Recognition of High-Frequency Sea-Level Fluctuations in Late Silurian to Early Permian Deposits, Perlis, Malaysia.


 The purpose of this paper is to present information on the past sea-level fluctuations of sedimentary rock succession of the Perlis area that covers the Mempelam Limestone, Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, Kubang Pasu Formation, and Chuping Formation at Bukit Tungku Lembu and Guar Sanai, Perlis, Malaysia. Based on sedimentology logging, cycle stacking patterns, and accommodation variations revealed by Fischer plots, 51 cyclic sequences of third-order depositional sequences are recognized. These sequences generally consist of transgressive and regressive events. As the thickness of the cycle column increases, it forms an increase in accommodation space and subsidence rate and results in rising sea level. As the thickness of the cycle column decreases, it will form a decrease in accommodation space and subsidence rate and resulting in sea-level fall. Generally, the facies of the cycle are vertically arranged, forming coarsening and fining upward patterns observed from sedimentology logging. The Silurian Mempelam Limestone-Carboniferous Chepor Member sequence is characterized by a progressive increase and decrease in accommodation space, indicating a rise and fall in sea level. In contrast, the Carboniferous Uppermost Kubang Pasu-Permian Chuping Limestone sequence is characterized by a progressive decrease in accommodation space, indicating a longer-term fall in sea level. The regressive-transgressive cycles recognize deviations in the accommodation space and sediment supply from the cyclic successions. In turn, these cycles are expressing the long-term of Perlis’s sea-level fluctuations. The results notably reflect the cycles consistent with the long-term rising and falling trend on different regions globally in Paleozoic times.


Introduction
and Gobbett (1973) elucidated the Paleozoic to Mesozoic sedimentary successions in the north-western part of Peninsular Malaysia. It exhibits an in-depth study on the geological work sequence of Upper Cambrian to Holocene. These rock stratigraphies are grouped into the oldest to youngest, the Machinchang Formation, Setul Formation, Singa Formation, Chuping Formation, Bukit Arang Coal Bed Granite, and Alluvium. Foo (1983) quoted that these rocks are comprised of clastics and carbonates sedimentary rock. Its depositional environment is primarily in shelf sediments of shallow marine settings (Foo, 1983). Lee (2009) and  had also introduced a revised Paleozoic rock of Perlis into several separated subunits, from oldest to youngest; Timah Tasoh Formation, Sanai Limestone, Telaga Jatoh Formation, Kubang Pasu Formation, and Chuping Limestone (Figure 1). In addition, Meor and Lee (2005) discovered a new stratigraphic formation of the Early Carboniferous-Devonian Jentik Formation that represents the transitional boundary between the underlying Ordovician-Silurian Setul Formation and the overlying Carboniferous Kubang Pasu. Figure 1 provides an updated regional stratigraphic succession chart/column of Perlis.
The lithostratigraphy and depositional environment of the transitional zone from the Setul Limestone to the Kubang Pasu Formation studied in Guar Sanai, Kampung Guar Jentik, Beseri, Perlis on the sedimentology and paleontology analysis (Meor & Lee, 2002). A new lithostratigraphic unit has been distinguished; the Jentik Formation consists of six informal units: Unit 1, Unit 2, Unit 3, Unit 4, Unit 5, and Unit 6 (Meor & Lee, 2002). Unit 1 predominantly comprises black shales that are of an early Devonian age-dating faunal assemblage (Dacryoconarid-Monograptus-Plagiolaria). Light-coloured, unfossiliferous sandstones and shales are fall in Unit 2. In addition, Unit 3 consists primarily of thick and red sandstone, interbedded with sandstone and occasionally showing graded layer/bed. Unit 4 allocates a dark wellbedded limestone layer having straight coned nautiloid fossils. As for Unit 5, it is made up of interbedded layers of cherts and slump structure in beds of black mudstone. Fossil of brachiopod and gastropod is found at the base of the bed unit. Unit 6 comprises primarily brownish to red thickly bedded of mudstone, interbedded with sandstone. Macrobole-crinoid fossil assemblage in the thick-redded mudstones resembled the Early Carboniferous dating age. The Jentik Formation is located underlying the Kubang Pasu Formation. Thus, these features generally suggested that the environments re ect depositional settings within relatively deep water marine environments.
The Unit 3 of the Jentik Formation (Meor & Lee, 2002) or the Rebanggun Beds (Gobbett, 1972) or the Langgun Red Beds (Kobayashi & Hamada, 1973) is exposed in the Hutan Aji District, conformably overlying the light-coloured areno-argillites of Unit 2 (Meor & Lee, 2002) or the Upper Detrital Member (Jones, 1981). The Mid-Paleozoic red beds have indicated that this formation corresponds to the transgressive event documented worldwide, the Hangenberg Event. Hassan and Peng (2004) presented comprehensive sedimentology and paleontology studies to determine the depositional environment of the Late Devonian-Early Carboniferous red beds sequence. The sedimentological logged revealed that the formation is constituted by massive mudstone, thin mudstone to sandstone couplets, and thin tabular sandstone. The rocks of the Jentik Formation in Unit 3 can be divided into eight facies which; massive mudstone facies, thin mudstone and sandstone couplet facies, pebbly sandstone facies, massive sandstone facies, cross-strati ed sandstone facies, black mudstone facies, hummocky cross-laminated sandstone facies, and laminated sandstone facies. These ndings demonstrate that it was deposited in a marine prodelta to delta front environment with conditions above the storm-wave base of deep water.
According to these data and eld observations, the red beds' sequence can be considered part of the Jentik Formation deltaic marine deposits. The uppermost section of Kubang Pasu Formation clastic deposition shifts to Chuping Formation carbonates using the logging method in Bukit Chondong and Bukit Tunku Lembu. For which three facies associations (with eleven facies) have been identi ed re ecting different depositional settings. The stack facies' patterns show a gradually coarsening upward sequence ranging from the offshore to distal lower shoreface to proximal lower shoreface facies. As a result, a depositional-environmental model depicting a prograding storm-and wave-in uenced coast, attributed to the upward shoaling pattern of the facies association predominance of a storm-and wave-generated facies. This paper reviews the sedimentological variation of Perlis's rock formation to correlate with the major eustatic sea-level history during the Palaeozoic time scale. Because there is no information on sea-level history based on stratigraphy studies from the previous researcher.
Previous studies have not explained the sea-level uctuation activities in North-western Peninsular Malaysia. Thus, this study is signi cant to reveal Silurian-Permian relative sea-level changes of the sedimentary formations in north-western Peninsular Malaysia. A precise and accurate sea-level model is essential to verify the events imprinted in the rock record. We suppose that correlations must be su ciently accurate to demonstrate the synchronous occurrence of rising and falling events in different regions of the world. Hence, it is now possible to interpret the Silurian-Permian sea-level activities through sedimentology logging and Fischer plotting. The study's main objective is to construct and correlate the Devonian-Permian sea-level uctuations to Paleozoic major eustatic sea-level history. Previous studies have not explained the sea-level uctuation activities in North-western Peninsular Malaysia. Therefore, this study is signi cant to reveal Devonian-Permian relative sea-level activities of the sedimentary formations in north-western Peninsular Malaysia. A precise and accurate sea-level model is essential to verify the events imprinted in the rock record. Furthermore, we suppose that correlations must be su ciently accurate to demonstrate the synchronous occurrence of rising and falling events in different regions of the world. Hence, the cycle stacking patterns and the lithology correlatability of Fischer plots may de ne a eustatic control on sea-level uctuation on the sedimentary formations.

