Crocker Formation Research Articles

A New Approach of Adjustment Factor 2023 (NAAF23) for Modified Slope Mass Rating (M-SMR)

The Modified Slope Mass Rating (M-SMR) system is a SMR-based geomechanical classification system utilized for rock slope characterization in the Crocker Formation. The M-SMR rating is derived from the sum of the basic Rock Mass Rating (RMRb) and an adjustment factor. However, it has been observed that the parallelism correction parameter, F1, within both the M-SMR and SMR systems, can sometimes be overestimated, especially for toppling failures when the discontinuity dip direction (αj) is less than the slope dip direction (αs). This study was conducted on six rock-cut slopes to not only evaluate the production of a convincing F1 value but also to introduce a simplified New Approach of Adjustment Factor 2023 (NAAF23) diagram for the M-SMR. This adjustment factor (F) includes four correction parameters (F1, F2, F3, and F4), similar to those used in SMR, but modifies the calculation approach for F1. The calculation now involves subtracting the higher value from the lower value among the discontinuity dip, slope dip, or intersection line orientations. The symbols A, B, C, and D represent the subtracted values, with A and B used when the discontinuity dip direction is higher than the slope dip direction and vice versa, and C and D used when the intersection line is higher than the slope dip direction and vice versa. For plane failures, A or B becomes the value, while for wedge failures, C and D are used. For toppling failures, the formula is 180 − A or B if A or B is less than 180, and A or B − 180 if A or B is greater than 180, eliminating the need for absolute symbols. A comparison F1 calculation using SMR is also conducted. The results show that F1 values become more convincing when using NAAF23.

Sedimentological Analysis of Thin-Bedded Sequence of Eastern Part of West Crocker Formation, Northwest Sabah, Malaysia

Sedimentological Analysis of Thin-Bedded Sequence of Eastern Part of West Crocker Formation, Northwest Sabah, Malaysia

The onshore West Baram Delta deposits: Provenance and drainage in the Middle Miocene to Pliocene in NW Borneo and comparison to the Champion Delta

The Baram Delta province in NW Borneo forms a major hydrocarbon reservoir offshore northern Sarawak and Brunei. The delta sequence is thereby subdivided into the West Baram delta to the south and the Champion delta to the north. Onshore are the remains of the Neogene delta deposits exposed and provide the possibility to study the equivalent offshore successions in outcrop. This study focuses on the Neogene West Baram delta successions which were studied for sedimentological facies and provenance characteristics. The successions consist of the Lambir, Miri, Tukau, and the enigmatic southern Lambir/Belait-Sarawak formations. Deposition took place in various mixed-energy delta environments between the Langhian and early Pliocene. The sediments are all quartz-rich and heavy minerals are dominated by ultra-stable zircon, rutile and tourmaline. Dominant detrital zircon age clusters are in the Early Cretaceous and Permian-Triassic. Based on light mineral petrography, heavy mineral assemblages, and detrital zircon U–Pb geochronology, all formations are interpreted as derived from multi-recycled sources, likely the underlying Paleogene Rajang Group turbidites and the Oligocene to Lower Miocene Nyalau-Tatau delta deposits. Additionally, literature data of the Champion Delta and one sample from Labuan analysed for provenance in this study are used to demonstrate that the Champion Delta can be distinguished from the West Baram Delta by having higher chrome spinel and garnet contents and slightly different detrital zircon age populations. The Champion Delta deposits are interpreted as sourced by recycling of the Crocker Formation and older turbidites (e.g., Sapulut Formation) with potentially input from ultra-mafic basement rocks of Sabah.

