| Инд. авторы: | Sklyarov E.V., Lavrenchuk A.V., Fedorovsky V.S., Pushkarev E.V., Semenova D.V., Starikova A.E. |
| Заглавие: | Dismembered Ophiolite of the Olkhon Composite Terrane (Baikal, Russia): Petrology and Emplacement |
| Библ. ссылка: | Sklyarov E.V., Lavrenchuk A.V., Fedorovsky V.S., Pushkarev E.V., Semenova D.V., Starikova A.E. Dismembered Ophiolite of the Olkhon Composite Terrane (Baikal, Russia): Petrology and Emplacement // MINERALS. - 2020. - Vol.10. - Iss. 4. - Art.305. |
| Внешние системы: | DOI: 10.3390/min10040305; РИНЦ: 43270755; WoS: 000535581500013; |
| Реферат: | eng: Dismembered ophiolites in the Early Paleozoic Olkhon terrane, a part of the Baikal collisional belt in the southern periphery of the Siberian craton, occur as fault-bounded blocks of ultramafic and mafic rocks from a few meters to hundreds of meters in size. The ultramafic rocks are mainly dunite-harzburgite peridotites with gradual transitions between the lithologies, as well as moderate amounts of enstatitite, wehrlite, and clinopyroxenite, but no lherzolite. Most peridotites have strongly depleted chemistry and a mineralogy corresponding to the harzburgite type usual for ophiolites of suprasubduction zones (SSZ). The mafic rocks are leuco- to melanocratic gabbros with different relative percentages of clinopyroxene, olivine, and plagioclase, which enclose thin layers and lenses of clinopyroxenite and anorthosite. They bear back-arc basin geochemical signatures, a setting inferred for the Neoproterozoic southern Siberian craton. The gabbroic rocks are of two geochemical groups; most of their trace-element patterns show Ta-Nb minimums and Sr maximums common to suprasubduction zone ophiolites. Judging by the Ol + Opx + Chl + Chr mineral assemblages, the Olkhon peridotites underwent low amphibolite and amphibolite regional metamorphism at 500-650 degrees C. The occurrence of the ultramafic and mafic bodies is consistent with formation in an accretionary wedge metamorphosed during a collisional orogeny. The mantle and crustal parts of the Olkhon ophiolite suite apparently were incorporated into the terrane during the frontal collision of perio-oceanic structures with the Siberian craton. Then, in a later oblique collision event, they became dismembered by strike-slip faulting into relatively small bodies and fault blocks exposed in the present erosional surface.
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| Ключевые слова: | REGION; GENESIS; PERIDOTITES; METAMORPHISM; EVOLUTION; GEOCHEMISTRY; ISLAND-ARC; CHROMIAN SPINEL; U-PB; collisional orogeny; Olkhon terrane; CAOB; petrology; amphibolite; gabbro; ultramafic rocks; ophiolite; PETROGENESIS; |
| Издано: | 2020 |
| Физ. характеристика: | 305 |