Altai Range Research Articles

Seasonal space use and habitat selection of GPS collared snow leopards (Panthera uncia) in the Mongolian Altai range.

Although the home range and habitat selection of animal species is among the fundamental pieces of biological information collected by research projects during recent decades, published information on the snow leopard (Panthera uncia) home range is limited. The Altai Mountains of central Asia contain some of the largest and most important remaining conservation landscapes for snow leopards globally, but there is a limited understanding of the species' ecology in this region. First, we used the data from 5 snow leopards equipped with GPS collars at four study sites in the Altai Mountains of Mongolia to broadly characterize patterns of home range use between 2013 and 2019. The data was used to calculate home range size from a 10 month period using three different estimators: minimum convex polygons (MCP), kernel density distributions (KDE), and local convex hulls (LoCoH). Second, ten data sets from 8 individual snow leopards were combined to cover all 12 months of a year and to generate a general additive mixed model of seasonal home range use and seasonal resource use. We found 1) large variation in home ranges between sites during the monitoring period ranging minimally between 26.1 and 395.3km2 (MCP); 2) Local convex hull home ranges were smaller compared to home ranges based on minimum convex polygons and kernels and yielded more biologically appropriate home range estimates; 3) monthly home ranges of males were larger than females; 4) female monthly home ranges decreased in summer, while male monthly range use remained stable throughout the year; and, 5) while both sexes shared similar habitat preference in winter (steep south-western slopes at high elevation), our data suggest different habitat preferences between sexes in summer. Knowledge of the space use of threatened species is crucial for their conservation, and this is especially true for apex predators who often provide benefits for an entire ecosystem. Our study provides a preliminary understanding of the spatial ecology of this important species in an area of critical conservation concern.

Damage of soil cover due to the impact of tourism in the Altai mountains

This article presents the results of a study on soil cover damage caused by uncontrolled tourism in the Kazakhstan Altai and Mongolian Altai ranges. According to the expedition and laboratory work, it was determined that the soil cover of 182,7 km long territory in the Mongolian Altay range was damaged due to the ruts of vehicles and the trampling of tourists. More than 56,9% of these measured areas were completely destroyed, and 35,4% became rocky or desert. In the Altai ridge of Kazakhstan, the soil cover was damaged due to the formation of branch roads on an area of ​​705,7 ha, which was 55,3 km long. Approximately 84,4% of the total recorded area is moderately damaged and the growth of plants and grasses has decreased. During the determination of soil contamination with heavy metals, a total of 40 samples were taken from 8 coordinates and analyzed. The amount of lead and nickel in the soil has increased by 2-4 times due to the influence of tourism in both the Mongolian Altai Range and the Kazakh Altai Range. Cadmium element was not found at all. The content of other heavy metals such as chromium, copper, and zinc is slightly increased and accumulated at the bottom of the road. In both Kazakhstan and Mongolia, it was determined that the soil is polluted with heavy metals only by tourists' cars, as there is no mining, metallurgical plants, or resorts within 300 km.   Keywords:  Kazakhstan Altai Ridge, Mongolian Altai Ridge, soil cover, soil pollution.

Petrostructural and Geochronological Constraints on Devonian Extension‐Shortening Cycle in the Chinese Altai: Implications for Retreating‐Advancing Subduction

AbstractStructural and metamorphic effects of a Devonian extension‐shortening cycle in the NW Chinese Altai were investigated using combined structural‐petrological analysis and zircon and monazite U‐Pb geochronology. Structural observations revealed a ubiquitous, sub‐horizontal metamorphic fabric (S1), which was originally sub‐parallel with horizontal bedding (S0) of supracrustal Devonian volcanic‐sedimentary basins. This metamorphic fabric is defined by a sillimanite‐bearing migmatitic gneissosity associated with extensional shear bands and a cordierite‐bearing schistosity in the orogenic lower and middle crust, respectively. Staurolite relics preserved in the S1 fabric are interpreted as relics of older, higher pressure Barrovian‐type metamorphism. These structural‐metamorphic features are correlated with decompression and heating and interpreted as reflecting a crustal‐scale extensional phase. S1 was folded to form N‐S‐oriented upright antiforms cored by migmatites and locally transposed by steep S2 foliation during a ∼W‐E‐directed shortening (in current coordinates). Andalusite and cordierite overgrew the migmatitic S2 foliation attesting to decreasing pressure associated with vertical extrusion of migmatites in cores of F2 antiforms. New U‐Pb age data from subhorizontally foliated migmatites suggest that the D1 extension started at least before ∼410 Ma. Age data of syn‐D2 granite intrusions and dykes constrain the D2 shortening starting soon after D1 extension and ending at ∼378 Ma. Combined with regional data, cycles of extensional and contractional tectonic regimes can be defined, which also show eastward migration along‐strike of the Altai range. Such extension‐shortening cycles could result from alternating retreating and advancing subduction, which governed the evolution of the Altai accretionary system from the Ordovician until the Carboniferous.

