Northwestern Borneo Research Articles

Local scale, proxy evidence for the presence of closed canopy forest in North-western Borneo in the late Pleistocene: Bones of Strategy I bats from the archaeological record of the Great Cave of Niah, Sarawak

The limits of the distribution of closed canopy forest in Southeast Asia during the glacial cycles of the Pleistocene are the subject of continuing debate. In this context, this paper reports the results of an analysis of a novel line of evidence as a local scale case study.22 dated assemblages of bat bones that were recovered from the archaeological sequences of the Great Cave of Niah in Sarawak, Malaysian Borneo were examined. By examination of the morphological characteristics of the distal articulation of the humerus, seven families and nine genera were identified. Five species level attributions could be made. These assemblages formed a time series of 14 chronological intervals 48–0.35kyBP (kyBP: 103 calibrated years before present [1950]) incorporating samples from the high glacial interval (26–18kyBP) and Last Glacial Maximum (23–19kyBP).Bones of bat taxa that are adapted to forage in the cluttered environments in the interior of closed canopy forest (“Strategy I” bats) were employed as proxy evidence for the presence of closed canopy forested habitats in the vicinity (<30km radius) of the Great Cave.Bones of Strategy I bats (principally small Hipposideros spp.) were identified in all examined assemblages and intervals in the time series. Statistical testing indicated no evidence of differences in the absolute frequency of distal humeri from Strategy I bats in the Pleistocene samples 48–11.8kyBP, or in the entire time series 48–0.35kyBP and no significant linear trend was found in the time series to suggest an increase of the bones Strategy I bat taxa with the onset of the Holocene. These findings suggest that closed canopy forest habitats have been a persistent component in the landscape around the Great Cave of Niah since 48kyBP. A taphonomic hypothesis is proposed to explain the dichotomy between the findings of this study and the pollen record of the site.

Ancestry of the Iban Is Predominantly Southeast Asian: Genetic Evidence from Autosomal, Mitochondrial, and Y Chromosomes

Humans reached present-day Island Southeast Asia (ISEA) in one of the first major human migrations out of Africa. Population movements in the millennia following this initial settlement are thought to have greatly influenced the genetic makeup of current inhabitants, yet the extent attributed to different events is not clear. Recent studies suggest that south-to-north gene flow largely influenced present-day patterns of genetic variation in Southeast Asian populations and that late Pleistocene and early Holocene migrations from Southeast Asia are responsible for a substantial proportion of ISEA ancestry. Archaeological and linguistic evidence suggests that the ancestors of present-day inhabitants came mainly from north-to-south migrations from Taiwan and throughout ISEA approximately 4,000 years ago. We report a large-scale genetic analysis of human variation in the Iban population from the Malaysian state of Sarawak in northwestern Borneo, located in the center of ISEA. Genome-wide single-nucleotide polymorphism (SNP) markers analyzed here suggest that the Iban exhibit greatest genetic similarity to Indonesian and mainland Southeast Asian populations. The most common non-recombining Y (NRY) and mitochondrial (mt) DNA haplogroups present in the Iban are associated with populations of Southeast Asia. We conclude that migrations from Southeast Asia made a large contribution to Iban ancestry, although evidence of potential gene flow from Taiwan is also seen in uniparentally inherited marker data.

Host specificity and niche partitioning in flea-small mammal networks in Bornean rainforests

The diversity of ectoparasites in Southeast Asia and flea-host associations remain largely understudied. We explore specialization and interaction patterns of fleas infesting non-volant small mammals in Bornean rainforests, using material from a field survey carried out in two montane localities in northwestern Borneo (Sabah, Malaysia) and from a literature database of all available interactions in both lowland and montane forests. A total of 234 flea individuals collected during our field survey resulted in an interaction network of eight flea species on seven live-captured small mammal species. The interaction network from all compiled studies currently includes 15 flea species and 16 small mammal species. Host specificity and niche partitioning of fleas infesting diurnal treeshrews and squirrels were low, with little difference in specialization among taxa, but host specificity in lowland forests was found to be higher than in montane forests. By contrast, Sigmactenus alticola (Siphonaptera: Leptopsyllidae) exhibited low host specificity by infesting various montane and lowland nocturnal rats. However, this species exhibited low niche partitioning as it was the only commonly recorded flea from rats on Borneo. Overall complementary specialization was of intermediate intensity for both networks and differed significantly from random association; this has important implications for specific interactions that are also relevant to the potential spread of vector-borne diseases.

