Basalt-kahusite Lava Splitting In The Paleoproterozoic Pechenga Depression In Kola Peninsula

摘要

Kahusite is an ultrasilicic (up to purely quartz) volcanic rock first described in 1934 from lava flows of Kahusi Volcano (Africa). In volcanic rocks of the Pechenga Depression (Kola Peninsula), this rock (74-95 wt % SiO_2) was found by Skuf in near the Zhdanov Cu-Ni sulfide deposit and in the basaltic Matert Formation. The basalt overlies the terrigenous rocks of the Zhdanov Formation, which divides basalts of the Pechenga Depression into the lower (tholeiitic basalt) and upper (subalkali basalt) sequences. Although the Zhdanov Formation is relatively thin (～1.5 km), it was intruded selectively by all (more than 300) layered gabbro-wehrlite intrusions, including ore-bearing sills that host Cu-Ni mineralization (Fig. 1).