Petrology and geochronology of andalusite- and sillimanite-bearing kyanite metapelites from the Gobi Altai Mountains: Evidence for prolonged convergent tectonics in the Central Asian Orogenic Belt

To further constrain the tectonic evolution of the convergent margin of the West Mongolian segment in the Paleo–Asian Ocean, we have investigated coarse-grained kyanite metapelites associated with quartz veins in the Gobi Altai Mountains, Mongolia, where the metamorphic belt is in a thrust contact with a Paleozoic accretionary complex. The metapelites contain coarse-grained granoblastic kyanite grains that are surrounded by sillimanite (Sil-II) with moat-like andalusite (And-II). The garnet grains in the garnet-bearing kyanite metapelites contain inclusions of andalusite (And-I) in their cores and sillimanite (Sil-I) in their mantles. Detailed textural characterization of the aluminosilicate phases indicates five distinct generations in the sequence andalusite (And-I), sillimanite (Sil-I), kyanite (Ky), sillimanite (Sil-II), and andalusite (And-II). Thermobarometric calculations and thermodynamic modeling suggest a hairpin-shaped P–T evolution with prograde conditions starting from ~530 °C at 3.5 kbar, reaching a peak of 600 °C at 6 kbar, and then a retrogression to ~550 °C at 4 kbar. U-Pb zircon and U–Th–Pb monazite ages indicate that the multistage aluminosilicate formation has occurred during c. 260–245 Ma. The detrital zircon age distribution is essentially similar to those in the accretionary sedimentary rocks from the entire Altai Range (a sharp peak at 550–490 Ma and a broad peak at 900–700 Ma), but is characterized by more abundant Proterozoic zircon grains and an older maximum deposition age (Early Ordovician) compared with Devonian pelitic gneisses in the Mongolian Altai. These petrological and geochronological results indicate the following development of the orogen: (1) Subduction of an oceanic plate beneath a microcontinental block as early as 550 Ma, evidenced by the youngest peak of detrital zircon ages. (2) Development of the accretionary wedge and volcanic front due to maturation of the arc until c. 360 Ma. The development of the volcanic front due to the magmatism has provided abundant Paleozoic detritus to the accretionary wedge and has stemmed supply of Proterozoic detritus from the inland at the same time. (3) Burial of the youngest accretionary wedge at c. 360–350 Ma, which is not observed in the current samples. Ridge subduction has also been suggested to have occurred in this period. (4) Arc magmatism in the upper (older) part of the accretionary wedge during the late Permian that resulted in prograde high-T and low-P metamorphism (formation of And-I). (5) Burial of the heated accretionary wedge to a depth of ~20 km due to subsequent collision (formation of Sil-I and Ky) at c. 260 Ma. (6) Rapid exhumation of the buried accretionary wedge to a shallow depth by thrusting (formation of Sil-II and And-II) at c. 245 Ma. In summary, the metapelites in the Altai Range clearly preserve the evolution of both the accretion and collision events as well as their transformation processes, which are likely to be a good natural example of the Wilson cycle for a period of ~300 Myr.

