<p>The Utch Khattak Limestone (Late Precambrian), exposed in the southern Gandghar Range of District Haripur, has experienced significant diagenetic alteration due to the intrusion of doleritic dikes. These dikes, widespread across the study area, have occluded pore spaces and fractures in the host limestone, leading to notable mineralogical changes from hydrothermal fluid interactions. Despite its importance, this phenomenon has not been extensively studied in the region. This research explores the diagenetic alterations induced by these intrusions through field observations, petrography, XRD analysis, and carbon–oxygen stable isotope analysis, aiding in the reconstruction of the paragenetic history of the altered carbonates. Fieldwork reveals multiple dikes, approximately 2&#xa0;m thick, which have caused contact metamorphism, recrystallized limestone, dolomites, and fracturing. Petrographic studies confirm that dolomitization occurred post-intrusion, supporting the hypothesis of alteration. Hydrothermal fluids infiltrated the host rock via fractures and joints, modifying its mineral composition, with marble at the contact zone serving as a partial barrier. Microscopic analyses identify matrix-replacive dolomites (MD), saddle dolomites (SD), and white pore-filling dolomite cements (DC). XRD analysis indicates the presence of dolomite, clay minerals, and alteration products resulting from the intrusions. These diagenetic processes have significantly impacted the porosity and permeability of the host carbonates, influencing their reservoir properties. Isotopic analysis reveals that the precursor limestone has depleted δ¹⁸O values ranging from −12.64‰ to −10.07‰ and δ¹³C values between +1.45‰ and +3.16‰, suggesting high-temperature hydrothermal fluid influence. Diagenetic phases show distinct isotopic signatures, with matrix replacive dolomites displaying δ¹⁸O values between −9.37‰ and −7.06‰ and δ¹³C values ranging from −0.95‰ to +3.1‰, while saddle dolomites exhibit more depleted δ¹⁸O values between −12.43‰ and −10.65‰ and enriched δ¹³C values between +2.42‰ and +2.75‰, indicating higher-temperature conditions. These isotopic trends reflect complex diagenetic processes and deviations from typical Proterozoic seawater signatures. Stable isotope analysis also aids in reconstructing paleotemperature conditions during the formation of different diagenetic phases. The study concludes that hydrothermal fluid interaction has driven mineral substitution and the formation of various rock types, significantly altering the porosity and permeability of the Utch Khattak Limestone.</p>