Eastern Gobi Research Articles

Distribution of carpenter-moths (Lepidoptera, Cossidae) in the Palaearctic deserts

Specific features of the carpenter-moths (Cossidae) distribution in the Palaearctic deserts are considered. The Palaearctic frontier was delimited to the Arabian Peninsula (the eastern and northern parts of Arabia are attributed to the Palaearctic Region; Yemen, southwestern Saudi Arabia, and southernmost Iran belong to the Afrotropical Region). Cossidae are highly endemic to arid areas. Some Palaearctic carpenter-moth genera penetrate to Africa southward of the Sahara Desert (an important characteristic distinguishing them from most of the other Lepidoptera). The local faunas of the Palaearctic deserts are united into 4 groups: the Sahara-Arabian-Southern-Iranian, Central-Asian-Kazakhstanian, Western-Gobian, and Eastern-Gobian. In the Eastern Gobi Desert, the fauna is the most specific; it should be considered as a separate zoogeographical subregion.

Computational fluid dynamics evaluation of the effect of different city designs on the wind environment of a downwind natural heritage site

Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a site. This study conducted 3D computational fluid dynamics (CFD) simulations to evaluate the effect of a proposed city design on the wind environment of the Crescent Spring, a downwind natural heritage site located in Dunhuang, Northwestern China. Satellite terrain data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) were used to construct the solid surface model. Steady-state Reynolds Averaged Navier-Stokes equations (RANS) with shear stress transport (SST) k-ω turbulence model were then applied to solve the flow field problems. Land-use changes were modeled implicitly by dividing the underlying surface into different areas and by applying corresponding aerodynamic roughness lengths. Simulations were performed by using cases with different city areas and building heights. Results show that the selected model could capture the surface roughness changes and could adjust wind profile over a large area. Wind profiles varied over the greenfield to the north and over the Gobi land to the east of the spring. Therefore, different wind speed reduction effects were observed from various city construction scenarios. The current city design would lead to about 2 m/s of wind speed reduction at the downwind city edge and about 1 m/s of wind speed reduction at the north of the spring at 35-m height. Reducing the city height in the north greenfield area could efficiently eliminate the negative effects of wind spee. By contrast, restricting the city area worked better in the eastern Gobi area compared with other parts of the study area. Wind speed reduction in areas near the spring could be limited to 0.1 m/s by combining these two abatement strategies. The CFD method could be applied to simulate the wind environment affected by other land-use changes over a large terrain.

Mass concentration of PM10 and PM2.5 fine-dispersed aerosol fractions in the Eastern Gobi Desert

Results are presented of monitoring measurements of the mass concentration of PM10 (particles with the size of less than 10 μm) and PM2.5 (less than 2.5 μm) fine-dispersed aerosol fractions at the Sainshand and Zamyn-Uud stations located in the Gobi Desert of Mongolia. Revealed are the annual variations of the mass concentration of PM10 and PM2.5 fine-dispersed aerosol fractions at these stations in 2008. The maximum values of monthly mean concentration during the year were observed in May in the period of dust storms. On the days with the steady calm weather, the mass concentrations of PM10 and PM2.5 varied within 5–8 μg/m3 (PM10) and 3–5 μg/m3 (PM2.5) at the Sainshand station. During the dust storms, the maximum values of concentration exceeded 1400 μg/m3 (PM10) and 380 μg/m3 (PM2.5) that is by 28 (PM10) and 15 (PM2.5) times higher than the maximum permissible concentration for the European Union. Results are given of studying the frequency and duration of dust storms in recent 20 years (1991–2010) in the Eastern Gobi Desert.