Origin of Permian mafic intrusions in southern Chinese Altai, Central Asian Orogenic Belt: A post-collisional extension system triggered by slab break-off

Distinct types of mafic rocks, including gabbro-norite, gabbro-diorite, and monzogabbro-diorite, are exposed in the southern Chinese Altai. Zircon U-Pb dating of these intrusions reveals that they were emplaced at ca. 283–275 Ma. Geochemical data show that these intrusions are characterized by low Ce/Pb (3.1–10.3), low Nb/U (5.5–38.9), and high Th/Yb (0.4–2.4) ratios. They are slightly LREE enriched, with selective enrichments of LILE and LREE over HFSE and significant Nb-Ta and Zr-Hf depletions. These rocks have depleted Nd isotopic compositions (εNd(t) = 1.8–5.0). In addition, the monzogabbro-diorite samples contain abundant primary amphibole and biotite and show high Rb/Y ratios. The above geochemical characteristics and mineral associations indicate that their parental magmas were hydrous and likely resulted from partial melting of subduction-metasomatized sub-continental lithospheric mantle (SCLM). In contrast, the orthopyroxene-bearing gabbro-norite and gabbro-diorite intrusions show anhydrous and high-T mineral assemblages, implying that the hot asthenosphere must have been also involved in their magma genesis. Given the absence of oceanic island basalt (OIB)-like signals in our samples, the contribution of the coeval Tarim mantle plume can be precluded. A slab break-off scenario is proposed for the Chinese Altai after its collision with the East Junggar in Permian, with products of mafic magmas generated by the interaction between partial melts of SCLM and upwelling depleted asthenospheric mantle. Apart from the Altai Range, the coeval mafic-ultramafic magmatism in the Beishan and East Tianshan orogens share comparable petrogenesis, indicating a general tectonic regime of the western CAOB during this transitional period.

モンゴル・アルタイ山脈，粗粒藍晶石を含む泥質変成岩中の紅柱石と珪線石

モンゴル・アルタイ山脈，粗粒藍晶石を含む泥質変成岩中の紅柱石と珪線石

Genesis of oceanic island basalt in ophiolitic mélange from core area of Central Asian Orogenic Belt

The Central Asian Orogenic Belt (CAOB) is one of the largest orogens in the world and comprises island arcs, seamounts, accretionary wedges, oceanic plateaux and microcontinents accreted during the closure of the Paleo-Asian Ocean which is a long-lived ocean that existed for ~800 Ma from the late Mesoproterozoic to the Mesozoic. The CAOB extends from the Urals in the west, through Kazakhstan, northern China, and Mongolia to the eastern Russian coast. The core area, which extends from central Kazakhstan to Xinjiang (northwestern China), are divided into three main geological domains. To the northeast, (1) the Altai range is composed by Early and Late Palaeozoic units that were accreted and docked to the Siberian margin and affected by high-grade metamorphism. To the south, the convergence between the Tarim Block and several micro continents such as Yili and Central Tianshan formed the (2) Palaeozoic Tianshan Orogen. The central and northwestern parts of Central Asia display a horseshoe shape that can be followed from North Tianshan to West Junggar around the Balkash Lake area. This megastructure is termed the (3) Kazakh Orocline. Until now so many studies focused on this area. However, the architecture and orogenic processes of the CAOB are still hotly debated. Remnants of oceanic island basalts (OIB) in association with ophiolites have been identified in several accretionary complexes in core area of CAOB. The nature of occurrence, geochemical characteristics of these OIBs and ophiolites has been taken to indicate extensive crust-mantle cycling magmatism. Therefore, in this paper, we provide an overview of the salient features of twelve OIB-hosting with age of Late Neoproterozoic to Early Carboniferous in core area of CAOB, and distinguish rock association of typical seamount from ophiolitic melanges, including pillow basalt, volcanic breccia, reef limestone, olistostromes rocks, and terrestrial clastic rocks. Combined with unique structural features of seamount, we preliminary reconstruct stratigraphic framework of paleoseamount. Geochemically, the volcanic rocks from paleoseamount are mainly alkaline basalts with litte tholeiitic basalts. The alkaline basalts are characterized by LREE enrichment and HREE depletion, and no obvious Nb, Ta and Ti negative anomalies, suggesting typical OIB affinity. The Nd, Sr and Pb isotopic features indicate that the magma source have enriched components and show fluid metasomatism. In short, this are consistent with geochemical features of Louisville, Ontong Java and Hawaiian seamounts which are related to mantle plume, but not develop high magnesium picrite and komatitic basalt. The OIB in core area of CAOB are at least two possible sources: (1) seamount fragments were scraped and retained in the accretionary wedge; (2) partial melting of mantle metasomatism rocks. However, we can not rule out the possibility of partial melting of subducted oceanic crust and terrigenous sediments. Therefore, the source of OIB in core area of CAOB are very complex and show crust-mantle interaction. This is similar to mantle plume activity and seamounts evolution in modern ocean.