&lt;I&gt;Nepenthes baramensis&lt;/I&gt; (&lt;I&gt;Nepenthaceae&lt;/I&gt;) – a new species from north-western Borneo

Nepenthes baramensis, a new species from peat swamp and heath forests in north-western Borneo, is described. It is distinguished from related species on the basis of its modified pitchers, which facilitate a facultative mutualistic interaction with Hardwicke’s Woolly Bat, Kerivoula hardwickii, which roosts in its pitchers and may provide the plant with a substantial proportion of its foliar nitrogen.

Erratum : Lithology and reefal fauna of the Bau Limestone Formation in northwestern Borneo, Malaysia.

Erratum : Lithology and reefal fauna of the Bau Limestone Formation in northwestern Borneo, Malaysia.

Lithology and reefal fauna of the Bau Limestone Formation in northwestern Borneo, Malaysia.

Lithology and reefal fauna of the Bau Limestone Formation in northwestern Borneo, Malaysia.

Spatial pattern of landslides due to heavy rains in a mixed Dipterocarp forest, North-Western Borneo

Spatial pattern of landslides due to heavy rains in a mixed Dipterocarp forest, North-Western Borneo

Variation in juvenile survival and related physiological traits among dipterocarp species co-existing in a Bornean forest

Abstract Question: What environmental factors and physiological traits determine the juvenile survival rates of 11 dipterocarp species (Dipterocarpaceae) co-occurring in a Bornean tropical rain forest? Location: Tropical northwestern Borneo. Methods: In 248 quadrats, distributed over 12 ha, the juvenile (height< 2.0 m) survival of 11 shade-tolerant dipterocarp species was monitored for one year. The probability of survival for each species was expressed as a logistic function of plant height and three environmental factors: canopy openness, soil water potential and conspecific individual density. The correlation between survival under shaded conditions and several physiological traits of juveniles was tested by normal Pearson correlation and a phylogeny based manner using independent contrasts. Results: Seven species had increased survival under more open canopies, one species had increased and two species had decreased survival at drier sites. Six species had higher survival as the density of conspecific...

Interaction between critical wedge geometry and sediment supply in a deep-water fold belt

Research Article| February 01, 2007 Interaction between critical wedge geometry and sediment supply in a deep-water fold belt C.K. Morley C.K. Morley 1272 Baan Yosawaadi, 7, Pahonyohothin, Bangkok 10500, Thailand Search for other works by this author on: GSW Google Scholar Geology (2007) 35 (2): 139–142. https://doi.org/10.1130/G22921A.1 Article history received: 21 Apr 2006 rev-recd: 13 Sep 2006 accepted: 25 Sep 2006 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation C.K. Morley; Interaction between critical wedge geometry and sediment supply in a deep-water fold belt. Geology 2007;; 35 (2): 139–142. doi: https://doi.org/10.1130/G22921A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The late Miocene–Holocene deep-water fold-and-thrust belt of offshore northwestern Borneo displays one of the most acute angles recorded for a submarine critical-taper wedge. The very low surface (1°–2.5°) and basal detachment (2°–5°) dips require basal pore-fluid pressures near lithostatic pressure for the wedge to propagate at such angles. In the deep-water environment, sedimentary processes act against the wedge attaining critical taper. In places of lower sedimentation rates, the fold-and-thrust belt extends to the base of the slope and dips ∼1.5°–2.5°. In areas of the highest sedimentation rates (Baram Delta), the slope has a lower angle (1°) and the slope continues beyond the limit of the fold-and-thrust belt. Slope morphology changes along the margin from concave up (relatively low sedimentation rate, low shortening rate), to convex up (relatively high sedimentation rate, low shortening rate), to stepped (relatively low sedimentation rate, high shortening rate). You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Geochemical and Nd isotopic variations in sediments of the South China Sea: a response to Cenozoic tectonism in SE Asia

