NE Thailand Research Articles

Preliminary Report on the Distribution and Status of Macaques in Thailand

We report here the preliminary results of studies on the distribution and status of five macaque species in Thailand. The latter lies in the center of the Indochinese Peninsula and is an important biogeographical region in SE Asia. We are conducting surveys through out Thailand in the order of questionnaire, census, and capture-and-release fieldwork where feasible. We have determined seven localities of stump-tailed macaques (M. arctoides); 36 localities of long-tailed macaques (M. fascicularis); eight localities of rhesus macaques (M. mulatta); six localities of assamese macaques (M. assamensis); and two localities of pig-tailed macaques (M. nemestrina leonina). Long-tailed and rhesus macaques belong to the same species-group, and are generally distributed allopatrically. The boundary between the two species in NE Thailand appears to lie close to latitude of 16oN. The phenotypic (pelage color and relative tail-length) and genetic characters (mtDNA and TSPY locus) of rhesus macaques resident in the area supposed close to the boundary have been analyzed; the results support the "Hybridization hypothesis" by Fooden ([2000], Fieldiana Zoology 96: 1-180). Troops of long-tailed macaques in Thailand, although their numbers sometimes exceed 1,000 animals, are isolated from other conspecifics. In addition, the genetic disturbance (pollution) introduced by artificial means, e.g., the breeding of released pets and human transfer of macaque troops threatens the innate biodiversity of the Thai macaque species.

Yield, growth and mortality rate of the Thai river sprat, Clupeichthys aesarnensis, in Sirinthorn Reservoir, Thailand

AbstractThe Thai river sprat, Clupeichthys aesarnensis Wongratana, is a clupeid with a short life span, and supports artisanal fisheries in a number of reservoirs in the Mekong Basin. The growth parameters, mortality rates and the status of the Thai river sprat in Sirinthorn Reservoir (28 800 ha), NE Thailand (15°N; 105°E), are presented. The fishery is based on lured lift‐nets, operated 7–14 days in the new moon period, September to April each year. It was shown that the von Bertalanffy growth function (VBGF) model was Lt (mm) = 78.43[1 − exp{−0.211[t − (−0.7996)]}] and its growth conformed to an isometric pattern. Natural mortality rate (month−1) was 0.13 month−1. Total mortality rates ranged from 0.69 to 1.53 month−1 depending on the weather and the fishing season. Recruitment was continuous throughout the year but peaked in June and July. The yield per recruit model indicated that the exploitation rate of this fishery is probably too high.

Orchidantha foetida (Lowiaceae) a new species from Thailand

Orchidantha foetida sp. nov. from NE Thailand is described and illustrated and a key to the three species occurring in Thailand is presented.

Isotope Geology of Upper Paleozoic Carbonates, Loei Area, NE Thailand: Implication for Paleoenvironments and Tectonic Setting

Isotope Geology of Upper Paleozoic Carbonates, Loei Area, NE Thailand: Implication for Paleoenvironments and Tectonic Setting

The geoarchaeology of the prehistoric ditched sites of the upper Mae Nam Mun Valley, NE Thailand, III: Late Holocene vegetation history

The upper Mae Nam (River) Mun Valley of northeast Thailand has been occupied at least since the Bronze Age, but is notable for the rapid expansion of intense town-based Iron Age settlement. The area presently forms the seasonally-arid core of mainland southeast Asia, and is presently dominated by increasingly saline soils, low-productivity rice cultivation and regrowth semi-arid scrub. However, the archaeological evidence for this region indicates a highly-productive natural environment within the last two millennia. Pollen sequences from the infill of Iron Age features provide the first palynological evidence for this part of northeast Thailand, detailing Late Holocene vegetational change. The area around the sites was initially dominated by forest, which then underwent two phases of the replacement by mosaics of grassland, probable rice cultivation, arboriculture and scrub, prior to a subsequent phase of forest and woodland regeneration. Spatial patterning of the study area's palaeovegetation appears to have been complex. While a general progress of landscape change is evident, local compositional differences are also clear. Although the region's archaeological and, especially, geomorphological evidence suggests significant climatic change during this period, the pollen record, as in studies further north in the region for the same period, appears to have been dominated by human influences. Of note are the effects of intensified human settlement and thus increased land and natural resource use. At present this Late Holocene pollen sequence yields no evidence for a direct relationship with climatic change.

