Petrology and geochemistry of a peridotite body in Central- Carpathian Paleogene sediments (Sedlice, eastern Slovakia)

Abstract

Abstract:We studied representative samples from a peridotite body situated NE of Sedlice village within the CentralCarpathian Paleogene sediments in the Central Western Carpathians. The relationship of the peridotite to the surrounding Paleogene sediments is not clear. The fractures of the brecciated peridotite margin are healed with secondary magnesite and calcite. On the basis of the presented bulk-rock and electron microprobe data, the wt. % amounts of mineral phases were calculated. Most of calculated "modal" compositions of this peridotite corresponds to harzburgites composed of olivine (~70-80 wt. %), orthopyroxene (~17-24 wt. %), clinopyroxene ( < 5 wt. %) and minor spinel ( < 1 wt. %). Harzburgites could originate from lherzolitic protoliths due to a higher degree of partial melting. Rare lherzolites contain porphyroclastic 1-2 mm across orthopyroxene (up to 25 wt. %), clinopyroxene (~5-8 wt. %) and minor spinel ( < 0.75 wt. %). On the other hand, rare, olivine-rich dunites with scarce orthopyroxene porphyroclasts are associated with harzburgites. Metamorphic mineral assemblage of low-Al clinopyroxene (3), tremolite, chrysotile, andradite, Cr-spinel to chromite and magnetite, and an increase of fayalite component in part of olivine, indicate low-temperature metamorphic overprint. The Primitive Mantle normalized whole-rock REE patterns suggest a depleted mantle rock-suite. An increase in LREE and a positive Eu anomaly may be consequence of interactive metamorphic fluids during serpentinization. Similar rocks have been reported from the Meliatic Bôrka Nappe overlying the Central Western Carpathians orogenic wedge since the Late Cretaceous, and they could be a potential source of these peridotite blocks in the Paleogene sediments.

Origin and Age Determination of the Neotethys Meliata Basin Ophiolite Fragments in the Late Jurassic–Early Cretaceous Accretionary Wedge Mélange (Inner Western Carpathians, Slovakia)

“…The abyssal type harzburgites in the Jaklovce Unit ophiolite complex, having a character of weakly depleted harzburgites are consistent with the marginal basin with the subduction-unrelated mantle rocks [7,[90][91][92][93][94]. They are also typical of the mantle portion of the ophiolitic complexes [93,94] from the passive margins reported by [129], and which evolved during rift-drift and seafloor spreading [130].…”

“…(2) Oceanic margin crust; composed of the Middle (Ladinian) to Upper Triassic (Carnian-Norian and younger) pelagic cherty sediments, N-MORBs and rare alkaline OIBs associated with serpentinized and rodingitized, mostly harzburgitic, mantle fragments (cf. [2,4,7,8,77,[90][91][92]).…”

“…Serpentinized ultramafic bodies of the Meliaticum were reported by [26]. Their genetic aspects were published by [7,[90][91][92], who assigned them to the abyssal peridotites.…”

Mineral chemistry and geochemistry of serpentinites from the Bianmagou ophiolite in the North Qilian Belt, NW China: Implications for protoliths, melt extractions, and melt/fluid metasomatism

“…Studies have demonstrated that the Cr # values of spinels have a covariant relationship with the degree of melt extraction of mantle peridotites (e.g., Hellebrand, Snow, Dick, & Hofmann, 2001;Koppa, Koller, & Putiš, 2014;Liu et al, 2012). To calculate the extent of melting (F), Hellebrand et al (2001) proposed a logarithmic equation in terms of spinel Cr # values from 0.10 to 0.60:…”

Metamorphic Conditions of Neotethyan Meliatic Accretionary Wedge Estimated by Thermodynamic Modelling and Geothermobarometry (Inner Western Carpathians)

“…The Jaklovce Unit (Figure 5) is the most characteristic oceanic or ophiolitic sedimentary-magmatic succession of the Meliaticum composed of pelagic cherty sediments to radiolarites, N-MORBs and rare alkaline OIBs associated with serpentinised and rodingitised, mostly abyssal harzburgitic, mantle fragments [9,11,14,15,53,[60][61][62]. The oceanic Jaklovce Succession was more precisely defined using our new biostratigraphic data from radiolarites and cherty carbonates which distinguished the Lower (Ladinian), Middle, and Upper (Carnian to Norian?)…”