モンゴル南東部，ゴビ砂漠における湖成堆積物中のジュラ系-下部白亜系カイエビの古生物学的研究

モンゴル南東部，ゴビ砂漠における湖成堆積物中のジュラ系-下部白亜系カイエビの古生物学的研究

A small alvarezsaurid from the eastern Gobi Desert offers insight into evolutionary patterns in the Alvarezsauroidea

ABSTRACT A partial postcranial skeleton of a small alvarezsaurid from the Late Cretaceous of the Mongolian eastern Gobi Desert locality of Khugenetslavkant represents the first reported articulated theropod material from that locality. The specimen is recognized as the holotype of a new taxon herein named Albinykus baatar, gen. et sp. nov. Phylogenetic analysis places Albinykus within Alvarezsauridae as the sister taxon of Shuvuuia, another Late Cretaceous Mongolian taxon from the slightly younger Djadokhta Formation. The complete coossification of the proximal tarsals with the tibia, and of the distal tarsals and proximal metatarsals, present in Albinykus are previously unknown in Alvarezsauridae. Extensive fusion is consistent with histological data from the tibia indicating that the individual was a subadult. These results are striking given that Albinykus is among the smallest known non-avian dinosaurs with a body mass no greater than 1 kg and ranks among the smallest known alvarezsaurids. Alvarezsauridae shows a decreasing size trend throughout its evolutionary history, a rarity among dinosaurian clades. Within maniraptoran dinosaurs, such a trend has thus far only been recognized within Avialae and at the origin of Paraves with respect to other coelurosaurs. The holotype was recovered articulated in a ‘seated’ position, with hind limbs aligned and the feet tucked under the body. This body posture, which is present in Aves, has been previously noted in other maniraptoran clades (i.e., Oviraptoridae Troodontidae) and is now recognized in Alvarezsauridae.

A small alvarezsaurid from the eastern Gobi Desert offers insight into evolutionary patterns in the Alvarezsauroidea

ABSTRACT A partial postcranial skeleton of a small alvarezsaurid from the Late Cretaceous of the Mongolian eastern Gobi Desert locality of Khugenetslavkant represents the first reported articulated theropod material from that locality. The specimen is recognized as the holotype of a new taxon herein named Albinykus baatar, gen. et sp. nov. Phylogenetic analysis places Albinykus within Alvarezsauridae as the sister taxon of Shuvuuia, another Late Cretaceous Mongolian taxon from the slightly younger Djadokhta Formation. The complete coossification of the proximal tarsals with the tibia, and of the distal tarsals and proximal metatarsals, present in Albinykus are previously unknown in Alvarezsauridae. Extensive fusion is consistent with histological data from the tibia indicating that the individual was a subadult. These results are striking given that Albinykus is among the smallest known non-avian dinosaurs with a body mass no greater than 1 kg and ranks among the smallest known alvarezsaurids. Alvarezsauridae shows a decreasing size trend throughout its evolutionary history, a rarity among dinosaurian clades. Within maniraptoran dinosaurs, such a trend has thus far only been recognized within Avialae and at the origin of Paraves with respect to other coelurosaurs. The holotype was recovered articulated in a ‘seated’ position, with hind limbs aligned and the feet tucked under the body. This body posture, which is present in Aves, has been previously noted in other maniraptoran clades (i.e., Oviraptoridae Troodontidae) and is now recognized in Alvarezsauridae.