Application of Modified Slope Mass Rating (M-SMR) System in Ultrabasic Rock: A Case Study in Telupid, Sabah, Malaysia

Modified Slope Mass Rating (M-SMR) was proposed as a geomechanically classification scheme for sedimentary Crocker Formation rock slope in the Kota Kinabalu area, but has never been applied in ultrabasic rock. Then, this study was conducted on ultrabasic rock cut slopes in Telupid, Sabah, Malaysia. This system was used to characterize and to propose preliminary rock cut slope design, slope stabilization, protection measures, and recommendation levels for slope re-investigation. The UCS test, Deere RQD method, a weighted average of discontinuity set spacing, weighted average and statistical mode, weighted average, and new approach of adjustment factor (NAAF) methods were used to evaluate the uniaxial compressive strength (UCS), RQD, discontinuity spacing, discontinuity condition, water flow and discontinuity orientation parameters, respectively. The result of this study shows that the M-SMR classes for the slopes are class III (moderate), IV (poor,) and class V (very poor). Recommended and highly recommended for slope re-investigation by well-trained, experienced, or expert engineering geologist/geotechnical engineer are for classes III, IV, and V, respectively. The recommendation for slope stabilization and protection measures are local trimming, surface drainage, horizontal drain, weep hole, systematic bolting, dowels, concrete detention or buttress, shotcrete, wire mesh or rope nets, and rock trap ditch.

Sedimentological Analysis of the Turbidite Sequence in the Northern Part of the West Crocker Formation, Northwest Sabah

Gravity-flow deposits form the northern part of the Crocker Formation (Oligocene–Early Miocene), with the most significant interpretation as a sand-rich system in the proximal and a mud-rich system in the distal area of the deep-water turbidite depositional setting. Seven outcrop localities in the northern-part area were selected for mapping and sampling, starting from Kota Kinabalu up to the Telipok area to evaluate the sedimentary sequence. This study used mapping, field observation, and log sketches in the field, as well as extensive analysis and interpretation of sedimentological methods to investigate the sequence of sediment outcrops in the Crocker Formation area of northwest Sabah. During the fieldwork, five main facies were found, namely, massive sandstone facies (f1), graded sandstone facies (f2), laminated sandstone facies (f3), interbedded sandstone and mudstone facies (f4), and mudstone facies (f5). These northern-part outcrops are interpreted as being deposited from the highest to the lowest turbidity currents and the actuality of pelagic mudstone deposition, based on their fining-coarsening-upward pattern. The five geometrical bodies were proposed as laterally contiguous depositional environments, namely, (1) inner fan channel, (2) inner fan channel–levee complex, (3) mid-fan channelized lobes, (4) non-channelized lobes/distal lobes, and (5) basin plains. The facies interpretation shows that the study area consists of lobes, channel–levee complexes, and levees formed in a fan of a deep-water basin setting, with the basinal plain enveloped by thick mudstone deposits. This northern part of the Crocker Formation is interpreted as a multiple-sourced sediment, shelf-fed, Type II, low-efficiency, and sand-rich turbidite depositional system.

Debris flow susceptibility analysis using a bivariate statistical analysis in the Panataran River, Kg Melangkap, Sabah, Malaysia

This study area is part of the Kadamaian watershed and is located on the North-West flank of Mount Kinabalu, composed of sedimentary rock from the Crocker Formation and the Mt. Kinabalu granitic pluton. Many loose seismic materials were found on the slopes during the 2015 Sabah Earthquake with a moment magnitude of 6.0. These materials later served as the source material for rainfall-induced debris flows or shallow landslides. The community closest to the Panataran river in the Kg Melangkap area is the most affected. Therefore, the objective of this study is to study the debris flow susceptibility analysis using a bivariate statistical analysis approach, namely the Frequency Ratio (FR) model. Forty-eight landslides were identified using remote sensing interpretation. Characteristics of the research area, such as slope gradient, elevation, slope aspect, lithology, slope curvature, and topographic wetness index, were selected as the factors to evaluate the debris flow susceptibility analysis. The correlations between these factors and the occurrence of landslides were established, and the results were assessed and validated based on those results. Validation findings demonstrate that this technique provides high accuracy, with an AUC of 81.8 for success rate. As a result, it can be stated that this model accurately predicted landslide susceptibility in the research area, and that it can help local authority with future land-use planning, as well as give tools for hazard mitigation.

