Volkhovites are tektite-like glasses of mafic and ultramafic composition discovered in the fluvioglacial drift of the Valdai glaciation (10-60 ka ago) along the right bank of the Volkhov River (59 ° 27 ′ N, 32 ° 01 ′ E). Volkhovite particles are small in size (0.1-3.0 mm) and irregular in shape, with various microtektite aerodynamics (globular, droplike, and dumbbell-like forms). They are perfectly preserved, and, thus, postglacial in age. Sporadic volkhovite grains (up to 20 items per 1 kg of loam) were detected over an area 1.0 × 1.5 km 2 . Some samples from local spots 20 × 30 m 2 in size are anomalously enriched, up to 1700 volkhovite grains per 1 kg of loam. Tiny Ti-Fe, Fe, and Cu-Au spherules, particles of quenched glass and cinder, and fragments of the Precambrian and Paleozoic rocks are spatially associated with volkhovites. The suggested cryptomagmatic model assumes that the glass and cinder are pre-Holocene in age, whereas volkhovites were formed in the postglacial time as a result of the outburst of the slag-stone-melt-mud-gas mixture that ascended from the asthenosphere to the surface. Drops of the melt solidified in the air instantaneously to form tectite-like glasses, and the tuffisite-like agglomerate mixed with the fluvioglacial drift.
Mineralogical and geochemical characteristics of zircon from diorite porphyry dyke in Sergozerskoe gold occurrence (the Strel'ninsky greenstone belt, Kola region) Аннотация. Проведено минералого-геохимическое изучение циркона из дайки диоритовых порфиров Сергозерского рудопроявления золота. Изучение морфологии циркона, внутреннего строения, а также содержания и распределения редкоземельных элементов позволило получить важную информацию об условиях кристаллизации циркона и последующих метасоматических изменениях. Циркон из диоритовых порфиров обладает признаками кристаллизации из расплава, обогащенного флюидной фазой. Воздействие флюида продолжалось и после кристаллизации, отразившись в неравномерном составе циркона и, соответственно, в конфигурации спектров распределения REE, которые характерны для циркона метасоматического генезиса. Подобные характеристики отмечены для циркона из других рудопроявлений золота, размещенных в зеленокаменных поясах Кольского региона.
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