Petrogenesis of the Paleoproterozoic Näränkävaara layered intrusion, northern Finland, Part I: The northern peridotites and their relationships with the layered series and recharge events

The Paleoproterozoic Näränkävaara layered intrusion, northern Finland, has a surface area of 25 km x 5 and stratigraphic thickness ~3 km. main body the intrusion includes 1.5–2 thick basal dunite series 1.3 peridotitic-dioritic series, latter with two peridotitic reversals related to magma recharge. In addition, poorly known elongate poikilitic harzburgitic intrusions (the peridotites) are found along NE contact between granite-gneiss basement complex. We investigate new mineral whole-rock geochemical data from peridotites, aim clarifying their petrogenetic relationship intrusion. peridotites form 200–400 m cumulate grading olivine orthocumulates (OC) at complex olivine-orthopyroxene heteradcumulates (HAC) towards in south. OC show chemical trends consistent origin as rapidly cooled olivine-melt mixtures. HAC have crystallized situ relatively Cr- SiO2-rich magma. Based on lithological stratigraphical correlations, linked emplacement that caused first reversal series: marginal were formed initial pulse LREE-enriched siliceous high-MgO basaltic (SHMB) into chamber, followed by heteradcumulate formation fractionating added external SiO2 fluid. Ubiquitous xenoliths felsic veins drill core suggest assimilation may been local process. peridotite parental shows undepleted metal ratios suggesting no sulfide saturation occurred prior emplacement.