Kaempfería grandifolia sp. nov. (Zingiberaceae) a new species from Thailand

Kaempfería grandifolia is described and illustrated from the Phu Phan National Park in NE Thailand. The somatic chromosome number is established to 2n = 22. Its affinities are discussed.

Luminescence characterisation of quartz-rich cover sands from NE Thailand

The genesis of a several-meter-thick cover sand layer, which is widely distributed in mainland SE Asia has been the subject of much debate, being considered by some to be an aeolian mantle of late Pleistocene/early Holocene origin, and by others to represent a Holocene biomantle. Samples were collected from three sites in NW Thailand in 1998 to assess the potential of luminescence studies for characterisation and chronometric studies of the layer. The material is a quartz-rich, iron-stained sand, with high-luminescence sensitivities, a pronounced 325°C TL peak, and high sensitivity to phototransfer and OSL. A number of methods for estimating stored dose were assessed, of which additive TL and regenerative OSL procedures produced good laboratory results.These methods have been used to produce stored dose and apparent age profiles for one of the sites. The data are consistent with a late Pleistocene/Holocene aeolian deposition process, possibly modified in the upper layers by bioturbation. However, the possibility that the recorded profiles are the result of heterogeneous mixing of bleached and unbleached grains within the biomantle model cannot at this stage be excluded. The material has excellent luminescence properties, and it is likely that further luminescence studies will be able to distinguish between the formation models, and contribute significantly to understanding of these regionally significant sediments.

ABSTRACT: Multiple inversion of the Khorat Plateau Basin, NE Thailand, with the formation and preservation of a productive gas play

ABSTRACT: Multiple inversion of the Khorat Plateau Basin, NE Thailand, with the formation and preservation of a productive gas play

Clinical features of renal diseases in South‐East Asia

Summary: The renal diseases in South‐East Asia are similar to other parts of the world (i.e. glomerulonephritis, diabetes mellitus, HT, obstructive uropathy, adult‐onset polycystic kidney disease, nephrolithiasis and tubulointerstitial diseases). IgA nephropathy with haematuria is most common in Singapore, while IgM nephropathy with nephrotic syndrome is common in Thailand. Lupus nephritis is the most common cause of secondary glomerulonephritis and a major cause of rapidly progressive glomerulonephritis. Acute renal failure from specific infection (malaria, leptospirosis, melioidosis), from toxin exposure (snake bite, wasp sting), from exertional heat stroke, and from drugs is frequently found. Nephrolithiasis, distal renal tubular acidosis and hypokalaemia are endemic in NE Thailand. In conclusion, the broad clinical features of renal diseases in South‐East Asia are similar to other regions, with additional specific causes from infections, toxic, metabolic and environmental derangements associated with these tropical locations.

Diagenetic origin of Basal Anhydrite in the Cretaceous Maha Sarakham salt: Khorat Plateau, NE Thailand