Assessment of Carbon Stock at Oil Palm Plantation in Klias Peninsular West Coast of Sabah

The assessment of carbon stocks in oil palm plantation were carried out in the Klias Peninsular West Coast of Sabah. The geological setting of the oil palm plantation mainly consists of Crocker Formation and Quaternary Alluvium which in mainly composed of peat soil. The peat soil from 10 sites was collected for the carbon percentage values and physico-chemical analysis. The geophysical surveys were performed to measure the thickness of peat deposits and the water table, which influenced the value of carbon stocks. The geochemical analysis of the peat soil at 0.5m depth shows an acidic pH value (3-4) and a high organic matter (30-100) %. The results of the geophysical surveys show the water table in oil palm plantation ranging from 0.3m-1.5m. Moreover, the thickness of peat as carbon storage at oil palm plantation varies from 0-6m. The bulk density obtained at selected depth varies from (0.09-0.59) g/cm3.The carbon stock in oil palm plantation is calculated around 50 tanC/ha - 900 tanC/ha. Site OP7 shows the highest carbon stock (947.73 tanC/ha) compared to site OP1 (91.33 tanC/ha). The high estimated carbon stocks resulted from a high-water table and a thick layer of organic matter.

GEOPHYSICS ELECTRICAL CHARACTERIZATION FOR IDENTIFICATION OF SEAWATER INTRUSION IN THE COASTAL AREA OF PAPAR, SABAH

Seawater intrusion is known to be a major problem that influences the quality of groundwater within coastal regions globally. The groundwater table within the coastal area is usually close to the ground surface due to low topography or human development activities such as land reclamation and man-made drainage systems that keep the water table at constant low level. Electrical resistivity method is one of the geophysical methods that has been extensively used to investigate seawater intrusion due to the high electrical conductivity contrast produced by saline water. Papar, Sabah is located at the west coastal region of Sabah and is generally formed by Crocker formation and Quaternary alluvium. The sedimentary rock of Crocker Formation mainly consists of thick sandstone unit, interbedded sandstone, siltstone and shale unit and shale unit. A total of Five 2D electrical resistivity imaging (ERI) methods were carried to image and model the subsurface within the research area to investigate the possibility of seawater intrusion. The ERI results are also supported by four groundwater samples and detailed lithologies from the borehole. Interpretation of the results divided the research area into three main zones of seawater intrusion potentials. Zone 1 is considered the highest potential of seawater intrusion, Zone 2 interpreted as potential extended zone or mixing zones between seawater and fresh water and finally Zone 3 did not indicate any low resistivity or potential of seawater intrusion. The seawater intrusion map produced from this research initiated and divided the potential zones based on the occurrence of seawater in the subsurface.

Geochemical Distribution of Heavy Metals in Peat Soil Profile and Estimation of Water Table Patterns in Peatland at Klias Peninsular, Sabah.

The geochemical distribution of heavy metals in peat soil profile and estimation of water table patterns of peatland in oil palm plantation were carried out in the Klias Peninsular West Coast of Sabah. The geological setting of the Klias Peninsular mainly consists of the Crocker Formation and Quaternary Alluvium which in mainly composed of peat soil. The peat soil from 10 sites were collected for the geochemical analysis. The geophysical surveys were performed to measure the water table, which influenced the concentration of trace metals. The geochemical analysis of the peat soil at 0-6m depth shows an acidic pH value (3.0-4.0), moisture content (90%-1000%) and organic matter content (30-99) %. The texture of the peat soil profile varies from peat at the top of profile to silty clay at the bottom of the peat profile. The result of geochemical analysis shows that the element of Fe has the highest concentration (37.54-2049.18)mg/kg and followed by Zn(5.13-270.06)mg/kg, Mn(0.1-253.56)mg/kg, Pb(0.71-157.46)mg/kg, Cr(0.05-152.62)mg/kg, Ni(0.1-64.48) mg/kg and Cu(1.81-61.39)mg/kg. The water table ranging from (0.25m-0.3m) induced the oxidation of Fe. The concentration of Fe2+ tends to absorb other elements such as Zn and Mn. Whereas, the organic matter at pH value (5-5.5) enhanced the absorption of elements Pb, Cr, Ni and Cu in the peat soil profile.

