The SL1 and SL2 composited section of Guar Sanai, Kampung Guar Jentik area comprises Mempelam Limestone, Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, and Chepor Member of Kubang Pasu Formation (Figures 3 and 4). SL1 and SL2 sedimentology logs can be divided into five facies: limestone, black shale, chert and mudstone, sandstone, and mudstone. Meanwhile, SL3 and SL4 logs for Bukit Tungku Lembu, Beseri of Uppermost Kubang Pasu Formation, have five different facies: coal facies, silty shale facies, shale, sandstone, and silty shale interbedded with sandstone facies (Figure 5). The SL5 comprises of Chuping Formation (Figure 6). SL3 sedimentology log has been identified to have six different facies, which are: limestone interbedded with black mudstone, black shale interbedded with sandstone, black mudstone interbedded with chert, mudstone, sandstone, and diamictite facies.
These facies are interbedded with different thickness, grain size, and a difference in the content of fossils. From the interbedded facies, some cycle patterns can be formed, which are coarsening upward and fining upward. Besides, there is also a distinct transition, changed from carbonate rocks to clastic rocks.
The Fischer plots are used to recognize changes in accommodation space from cyclic carbonate successions (Husinec et al., 2007). Therefore, this study yields to extract long-term relative sea-level changes from the Perlis’s Formation. The thickness between two maximum regressive surfaces equals a cycle thickness.
From the composited section of Mempelam Limestone, Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, Kubang Pasu Formation, and Chuping Formation, some cycle patterns can be formed, which are coarsening upward and fining upward. Besides, there is also a distinct transition, changed from carbonate rocks to clastic rocks.
The Fischer plots are used to recognize changes in accommodation space from cyclic carbonate successions (Husinec et al., 2007). Therefore, extracting long-term relative sea-level changes from sedimentary formations of Guar Sanai, Kampung Guar Jentik in this study. Fischer plots of major formations of Perlis were generated by keying in the cycle thickness to the excel spreadsheet. The cycle thickness was determined based on the sedimentology log and facies association done in this study. The thickness between two maximum regressive surfaces equals a cycle thickness.
Thus, concerning the composited logs, the formations can be divided into 51 sedimentary cycles. The sedimentary logs can be observed from Figures 3, 4, 5, and 6, and from there, the cycle thickness can be determined using the Excel spreadsheet program to generate the Fischer plot (Husinec et al., 2007). The Fischer plots generated by using this excel spreadsheet are shown in Figure 7.
Figure 7 conveys the transgressive-regressive cycle’s deposition trend via the Fischer plot method by defining cumulative departure from mean cycle thickness versus the cycle number. The plot shows the third order of sea level and a long-term rise and fall. According to Haq et al. (1987), the third-order sequences were said to have durations of 0.5±3 million years ago.
The column beside the relative sea-level curves contains the interpretation of the systems tracts represented by a negative trend and a positive trend of the Fischer plots and sedimentary cycles, associated with each identifiable facies for Perlis’s stratigraphic nomenclature. The regression and transgression cycle showed one complete cycle of rising and falling sea level. In most cases, the transgressive system tracts (TST) are known rather than regressive system tracts (RST) in rock history. In most cases, for regressive systems tracts (RST) associated with the sea-level fall, the sea-level reaches a minimum represented by low-stand systems tract (LST) and is overlain directly by transgressive deposits.
The first accommodation events of the third-order Silurian-Permian age happened with a complete fall sea-level cycle in Mempelam Limestone Formation and Timah Tasoh Formation. There is a good match between the regressive and sea-level curves as interpreted from the Fischer plots. Immense thickness in Cycle 5 indicates a eustatic sea level is rising or subsidence activity of basin. No transgressive episode during this period. This sediment’s formation indicates an upward deepening and fining sequence. Also, the Fischer plot illustrated that the accommodation space of sea-level cycle 2 begins to increase up to cycle 9 and decrease to cycle 12 in Sanai Limestone, positioned in Jentik Formation. Several cycles of continuous rising and falling of sea-level can be seen in the lowermost section of Kubang Pasu Formation and decreasing accommodation space at sea level for the rest of the Kubang Pasu Formation and Chuping Limestone Formation.
There is an unconformity developed between the Timah Tasoh (black shale) and Sanai Limestone. Hence, it is interpreted as a sequence boundary at the base of the Sanai Limestone Formation. The lower Sanai Limestone sequence is classified into a highstand system tract (HST) and transgressive system tract (TST). The conodonts limestone indicates the transgression surface and the start of transgressive system tracts (TST). This sequence shows a shallowing and thickening upward sequence. A pro-gradational stacking pattern throughout the highstand systems tract is usually shown by the coarsening-upward trend from shore (Kwon et al., 2006). Also, the Fischer plot illustrated that the accommodation space of sea-level cycle 5 to 6 increases in Sanai Limestone, positioned in Jentik Formation (Hassan & Peng, 2003). Sea-level cycle 7 to 11 shows the accommodation space decreases in the upper part of the Sanai Limestone Formation, followed by little increasing accommodation space in sea-level cycle 12 and 13. The sea level reaches the maximum flooding surface in this cycle. It stands at the boundary underlain by transgressive system tract (TST) and overlain by high stand system tract (HST). The Sanai Limestone depicts a long-term cycle of sea-level rise that portrays a good match between transgressive cycles and the sea-level curve as interpreted from the Fischer plots. This was inferred from the distinct transition of limestone to black shale cycles. It portrays a good match between transgressive and regressive cycles and the sea-level curve interpreted from the Fischer plots.