Materials And Methods
Fischer plot is a valuable instrument for graphically portray the sea-level correlation in cyclic sequences of varying thicknesses. Fischer (1964) was rst established a vertical space-time diagram to expound the cyclic events seen in the calcareous Alps of peritidal Triassic Lofer cyclothems. There are no assumptions made regarding the elapsed time between the cycles of the sequence cyclic events. Hence, Sadler (1993) renamed the axes "cumulative deviation from mean cycle thickness" for the vertical axis and "cycle number" for the horizontal axis. Day (1997) suggested that the traditional Fischer diagram (event-domain diagram) is converted into the depth domain to distinguish the stratigraphic sequence features, especially when dealing with log and core data. Hence, stratigraphers will analyse the stratigraphic unit data when integrating both materials from the event-domain and the depth-domain diagrams.

Husinec et al. (2007) developed the FISCHERPLOTS program using an Excel Spreadsheet computer
program to construct Fischer plots. It plots the cumulative departure from mean cycle thickness against the cycle number or stratigraphic distance. The Fischer plots are used to recognize changes in accommodation space from cyclic carbonate successions (Husinec et al., 2007). Fischer plots of longterm relative sea-level changes from major formations in Perlis were extracted by keying in the cycle thickness to the excel spreadsheet. The cycle thickness was determined based on the sedimentology log and facies association.
The Western longitudinal belt of Peninsular Malaysia forms part of the Sibumasu terrane that was rifted from Northwestern Australian Gondwana in the early Permian period (Metcalfe, 1984;2011). Perlis is part of the fold-thrust belt developed due to the collision between the Sibumasu and East Malaya/Indochina blocks during the Late Triassic (Metcalfe, 2011). Thus, the main outcrop areas which have been chosen for this study are indicated by numbers in Figure 2 and as below;  Figure   5). The SL5 comprises of Chuping Formation ( Figure 6). SL3 sedimentology log has been identi ed 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 ning 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 ning 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. 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 classi ed 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 progradational 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 ooding 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 uctuation 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 uctuations. 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 ner ones in the bottom and the coarser ones at the top.
The rst accommodation events of the third-order early Permian age happened with a complete fall sealevel 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 uctuations using Fischer plot analysis. The interpreted transgressive-regressive cycles from the Fischer plots are then compared with the eustatic sea-level uctuation studied by Haq & Schutter, 2008;Bahlburg & Breitkreuz, 1993;andVeevers &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 de ned 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 With that, the resulting integration of the sedimentology logging from geological and Fischer plotting from stratigraphical framework approaches has undoubtedly shown a good relation. These techniques give considerable information to unveil the history of Devonian to Carboniferous age relative sea-level changes. The regressive and transgressive cycles recognize deviations in the accommodation space and sediment supply from the cyclic successions. In turn, these cycles are expressing the long-term of Perlis's sea-level uctuations in this study. The third-order sea-level curve illustrated based on the sedimentology log correlates with the third-order sea-level de ned by other previous works (