Seismostratigraphic and sedimentological characterization of deepwater channel systems on the NW Borneo margin: Sediment sources and structurally-controlled routing system

• Late Miocene folding in deepwater NW Borneo influenced submarine channel development. • The Champion sediment-supply system comprised in its onshore part multiple rivers. • The paleo-Padas River was one of the primary rivers supplying lithic-rich sediment. • Variation in catchment-area geology influenced deepwater sediment composition. The northwest (NW) Borneo margin is one of the geologically most complex regions of Southeast Asia characterized by a steep slope gradient and an extensive deepwater fold and thrust belt. This area is economically important because of large-volume hydrocarbon accumulations in the deep-marine sandstones in fold and thrust anticlines. Although much attention has been paid to the distribution of deepwater reservoir rocks, the provenance of these rocks and compositional variations are yet not fully understood. In this study we present geomorphological and petrological analyses of Late Miocene deepwater channel deposits that form important reservoirs in the region. Our results reveal the presence of a northwest-trending deepwater channel system displaying morphological variations induced by syn -sedimentary structural development. Petrological analyses of core samples show a predominant lithic-rich rock composition in the reservoir sandstones, suggesting sediment supply from a lithic-rich Crocker Formation hinterland, probably through a paleo-Padas River. This rock composition differs from the quartz-rich rock composition of an adjacent contemporaneous deepwater reservoir mainly comprising reworked quartz-rich Meligan sandstones. The observed petrological differences are interpreted to reflect a Late Miocene multi-source sediment supply system that drained offshore different NW Borneo hinterland areas. Offshore, sediment transport to and across the slope was dominantly margin-perpendicular, linear or of low sinuosity, in the deepwater locally affected by faulting and folding. This study provides new insights into the complexity of sediment routing systems along continental margins, highlighting the influences of the configuration of the sediment supply system and tectonics on deepwater sedimentation.

Insights on deepwater turbidite sedimentary features from outcrops in onshore Northwest Sabah, Malaysia

This paper discusses findings of sedimentary features observed from deepwater outcrops in Northwest Sabah. The observations were based on 7 outcrop localities of Lower Oligocene – Upper Oligocene sections around Klias and Kudat Peninsulas, and Kota Kinabalu, covering Temburong, Belait, West Crocker, and Kudat formations. Temburong Formation (Lower Oligocene-Lower Miocene) was observed at Menumbok (Stop 1) and Tanjung Aru (Stop 2). It comprises interbedded shale and sandstone turbidite sequence representing deposition in deepwater setting. At Batu Luang (Stop 3) the deepwater turbidite Temburong Formation is observed overlain unconformably by stacked fluvial channel deposits of Belait Formation (Middle to Upper Miocene). Here, the overlying fluvial deposits comprise predominantly conglomerates which are believed to represent basal Belait Formation lies over regional unconformable surface correlatatable to Deep Regional Unconformity (DRU). Deepwater West Crocker Formation (Lower Oligocene-Lower Miocene) was observed at King Fisher-Sulaman, Kota Kinabalu (Stop 4), composed of predominantly thick sandstone interbedded with shale. Meanwhile, Sikuati Member of the Kudat Formation (Lower Miocene) was observed at Pantai Sikuati (Stop 5) and Bukit ‘V’ (Stop 6) outcrops. It consists of interbedded sandstone and shale of turbidite successions. At Tanjung Simpang Mengayau (Stop 7) thick sandstone interbedded with thin shales of Kudat Formation was observed. In general, the Temburong Formation at Stops 1 and 2 show Bouma sequence of Ta-Tb-Te successions, but relatively thicker Te at Stop 1 suggesting a prolonged mud suspension deposit compared to Stop 2. At Stop 3, the deepwater Temburong Formation was subjected to a substantial tectonic uplift and massive erosion associated with DRU. Further northwards at Stop 4 West Crocker Formation exhibits thicker Ta successions which implies deposition within a slightly higher energy regime as compared to that of Temburong Formation at Stop 3. Meanwhile, at Stops 5 and 6 different depositional energy levels are shown in the lower and upper stratigraphic intervals. In the lower interval deposition took place within a higher energy condition as shown by thick Ta. It was followed by gradual decreasing depositional energy regime in the upper interval as shown by predominance Tc-Td-Te. Meanwhile, at Stop 7 a thick massive graded sandstone overlain by thin mudstone bed was observed which implies a prolonged Ta succession followed by short-term Te of mud suspension deposits.