Geophysical‐petrological model of the crust and upper mantle in the India‐Eurasia collision zone

AbstractWe present a new crust and upper mantle cross section of the western India‐Eurasia collision zone by combining geological, geophysical, and petrological information within a self‐consistent thermodynamic framework. We characterize the upper mantle structure down to 410 km depth from the thermal, compositional, and seismological viewpoints along a profile crossing western Himalayan orogen and Tibetan Plateau, Tarim Basin, Tian Shan, and Junggar Basin, ending in the Chinese Altai Range. Our results show that the Moho deepens from the Himalayan foreland basin (~40 km depth) to the Kunlun Shan (~90 km depth), and it shallows to less than 50 km beneath the Tarim Basin. Crustal thickness between the Tian Shan and Altai mountains varies from ~66 km to ~62 km. The depth of the lithosphere‐asthenosphere boundary (LAB) increases from 230 km below the Himalayan foreland basin to 295 km below the Kunlun Shan. To NE the LAB shallows to ~230 km below the Tarim Basin and increases again to ~260 km below Tian Shan and Junggar region and to ~280 km below the Altai Range. Lateral variations of the seismic anomalies are compatible with variations in the lithospheric mantle composition retrieved from global petrological data. We also model a preexisting profile in the eastern India‐Eurasia collision zone and discuss the along‐strike variations of the lithospheric structure. We confirm the presence of a noticeable lithospheric mantle thinning below the Eastern Tibetan Plateau, with the LAB located at 140 km depth, and of mantle compositional differences between the Tibetan Plateau and the northern domains of Qilian Shan, Qaidam Basin, and North China.

THE EARLY UPPER PALEOLITHIC OF THE GOBI ALTAI REGION IN MONGOLIA (Based on Materials from the Chikhen-2 Site)

Here, we present technological, typological and morphological analyses of the Pleistocene lithic assemblages excavated from Horizons 3–2.5 of the multicomponent Chikhen-2 site located on the southern piedmont of the Gobi Altai Range, southern Mongolia. Descriptions of geomorphology, stratigraphy, and archaeological finds are given, along with an analysis of reduction and secondary trimming techniques and retouch typology. Single-platform mono-frontal flat cores, double-platform bi-longitudinal cores, orthogonal cores, and narrow-front cores dominate the reduction strategy. Microcores are also present. Levallois-like cores appear initially in Horizon 2.7. Within the tool assemblage, retouched blades, end-scrapers on blades, notched-denticulate tools and large side-scrapers (skreblos) were identified. There are also various micro-tools present, including bladelets with blunt edges, oblique points, and truncated tools. The lithic industries of Horizons 3–2.5 are classified as Early Upper Paleolithic; a conclusion supported by radiocarbon determinations (ca. 30,000 BP). The lithic complexes described here are broadly analogous with other known Early Upper Paleolithic sites both in Mongolia (e.g., Chikhen-Agui; Orkhon-1 and -7; Tolbor-4, -15, and -16), and within a larger territory including the Russian Trans-Baikal region, North China, and the Altai Mountains. Archaeological materials from the lowermost strata at Chikhen-2 are important because they illustrate the emergence of the Upper Paleolithic in southern Mongolia.

Multiple growth of garnet, sillimanite/kyanite and monazite during amphibolite facies metamorphism: implications for theP–T–tand tectonic evolution of the western Altai Range, Mongolia