Secular variations in geochemistry and Nd isotopic data have been documented in sediment samples at ODP Site 1148 in the South China Sea. Major and trace elements show significant changes at ca. 29.5 Ma and 26–23 Ma, whereas ϵ Nd values show a single change at ca. 26–23 Ma. Increases in Al/Ti, Al/K, Rb/Sr, and La/Lu ratios and a decrease in the Th/La ratio of the sediments beginning at 29.5 Ma are consistent with more intense chemical weathering in the source region. The abrupt change in Nd isotopes and geochemistry at ca. 26–23 Ma coincides with a major discontinuity in the sedimentology and physical properties of the sediments, implying a drastic change in sedimentary provenance and environment at the drill site. Comparison of the Nd isotopes of sediments from major rivers flowing into the South China Sea suggests that pre-27 Ma sediments were dominantly derived from a southwestern provenance (Indochina–Sunda Shelf and possibly northwestern Borneo), whereas post-23 Ma sediments were derived from a northern provenance (South China). This change in provenance from southwest to north was largely caused by ridge jumping during seafloor spreading of the South China Sea, associated with a southwestward expansion of the ocean basin crust and a global rise in sea level. Thus, the geochemical and Nd isotopic changes in the sediments at ODP Site 1148 are interpreted as a response to a major plate reorganization in SE Asia at ca. 25 Ma.

Depositional sequences controlled by high rates of sediment supply, sea-level variations, and growth faulting: the Quaternary Baram Delta of northwestern Borneo

Abstract The shelf off the Baram Delta is 50–70 km wide, and is underlain by 8–9 km of post-Eocene upper slope, prodelta, delta-front, fluvial, shelf–shoreface, and estuarine (incised-valley and tidal-embayment) deposits. The shelf break is defined by a prominent fault scarp ∼130 m below sea level. Beyond, the seabed descends at an average of 2–3° to the Borneo Trough at >2750 m depth. The outer-shelf Quaternary succession is locally >1 km thick. Uppermost Quaternary units then thicken by a factor of 2–5 across an en echelon set of shelf-edge growth faults. Five widespread ‘key’ reflectors, traced with the aid of 1500 line-km of high-resolution seismic profiles, are downlap surfaces beneath clinoforms on the shelf. Two of these reflectors directly overlie fluvial channels. These are interpreted as erosional ravinement surfaces that formed during shelf-crossing post-glacial transgressions, and correlate with surfaces of maximum regression in the slope succession. Acoustic facies on the shelf, calibrated by 15 60–100 m-long geotechnical borings, are interpreted as muddy prodelta, transgressive, and incised-valley deposits; forced-regressive and lowstand fluvial channel sands; shelf-edge sandy deltas; and reworked sands along ravinement surfaces. Muddy prodelta deposits drape the slope. Isopach maps of strata between ‘key’ reflectors reveal shingled highstand to lowstand delta lobes. A widespread 4th-order Lowstand–Bypass Sequence developed during the 120–10 ka sea-level cycle. It reaches 400 m thickness and resembles 3rd-order sequences of Vail and coworkers, but with a thinner Transgressive Systems Tract and a thick Forced Regressive Systems Tract (FRST). The FRST includes sandy shelf-edge deltas deposited by small rivers after the Baram system began to bypass the shelf through an incised valley. The incised valley belongs to a contemporaneous Valley–Canyon Sequence and is filled with lower FRST to Lowstand Systems Tract fluvial deposits, and upper backstepping deltaic deposits of the retreating Baram Delta.

The ecoclimatology of Danum, Sabah, in the context of the world's rainforest regions, with particular reference to dry periods and their impact.

Climatic records for Danum for 1985-1998, elsewhere in Sabah since 1879, and long monthly rainfall series from other rainforest locations are used to place the climate, and particularly the dry period climatology, of Danum into a world rainforest context. The magnitude frequency and seasonality of dry periods are shown to vary greatly within the world's rainforest zone. The climate of Danum, which is aseasonal but subject, as in 1997-1998, to occasional drought, is intermediate between less drought-prone north-western Borneo and the more drought-prone east coast. Changes through time in drought magnitude frequency in Sabah and rainforest locations elsewhere in South-East Asia and in the Neotropics are compared. The 1997-1998 ENSO-related drought event in Sabah is placed into a historical context. The effects of drought on tree growth and mortality in the tropics are assessed and a model relating intensity and frequency of drought disturbance to forest structure and composition is discussed.