Geophysical Investigation and Geochemical Study of Sediment along the Coastal Area in Kota Belud Sabah, Malaysia

This article discusses the geophysical investigation of sediment and the status of heavy metals pollution in the coastal sediment from Usukan Beach, Kota Belud Sabah Malaysia. Study area is located at the northwest coast of Sabah which is bounded by the South China Sea and made up of Crocker Formation which age from Late Eocene to Early Miocene, Wariu Formation with Middle Miocene age and Quaternary Alluvium. This study using geoelectrical method namely electrical resistivity (IR) and induced polarization (IP) to measure the thickness of sediment and the parent rock lithology respectively. Whereas the heavy metal contents were measured using the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP- OES). Three sets of subsurface cross-sections were conducted for the geophysical survey and covered the depth around 37 meters for all the survey line. The result of geophysical survey shows that the alluvium quaternary deposits in the low-lying flat area have a thickness up to 13 metres and overlie the mudstone dominated rock of the Crocker Formation. The geochemical analysis shows a decreasing ranking order of elemental concentrations Fe>Mn>Zn>Cu>Pb>Cr>As. The analyses show all elements are within the background values and acceptable standard limits of the Sediment Quality Guidelines (SQG) by USEPA for coastal sediments. The assessment of heavy metals revealed only minimal degree of pollution in the coastal sediments.

GEOPHYSICAL APPLICATION FOR GROUNDWATER POTENTIAL AND WATER QUALITY ANALYSIS OF MELANGKAP AREA, KOTA BELUD, SABAH

The study area is located at Melangkap area of Kota Belud, Sabah, Malaysia which comprises of Crocker Formation aged Late Eocene to Early Miocene and Quaternary alluvium deposits. This study focuses on groundwater potential using electrical resistivity method and water quality analysis of the study area. Schlumberger array using ABEM Terrameter LS instrument and Res2DINC software is used for data acquisition. Three survey lines were conducted in Kg. Melangkap, Kg. Kebayau dan Kg. Tambatuon. Water samples from existing boreholes from these locations were analysed based on Drinking Water Standard by Malaysian Department of Environment. Subsurface interpretation showed the layer of shale with resistivity value of 20 – 40 ohm-m, fractured sandstone with 20 -175 ohm-m, interbedding of shale and sandstones with 60 – 500 ohm-m, saturated sandstones with 40 – 1000 ohm-m, thick sandstones with 500 – 1000 ohm-m and gravel deposits with 175 – 1000 ohm-m. Each survey line showed 3 zones of different materials. Kg Kebayau shows the best potential for groundwater supply than Kg Melangkap and Kg Tambatuon, due to existence of 12 m thickness of sandstone aquifer. Water quality analysis shows the heavy metals concentration for all samples are within permitted range for drinking water consumption. However, water sample from Kg Kebayau borehole has the lowest value of electrical conductivity, total dissolved solids, chloride content and heavy metals concentration made it the cleanest among all samples, which is widely used by the villagers of Kg Kebayau for drinking and external purposes.

Facies Analysis Of The Late Eocene Deep-Marine Middle- To Outer-Fan Sequence Of The Crocker Formation In Tenom District, Sabah, Malaysia

The Crocker Formation, Late Eocene to Middle Miocene in age, was deposited in a deep-marine environment by a turbidity current. Most of the facies identified in the field are related to the sedimentary bed-form structures belonging to Bouma sequences. These prominently include unit divisions such as Ta referring to grading sand, Tb for parallel laminae, Tc for cross laminae, Td for mud laminae, and Te referring to hemipelagic mud. Five facies have adequately been identified using Bouma sequence implications, namely Facies 1 (F1: Ta-Tb layers), Facies 2 (F2: Ta-Te layers), Facies 3 (F3: Tb-Te layers), Facies 4 (F4: Tb / Tc-Te layers), and Facies 5 (F5: Td-Te layers). Based on the Crocker Formation facies analysis, three distinct groups of facies associations were recognised: Deep-Marine Channel-Lobe Association (Type A1), Deep-Marine Channel-Levee Association (Type A2), and Distal Lobe Association. These facies associations precisely revealed that the Crocker Formation's depositional environments were likely deposited in the middle-fan with associated outer-fan settings.

