Microfacies and diagenesis of Setul Formation, Langkawi, Malaysia: Implications for the depositional environment

Abstract

The ongoing investigation into the microfacies and diagenesis of the Setul limestone reveals a considerable expanse of the formation that remains relatively unexplored. The comprehension of microfacies and diagenetic processes within sedimentary rocks holds paramount significance in predicting their viability as hydrocarbon reservoirs, decoding the geological history and depositional environment of a given region, reconstructing past climatic conditions, and understanding the fossil record. To meet the stipulated research objectives, which encompass the identification of microfacies and diagenesis within the Setul limestone, and the discourse on the diagenetic mechanisms operative within the limestone from the Gua Cherita outcrop, a multifaceted approach has been undertaken. This encompasses field observations, acid tests, thin section analyses, and X-ray Diffraction (XRD) analyses. The distinguished microfacies within the Setul limestone encompass packstone, wackestone, grainstone, and mudstone. Among the discerned minerals and grain constituents are dolomite, calcite, calcite veins, ooids, micrite, peloids, pellets, and vestiges of biota like ostracods and brachiopods. This variety of microfacies signifies a shallow marine depositional environment characterized by varying energy levels. Simultaneously, the diagenetic processes analysed in this study include dolomitization, cementation as well as compaction or stylolitization. The validity of this assertion is supported by the occurrence of dolomite, cemented grains, micrites, and the obvious presence of stylolitic structures observed in the samples. In essence, the prevailing expectation is that the results of this study will provide important and valuable insights for the geological community, with a specific emphasis on explaining the complex relationship between facies characteristics and the effectiveness of limestone reservoirs. Furthermore, this research is set to offer comprehensive insights into the physical properties of carbonate rocks, thereby establishing a strong basis to support future efforts within the realm of oil and gas exploration. The implications extend across both economic and industrial domains, highlighted by the inherent potential for the practical use of these findings.