AbstractFour amphibolite facies pelitic gneisses from the western Mongolian Altai Range exhibit multistage aluminosilicate formation and various chemical‐zoning patterns in garnet. Two of them contain kyanite in the matrix and sillimanite inclusions in garnet, and the others have kyanite inclusions in garnet with sillimanite or kyanite in the matrix. The Ca‐zoning patterns of the garnet are different in each rock type. U–Th–Pb monazite geochronology revealed that all rock units experienced ac. 360 Ma event, and three of them were also affected by ac. 260 Ma event. The variations in the microstructures and garnet‐zoning profiles are caused by the differences in the (i) whole‐rock chemistry, (ii) pressure conditions during garnet growth atc. 360 Ma and (iii) equilibrium temperatures atc. 260 Ma. The garnet with sillimanite inclusions records an increase in pressure at low‐P(~5.2–7.2 kbar) and moderate temperature conditions (~620–660 °C) atc. 360 Ma. The garnet with kyanite inclusions in the other rock types was also formed during an increase in pressure but at higher pressure conditions (~7.0–8.9 kbar at ~600–640 °C). The detrital zircon provenance of all the rock types is similar and is consistent with that from the sedimentary rocks in the Altai Range, suggesting that the provenance of all the rock types was a surrounding accretionary wedge. One possible scenario for the different thermal gradient is Devonian ridge subduction beneath the Altai Range, as proposed by several researchers. The subducting ridge could have supplied heat to the accretionary wedge and elevated the geotherm atc. 360 Ma. The differences in the thermal gradients that resulted in varying progradeP–Tpaths might be due to variations in the thermal regimes in the upper plate that were generated by the subducting ridge. Thec. 260 Ma event is characterized by a relatively high‐T/Pgradient (~25 °C km−1) and may be due to collision‐related granitic activity and re‐equilibrium at middle crustal depths, which caused the variations in the aluminosilicates in the matrix between the rock units.

Phylogeography of Altai osmans fishes (Oreoleuciscus sp., Cyprinidae, Pisces) inferred from nucleotide variation of the mitochondrial DNA cytochrome b gene

In this study, analyses based on cytochrome b gene (Cyt-b) mtDNA sequences were undertaken to clarify phylogenetic and phylogeographical relationships among populations Oreoleuciscus sp. (Pisces: Cyprinidae) from Western Mongolia. Two major clusters, designated clusters A and B, and minor clusters were discriminated. Cluster A comprised specimens of Oreoleuciscus from the Valley of Lakes. The cluster B consists of two subclusters; one of them (B1) including populations Oreoleuciscus of the Hollow of the Big Lakes and lakes Big Altai Range. Second subclusters (B2) combines specimens of Oreoleuciscus from Hollow of the Lake Uvs, some isolated lakes of the North-Western Khangay and waterbodies of the Arctic Ocean Basin (Selenge and Orchon basins). On the basis of estimations of sizes genetic and time of a divergence of the revealed genetikal-geographical groups existence of three allopatric species of the within genera Oreoleuciscus is proved.

The late Quaternary slip-rate of the Har-Us-Nuur fault (Mongolian Altai) from cosmogenic 10Be and luminescence dating

The Altai range (western Mongolia) accommodates NNE–SSW shortening across the northern India–Eurasia collision zone by dextral slip on faults trending NNW–SSE, and anticlockwise, vertical-axis rotations of fault-bounded blocks. However, fault slip-rates and the way in which faulting evolves over time are poorly understood, and form the motivation for this study. We focussed on the Har-Us-Nuur fault, a major transpressional fault bounding the eastern margin of the Altai. Three abandoned alluvial fan surfaces, each displaced right-laterally by the fault, were targeted for dating with cosmogenic 10Be and quartz optically stimulated luminescence (OSL). The first surface (A2) shows an exponential decrease in 10Be with increasing depth, with a significant inherited component. Modelling this profile yielded a minimum age of 74.1 ka. Material from the same sampling pit was dated at ~ 19 ka with OSL, but we consider this younger age to be incorrect, possibly due to feldspar contamination or abnormal quartz OSL characteristics. The A2 surface is displaced by 175 m, implying a (maximum) dextral slip-rate of 2.4 ± 0.4 mm yr − 1 . A second fan surface (F1) was dated at ~ 6 ka with OSL and shows little variation in 10Be with depth, consistent with this young age. The inherited component is higher than for A2, indicating contrasting levels of inheritance for different periods of fan aggradation. A final surface (F2) shows scattered 10Be concentrations and lacks material suitable for OSL, so cannot be dated precisely. Using the total vertical displacement across the fault, we place the initiation of movement on the fault at ~ 2 Ma, significantly later than the late Oligocene to Miocene (28–5 Ma) onset of shortening in the Altai region. This suggests that deformation in the Altai has widened over time to incorporate new faults at the range margins (such as Har-Us-Nuur), possibly because older faults in the range interior have rotated about vertical axes into orientations that require work to be done against gravity.