Aseismic and seismic impact on development of soft-sediment deformation structures in deep-marine sand-shaly Crocker fan in Sabah, NW Borneo

Soft-sediment deformation structures are present within the deep-marine fan of the West Crocker Formation, Sabah Basin, NW Borneo. Focus of this study is to highlight the impact of seismic and aseismic activities on the development of these structures and their distribution in deep-marine fan. Twenty-nine types of deformation structures were identified during the study of twelve exposed sections. These structures were grouped into five categories: i) water-escape structures, ii) sole marks, iii) clastic intrusions, iv) deformed laminations, and v) syn-depositional brittle and ductile deformation structures. The sediment deformation is interpreted to be caused either by aseismic processes like slope failure, gravity collapse, sediment overloading, density gradient, seismic induced mechanisms such as earthquakes, tectonic uplift, or combined effect of seismic and aseismic events. These structures are classified based on type of features developed during semi-consolidated phase of rock deposition. The seismite structures i.e., clastic intrusions, deformed laminations, and syn-depositional structures are correlated with active collisional tectonics during the Late Paleogene times in the Sabah Basin. In the present work, a generalized conceptual model has also been proposed for the development of soft-sediment deformation structures in a submarine fan environment. Dewatering structurers and rapid sedimentation features are associated with inner fan, load and flame structures are present within middle fan, while contorted layers, slumps and mass-transport deposits are linked with distal fan settings.

Facies Heterogeneity and Lobe Facies Multiscale Analysis of Deep-Marine Sand-Shale Complexity in the West Crocker Formation of Sabah Basin, NW Borneo

Deepwater lobes constitute a significant volume of submarine fans and are primarily believed to exhibit a simple sheet geometry. However, recent studies interpret the geometries of these deep-marine lobes as distinct with respect to the complexity of the facies and their distribution. Hence, a conceptual model of deep-marine sediments is essential to discuss the deep-marine sediments associated with the fan and lobe architecture. The present study highlights the facies heterogeneity and distribution of various lobe elements at a multiscale level by considering a case study of the West Crocker Formation of Sabah in northwest Borneo. The formation was logged on a bed-to-bed scale from recently well-exposed sections, with a total vertical thickness of more than 300 m. The lithological characteristics, bed geometry, sedimentary textures and structures of individual beds were used to categorize the rock units into nine sedimentary lithofacies: five sandstone lithofacies (S1–S5), one hybrid bed facies (H), two siltstone facies (Si1 and Si2) and one shale or mudstone facies (M). These facies were grouped into four facies associations (FA1–FA4), which were interpreted as lobe axis (FA1), lobe off-axis (FA2), lobe fringe (FA3) and distal fringe to interlobe (FA4) facies associations. This study is applicable for the distribution of lobes and their subseismic, multiscale complexities to characterize the potential of hydrocarbon intervals in deep-marine sand-shale system around the globe.

Deep-Sea Trace Fossils In The West Crocker Formation, Sabah (Malaysia), And Their Palaeoenvironmental Significance

