Geology of slopes in the Crocker Range, Sabah, Malaysia

Tongkul, Felix; Benedick, H.; Chang, F. K.

doi:10.3126/jngs.v34i0.31881

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…In Sabah, Crocker and Trusmadi Range (CTR) became the major geological barrier that separates the western and eastern riverine and floodplains habitats. Crocker Range (CR) is the highest range in the mountainous western part of Sabah with an average altitude of 2000 m, more than 40 km wide, stretches about 200 km along, and mountains up to 4000 m in height [76]. Situated adjacent to the CR is the 80 km Trusmadi Range (TR), which houses the second-highest mountain peak in Malaysia.…”

Section: Phylogeography and Population Structurementioning

confidence: 99%

Phylogeographic Structure of Freshwater Tor sp. in River Basins of Sabah, Malaysia

Biun¹,

Sade²,

Robert

et al. 2021

Fishes

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We characterized the genetic diversity, phylogeography, and demography of Tor sp. (Cyprinidae) from Sabah, Malaysian Borneo, by examining nucleotide variation in the D-loop region of the mtDNA. Sequence analysis of 18 populations (N = 173) yielded 35 unique mtDNA haplotypes with mean haplotype and nucleotide diversity of 0.833 and 0.023, respectively. Phylogenetic reconstructions using Bayesian, neighbor-joining, and maximum parsimony methods, as well as haplotype network, revealed four well-defined clades, namely, the eastern, central, northwestern, and southwestern clades, which corresponded to evolutionarily significant units (ESUs). These ESUs were estimated to have become separated since the late Miocene to Pliocene era (between 5 and 1 million years ago), with the central highlands of Sabah Crocker Trusmadi Range (CTR) constituting the main barrier to genetic exchange between clades. Analysis of molecular variance (AMOVA) and pairwise genetic differentiation showed significant population structuring (Φct = 0.575–1.000, p < 0.05). We further identified eight major groups of river systems harboring reproductively isolated Tor subpopulations. Neutrality statistics and Bayesian skyline plots (BSP) suggested constant population size over time for most Tor populations. Tor sp. in Sabah is comprised of four ESUs (eastern, central, northwestern, and southwestern ESUs), and that each ESU can be compartmentalized into 1–4 MUs. Due to isolation by distance, the highest number of MU occurs in the low-elevation drainages of Eastern Sabah, which is the largest in terms of land area. The evidence provided by this study supports the hypothesis that the four ESU represent genetically distinct subpopulations of Tor and highlight the urgent need for the in situ conservation of these subpopulations.

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Section: Phylogeography and Population Structurementioning

confidence: 99%

Phylogeographic Structure of Freshwater Tor sp. in River Basins of Sabah, Malaysia

Biun¹,

Sade²,

Robert

et al. 2021

Fishes

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

2022

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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.

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Geology of slopes in the Crocker Range, Sabah, Malaysia

Cited by 2 publications

References 2 publications

Phylogeographic Structure of Freshwater Tor sp. in River Basins of Sabah, Malaysia

Phylogeographic Structure of Freshwater Tor sp. in River Basins of Sabah, Malaysia

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

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