Coexistence of abyssal and ultra-depleted SSZ type mantle peridotites in a Neo-Tethyan Ophiolite in SW Turkey: Constraints from mineral composition, whole-rock geochemistry (major–trace–REE–PGE), and Re–Os isotope systematics

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dc.contributor.author Uysal I.
dc.contributor.author Ersoy E.Y.
dc.contributor.author Karsli O.
dc.contributor.author Dilek Y.
dc.contributor.author Sadıklar M.B.
dc.contributor.author Ottley C.J.
dc.contributor.author Tiepolo M.
dc.contributor.author Meisel T.
dc.date.accessioned 2024-01-28T06:42:44Z
dc.date.available 2024-01-28T06:42:44Z
dc.date.issued 2012
dc.identifier.citation Lithos, 2012, 132-133, 50–69 ru_RU
dc.identifier.uri https://repository.geologyscience.ru/handle/123456789/42478
dc.description.abstract We present new, whole-rock major and trace element chemistry, including rare earth elements (REE), platinum-group elements (PGE), and Re–Os isotope data from the upper mantle peridotites of a Cretaceous Neo-Tethyan ophiolite in the Muğla area in SW Turkey. We also report extensive mineral chemistry data for these peridotites in order to better constrain their petrogenesis and tectonic environment of formation. The Muğla peridotites consist mainly of cpx-harzburgite, depleted harzburgite, and dunite. Cpx-harzburgites are characterized by their higher average CaO (2.27 wt.%), Al2O3 (2.07 wt.%), REE (53 ppb), and 187Os/188Os(i) ratios varying between 0.12497 and 0.12858. They contain Al-rich pyroxene with lower Cr content of coexisting spinel (Cr#=13–22). In contrast, the depleted harzburgites and dunites are characterized by their lower average CaO (0.58 wt.%), Al2O3 (0.42 wt.%), and REE (1.24 ppb) values. Their clinopyroxenes are Al-poor and coexist with high-Cr spinel (Cr#=33–83). The 187Os/188Os(i) ratios are in the range of 0.12078–0.12588 and are more unradiogenic compared to those of the cpx-harzburgites. Mineral chemistry and whole rock trace and PGE data indicate that formation of the Muğla peridotites cannot be explained by a single stage melting event; at least two-stages of melting and refertilization processes are needed to explain their geochemical characteristics. Trace element compositions of the cpx-harzburgites can be modeled by up to ~10–16% closed-system dynamic melting of a primitive mantle source, whereas those of the depleted harzburgites and dunites can be reproduced by ~10–16% open-system melting of an already depleted (~16%) mantle. Thesemodels indicate that the cpx-harzburgites are the products of first-stage melting and low-degrees of melt–rock interaction that occurred in a mid-ocean ridge (MOR) environment. However, the depleted harzburgites and dunites are the product of second-stage melting and related refertilization which took place in a supra subduction zone (SSZ) environment. The Re–Os isotope systematics of the Muğla peridotites gives model age clusters of ~250 Ma, ~400 Ma and ~750 Ma that may record major tectonic events associated with the geodynamic evolution of the Neo-Tethyan, Rheic, and Proto-Tethyan oceans, respectively. Furthermore, >1000 Ma model ages can be interpreted as a result of an ancient melting event before the Proto-Tethys evolution. ru_RU
dc.language.iso en ru_RU
dc.subject Upper mantle peridotites ru_RU
dc.subject Neo-Tethyan ophiolites ru_RU
dc.subject Partial melting ru_RU
dc.subject Melt percolation and refertilization in the upper mantle ru_RU
dc.subject Re/Os isotope systematics of peridotites ru_RU
dc.title Coexistence of abyssal and ultra-depleted SSZ type mantle peridotites in a Neo-Tethyan Ophiolite in SW Turkey: Constraints from mineral composition, whole-rock geochemistry (major–trace–REE–PGE), and Re–Os isotope systematics ru_RU
dc.type Article ru_RU


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