GPS rotation and strain rates in the Baikal–Mongolia region

Current deformation in Pribaikalia, Western and Central Mongolia, and Tuva has been studied from measured horizontal GPS velocities and respective computed strain and rotation rates using 1994–2007 data of the Baikal–Mongolian GPS triangulation network. The GPS velocity field shows two main trends: an NE trend within Jonggaria, the Mongolian Altay, and the Great Lakes Valley and an SE trend in the Hangayn and eastern Gobi Altay mountains, and in the Transbaikalian block of the Amur plate. The velocity magnitudes and vectors are consistent with an SE motion of the Amur plate at a rate of ∼2 mm/year. The derived strain pattern includes domains of crustal contraction and extension recognized from the magnitudes of relative strains. Shortening predominates in the Gobi and Mongolian Altay and in the Khamar-Daban Range, where it is at ɛ 2 = (19.2 ± 6.0)×10 −9 yr −1 being directed northeastward. Extension domains exist in the Baikal rift and in the Busiyngol–West Hangayn area, where the crust is stretching along NW axes at ɛ 1 = (22.2 ± 3.1) × 10 –9 yr –1. The eastern Hangayn dome and the Gobi peneplain on its eastern border show low and unstable strain rates. In central and northern Mongolia (Orhon–Selenge basin), shortening and extension are at similar rates: ɛ 2 = (15.4 ± 5.4)×10 −9 yr −1 and ɛ 1 = (18.1 ± 3.1)×10 −9 yr −1. The strain pattern changes notably in the area of the Mogod earthquake of 1967. Most of rotation throughout Central Asia is clockwise at a low rate of about Ω = 6×10 −9 deg·yr −1. High rates of clockwise rotation are observed in the Hangayn domain (18.1 ± 5.2)×10 −9 deg·yr −1, in the Gobi Altay (10.4 ± 7.5)×10 −9 deg·yr −1, and in the Orhon–Selenge domain (11.9 ± 5.2)×10 −9 deg·yr −1. Counterclockwise rotation is restricted to several domains. One is in western Tuva and northwestern Great Lakes Valley of Mongolia (Ω = 3.7×10 −9 deg·yr −1). Two more counterclockwise rotation regions occur on both flanks of the Baikal rift: along the craton edge and in basins of Transbaikalia on the rift eastern border, where rotation rates are as high as (13.0 ± 3.9)×10 −9 deg·yr −1, while rotation within the Baikal basin does not exceed the measurement error. Another such domain extends from the eastern Hövsgöl area to the Hangayn northern foothills, with the counterclockwise rotation at a highest rate of (16.3 ± 2.8)×10 −9 deg·yr −1.

Structural and geochronologic data from the Shin Jinst area, eastern Gobi Altai, Mongolia: Implications for Phanerozoic intracontinental deformation in Asia

The complex geology of central Asia records significant Phanerozoic growth and deformation of continental lithosphere, yet many questions about the timing and mechanisms of these processes remain. The Gobi Altai of southwestern Mongolia preserves much of this history in exposed mountain ranges and sedimentary basins. The Shin Jinst area (near latitude 44 21' to 44° 32', longitude 99°35' to 99° 25') contains important evidence of Paleozoic growth and accretion as well as subsequent Mesozoic and Cenozoic deformation. Detailed mapping and structural data, including data sets on folds and cross-cutting faults, point to repeated episodes of deformation and add to recent work that documents Triassic and Jurassic compression as well as Cenozoic tectonic activity in this region. New 40Ar/ 39Ar data are interpreted to record Permian to Jurassic convergent margin processes. In particular, these data, in combination with previous studies, suggest that southern Mongolia records protracted deformation throughout the Jurassic that likely resulted from compression associated with the subduction zone at the southern margin of Asia at that time.

Yamaceratops Dorngobiensis, a New Primitive Ceratopsian (Dinosauria: Ornithischia) from the Cretaceous of Mongolia

A new basal neoceratopsian taxon from the eastern Gobi Desert is described. Yamaceratops dorngobiensis, tax. nov., is probably of late Early Cretaceous age, and occupies a phylogenetic position intermediate between Liaoceratops and Archaeoceratops. It is the most basal taxon to display a number of traditional neoceratopsian synapomorphies concentrated in the cheek region and mandible. These include presence of an epijugal, lateral displacement of the coronoid process, a lateral ridge on the surangular for insertion of the jaw adductors, and a lateral wall to the mandibular glenoid. Yamaceratops shares two synapomorphies (tubercles on the ventral edge of the angular and shape of the jugal) with Liaoceratops, indicating that the transient presence of derived characters may be prevalent in the early evolutionary history of Ceratopsia. Yamaceratops shares aspects of frill morphology with Liaoceratops and Leptoceratops that suggest a function unrelated to display for this anatomical structure in basal neoceratopsians, and hints at a more complex evolutionary history for ceratopsian frills. Considerations of patristic distances and mosaic evolution among basal neoceratopsian taxa indicate that a greater diversity of these animals remains undiscovered.

