The nature and age of basic rocks of the Rai-Iz Ophiolite Massif (Polar Urals)

Shmelev, Vladimir R.; Meng, Fancong

doi:10.1134/s1028334x13070167

Cited by 10 publications

(15 citation statements)

References 1 publication

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“…The Ray-Iz ultrama c massif comprises mainly lherzolite-harzburgite, dunite-harzburgite, and metaperidotites (Fig. 1a), and the residual features indicate that they were formed by at least two partial melting events: the former occurring in a mid-ocean ridge setting and the latter in a suprasubduction zone setting (Shmelev 2011;Shmelev et al 2014Shmelev et al , 2019. The Moho transition zone is located at the southern end of the Ray-Iz massif, and the peridotites are in tectonic contact with a hornblende gabbro-dioriteplagiogranodiorite complex (Sob complex) to the south (Fig.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…As shown in Fig. 1a, spherulitic OPX-bearing harzburgite occurs in the "metaperidotite zone" (within the center of the Ray-Iz peridotite massif; Shmelev et al 2014). Notably, the occurrence of spherulitic OPX in metaperidotites has been reported elsewhere (Arai, 1974(Arai, , 1975Evans and Trommsdorff 1974;Frost 1975).…”

Section: Introductionmentioning

confidence: 99%

“…Notably, the occurrence of spherulitic OPX in metaperidotites has been reported elsewhere (Arai, 1974(Arai, , 1975Evans and Trommsdorff 1974;Frost 1975). The Ray-Iz spherulitic OPX-bearing metaperidotite has been described as a sagvandite (a magnesite-bearing orthopyroxenite), which implies that a CO 2 -rich uid was involved in its formation (Shmelev et al 2014). However, we did not observe any enrichment in carbonate minerals or the presence of a heat source close to the spherulitic OPX-bearing harzburgite block (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Spherulitic orthopyroxene–bearing metaperidotite in Ray-Iz ophiolites (Polar Urals): high-pressure deserpentinization in a mantle wedge

Ishimaru,

Sonoda,

Miura

et al. 2024

Preprint

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The Ray-Iz (or Rai-Iz) peridotite massif, the main part of the Paleozoic Ray-Iz ophiolite in the Polar Urals, comprises harzburgite, lherzolite, and dunite lenses, which contain abundant chromitite pods. The metaperidotite zone occurs as the ENE-WSW linear zone (width: ~4 km) at the center of the Ray-Iz peridotite massif. We sampled peculiar orthopyroxene-rich peridotites from the metaperidotite zone that contain spherulitic aggregates of orthopyroxene. This investigation provided insights into the key petrologic nature of the Ray-Iz peridotite massif, particularly its P-T history. The orthopyroxene-rich rocks and their surrounding metaperidotites contain various metamorphic minerals, such as tremolite, chlorite, serpentines (lizardite and chrysotile), and talc. Furthermore, the olivine and orthopyroxene grains in these lithologies contain minute inclusions of opaque spinels (ferritchromite and Cr-rich magnetite) and metamorphic minerals (tremolite, chlorite, serpentine minerals, etc.). The spinel occurring both as discrete grains and inclusions in the orthopyroxene-rich rocks exhibits low Al and high Fe3+ concentrations, and the contents of Ca, Al, and Cr in orthopyroxene are extremely low. The presence of high-Fe3+ spinel inclusions in olivine and orthopyroxene, combined with the presence of spherulitic aggregates and the extremely low Ca and Al concentrations in orthopyroxene, indicates deserpentinization as the origin of the metaperidotites, including the orthopyroxene-rich rocks. Contact metamorphism appears to be unbefitting as the cause of the deserpentinization because of the lack of a heat source close to the Ray-Iz massif. Instead, we propose that a hydration–dehydration path resulted from the subduction and exhumation of the forearc mantle wedge peridotite.

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Section: Geological Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spherulitic orthopyroxene–bearing metaperidotite in Ray-Iz ophiolites (Polar Urals): high-pressure deserpentinization in a mantle wedge

Ishimaru,

Sonoda,

Miura

et al. 2024

Preprint

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“…Шмелева и Ф.Ц. Мона [Shmelev, Meng, 2013] мелкозернистые габбро, относимые к I фазе собского комплекса, имеют возраст 418 млн лет.…”

Section: обсуждение результатовunclassified

MAFIC INCLUSIONS (SOBSKY COMPLEX, POLAR URAL): U‐Pb (SIMS) DATA

Удоратина

Кобл

Шуйский

et al. 2019

Geodin. tektonofiz.

