Granitic Rock Weathering and Clay Deposit Formation at the Al Barzah Area, Westcentral Arabian Shield, Saudi Arabia

Rami A. Bakhsh

doi:10.48084/etasr.16315

Authors

Rami A. Bakhsh Mineral Resources and Rocks Department, Faculty of Earth Sciences, King Abdulaziz University, Jeddah, Saudi Arabia

Volume: 16 | Issue: 2 | Pages: 34065-34074 | April 2026 | https://doi.org/10.48084/etasr.16315

Received: 17 November 2025 | Revised: 7 January 2026 and 30 January 2026 | Accepted: 7 February 2026 | Online: 4 April 2026

Corresponding author: Rami A. Bakhsh

Abstract

The present study investigates the progressive steps of the alteration and destruction of primary minerals and related textures in granitic rocks in the Al Barzah area during weathering processes. The study area is located in the west-central part of Saudi Arabia and represents a low, cultivated, closed area within the Arabian Shield. Geologically, the area includes Neoproterozoic weathered granite rocks, which are unconformably overlain by Tertiary red clays and sandstones of the Haddat Asham Formation, black basaltic volcanics, and Quaternary wadi deposits. The weathering processes of the studied granitic rocks involve the initial transformation of feldspar, biotite, hornblende, and quartz in the parent granitic rocks into kaolinized feldspar, chloritized hornblende, and hematitized biotite, respectively. As weathering progresses, the transformed minerals become highly obliterated, and newly formed secondary clay minerals mixed with iron oxide appear. This is accompanied by the complete destruction of the original crystalline textures. The clay deposits formed a characteristic white horizon below the Tertiary red clastics and overlying black basalts.

Keywords:

Saudi Arabia, Arabian shield rocks, weathering of granitic rocks

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