Erketu Ellisoni, a Long-necked Sauropod from Bor Guvé (Dornogov Aimag, Mongolia)

The first specimen of the new sauropod Erketu ellisoni, from the Lower Cretaceous of the eastern Gobi of Dornogov, Mongolia, is described here. The specimen comprises a well-preserved articulated anterior cervical series, an articulated lower hindlimb, and a sternal plate. This sauropod displays a unique combination of features including low, bifid neural spines, elongate cervical centra, and crescent-shaped sternal plates. Computed tomography imaging reveals the vertebrae were extensively invaded with pneumatic camellae. The holotype individual of Erketu was of modest mass relative to other neosauropods, but had an extremely elongate neck. Phylogenetic analysis indicates Erketu is a member of the Somphospondyli and may belong to a more exclusive clade therein.

New Avian Remains from the Eocene of Mongolia and the Phylogenetic Position of the Eogruidae (Aves, Gruoidea)

A well-preserved nearly complete avian tarsometatarsus was collected by the 2002 expedition of the Mongolian Academy of Sciences from upper Eocene deposits exposed at the locality of Alag Tsav in the Eastern Gobi desert (Dornogov Aimag) of Mongolia. The new specimen is identified as part of a proposed Eogruidae clade, although it is unclear whether it is appropriately the holotype of a new species within this clade or referable to a previously named species. The clade Eogruidae has, as its current contents, species named as part of the traditional families Eogruidae + Ergilornithidae, which include several taxa of completely didactylous and apparently flightless birds. Referral of the new fossil to the clade Eogruidae is on the basis of derived reduction/loss of the metatarsal II trochlea.A series of phylogenetic analyses was used to investigate the systematic position of Eogruidae (including the new fossil, IGM 100/1447), which have been proposed to be a dominant part of Eocene to Miocene Asian faunas. First, the Mayr and Clarke (2003) dataset for crown clade Aves was used to investigate placement of Eogruidae within Aves, using a more completely known eogruid, Eogrus aeola, as an exemplar taxon. Eogrus aeola was identical to the new tarsometatarsus for all scored characters. A strict consensus cladogram of three most parsimonious trees from 1000 replicate heuristic searches placed Eogrus aeola in an unresolved polytomy with Psophiidae and Gruidae (Trumpeters and Cranes).Given the results of this analysis, Eogruidae (including IGM 100/1447) was analyzed in the suborder Grues dataset of Livezey (1998). Eogruidae was placed as the sister taxon to an Aramidae + Gruidae clade in the strict consensus cladogram of the eight most parsimonious trees resulting from a branch and bound search. Because monophyly of the traditional order Gruiformes has been repeatedly questioned, and the outgroups used in the original Grues dataset were identified through analyses assuming monophyly, the impact of removing these assumptions was investigated. Placement was robust to both changing outgroup assumptions and to swapping in the more incompletely known IGM 100/1447 as an exemplar for Eogruidae.

Paleomagnetic and palynologic analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia

Cretaceous terrestrial sediments deposited in a series of intracratonic basins across the Gobi Desert region of southern Mongolia and northern China contain a unique and diverse vertebrate fauna. In 1996 an expedition jointly sponsored by the Mongolian Paleontological Center and the Hayashibara Museum of Natural Sciences revisited a number of famous vertebrate fossil localities in the eastern Gobi region of Mongolia and, as part of a broad geological and paleontological study, collected a series of paleomagnetic samples from measured sections at Bayn Shireh, Burkhant and Khuren Dukh, as well as from an unmeasured locality adjacent to Khuren Dukh. Expedition members also collected palynologic samples from Khuren Dukh and the adjacent locality. Paleomagnetic analysis shows that all the sites from which samples were collected display detrital remnant magnetization that is consistently normal in polarity. The measured Cretaceous magnetic directions are oriented to the east or northeast of the present day expected direction (declination 356.2°, inclination 65.2°), and they are wholly concordant with that expected for a mid-latitude Northern Hemisphere sampling locality, and with the directions for this period reported by other workers. These results, when considered in tandem with the known biostratigraphy, strongly suggest that the sedimentary deposits at all four localities in the eastern Gobi correlate to the normal polarity chron 34 (the Cretaceous Long Normal), which ranges in age from approximately 121 to 83.5 million years. Previous vertebrate, invertebrate and palynological data from Khuren Dukh suggest that the lower and middle parts of the stratigraphic interval exposed there (which have been assigned to the Shinekhudag Formation) are ‘Khukhtekian’ in age and correspond to the Aptian–Albian interval that can be broadly correlated to the older, Early Cretaceous part of the Cretaceous Long Normal, C34n. New palynologic data presented here indicate that these strata are no older than middle to late Albian. The rocks at Bayn Shireh (the Bayn Shireh Formation) have been assigned a ‘Baynshirenian’ biostratigraphic age that may range from Cenomanian to early Campanian. The magnetostratigraphy results presented here indicate that the strata at both the Bayn Shireh and Burkhant localities do not cross the Santonian/Campanian Stage boundary, however, as this is believed to lie at, or very near, the C34n/C33r reversal boundary. Thus, the Bayn Shireh Formation was most likely deposited near the end of the Cretaceous Long Normal Interval, no later than the latest Santonian.

New Lizards from the Middle Eocene Mergen Formation, Mongolian Gobi Desert

New lizard fossils are described from the middle Eocene Mergen Formation, eastern Gobi Desert in Mongolia. Some 30 isolated tooth-bearing jaws represent at least six lizard taxa. These include three new iguanians that are nonchamaeleonid acrodontans; two scincomorphs having uncertain relationships within the group; and one large anguimorph that may represent a platynotan taxon. Discovery of these fossil lizards is important for accumulating nonmammalian vertebrate data, in attempting to understand a major faunal change that took place in relation to the drastic uplifting of the Mongolian Plateau in Palaeogene time.

Effect of ectoparasites on hematochemicals and therapeutic studies on sarcoptic mange in Camel

Genital infestations caused by Wohlfahrtia magnifica (Schiner, 1862) has been reported as being a common problem encountered in female camels in the Gobi desert. Thus, a field investigation to establish the prevalence of wohlfarthiosis in camel herds in the eastern Gobi district was carried out between May and July 1994. The objectives of the study were to establish the relevance of genital myiasis, and to describe the disease patterns, clinical course and pathomorphological changes associated with it. The field study was designed to suit the specific ecological, infrastructural and logistic conditions. Two cross-sectional samples were taken from 45 selected herds in six different areas of the Chatanbulag Sumon to obtain data on herd structure, age distribution, and the breeding history of infested female animals. Post partum events and previous occurrence of genital myiasis were recorded by use of a standardised questionnaire. Clinically infested animals were first detected visually. All camels to be investigated further were subsequently immobilised using ropes and the genitals were examined for tissue lesions and the presence of larvae. Examination of 1676 Bactrian camels from 45 selected herds in six different areas of the Chatanbulag Sumon in the Eastern Gobi district, Mongolia, led to an estimate of Wohlfahrtia magnifica infestation rates between 8–10%. Most myiasis cases were found in older females (>4 yr), younger animals were infested at a lower rate. Highest prevalence rates were discovered during June and July, highest levels of infestation occurred in the Aman Us Chudak region with infestation rates up to 15%.