In the “flysch” series of the West Crocker Formation (Eocene–Oligocene), Kota Kinabalu, Sabah, trace fossils are fairly common although not ubiquitous. The trace fossils commonly occur as hypichnial semi- or full-reliefs on the sole of thin turbiditic sandstone beds (mainly Bouma Tc division) in the thinly bedded heterolithic sandstone-mudstone facies interpreted as submarine fan lobe deposits. Their presence in mainly the thinly bedded facies of the fan system suggests preferential production and preservation in the fine-grained “distal” parts of the Crocker submarine fan system. Trace fossil assemblages characteristic of the Nereites ichnofacies indicate sedimentary environments mainly in bathyal to abyssal water depths (>2000 m). This ichnofacies is dominated by horizontal grazing, farming and feeding traces, ranging from solitary to branching tubular burrows (Ophiomorpha, Palaeophycus and Planolites) to meandering trails and tunnels (Nereites, Cosmorhaphe, Helminthopsis), as well as the spiriform burrows Spirophycus. Graphoglyptids are the most diagnostic of the Nereites ichnofacies, produced by sediment grazers and farmers (agrichnia) and often displaying intricate networks of mainly horizontal tunnels preserved as hypichnial semi-reliefs. They include the delicate spiral traces of Spirorhaphe, as well as the enigmatic hexagonal network burrow Paleodictyon. Other ichnogenera include Planolites, Thalassinoides and Ophiomorpha which are facies-crossing and not environment specific. Detailed observations of the trace fossil assemblages and the degree of bioturbation enabled different sub-ichnofacies of the Nereites ichnofacies to be distinguished. Ophiomorpha is more common in sandy “proximal” facies and tend to penetrate deeply into pre-existing turbidite beds, its presence suggests a well-oxygenated newly deposited turbidite substrate, probably in the axial region of the fan lobes. Hence, channel axis and proximal fan deposits tend to be dominated by the Ophiomorpha rudis sub-ichnofacies. The Paleodictyon sub-ichnofacies is more typical of the lower energy lobe/fan fringe subenvironments. Proximal but off-axis areas are characterized by a mixture of the Ophiomorpha rudis and Paleodictyon sub-ichnofacies.

Causes and consequences of Oligocene-Miocene relative sea level change in Asia: An example from the Labuan Island (Sabah), Malaysia

Belait Formation: (A) Trough cross-bedded sandstone (fluvial) (B) Interbedded sandstone-mudstone (sandstone dominated) facies overlying mudstone facies (marine). • The Miocene Belait Formation in the Labuan Island formed due to forced regression. • The upper part of the Belait Formation indicates transgression and marine flooding. • The depositional environment changed during the Oligocene-Miocene in Sabah and Sarawak. • This was linked to regional tectonics and/or global relative sea level. • No record of paleoclimate shift like central Asia is inferred in this study. Labuan Island represents the emergent part of a north-eastward plunging anticline. The stratigraphic succession at Labuan is made up of four formations: the Crocker Formation, the Temburong Formation, the Setap shale Formation and the Belait Formation. The sedimentological aspects of the Labuan stratigraphic succession have been studied by several authors but the stratigraphic relationships between the formations is still a matter of conjecture. In this paper we have undertaken an outcrop based (1) sedimentary facies analysis of the Middle Miocene Belait Formation and (2) inferred the mode of stratigraphic sequence building of the Oligocene-Miocene successions. In significant contrast to the tide-storm interactive shallow-marine Belait Formation of Brunei and Sarawak, the Belait Formation of the Labuan island is made up of a lower fluvial and an upper shallow marginal marine to shelf facies association. The sedimentary succession from the Crocker, Temburong, Setap Shale and Belait formations represents a marine regression either due to a relative sea-level fall (forced regression) or to sediment supply exceeding the rate of sea-level rise (normal regression). The ~17 million years unconformity separating the fluvial facies association of the Miocene Belait Formation from the underlying shelfal sedimentary units (Oligocene Temburang and/or Setap shale formations) is a subaerial unconformity that is a consequence of rapid uplift and associated forced regression, and thus indicates the influence of regional tectonics on the mode of stratigraphic sequence building The change in paleocurrent pattern recorded by earlier researchers across the Oligocene-Miocene boundary also indicates tectonic tilt, and a change in sediment dispersal direction because of upliftment. The upper marginal marine facies association of the Belait Formation indicates transgression and the thick shelfal mudstone unit that overlies the marginal marine deposit indicates subsequent maximum flooding. Our sedimentological and stratigraphic analyses reveal that the shift in depositional environment during the Oligocene-Miocene transition is linked to regional tectonics and consequent sea level change and unrelated to paleoclimatic shift.

