Cretaceous basaltic rocks are widely developed in the northern slopes of Alborz in the north of Iran. The study area is located in NarenjLengeh village, 8 km south of Lahijan city in western Gilan province. In field studies, a total of 25 samples were collected from this area, of which 10 petrographic sections and 5 polished sections were studied for the mineral chemistry of magnetite. In petrographic studies, magnetite minerals are observed as semi-formed phenocrysts in the interseptal texture of the region's basalts. In this study, electron microprobe analysis (EPMA) of 45 points in magnetite mineral shows that ulvospinel is the dominant iron titanium oxide in the samples. The graphs drawn on the magnetite mineral indicate that the studied basalts form at high temperatures, and the average temperature of magnetite formation is 720°C-760°C degrees. In this study, the oxygen fugacity (fO₂) values ​​have been calculated based on the magnetite mineral chemistry, and the samples of the region are all in the HM category, indicating high oxygen fugacity.