Genital myiasis (Wohlfahrtiosis) in camel herds of Mongolia

Genital infestations caused by Wohlfahrtia magnifica (Schiner, 1862) has been reported as being a common problem encountered in female camels in the Gobi desert. Thus, a field investigation to establish the prevalence of wohlfarthiosis in camel herds in the eastern Gobi district was carried out between May and July 1994. The objectives of the study were to establish the relevance of genital myiasis, and to describe the disease patterns, clinical course and pathomorphological changes associated with it. The field study was designed to suit the specific ecological, infrastructural and logistic conditions. Two cross-sectional samples were taken from 45 selected herds in six different areas of the Chatanbulag Sumon to obtain data on herd structure, age distribution, and the breeding history of infested female animals. Post partum events and previous occurrence of genital myiasis were recorded by use of a standardised questionnaire. Clinically infested animals were first detected visually. All camels to be investigated further were subsequently immobilised using ropes and the genitals were examined for tissue lesions and the presence of larvae. Examination of 1676 Bactrian camels from 45 selected herds in six different areas of the Chatanbulag Sumon in the Eastern Gobi district, Mongolia, led to an estimate of Wohlfahrtia magnifica infestation rates between 8–10%. Most myiasis cases were found in older females (>4 yr), younger animals were infested at a lower rate. Highest prevalence rates were discovered during June and July, highest levels of infestation occurred in the Aman Us Chudak region with infestation rates up to 15%.

Geometry and style of partitioned deformation within a late Cenozoic transpressional zone in the eastern Gobi Altai Mountains, Mongolia

The Gobi Altai is the easternmost extension of the Mongolian Altai and consists of topographically discontinuous E-W-trending ranges with peaks averaging 2000–3000 m in elevation. The region is seismically active and characterized by prominent E-W left-lateral strike-slip faults that localize transpressional deformation and uplift along their lengths and at stepover zones. This report summarizes structural field investigations made in the easternmost Gobi Altai to document the structural geometry and style of late Cenozoic transpressional deformation in the region in order to better understand processes of intracontinental mountain building and the distant intracontinental strain response to the Indo-Eurasian collision. The Artsa Bogd range marks the northeastern terminus of the Gobi Altai and is topographically asymmetric with a high northern margin marked by N-vergent thrust faults and left-lateral oblique-slip faults. The northern side of the range is also bounded by a foreland basin that contains N-vergent thrust faults and folds that deform Quaternary sediments. The southern margin of Artsa Bogd appears tectonically inactive but contains S-vergent thrust faults and left-lateral wrench zones. The range appears to have a flower structure cross-sectional geometry that may reflect transpressional inversion of a Mesozoic basin. The isolated, high and narrow Tsost Uul range south of Artsa Bogd occupies a restraining bend position along the left-lateral Tsost Uul strike-slip fault system. Major faults within the range define a half-flower structure cross-sectional geometry. To the south of the Tsost Uul range, the Gobi Bulag left-lateral strike-slip fault system is marked by small push-up ridges and one major restraining bend mountain where the fault steps to the right near its western end. Throughout the region, Late Cretaceous-Tertiary basalts and Tertiary and Quaternary sediments are deformed by the major fault systems indicating late Cenozoic fault activity. These fault systems and the ranges formed along them occur at fairly regular intervals (approximately 20 km) between the North Gobi Altai fault system and the Gobi Tien Shan fault system, two major left-lateral strike-slip faults that cut across southern Mongolia. Together the faults define a parallel array of discrete linear belts of Cenozoic E-W left-lateral transpressional deformation south of the Hangay Dome. The regular spacing of the fault systems may suggest more uniform distributed left-lateral flow at depth. Eastward-directed lower crustal and lithospheric mantle flow is suggested by existing seismic anisotropy data for the eastern Gobi Altai and is believed to be the driving force for the upper crustal deformation.

