative δ 13 C values, which are observed in few calcite samples from the same rodingite type (-1.63‰ and -2.65‰), are comparable with those of the Lost City hydrothermal systems (-5‰ to +0.5‰) that also involve the contribution of seawater fluids [75,81]. The latter is further supported by the fact that marine bicarbonates show similar isotopic composition, in which δ 13 C ranges between -2‰ and 1‰ [82].…”

Section: C-o Isotopementioning

confidence: 99%

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Multiple Rodingitization Stages in Alkaline, Tholeiitic, and Calc-Alkaline Basaltic Dikes Intruding Exhumed Serpentinized Tethyan Mantle from Evia Island, Greece

et al. 2022

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In Pagondas and Kimi areas, central Evia Island, Greece, variably serpentinized ultramafic rocks of an ophiolitic origin are crosscut by rodingite dikes. Based on their protoliths, these rodingites are distinguished into the following: (i) rodingites of island arc tholeiitic dolerites, (ii) rodingites of Mg-rich tholeiitic gabbros, (iii) rodingites of alkaline basalts, and (iv) rodingites of calc-alkaline basalts. Rodingitization evolved in three successive phases (namely, stages 1, 2, and 3) of increasing metasomatic degree that occurred during the exhumation of the mantle wedge serpentinites. Thermodynamic modeling suggests that stage 1 was developed at ~5 kbar and 450-550°C, whereas at stage 2 and stage 3, gradually decreasing P-T conditions prevailed. Stage 1 affected the protoliths of all rodingite types and was characterized by the crystallization of grossular, diopside, chlorite, and prehnite leading to Ca and LOI enrichments. The observed Si and REE depletions are assigned to the dissolution of primary clinopyroxene and amphibole. Stage 2 mainly affected the rodingites that were derived from alkaline and calc-alkaline basalts, promoting the growth of andradite, vesuvianite, and chlorite at the expense of stage 1 rodingitization mineral phases. At this stage, the marginal zones of rodingite dikes from alkaline and calc-alkaline basalts experienced remarkable Mg and REE enrichments. Stage 3 corresponds to derodingitization and restricted carbonation processes of the previously formed rodingites, which are associated with Fe enrichments. During this stage, significant trace elements including REEs were transferred from the marginal zones to the inner cores of rodingite dikes that were derived from metasomatism of calc-alkaline basalts. Calcite δ18Ο-δ13C isotopic data suggest that carbonation processes were developed at shallow depths below the Tethyan ocean floor, through mixing of seawater and serpentinization-derived fluids. Such multiple stages of rodingitization processes that affected four different lithotypes, as well as the unusual case of alkaline basalts’ rodingitization, would render the Evia rodingites as an important and very rare example of metasomatism.

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Section: Methodsmentioning

confidence: 99%