Facies analysis and depositional environment of the Cambrian Machinchang Formation in Langkawi, Kedah.

Langkawi lies within the North-western Domain of Western Belt of Peninsular Malaysia which belongs to Sundaland and is composed of Palaeozoic sedimentary rocks, varying from the Cambrian to the Permian in age; Machinchang, Setul, Singa, and Chuping formations. Understanding the sediment depositional setting is a fundamental process in providing necessary information regarding the area's geologic history. The study's significance is to emphasize that the sedimentology, stratigraphy, and depositional environment must become the focal point of the inter-disciplinary research necessary to advance our understanding of the complex behaviors of the Earth. Updating and improving the sedimentary facies is vital to establishing a precise chronology of past events by completing the sedimentary sequences. The study involved the analysis of three sedimentary logs recorded within exposed rock sections of the Machinchang Formation in Langkawi. All sedimentary logs were then correlated to getting a composite log representing the entire succession sequence. The facies analysis belonging to Machinchang Formation shows the presence of nine facies types (F1 to F9) for this succession which can be assigned to four facies associations; tidal flat (FA1) represented by F1, F2, F3 and F4, upper shoreface (FA2) represents by F1 and F6, lower shoreface (FA3) represented by F1, F2 and F5 and foreshore (FA4) are represented by F1, F2, F7, F8 and F9. These sediments represent clastic types deposited in a shallow marine environment during a relatively short regression period. • Machinchang Formation is perhaps the best described Cambrian formation in Malaysia. • Machinchang Formation consists of three members; Hulor, Chinchin, and Tengkorak. • Update the sedimentary facies is vital to create a precise chronology of past events. • Sedimentology must become the focus to understand the complex process of the Earth. [ABSTRACT FROM AUTHOR]