Phylogenetic Systematics and Biogeography of Phallostethid Fishes (Atherinomorpha, Phallostethidae) of Northwestern Borneo, with Description of a New Species

Until recently, the distinctive phallostethid genus Phallostethus was known from a single collection made in 1902 from Johor on the Malay Peninsula, described in 1913 by Regan as Phallostethus dunckeri. In 1991 and 1993, specimens of Phallostethus were collected from disjunct coastal localities in Sarawak and Brunei, northwestern Borneo. These Borneo specimens differ from Phallostethus dunckeri in morphology of the priapium (a complex, bilaterally asymmetric, subcephalic copulatory organ), pigmentation, and paradentary bone dentition. They are described herein as Phallostethus lehi, bringing the number of recognized phallostethid species to 20. Phenacostethus smithi Myers, 1928, previously unknown from Borneo has been collected from Sarawak, Brunei, and Kalimantan, bringing the total number of Bornean phallostethid species recognized currently to six. The phallostethids of Borneo do not form a monophyletic group but, instead, have complex, repeated sets of relationships with species on the Malay Peninsula and in the Philippines. Components of their biogeographic relationships are shared with other members of the stream biota. Composite biotic relationships are consistent with a composite geological origin of modern Borneo.

Paleomagnetic results from Cretaceous and Jurassic rocks of South and Southwest Yunnan: evidence for large clockwise rotations in the Indochina and Shan-Thai-Malay terranes

Cretaceous and Jurassic redbeds have been sampled from South and Southwest Yunnan, China, for paleomagnetic study. The paleomagnetic directions resolved from the Cretaceous rocks indicate that the Xiaguan area, which is located on the Red River fault, has not been rotated with respect to stable Eurasia since at least Late Cretaceous times and that the Jinggu-Mengla area 200–400 km farther south has been rotated by 46–65° clockwise. The Jurassic results reveal the same rotation pattern. At face value, the differences between the observed Cretaceous paleolatitudes and those predicted from the Eurasian apparent polar wander path (APWP) indicate a southward extrusion of the region, but the amount of extrusion is not large enough to be resolved by paleomagnetic methods. Comparison with Mesozoic paleomagnetic data from central Yunnan, northern Thailand and northwestern Borneo suggests that the Red River fault is not a demarcation between unrotated and significantly rotated regions, and that Sundaland did not respond to the India-Asia collision as a single coherent unit. The existing paleomagnetic data from East Asia appear to indicate that the crust in central Tibet and Tien Shan north of Tarim directly in front of the Indian indentor has been substantially shortened and thickened whereas the crust in the syntaxial areas has probably been largely squeezed out. To further evaluate the relative importance of crustal thickening and extrusion in the tectonic evolution of the Tibetan plateau, paleomagnetic investigation should be intensified in the bounding zones to the Indian indentor and be expanded into the Cenozoic sedimentary rocks in Tibet and surrounding regions.

Comparisons of Structure Among Mixed Dipterocarp Forests of North-Western Borneo

Relationships between lowland rain-forest structure, dynamics and site conditions were examined by the establishment of plots and profile diagrams within mature-phase forest at 13 sites and with permanent plots at three of these sites where trees have been enumerated over 20 years. Most forest structural measures were intercorrelated but forest stature was uncorrelated with HCl-extractable soil nutrient concentrations and was apparently related to topography, soil depth and soil water. The relationship between diameter and height varied between forests and was correlated with HCl-extractable P and Mg for dry-land sites (...)

Early Tertiary plate reconstructions for the South China Sea region: constraints from northwest Borneo

Previous plate reconstructions and tectonic syntheses for the southeast Asia region (Leichti et al. 1960, Ben Avraham and Uyeda 1973, Hamilton 1979, Holloway 1982, Taylor and Hayes 1982) have all highlighted the problems of correlating events in northwest Borneo with contemporaneous extension of the South China Sea. Theoretical modelling of crustal scale deformation in Asia during the Tertiary (Tapponnier et al. 1982) following India's collision with Asia suggested that the opening of the South China Sea basin accommodated major sinistral displacement. Haile (1973) and Hamilton (1979) have proposed that active subduction of oceanic crust beneath northwestern Borneo during the late Cretaceous and early Tertiary was associated with the development of a major arcuate accretionary complex, the “Crocker-Rajang” complex (Haile 1973), which is exposed over a large area of West Malaysia. Contemporaneous outer arc basin sedimentation in west Sarawak and eastern Kalimantan is consistent with a southeasterly dipping orientation of subduction at the margin. The duration of subduction is poorly constrained, but the initiation of major clastic depocenter in the Baram-Belait area during the early Miocene (Brondjik 1963), indicates a major change in sedimentation and deformational style at the northwestern Bornea continental margin. Pre-Miocene geological and paleomagnetic evidence from Borneo is inconsistent with the simple model of estrusion tectonics and suggests that Borneo and Malaya were separate microplates during the early Tertiary.

