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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 subichnofacies. 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. [ABSTRACT FROM AUTHOR]

A timely and updated review of the Late Paleogene deep marine sedimentary successions is vital for a better understanding of the historical advances in sedimentology and stratigraphic evolution of West Sabah. The main objective of the study is to discuss the facies characteristics and depositional environment of the Late Paleogene rock formations. In addition, the stratigraphic aspects of the Paleogene interval will also be discussed. The Oligocene Temburong Formation exposed in several localities of West Sabah had been field researched with varying depositional processes and facies analysis. Moreover, the distribution of submarine fan, the observed variety of deep marine sediments associated with various sedimentary processes and the source of sediments of the co-eval West Crocker Formation were also investigated with contorted layers of mass transport deposits (MTD) reported first time in the formation. The upper and lower stratigraphic contacts of Late Paleogene formations, the age of individual rock formations and use of the term "Crocker Formation" in the literature are discussed with numerous unconformities and their stratigraphic positions in the Paleogene interval have been incorporated to understand the historical development of the Paleogene stratigraphy of the West Sabah. Owing to degrading tropical climate of the area, there are limitations and constraints on field-based research where the older outcrops are altered with housing development and dense vegetative cover. This review outlined the scientific developments and highlighted the ambiguities associated with stratigraphic placement of the Temburong and Crocker formations that still needed to be resolved to get an upgraded depiction of the Late Paleogene sediments of West Sabah. [ABSTRACT FROM AUTHOR]

The Belaga Formation is a deep marine turbidite interpreted in relation to a submarine fan and therefore a prospect worth evaluating. The scope of this paper will focus on the shales from the thick sedimentary sequence of the Belaga Formation (Upper Cretaceous to Eocene) consisting of five (5) members in Central Sarawak, Malaysia, of which attention is given to the depositional environment and clay minerals as factors to consider as predictive tools for organic matter richness and gas storage capacity using the spectral gamma ray method using Thorium (Th), Potassium (K) and Uranium (U) as indices for inferences. A mineralogical chart of Th/K (ppm/%) indicates that the dominating clay minerals of the shales are mixed-layer types. The Th/U as a redox indicator is used to assert that the shales are of anoxic conditions of deep-marine environments. Despite the relatively high insoluble Th values (9.93-20.13) ppm, the presence of U in substantial amounts, which only occurs in reducing conditions where it is preserved as a lower insoluble valence (U4+) explains for the low Th/U values ranging between (1.86-4.57) ppm/ppm of the fifty-eight analyzed shale samples. The overall Th/U value of the evaluated shales remain less than 7, where Th/U < 7 is suggestive of marine sediments, grey and green shales, whereas Th/U < 2 is indicative of marine black shales of reducing conditions. The 30Ma interval of sediment deposition of the Belaga Formation Eocene recorded varied climatic fluctuations influential to clay minerals contained in the shales and ascribe the paleoweathering state of the shales, which from the standard imitative ternary plot of normalized K-U-Th of shales from Northern America address the shales of the Belaga Formation as of deep weathering residuum. [ABSTRACT FROM AUTHOR]

The Temburong Formation comprises fine grain flysch, deposited in a distal part of a submarine fan system. Twenty five taxa of ichnofossils were identified. The ichnofossils are grouped into the Nereites ichnofacies. The ichnofacies was further divided into two subichnofacies namely Paleodictyon and Ophiomorpha rudis subichnofacies. The Paleodictyon subichnofacies is characterized by a high diversity of ichnofossils, discovered in the medium to thinly bedded turbidite at a distal lobe of a submarine fan. The Ophiomorpha rudis subichnofacies contains low diversity and is commonly found in thick-bedded sandstone channels and proximal lobes of a submarine fan system. [ABSTRACT FROM AUTHOR]