Dolomitization is one of the most substantial diagenetic reactions in carbonate systems, occurring where calcite (CaCO3) is replaced by dolomite (CaMg(CO3)2) under a wide range of crystallization temperatures and fluids. This approach led to investigating and documenting field characteristics related to the petrography and geochemistry of the Devonian carbonates in the Peshawar basin, Pakistan. Two hundred samples were collected from various types of dolomitization and studied their petrographic properties, while the geochemical compositions were examined using XRD and carbon–oxygen isotope analyses. These analyses were conducted to understand the diagenetic processes, the dolomitization, hydrothermal fluids, and their development. Dolomitized bodies are randomly distributed within the host limestone, which can be observed in the field where outcrops extend north east-south west in the study region from Kali Shilman to Bara Fort and have been changed by hydrothermal fluids and magmatic intrusions. This research aims to understand the origin, diagenetic evolution, and sedimentary features of the dolomites that make up the Khyber Limestone Formation and provide pertinent knowledge for comprehending the dolomitization-processes in the alteration of hydrothermal-related Devonian carbonates within the Khyber Limestone. Field relationships, petrographic studies, and geochemical analyses helped us understand the paragenetic history of carbonate rocks and their relationship to igneous intrusions. The phenomenon of fluid-rock interaction has received significant attention because hot fluids (hydrothermal) alter the composition of the host limestone in contact. Field observations indicate the host limestone to have thick, numerous mafic intrusions. In the study area, host limestone is altered into dolomite and marble due to these igneous intrusions (mafic composition). A petrographic study demonstrated host limestone alteration, resulting in digenetic alteration and metamorphism. The formation of marble as a result of contact metamorphism has also been observed to act as a barrier against the host limestone being altered by dolomitizing fluids. Field observations, hand specimen examinations, and thin-section studies show that the altered carbonate rocks are also exceptionally finely to moderately to coarsely crystalline. Five distinct types of dolomite rock textures are identified and classified as “planar” and “non-planar” dolomite based on the distribution of crystal sizes and the shape of the crystal boundaries. Planer dolomite crystals have straight boundaries and are divided into euhedral Dol-III and subhedral Dol-IV textures. In contrast, non-planar dolomite crystals (Dol-I) have arched, lobate, ridged, obscure, or irregular intercrystalline boundaries. Planar-subhedral dolomite has a unimodal mosaic structure and is subhedral to anhedral shape with straight compromise boundaries and numerous crystal-face junctions, while planar-euhedral dolomite (Dol-III) is composed of fine to coarse dolomite crystals with dense hazy rhombs. The bulk mineralogy was ascertained using XRD studies. Mostly dolomite and calcite were present along with other minerals like putoranite (Cu17(Fe,Ni)18S32), mangano calcite (Ca,Mn)CO3, quartz, and copper, which can be formed when magmatic activity occurs, so because of some copper-bearing fluids, they were deposited. The C and O isotopic variations of ancient ocean water demonstrate the effects of various diagenetic processes resulting from magmatic emplacement, hydrothermal fluids’ impact, and the consequent on the dolomitization of the Khyber Limestone. [ABSTRACT FROM AUTHOR]