Episodic Rifting and Subsidence in the South China Sea: ERRATUM

In Ke Ru and John D. Pigott's paper, Episodic Rifting and Subsidence in the South China (AAPG Bulletin, v. 70, no. 9, September 1986), two paragraphs on p. 1147 were scrambled. Text on p. 1147 should read as follows: occurred (Tang Xin, 1980). Because Mesozoic volcanism is absent in eastern Indochina (cf., Tang Xin, 1980), the Andean-type volcanic arc would have been located off the east coast of Indochina. We endorse Holloway's (1982) interpretation of a transcurrent fault in southwest Indochina required to offset this subduction system. Kinematically, the 20° clockwise rotation of China and Indochina, and the 45°-50° counterclockwise rotation of southwest Borneo (Hamilton, 1979) are considered by fixing mainland Asia and by placing Borneo in a position about 70° clockwise from today's position. The western edge of this arc-trench system may have formed a zone of crustal weakness, which could later be reactivated during a period of tectonic extension. However, later crustal ex ension in China is not limited to the Mesozoic accretional domain, as Cenozoic extension occurred throughout eastern and southeastern China (Tang Xin, 1980; Wang, 1982; Zhang et al, 1982; Li, 1984). Late Cretaceous The first rifting episode of the South China Sea (Figure 19B) began during the Late Cretaceous with widespread volcanic activity in southeast China, the Natuna arch, and in southwest Borneo (Tang Xin, 1980; Wang, 1982). Tectonic uplift generally characterized the entire region as documented by a regional Late Cretaceous unconformity. However, in the grabens of mainland and offshore China, thick sedimentary successions record this first episode of rifting and continental crustal extension (Wang, 1982). This rifting system trended predominantly northeast-southwest, corresponding to the general strike of the numerous and widespread normal faults on the China margin. As a consequence, the direction of extension is southeasterly. By the close of the Late Cretaceous, Borneo had started its counterclockwise rotation (Hamilton, 1979) with an approximate rotation center being offshore of the southwestern tip of present-day Borneo. Owing to the joint effect of the rotation and the southeastward extension of the continental crust to the northwest, the subduction of the preexisting oceanic crust along the Lupar line of northwestern Borneo, as evidenced by ophiolite outcrops (cf., Haile, 1973; Hutchinson, 1975; Hamilton, 1979), had begun. We infer that the major strike-slip fault southwest of Indochina End_of_Article - Last_Page 119------------

Neogene to Recent Species of Cytherelloidea (Ostracoda) from Northwestern Borneo

In the Neogene to Recent sediments of Sarawak, Brunei and Sabah, species of the genus Cytherelloidea Alexander, 1929, form a regular component of the ostracode assemblages. Fifteen species were found, of which ten are new.

XXXVI.—On a Collection of Birds from Mount Dulit, in North‐western Borneo.

IbisVolume 34, Issue 3 p. 430-442 XXXVI.—On a Collection of Birds from Mount Dulit, in North-western Borneo. R. Bowdler Sharpe LL.D., F.L.S., &c., R. Bowdler Sharpe LL.D., F.L.S., &c.Search for more papers by this author R. Bowdler Sharpe LL.D., F.L.S., &c., R. Bowdler Sharpe LL.D., F.L.S., &c.Search for more papers by this author First published: July 1892 https://doi.org/10.1111/j.1474-919X.1892.tb00316.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume34, Issue3July 1892Pages 430-442 RelatedInformation

XXXVII.—Description of a new species of Calyptomena from North-western Borneo

XXXVII.—<i>Description of a new species of</i> Calyptomena <i>from North-western Borneo</i>