Distribution of borehole temperature at four high-altitude alpine glaciers in Central Asia

The distribution of borehole temperature at four high-altitude alpine glaciers was investigated. The result shows that the temperature ranges from −13.4°C to −1.84°C, indicating the glaciers are cold throughout the boreholes. The negative gradient (i.e., the temperature decreasing with the increasing of depth) due to the advection of ice and climate warming, and the negative gradient moving downwards relates to climate warming, are probably responsible for the observed minimum temperature moving to lower depth in boreholes of the Gyabrag glacier and Miaoergou glacier compared to the previously investigated continental ice core borehole temperature in West China. The borehole temperature at 10 m depth ranges from −8.0°C in the Gyabrag glacier in the central Himalayas to −12.9°C in the Tsabagarav glacier in the Altai range. The borehole temperature at 10 m depth is 3∼4 degrees higher than the calculated mean annual air temperature on the surface of the glaciers and the higher 10 m depth temperature is mainly caused by the production of latent heat due to melt-water percolation and refreezing. The basal temperature is far below the melting point, indicating that the glaciers are frozen to bedrock. The very low temperature gradients near the bedrock suggest that the influence of geothermal flux and ice flow on basal temperature is very weak. The low temperature and small velocity of ice flow of glaciers are beneficial for preservation of the chemical and isotopic information in ice cores.

Tectonic development of the southern Chinese Altai Range as determined by structural geology, thermobarometry,40Ar/39Ar thermochronology, and Th/Pb ion-microprobe monazite geochronology

Research Article| September 01, 2009 Tectonic development of the southern Chinese Altai Range as determined by structural geology, thermobarometry, 40Ar/39Ar thermochronology, and Th/Pb ion-microprobe monazite geochronology Stephanie M. Briggs; Stephanie M. Briggs † 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA5William Lettis and Associates, Augusta, Georgia 30901, USA †E-mail: briggs@lettis.com Search for other works by this author on: GSW Google Scholar An Yin; An Yin 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA2Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095, USA3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China Search for other works by this author on: GSW Google Scholar Craig E. Manning; Craig E. Manning 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA Search for other works by this author on: GSW Google Scholar Zheng-Le Chen; Zheng-Le Chen 3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China Search for other works by this author on: GSW Google Scholar Xiao-Feng Wang Xiao-Feng Wang 3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China Search for other works by this author on: GSW Google Scholar Author and Article Information Stephanie M. Briggs † 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA5William Lettis and Associates, Augusta, Georgia 30901, USA An Yin 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA2Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095, USA3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China Craig E. Manning 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90095, USA Zheng-Le Chen 3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China Xiao-Feng Wang 3Structural Geology Group, School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China †E-mail: briggs@lettis.com Publisher: Geological Society of America Received: 04 Dec 2007 Revision Received: 03 Nov 2008 Accepted: 06 Nov 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2009 Geological Society of America GSA Bulletin (2009) 121 (9-10): 1381–1393. https://doi.org/10.1130/B26385.1 Article history Received: 04 Dec 2007 Revision Received: 03 Nov 2008 Accepted: 06 Nov 2008 First Online: 02 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 Stephanie M. Briggs, An Yin, Craig E. Manning, Zheng-Le Chen, Xiao-Feng Wang; Tectonic development of the southern Chinese Altai Range as determined by structural geology, thermobarometry, 40Ar/39Ar thermochronology, and Th/Pb ion-microprobe monazite geochronology. GSA Bulletin 2009;; 121 (9-10): 1381–1393. doi: https://doi.org/10.1130/B26385.1 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 SocietyGSA Bulletin Search Advanced Search Abstract The 2500-km Altai Range is located in the central part of the Central Asia Orogenic System, a tectonic collage comprising oceanic and continental fragments that were assembled during the Paleozoic continental growth of Eurasia. We conducted field mapping, 40Ar/39Ar thermochronology, metamorphic petrology, and Th/Pb ion-microprobe monazite dating in the southern Chinese Altai Range. This study demonstrates the presence of a south-vergent, Permo-Triassic thrust belt active across the region. Metamorphic conditions of 610 ± 35 °C and 5.7 ± 1.8 kbar were reached by schists with Permo-Triassic monazite ages. Mica 40Ar/39Ar ages range from Late Permian to Jurassic, and cooling in these rocks is correlated with thrust faulting. This shortening was synchronous with localized left-lateral, strike-slip shear deformation. Our work suggests that the high-grade schists of the Altai orogen were buried to depths of more than 18–20 km and were exhumed in the Permian to Jurassic. The Permo-Triassic Altai thrust belt was reactivated locally by Late Jurassic contraction after ca. 160 Ma, which may result from the final closure of the Mongol-Okhotsk Ocean or the collision of the Lhasa block onto the southern Asian margin. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Late Quaternary rates of uplift and shortening at Baatar Hyarhan (Mongolian Altai) with optically stimulated luminescence

