2026/08/01 by Nosheen Akhter, Abdus Sattar
paper · doi:10.17491/jgsi.2026.174515
crossref issued 2026/08/01 · crossref published 2026/08/01 · crossref published-online 2026/08/01 · crossref published-print 2026/08/01 · crossref created 2026/08/02 · crossref deposited 2026/08/02 · crossref indexed 2026/08/02
ABSTRACT Basaltic provinces worldwide are increasingly recognised as permanent reservoirs for CO2 mineral sequestration due to their abundance of Ca-Mg-Fe silicates and capacity for stable carbonate formation. The Panjal Volcanics of northern Pakistan comprise tholeiitic to mildly alkalic basaltic flows that have undergone extensive hydrothermal alteration and subsequent metamorphism, creating favourable conditions for long-term CO2 storage. Petrographic analysis reveals secondary assemblages of chlorite, epidote, albite, actinolite, sphene, quartz, and calcite, typical of lower greenschist facies. Whole rock geochemistry shows considerable variability, with SiO2 ranging from 46.5 to 51.2 wt%, Al2O3 from 12.9 to 15.6 wt%, CaO from 4.9 to 10.1 wt%, Na2O between 0.1 and 4.4 wt%, and K2O from 0.1 to 2.8 wt%. Trace element concentrations include Ba from 30 to 1760 ppm, Sr from 45 to 410 ppm, Rb up to 220 ppm, and Zr from 70 to 215 ppm. Loss-on-ignition values span 1.5 to 12.5 wt%, distinguishing mildly altered basalts (<4 wt%), strongly altered basalts (4-8 wt%), and severely altered samples (>8 wt%). Massbalance calculations relative to mid-ocean ridge basalts indicate enrichment in Na and K and depletion in Ca, reflecting seawaterrock interaction and spilitisation, with subsequent modification during Himalayan regional metamorphism. Despite these chemical shifts, immobile elements such as Ti, P, and Zr preserve magmatic signatures, while secondary porosity from fractures, vesicles, and hydrothermal overprinting enhances reactivity. These features collectively demonstrate that the Panjal Volcanics retain high carbonation potential and represent a promising natural reservoir for CO2 mineral sequestration. As one of the first detailed assessments of basalt carbonation potential in South Asia, this study positions the Panjal Volcanics as a valuable natural analogue to global projects such as CarbFix in Iceland, underscoring their significance in regional and international carbon storage strategies.