Development of a diagenetic anhydrite bed at the base of the Cretaceous Maha Sarakham Saline Formation (the `Basal Anhydrite' member) of the Khorat Plateau in north‐eastern Thailand took place due to leaching and/or pressure dissolution of salt at the contact between an underlying active sandstone aquifer system and an overlying massive halite‐dominated evaporite sequence. Basal evaporites composed of halite with intercalated anhydrite of the latter sequence are undergoing dissolution as a result of subsurface flushing, with anhydrite produced as the insoluble residue. The result is a 1·1 m thick interval of nodular anhydrite displaying unique, basin‐wide continuity. Observed textures, petrographic features and chemical data from the anhydrite and associated authigenic minerals support the origin of the Basal Anhydrite Member as an accumulation residue from the dissolution of the Maha Sarakham salts. Petrographically, the anhydrite in this unit is made up of crystals that are blocky and recrystallized, sheared, generally elongated and broken, and is bounded at the bottom by organic‐rich stylolite surfaces. Authigenic and euhedral dolomite and calcite crystals are associated with the anhydrite. Traces of pyrite, galena and chalcopyrite are present along the stylolite surfaces suggesting supply of fresh water from the underlying sandstone at highly reducing conditions of burial. The δ34S of sulphate in the Basal Anhydrite averages 15 ‰ (CDT) and falls within the isotopic composition of the anhydrite in the Cretaceous Maha Sarakham Formation proper and the Cretaceous values of marine evaporites. Measured δ18O in dolomite range from −4·37 to −14·26‰ (PDB) suggesting a re‐equilibration of dolomite with basinal water depleted in 18O and possible recrystallization of dolomite under relatively elevated temperatures. The δ13C, however, varies from +1·57 to −2·53‰ (PDB) suggesting a contribution of carbon from oxidation of organic matter. This basal anhydrite bed, similar to basinwide beds found at the bottom of many giant evaporite sequences, has always been considered to be depositional. Here, at the base of the Maha Sarakham Formation, we demonstrate that the anhydrite is diagenetic in origin and was formed by accumulation of original anhydrite by dissolution of interbedded halite from waters circulating though the underlying aquifer: it represents an `upside‐down' caprock.

GEOLOGY AND PETROLEUM POTENTIAL OF THE KHORAT PLATEAU BASIN IN THE VIENTIANE AREA OF LAO P.D.R.

The Vientiane area of southern‐central Lao Peoples' Democratic Republic (Laos) includes an extension of the Khorat Plateau Basin, which covers most of neighbouring NE Thailand. This basin contains one producing gasfield and several other gas discoveries. The Vientiane area is in the initial stages of petroleum exploration, and no drilling has yet occurred.With the aid of new seismic data, the structure and stratigraphy of the Vientiane area are described in relation to the region's tectonic history. Some aspects of this history are still poorly understood. We suggest that the age of the regional base‐Khorat unconformity is Late Jurassic instead of Late Triassic as most previous studies have assumed. Recent studies have also shown that the structural inversion of the Khorat Group began in the mid‐Cretaceous and not in the Tertiary.With reference to published information from petroleum exploration in NE Thailand, new data from Laos are interpreted as showing that the Vientiane area has encouraging petroleum potential. Exploration risk, which is associated with the presence and reservoir quality of the Permian carbonates which form the primary target, is judged to be lowest in traps containing Permian palaeo‐highs.

STRATIGRAPHY AND RESERVOIR POTENTIAL OF THE MESOZOIC KHORAT GROUP, NE THAILAND: Part 2: Diagenesis and Reservoir Quality

The Mesozoic Khorat Group in NE Thailand consists of a series of continental red‐beds, divided here into five formations, which unconformably overlie the lithologically‐similar Nam Phong Formation. The reservoir quality of the Khorat Group decreases progressively with increasing age, owing to burial compaction and diagenesis. Compactional fabrics suggests a maximum burial depth of more than seven km, although the Sao Khua Formation (in the middle of the Khorat Group) shows early calcite cements which stabilised the sediment fabric at burial depths of about one km. Porosities vary from 11% in the uppermost part of the Khorat Group (Khok Kruat Formation) to 4.9% in the Nam Phong Formation. The ratio of secondary grain‐dissolution porosity to primary porosity increases with age (and depth). Authigenic minerals consist of quartz (1.3 ‐ 9.3%), calcite (0 ‐ 26.5%) and kaolinite (0 ‐ 4.0%). The occurrence of detrital clays (0.8–9.6%) in particular causes downgrading of the porosity of many of the sandstone samples examined.