We investigate mountain building in the Altai range of western Mongolia, focusing on Baatar Hyarhan, a NW-trending massif bounded by active thrust faults. Our primary aims are to describe how thrusting has evolved over time, to calculate late Quaternary slip rates by dating offset alluvial markers with optically stimulated luminescence (OSL) and to compare these late Quaternary rates with measurements of deformation on decadal and geological timescales. Patterns of topography and drainage suggest that Baatar Hyarhan has grown in length and has propagated laterally from the SE towards the NW over time. On the NE side of the massif, the range-bounding Zereg fault appears active only along younger parts of Baatar Hyarhan; next to the oldest, SE part of the massif faulting has migrated into the adjacent Zereg Basin, where it has uplifted low, linear ridges of folded sediment, known locally as forebergs. On the SW side of the massif, only the range-bounding Tsetseg fault appears active. Using OSL, we establish ages of ∼15, ∼20 and ∼85 kyr for alluvial deposits cut by these faults. These ages are close to those of alluvial markers in the separate Gobi Altai range, suggesting that periods of fan and terrace formation may correlate over wide tracts of Mongolia, presumably under the primary control of climate. Combining our OSL ages with offsets measured with differential GPS, we calculate Late Quaternary slip rates across forebergs in the Zereg Basin and across the range-bounding Zereg and Tsetseg faults. Uncertainties in fault dip (due to lack of clear fault exposures) and burial ages (due to incomplete resetting of the luminescence clock) mean that the exact slip rates are poorly constrained. Nevertheless, the vertical displacement rates we calculate across the Zereg and Tsetseg range-front faults—0.2–0.6 and 0.1–0.4 mm yr−1, respectively—are at the lower end of long-term (∼5 Myr) estimates of 0.4–0.8 and 0.3–0.7 mm yr−1, respectively. Vertical rates of deformation may, therefore, have remained constant over the past ∼5 Myr, but equally the late Quaternary rates might be lower than the geological ones. This possible discrepancy could be accounted for if some of the shortening has shifted away from the range-front faults onto other nearby structures. The forebergs in the eastern Zereg Basin are an obvious candidate, but they show at least 10 km cumulative shortening (which would take a few Ma to accumulate at late Quaternary rates) and cannot simply be regarded as the latest stage of outward mountain growth. The total Late Quaternary shortening rate across all three areas of faulting is 0.7–2.4 mm yr−1, making up between one tenth and one third of the ∼7 mm yr−1 convergence across the whole Altai range.

Phylogeography of a widespread terrestrial vertebrate in a barely-studied Palearctic region: green toads (Bufo viridis subgroup) indicate glacial refugia in Eastern Central Asia

The phylogeography of western Palearctic species is relatively well studied, but data on Eastern Central Asia are scarce. We present one of the first data sets from a widespread terrestrial vertebrate (Bufo pewzowi) inhabiting Eastern Central Asian mountains and deserts to gain knowledge on its phylogeography in this region. We applied combined phylogenetic and demographic analyses to understand the evolutionary history using mitochondrial DNA D-loop variation of toads from 37 locations. Genetic structure of Bufo pewzowi is strongly affected by landscape: we found three haplotype groups in eastern Kazakhstan, Dzungaria and Tarim Basin, divided by the Tian Shan and Dzungarian Alatau ranges. A vicariant hypothesis may explain divergence among groups. The divergence time of the three major clades was estimated about 0.9 million years ago (confidence interval 0.5-1.4), and is discussed with respect to Quaternary uplifting and glaciation in the Tian Shan. Demographic analyses provided evidence for both historical bottlenecks and population expansions and suggested Pleistocene signatures. Glacial refugia were inferred in the Tarim Basin (around the Turpan depression), in southern Dzungaria (Urumqui region), at the northern foot of the Tian Shan (Gongnaisi) and perhaps at the Altai range (Terekti). Regional Post-Last Glacial Maximum dispersal patterns are proposed. A taxonomic hypothesis is presented. This study provides a detailed history of how a widespread terrestrial vertebrate responded to geological change and Quaternary glacial events in Eastern Central Asia and may have significance for future phylogeographic research in this understudied region.