A tuffaceous volcaniclastic turbidite bed of Early Miocene age in the Temburong Formation of Labuan, North‐West Borneo and its implications for the Proto‐South China Sea subduction in the Burdigalian

AbstractA 2 m thick bed of smectite‐rich clay within a sequence of distal deep water turbidites and marine mudstones of the Temburong Formation on the island of Labuan, Sabah, North‐West Borneo, is an altered, re‐sedimented pyroclastic tuff which is geochemically of rhyolite‐dacite composition. The tuff bed was deposited in deep water, although probably <1,000 m, by traction currents and retains relic siliceous shards, feldspar phenocrysts and biotite crystals but was dominated by ash‐grade material. The tuff is interpreted as a turbidite deposit and most probably records long distance sub‐marine transport down the depositional slope from an active volcanic system in the hinterland. It has a zircon U–Pb weighted mean age of 19.6 ± 0.1 Ma whilst combined forminiferal and nannofossil ages from the enclosing marine mudstones range from 21.5 to 19.4 Ma; together these indicate an early Miocene age for the Temburong Formation. The tuff is the result of a very short‐lived volcanic arc magmatic episode and was either related to similar aged volcanics of the Sintang Suite in central Borneo or a product of the Proto‐South China Sea subduction beneath the Cagayan arc north‐east of Borneo. The age indicates that deep water sedimentation in North‐West Borneo continued into the Burdigalian suggesting the subduction trench of the Proto‐South China Sea was active into the early Miocene, beneath the depocentre of the Temburong turbidite fan. By contrast, sandstones representative of the typical marine Temburong Formation yield abundant zircons which are dominately Cretaceous in age indicating an important switch in source provenance during the Early Miocene from the Crocker Formation that is dominated by Permian‐Triassic zircons. This difference in zircon populations likely reflects an important tectonic event in the early Miocene that resulted in uplift of central Borneo to supply sediment to the Sabah Trough whilst the input of material derived from the western terrains diminished. The Temburong Formation was sourced by reworking of uplifted Rajang Group, Sapulut or Trusmadi formations.

LANDSLIDE HAZARD IDENTIFICATION (LHI) BASED ON GEOELECTRICAL MAPPING ANALYSIS (GEM): CASE STUDY FROM LUYANG, KOTA KINABALU, SABAH, MALAYSIA

Landslides are amongst the most damaging natural hazards in Malaysia. The study of landslides has drawn nationwide attention mainly due to increasing awareness of the socio-economic impact of landslides, as well as the increasing pressure of urbanization. Landslide Hazard Identification (LHI) is part of the process used to evaluate if any particular situation, item, thing, etc. may have the potential to cause harm. The description of LHI should include the location, volume (or area), classification and velocity of the potential landslides and any resultant detached material, and the probability of their occurrence within a given period of time. In this paper, we present the results of the measurement for the subsurface resistivity within by using the pole-dipole electrode array and present the 2D view of each resistivity profile. The result presented successfully detect the dominant layer consists of interbedded sandstone and shale of the Crocker Formation with highly weathered. This both layers have high porosity and potential to contain high water content which can trigger landslide to occur. Besides that, there are several boulders zone (weathered to fresh rock) that can be found at the top of the subsurface profile at about 1.5m to 15m in depth. The bedrock layer was estimated to be found at 4m to 32.5m in depth from the original ground and one possible fault line that had been identified. This fault line believed plays a role in the occurrence of landslide in which rock materials have lower strength compared to surrounding rocks. High density of fault means lower stability. Therefore the faut line have been regarded as a critical factor in triggering landslide in the study area. The results of these study findings are expected to be used as uniform guidelines and principles are very useful and have integrity in providing coordination of standards or policies for each planning activities for new development in the future. As a result of the lack of concern for the developer of the concept of Sustainable Development Goals (SDG) or balancing and control of environmental health, the results of this study can also be used as a yardstick to party developers who intend to develop a high ground and hillside in deciding whether to continuing development planning or not.