PETROGRAPHY AND GEOCHEMISTRY OF LATE CARBONIFEROUS DOLOSTONE-HOSTED SOAPSTONE IN THE SHERWAN FORMATION, HAZARA BASIN: INSIGHTS INTO HYDROTHERMAL AND DYNAMIC METAMORPHIC PROCESSES

Khawaja Umair Majeed¹Muhammad Saleem Mughal^1*George Kontakiotis^2,3*Syed Kamran Ali¹Shamim Akhtar⁴Hammad Tariq Janjuhah^5,6Kamaran Siddique¹Evangelia Besiou²Assimina Antonarakou²

• ¹University of Azad Jammu and Kashmir, Muzaffarabad, Azad Kashmir, Pakistan
• ²Faculty of Geology and Geoenvironment, School of Science, National and Kapodistrian University of Athens, Athens, Greece
• ³National and Kapodistrian University of Athens, Athens, Greece
• ⁴University of Sargodha, Sargodha, Punjab, Pakistan
• ⁵INTI International University, Nilai, Negeri Sembilan Darul Khusus, Malaysia
• ⁶Nilai, Negeri Sembilan, Malaysia

This study examines the petrography and geochemistry of soapstone-bearing dolomite in the Sherwan Formation, Hazara Basin with a focus on hydrothermal dynamic metamorphism and the resolution of its age controversy. Field and petrographic analyses confirm that talc formed through the hydrothermal alteration of Late Carboniferous dolomite, influenced by faulting, folding, and the infiltration of silica-rich fluids. Key geological features, including stromatolitic dolomite, pseudotachylitic veins, and mylonitization, indicate episodic brittle deformation and high-temperature conditions. The age controversy is resolved by assigning a Late Carboniferous age to the host dolomite, supported by the presence of Anthracoporella spectabilis in both field and petrographic studies. The resultant soapstone is dated to the Permian period, which is linked to the Pre-Himalayan orogeny and volcanic activity from the Panjal Formation, as well as dolerite intrusions associated with Permian Gondwana rifting.Petrographic and geochemical analyses, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS), reveal that soapstone primarily consists of talc (steatite), with secondary minerals such as brucite, magnesite, willemseite, and montmorillonite. The presence of pyrite and hematite suggests interactions with hydrothermal fluid, leading to metal enrichment and oxidation. Geochemical data indicate silica enrichment and structural weakening, which facilitate the transformation of dolomite-to-talc. Trace amount of chromium (100-300 ppm) raises concerns about Cr⁶⁺ toxicity; however, the absence of arsenic, lead, cadmium, and mercury suggests minimal contamination, supporting the industrial viability of the soapstone. This study provides a comprehensive understanding of the tectonic, metamorphic, and geochemical processes that have shaped the Sherwan soapstone, highlighting the role of fluid-rock interactions and multiple metamorphic events in its evolution.