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Spinel-group minerals in peridotites of the Guli and Bor-Uryakh intrusions (Meymecha-Kotuy province, Northern Siberia)статья
- Авторы: Ivan Chayka, Kamenetsky Vadim, Vasilyev Yuriy, Prokopyev Ilya
- Сборник: Proceedings of 20th International Multidisciplinary Scientific GeoConference SGEM 2020
- Том: 20
- Год издания: 2020
- Первая страница: 301
- Последняя страница: 308
- DOI: 10.5593/sgem2020/1.1/s01.038
- Аннотация: The Guli and Bor-Uryakh massifs, a part of the Siberian Large igneous province (LIP)are mafic-ultramafic intrusive complexes, with strong alkaline affinity. They containdeposits of apatite and are also known to be source rocks of Os-Ir-Ru placers. Thesemassifs are of great interest for petrologists worldwide, as they are composed of anunusual variety of rocks (dunites/olivinites, shonkinites, melilitites, alkali syenites andcarbonatites) and being coeval with Siberian trap volcanic rocks, includingdiamondiferous kimberlites. Since mineralogical approaches based on spinel-groupminerals have been proved to be efficient in constraining origin of the ultramafics, wepresent the first descriptive study of chromite and magnetite mineralization, observed inolivine-dominated rocks of the Guli and Bor-Uryakh intrusions. In dunites of Guli massifspinel-group minerals are dominated by Mg-poor chromite (FeMg)Cr2O4 and Cr-Ti-richmagnetite FeFe2O4, while in Bor-Uryakh massif spinel-group minerals are predominantlymagnetite with only minor Mg-poor chromite. These minerals form either small euhedralinclusions in olivine or large subhedral to anhedral grains in serpentinized fractures andinterstitial space. The latter type of grains can have intricated irregular shape and containinclusions. We also observed abundant Cr-magnetite lamellae in olivine andchromite/magnetite micro-grains within olivine-hosted multiphase inclusions. Spinel(MgAl2O4) is occasionally found in intergrowths with chromite and magnetite. Theobtained data show that spinel-group minerals in the massifs do not correspond toprimary-magmatic varieties and suggest extensive alteration during post-magmaticprocesses. Textural and chemical evidence of substantial modification of initiallycumulativelithologies of Guli and Bor-Uryakh massifs favors meta-magmatic origin forthese massifs.
- Добавил в систему: Чайка Иван Федорович