Petrography and geochemistry of alkaline rocks from Michni (Warsak) area, NW Himalayas, Pakistan: Insights into petrogenesis and tectonic setting

Abstract

The Michni area within the Warsak complex that is part of the Peshawar plain alkaline igneous province (PPAIP) in NW Pakistan, hosts a diverse suite of alkaline and carbonatitic rocks whose origin and evolution remain poorly constrained. This study focuses on this locality due to its complex lithological assemblage and the first discovery of carbonatite intrusions in the area, which fills a significant gap in the regional petrogenetic framework. Detailed fieldwork, petrographic analysis, and whole-rock geochemistry (XRF-based major and trace elements) were employed to investigate the petrogenesis and tectonic setting of these rocks. The intrusive suite includes pyroxenite, melteigite, ijolite, urtite, nepheline syenite, fenite, and both calcio- and ferro-carbonatites. Geochemical data reveal strong silica undersaturation and systematic fractionation trends, indicating magmatic differentiation from a shared parental magma. Pervasive fenitization and secondary phases such as cancrinite, phlogopite, and carbonate suggest metasomatic alteration driven by late-stage carbonatitic fluids. While petrographic and geochemical coherence supports a potential genetic link between silicate and carbonatite suites. This study enhances understanding of the magmatic and metasomatic evolution in PPAIP and recommends future high-resolution isotopic and mineral chemical analyses to further constrain magma source characteristics and alteration processes.