STRATIGRAPHY AND RESERVOIR POTENTIAL OF THE MESOZOIC KHORAT GROUP, NE THAILAND: Part 1: Stratigraphy and Sedimentary Evolution

In this paper, the sedimentology, petrography and biostratigraphy of the Nam Phong Formation and the overlying Mesozoic Khorat Group in NE Thailand are described. Data were gathered during extensive studies in the field (about 100 outcrop localities were investigated) and from laboratory analyses of over 500 surface samples.The Nam Phong Formation is dated accurately for the first time as late Norian to Rhaetian, while the Phra Wihan, Sao Khua, Phu Phan and Khok Kruat Formations (of the Khorat Group) are reassigned to the Early Cretaceous (Berriasian to Aptian) on the basis of new palynological data. The age of the intervening Phu Kradung Formation, which is conventionally assigned to the Lower Jurassic, is probably Late Jurassic or Early Cretaceous, although this cannot be determined with confidence. Changes in provenance between the Nam Phong Formation and the overlying Phu Kradung Formation suggest a possible sedimentary hiatus. Palaeocurrent data suggest that sediments were mainly sourced from the north and east.Part 1 of this paper describes the sedimentology and biostratigraphy of these units; Part 2, which is scheduled to appear in the April, 1996 issue of this Journal, reports on their diagenesis and reservoir quality.

Taxonomic Notes on Asiatic Chionanthus (Oleaceae)

Chionanthus amblirrhinus sp. nov. is described from Thailand and C. decipiens sp. nov. from Burma and Thailand. The following new combinations are made: C. eriorachis (from Thailand), C. malaelengi subsp. linocieroides (from S India) and subsp. terniflorus (from NE India, Burma, Thailand and IndoChina), C. microbotrys (from Thailand), C. microstigma (from Thailand and Indo-China), C. sutepensis (from Thailand), C. thorelii (from Thailand and Indo-China) and C. velutina (from Thailand).

Source of Australasian tektites: Investigating possible impact sites in Laos

Abstract— The site of an impact event that spread ejecta in the form of tektites and microtektites over ∼5 × 107 km2 of the southern Pacific and Indian Ocean area has not yet been discovered. A number of lines of evidence point toward a source in eastern Indochina. From an examination of a digital topographic data set and Landsat imagery, we identified four candidate structures in southern Laos, and we visited these sites in 1995 February. No evidence of impact origin of these structures could be found; flat‐lying, undisturbed Mesozoic sedimentary rocks similar to those on Thailand's Khorat Plateau were found over the region. Small layered tektite fragments are relatively common in a lateritic horizon that is characterized by the presence of quartz pebbles. This scene is identical to the situation found several hundred kilometers to the southeast in Thailand. New tektite sites identified on this trip support a previous suggestion that there is a large region in southern NE Thailand and Laos that is rich in Muong Nong‐type (layered) tektites but seemingly devoid of the splash‐form type tektites.

Determining Irrigation Service Area under Monsoonal Rainfall Conditions: An Example from Northeast Thailand

ABSTRACT This study utilizes chance-constrained programming (CCP) to determine the optimal service area for Huai Aeng Reservoir in NE Thailand. CCP allows for an explicit incorporation of erratic monsoon rainfall amounts in design considerations. In contrast to the present situation, which was designed based on average flows, where both the wet and dry season service areas are 3,371 ha with a low rate of utilization for the dry season area, using CCP the optimal design (taking into account rainfall and resulting inflow variability) is an irrigated area of 2,192 ha using extensive canals for wet season rice and 1,179 ha using intensive canals and farm ditches for dry season field crops as well as wet season rice. Excluding farm labor costs, the new design has a B/C ratio of 1.77:1 compared to a B/C ratio of 1.03:1 for the present design.

