Paleoclimatic Interpretation of Red Bole-Green Bole Horizons Using Major, Trace and Rare Earth Element Geochemistry

Abstract Intertrappean bole horizons occurring between successive basaltic lava flows represent periods of volcanic quiescence during which weathering and soil formation took place. These horizons preserve geochemical signatures that can be used to reconstruct paleoclimatic conditions. Twenty-eight samples of red bole and green bole horizons were analyzed for major oxides, trace elements and rare earth elements. Chemical Index of Alteration (CIA), trace-element relationships (Cr–Ni, V–Cr, Sr–CaO, Zr–TiO₂) and REE correlations (La–Ce) were used to evaluate weathering intensity and paleoclimate. Red bole horizons show higher CIA values and enrichment of immobile elements, indicating intense chemical weathering under humid climatic conditions, whereas green bole horizons represent comparatively less weathered material formed under moderate weathering conditions. The results suggest that bole horizons represent paleosol layers developed during warm and humid climatic intervals between basaltic eruptions.