Combining InSAR and seismology to study the 2003 Siberian Altai earthquakes-dextral strike-slip and anticlockwise rotations in the northern India-Eurasia collision zone

SUMMARY The 2003 September 27 M w 7.2 Siberian Altai earthquake was the largest to have struck the Altai mountains in more than seventy years, and was closely followed by two M w 6.2 and 6.6 aftershocks. We use radar interferometry, seismic bodywaves and field investigations to examine the source processes of these earthquakes. The main shock of the initial earthquake ruptured a subvertical, ∼NW‐SE striking dextral strike-slip fault. The fault was previously unrecognised; although it approximately follows the southwestern boundaries of two intermontane depressions within the interior northwestern Altai, it has very little topographic expression. A ∼NE-dipping M w ∼ 6.7 reverse subevent, possibly triggered by shear waves from the main shock, occurred ten seconds afterwards strike to the southeast. The later M w 6.2 and 6.6 aftershocks were dextral strike-slip events which contributed further to deformation in the northwest part of the fault zone. However, interferometric and bodywave models disagree significantly on the source parameters of the earthquakes, in particular the total moment released and the dip of the fault planes. Trade-offs of fault dip with moment and centroid depth in the bodywave modelling can account for some, but not all, of these discrepancies. The interferometric data is unevenly distributed, containing many more data points on one side of the fault zone than the other; however, on the basis of calculations with synthetic data we rule this out as a reason for the discrepancies in fault parameters. The lower moment predicted by interferometry could be explained by the lack of coherent data close to the faulting, if slip was concentrated at very shallow depths. The dip yielded by the interferometric modelling might be influenced by lateral changes in elastic properties, although these would also affect the bodywave solutions. The earthquake sequence occurred close to recent palaeomagnetic measurements of late Cenozoic anticlockwise rotations. These suggest that the right-lateral strike-slip faulting that ruptured in the 2003 earthquakes accommodates regional ∼NNE‐SSW shortening by rotating anticlockwise over time. The reverse subevent is a rare case of pure shortening perpendicular to the trend of the Altai range.

The Tamyrs: A Tale of Two Peoples

Translator's Note Tamyrs (Die Tamyr) was published in 2002 in a German-language collection of short fiction called Dew and Grass (Tau und Gras). Written in oral narrative style, the story begins in 1922, after the Mongolian revolution and the overthrow?with the aid of the Soviets?of the Chinese occupation. Tribal warfare within Mongolia was intense. In the mountains separating China and Mongolia, two groups of refugees? Tuvans and Kazakhs, as the reader learns at the end of the story?engage each other in a battle. While the setting is historical, the story's theme is also topical: the relationship is precarious between the minority Tuvans and majority Kazakhs in the high Altai range of the western Mongolian province of Bayan-Olgiy, which is the traditional homeland of the Tuvans. The province borders on the Russian Federation to the north and the Peo ple's Republic of China to the south. As the chieftain of the Tuvans, Galsan Tschinag works tirelessly to pro mote interethnic understanding and foster economic opportunities for both the Tuvans and the Kazakhs.

Stratigraphic Occurrence, Paleoenvironment, and Description of the Oldest Known Dinosaur (Late Jurassic) from Mongolia

Dinosaur fossils found in July, 1995, near Dariv, western Mongolia, represent the first dinosaurs of Jurassic age described from Mongolia. The fossils derive from at least three types of dinosaurs, and include the right foot of a sauropod tentatively identified as Mamenchisaurus sp. The dinosaur fossils occur in Upper Jurassic floodplain deposits that accumulated in a seasonally wet, collisional foreland basin just prior to an episode of uplift of the ancestral Altai Range in latest Jurassic time.

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.