Discussion on structural evolution of Mesozoic Peninsular Malaysia

C. S. Hutchison and S. P. Sivam write: Harbury et al ‘ s 1990 paper is a useful contribution to our knowledge of the Mesozoic Tembeling Formation. However, the generalizations on stratigraphy and orogenesis for the whole Peninsular Malaysia are based on inadequate literature research and a general unfamiliarity with the region. Accordingly we feel obliged to bring to your attention the most obvious shortcomings of the paper. The timing of the Indosinian Orogeny of Southeast Asia ( Belov et al. 1986 ) traditionally was based on the widespread elimination of marine sedimention and general uplift by early Jurassic time. The predominantly Carnian-Norian strata (collectively called Upper Triassic flysch), were followed by predominantly Jurassic-Cretaceous molasse: the characteristically red Tembeling Group (Malaysia) and the Terrain Rouge (Indochina), and the non-oxidized Gagau Group and Tebak Formation (Malaysia) and the Grès Supérieurs of Indochina. The critical locality in Peninsular Malaysia is at Jengka Pass, where the gently dipping marine Tembeling Formation is late Triassic to early Jurassic, unconformably underlain by vertically bedded Late Permian limestone, shale and sandstone ( Ichikawa et al. 1966 ). This situation is an analogue of the western margin of the Khorat Basin of NE Thailand, where the Upper Triassic to earliest Jurassic Huai Hin Lat Formation unconformably overlies late Permian Saraburi Limestone ( Kon’no & Asama 1973 ). Jurassic redbeds succeed the Huai Hin Lat Formation, and in Peninsular Malaysia the marine Jengka Pass sequence is succeeded eastwards by continental redbed facies. The information of the foregoing paragraph has been distorted by Harbury et

Peanut Cultivar Responses to Bradyrhizobium Inoculation in Northeast Thailand

Abstract Effective combinations of peanut (Arachis hypogaea L.) cultivars and Bradyrhizobium strains were determined under field conditions in NE Thailand in experiments conducted in 1985 and 1986. The experiments measured yields and N2 fixation (N-15 dilution) responses of peanut cultivars Tainan 9, Moket and KAC431 to inoculation with inoculants composed of Bradyrhizobium strains TH205, 32HI or NC92 or mixed cultures of bacteria. Midseason parameters of nodule number and weight and acetylene reduction levels were also determined. Peanut yields varied between years and locations. Cultivar Tainan 9 was shown to be the cultivar with the best average yield for the locations tested. Inoculation with bradyrhizobia resulted in increased seed yields and amounts of N in the plants in most cases. Inoculated peanuts received an average of 71 kg N/ha from fixation; uninoculated peanuts received an average of 62 kg N/ha. Of this N, 55 to 77% remained in the stover. Midseason measurements of plant performance were of minimal value for predicting the relative performance of the three cultivars.

A preliminary sulphur and oxygen isotope study of the Maha Sarakham evaporitic anhydrite from Bamnet Narong Area of NE Thailand

A preliminary sulphur and oxygen isotope study of the Maha Sarakham evaporitic anhydrite from Bamnet Narong Area of NE Thailand

Dry-season Legume Forages to Follow Paddy Rice in NE Thailand. III. Influence of Time and Intensity of Cutting on Crotalaria juncea

SUMMARYAn experiment at the University of Queensland studied the response of Crotalaria juncea to a single cut above node 4 or 10 at 6, 8 or 10 weeks after planting under long or short (inductive) daylengths. Initial deleterious effects of cutting on plant parts were in the sequence nodules > roots > shoots. Subsequent greater regrowth from plants cut earliest and at the higher node was associated with higher residual leaf area and negative growth rates were inferred below 90 cm2 pot−1. Redistribution of assimilate from stem to leaf production followed cutting; in inductive daylengths of 11.4 hours, flowering was delayed and the proportion of leaf increased from 21.0 to 32.4%. The high nitrogen content of leaf (3.5–5.3%) compared to stem (0.6–1.7%) indicated that early cutting was important in producing good quality hay.