Quaternary alluvial fans in the Gobi of southern Mongolia: evidence for neotectonics and climate change

Alluvial fans in southern Monglia occur along a group of narrow discontinuous mountain ranges which formed as transpressional uplifts along a series of strike-slip faults. They provide information on the nature of neotectonic activity in the eastern Gobi Altai range and on palaeoclimate change. Alluvial fan formation was dominated by various geomorphological processes largely controlled by climatic changes related to an increase in aridity throughout late Quaternary times. Their sedimentology shows that initially they experienced humid conditions, when the sedimentary environments were dominated by perennial streams, followed by a period of increasing aridity, during which coarse fanglomerates were deposited in alluvial fans by ephemerial streams and active-layer structures were produced by permafrost within the alluvial fan sediments. With climatic amelioration during early Holocene times, the permafrost degraded and fan incision and entrenchment dominated. Sedimentation was then confined to the upper reaches of the fans, adjacent to steep mountain slopes, and within the entrenched channels. The alluvial fans have been neotectonically deformed, faulted and their surface warped by small thrust faults that propagate from the mountain fronts into their forelands. Localised uplift rates are in the order of 0.1 to 1 m Ka -1 . © 1997 John Wiley & Sons, Ltd. alluvial fans; neotectonics; Gobi; Mongolia; cryoturbation.

Isoetalean megasporophylls with megaspores from the Upper Cretaceous of Mongolia

Detached megasporophylls bearing relatively large sporangia with megaspores are described from the lower Maastrichtian dinosaur beds of the Nemegt Basin, eastern Gobi, Mongolia. The megasporophylls are fertile along their entire length except a short tip. The megaspore tetrads are aligned in a single file. On the base of these distinctions the Mongolian fossils are assigned to a new genus Monilitheca of the Isoetalean affinities. The megaspore casts show replicas of both the external and internal reticulate structures. The megaspores are comparable with dispersed spore genera Horstisporites and Erlansonisporites thus suggesting their isoetalean affinities.

Geographical Ecology of Mongolian Desert Rodent Communities

We analysed the spatial organization of Mongolian desert rodent fauna by stepwise discriminant function analysis and cluster analysis. Geographical variation in niche breadth and niche position among three community types of Southern, Western and Eastern Gobi was considered in overall coordinates for the whole desert. To reduce the environmental constraints in regional communities, niche breadth was estimated along comparable parts of discriminant axes and was measured by use of the Shannon-Weaver index. Niche overlap values were calculated for each of the three communities as a probability of displacement along the discriminant axis. Guild structure of the fauna reflects the adaptation of species to the range of main landscape types of the desert zone. Species shift their preferences along the axes of ecological space independently. These results challenge the viewpoint that the spatial-guilds are stable co-adapted assemblages. The nearest neighbor analysis of niche overlap indicates the absence of dense niche packing in the southern Mongolian desert, whereas the relatively even distribution of niche overlap in communities of the northern Mongolian desert suggests more dense niche packing. We did not find any features of regularity in body size distribution among Mongolian desert species. Pairs of congeneric species with low and high niche overlap have the same body weight ratio.

Regional Tectonic Synthesis of Eastern Mongolian People's Republic

Geologic interpretation of 36 contiguous Landsat scenes covering the Nyalga, Choibalsan, Tamtsag, and Eastern Gobi basins of eastern Mongolia reveals many previously undetected structural features. Situated between the Siberian and North Sinic shield, the region is composed of continental, oceanic basin, and island are microplates accreted onto the Siberian shield from the Precambrian to the middle of the Paleozoic. Even though the region was not directly involved in plate collision in post-late Paleozoic, collisional events in adjacent areas have profoundly influenced the structure of the area. Regional extension during Late Jurassic and Early Cretaceous produced numerous rift-related basins. Sediments that accumulated in these basins constitute the source and reservoir rocks for existing production. Later compression (probably related to collision of plates along the southern margin of the North China plate) has inverted many of the previous structural features, creating numerous faults and folds. The present episode of deformation (east-west oriented left-slip faulting, conjugate right-slip faulting, and attendant east-west extension) is related to the collision and continued penetration of the Indian plate on the south edge of Eurasia. Satellite imagery provides a synoptic view that assists in recognizing and understanding the structural overprinting and allows one to infer relationships among untestedmore » structures and production in Mongolia and adjacent basins in China.« less