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The rocks of the Sobsky complex, composing the bulk of the Sobsky batholith in the Polar Urals, contain mafic inclusions. The geological, petrographic and petro‐geochemical data show that the mafic inclusions of the Sobsky rocks belong to igneous formations, which are similar in their characteristics to autoliths. According to all the characteristics, these are the structures non‐contrasting to host rocks and having different structural‐textural features, a more basic composition of minerals and a more basic composition of rocks. The contact with the rocks of the complex is sharp and clear. The rocks of the complex in contact with autoliths are medium‐grained massive diorite rocks, quartz diorites, tonalites, mafic inclusions rocks – fine‐grained gabbros, gabbro‐diorites, and diorites. Isotopicgeochemical (U‐Pb, SIMS) data on zircons from the mafic inclusions suggest that their age is close, within the error limits, to the age of zircons from the enclosing Sobsky complex rocks.

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“…This ophiolite was obducted as a slice of the Neo-Tethyan oceanic lithosphere due to collision of the two continents in the Early Paleogene (around 65 Ma) [51], and experienced later modification at a subduction zone environment before its obduction [50]. The Ray-Iz ophiolite, another example of the UHP chromitite occurrence [7], is located in the Polar Ural region (Figure 11c-e), and was emplaced by collision of the Magnitogosrk arc and the East Europian continent block in the mid-Paleozoic around 400 Ma [52]. Ultramafic and mafic rocks in this region reflect a series of westward-directed thrust stacks in which the oceanic and arc sequences lie on the continental margin of the European plate [53].…”

Section: Comparison With the Uhp Chromitites From Tibet And The Polarmentioning

confidence: 99%

Petrology of Chromitites in the Higashi-Akaishi Ultrahigh-Pressure (UHP) Peridotite Complex, Japan: Toward Understanding of General Features of the UHP Chromitites

et al. 2018

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Ultrahigh-pressure (UHP) chromitites containing UHP minerals such as coesite and diamond have been reported from some ophiolites in Tibet and the Polar Urals. Their nature, i.e., origin, P-T path and abundance, however, are still controversial and left unclear. Here we describe chromitites in the Higashi-akaishi (HA) ultramafic complex in the Cretaceous Sanbagawa metamorphic belt, Japan, which experienced UHP condition (up to 3.8 GPa) at the peak metamorphism via subduction, in order to understand the nature of UHP chromitites. The HA peridotites typically contain garnets and are associated with eclogites, and their associated chromitites are expected to have experienced the UHP metamorphism. The Higashi-akaishi (HA) chromitites show banded to massive structures and are concordant to foliation of the surrounding peridotite. Chromian spinels in the chromitite and surrounding peridotites were sometimes fractured by deformation, and contain various inclusions, i.e., blade- and needle-like diopside lamellae, and minute inclusions of pyroxenes, olivine, and pargasite. The peculiar UHP minerals, such as coesite and diamond, have not been found under the microscope and the Raman spectrometer. Spinels in the HA chromitites show high Cr#s (0.7 to 0.85), and low Ti contents (<0.1 wt %), suggesting a genetic linkage to an arc magma. The HA chromitites share the basic petrographic and chemical features (i.e., diopside lamellae and arc-related spinel chemistry) with the UHP chromitites from Tibet and the Polar Urals. This suggests that some of the characteristics of the UHP chromitite can be obtained by compression, possibly via deep subduction, of low-P chromitite.

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The nature and age of basic rocks of the Rai-Iz Ophiolite Massif (Polar Urals)

Cited by 10 publications

References 1 publication

Spherulitic orthopyroxene–bearing metaperidotite in Ray-Iz ophiolites (Polar Urals): high-pressure deserpentinization in a mantle wedge

Spherulitic orthopyroxene–bearing metaperidotite in Ray-Iz ophiolites (Polar Urals): high-pressure deserpentinization in a mantle wedge

MAFIC INCLUSIONS (SOBSKY COMPLEX, POLAR URAL): U‐Pb (SIMS) DATA

Petrology of Chromitites in the Higashi-Akaishi Ultrahigh-Pressure (UHP) Peridotite Complex, Japan: Toward Understanding of General Features of the UHP Chromitites

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