The Sanai Limestone in the sections underlies the Telaga Jatoh Formation paraconformably. This sediment pattern of limestone gradually transited into black mudstone and cherts indicates sea-level falling. According to Meor and Lee (2005), major regression activity had taken place after the Hangenberg Anoxic Event. These cycles show the falling stage systems tract (FSST) and low-stand system tract (LST). When the sea level is falling, it will expose the shelf deposits and consequently develop an unconformity.
The cycles of Chepor Member of Kubang Pasu Formation) show a good match between the regressive cycles for Kubang Pasu Formation and the sea-level curve as interpreted from the Fischer plots. Following with the Chuping Formation will have a rapid fall fluctuation to the end of the Perlis’s rock sequence.
The Chuping Formation of Guar Sanai is interpreted as shallowing upwards, or regressive cycle with the regression peak begin at cycle 30. From the sedimentology log in Figure 6, carbonates gradually become more common as the bed is graded upward from Kubang Pasu Formation into Chuping Limestone Formation. The lithological change from a siliciclastic sequence and gradually to a carbonate sequence is possibly closely related to sea-level fluctuations. The coarsening-upward sequence was presumably aroused in response to the occurrence of the high-frequency eustatic sea-level regression process. This process contributes to changes in the sediment deposition, where the finer ones in the bottom and the coarser ones at the top.
The first accommodation events of the third-order early Permian age happened with a complete fall sea-level cycle in Chuping Formation cycle 30 to cycle 51. A clear downward trend in sea level is observed. The documented relative sea-level falling by Ross and Ross (1985) is most likely related to worldwide Carboniferous eustatic episodes.
All in all, there are 51 sedimentology cycles found from sedimentary rock succession of Perlis comprising Mempelam Limestone, Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, Chepor Member of Kubang Pasu Formation, Uppermost Kubang Pasu Formation, and Chuping Formation. The sea-level curve was successfully constructed to manifest several cycle patterns and putative links to eustatic sea-level fluctuations using Fischer plot analysis. The interpreted transgressive-regressive cycles from the Fischer plots are then compared with the eustatic sea-level fluctuation studied by Haq & Schutter, 2008; Bahlburg & Breitkreuz, 1993; and Veevers & Powell, 1987 Johnson et al. (1985) (Figure 8).
The interpreted transgressive-regressive cycles of the Silurian Mempelam Limestone Formation to Early Permian Chuping Formation from the Fischer plots are compared with other Late Silurian to Early Permian relative sea-level studies from other parts of the world (Figure 8). Eustatic sea-level activities curve (transgressive-regressive cycles) are correlated with events of Paleozoic-aged sea-level changes (Haq & Schutter, 2008) and transgressive-regressive trends in N. Chilean Andes (Bahlburg & Breitkreuz, 1993) and transgressive-regressive trends in Russian Platform (Veevers & Powell, 1987).
Sometimes the global events are applicable worldwide, or their magnitude of change at various places may differ depending on local conditions, such as local tectonic changes (Haq & Al-Qahtani, 2005). The third-order sea-level curve illustrated based on the studied formations sedimentology log using Fischer Plots correlates well with the third-order sea-level defined by Haq and Schutter (2008).
From Figure 8, these four curves have a particular trend. First, there is a beginning of sea-level rising at the early Carboniferous age. It represents the worldwide extinction event called the Latest Devonian Hangenberg Anoxic Event. (Walliser, 1984). There was a major transgressive episode recorded worldwide during the Tournaisian (Burlington Cycle). This event is marked by the black shales (Racka et al., 2010) or deepwater chert deposition of Unit 5 of Jentik Formation (Meor & Lee, 2002) or Lower Part of Kubang Pasu Formation (Malaysia Working Group, 2009). Third, the ice sheets began to shed icebergs over the Himalayan–NW Australian Gondwana bound. Meor et al. (2014) reported that the deposition of glacial-marine diamictites marks this event in the Kubang Pasu Formation of Chepor Member. Finally, an apparent declining trend towards the Permian age shows a fall in sea-level fluctuations. Hassan and Peng (2004) concluded that the pre-Carboniferous paraconformity seen in the middle of Paleozoic aged successions of Sibumasu/Shan-Thai Terrane is caused by major regression immediately followed after the global transgressive event of the Hangenberg episode. Tectonically, the glaciation of the Gondwana was at its peak during Late Carboniferous until the Early Permian.