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The Upper Triassic flysch sediments (Nieru Formation and Langjiexue Group) exposed in the Eastern Tethyan Himalayan Sequence are crucial for unraveling the controversial paleogeography and paleotectonics of the Himalayan orogen
. This work reports new detrital zircon U-Pb ages and whole-rock geochemical data for clastic rocks from flysch strata in the Shannan area. The mineral modal composition data suggest that these units were mainly sourced from recycled orogen provenances. The chemical compositions of the sandstones in the strata are similar to the chemical composition of upper continental crust. These rocks have relatively low Chemical Index of Alteration values (with an average of 62) and Index of Compositional Variability values (0.69), indicating that they experienced weak weathering and were mainly derived from a mature source. The geochemical compositions of the Upper Triassic strata are similar to those of graywackes from continental island arcs and are indicative of an acidic-intermediate igneous source. Furthermore, hornblende and feldspar experienced decomposition in the provenance, and the sediment became enriched in zircon and monazite during sediment transport. The detrital zircons in the strata feature two main age peaks at 225–275 Ma and 500–600 Ma, nearly continuous Paleoproterozoic to Neoproterozoic ages, and a broad inconspicuous cluster in the Tonian–Stenian (800–1200 Ma). The detrital zircons from the Upper Triassic sandstones in the study area lack peaks at 300–325 Ma (characteristic of the Lhasa block) and 1150–1200 Ma (characteristic of the Lhasa and West Australia blocks). Therefore, neither the Lhasa block nor the West Australia blocks likely acted as the main provenance of the Upper Triassic strata. Newly discovered Permian–Triassic basalt and mafic dikes in the Himalayas could have provided the 225–275 Ma detrital zircons. Therefore, Indian and Himalayan units were the main provenances of the flysch strata. The Tethyan Himalaya was part of the northern passive margin and was not an exotic terrane separated from India during the Permian to Early Cretaceous. This evidence suggests that the Neo-Tethyan ocean opened prior to the Late Triassic and that the Upper Triassic deposits were derived from continental crustal fragments adjacent to the northern passive continental margin of Greater India
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The Mw 7
.8 Gorkha earthquake in Nepal on April 25, 2015, produced thousands of landslides in the Himalayan mountain range. After the earthquake, two field investigations along Araniko Highway were conducted. Then, using remote sensing technology and geographic information system (GIS) technology, 1481 landslides were identified along the Bhote Koshi river. Correlations between the spatial distribution of landslides with slope gradient and lithology were analyzed. The power-law relationship of the size distribution of earthquake-induced landslides was examined in both the Higher Himalaya and Lesser Himalaya. Possible reasons for the variability of the power exponent were explored by examining differences in the geological situations of these areas. Multi-threshold cellular automata were introduced to model the complexity of system components. Most of the landslides occurred at slope gradients of 30°–40°, and the landslide density was positively correlated with slope gradient. Landslides in hard rock areas were more common than in soft rock areas. The cumulative number-area distribution of landslides induced by the Gorkha earthquake exhibited a negative power-law relationship, but the power exponents were different: 1.13 in the Higher Himalaya, 1.36 and Lesser Himalaya. Furthermore, the geological conditions were more complex and varied in the Lesser Himalaya than in the Higher Himalaya, and the cellular automata simulation results indicated that, as the complexity of system components increased, the power exponent increased. Therefore, the variability of the power exponent of landslide size distribution should ascribe to the complexity of geological situations in the Bhote Koshi river watershed. © 2017, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany
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Low elevation coastal zone (LECZ) in China is densely populated and economically developed, which is exposed to increasing risks of hazards related to climate change and sea level rise
. To mitigate risks and achieve sustainable development, we need to better understand LECZ. As the first step, in this paper we define the extent of the LECZ in China, and analyze the spatial distribution of LECZ and its population, using a geographic information system software (ArcGIS) to combine elevation models and population data sets. Our findings show that, overall, this zone covers 2.0 % of China’s land area but contains 12.3 % of the total population, which is the largest population living in LECZ in the world. There are large regional variations in the distribution of both LECZ and LECZ population, with half of the LECZ within 30 km from the coastline, and Jiangsu Province having the largest LECZ area and population. The LECZ is also concentrated in three major economic zones in China, which accounts for 54 % of LECZ and three quarters of all LECZ population in China. The impact of future climate change on China’s LECZ is exacerbated by rapid economic and population growth, urbanization and environmental degradation. Coordinating development in coastal and inland China, enhancing adaptive capacity and implementing integrated risk management for LECZ are needed to reduce the risks related to climate change and to achieve sustainable development
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We use a data set of 86 surface pollen samples from moss polsters and surface soils from northeastern Qinghai-Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns
. The samples span seven main vegetation zones from east to west: mountain forest, alpine shrub, alpine meadow, temperate steppe, steppe desert, shrub/semi-shrub desert and desert. Principal components analysis (PCA) was used to determine the relationships between modern pollen, vegetation, and regional climatic gradients. The results show that the major vegetation communities occurring today in the northeastern Qinghai-Tibetan Plateau can be clearly differentiated by their modern pollen assemblages. The representation of surface pollen varies with genera and species. For instance, relative to Betula, a low representation of Picea and Cupressaceae was found in the forest zone; Artemisia, Chenopodiaceae and Ephedraceae had high representation values, while Cyperaceae, and Nitraria showed values in the middle range, and Poaceae, Asteraceae, Tamarixaceae, Calligonum, Polygonaceae, Ranunculaceae, Fabaceae, Scrophulariaceae and Primulaceae had low representation values. Rosaceae have low representation values in the sampling sites in alpine shrub community where the dominant plant species are Potentilla fruticosa and Potentilla glabra. PCA results indicated a high correlation between the modern pollen assemblages and mean annual precipitations (MAP) and July temperature (Tjuly). The Artemisia/Chenopodiaceae (A/C) ratio is sensitive to variations in MAP in this region and is a useful tool for qualitative and semi-quantitative palaeoclimate reconstruction on the northeastern Qinghai-Tibetan Plateau
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Piao, S.; Ciais, P.; Huang, Y.; Shen, Z.; Peng, S.; Li, J.; Zhou, L.; Liu, H.; Ma, Y.; Ding, Y.; Friedlingstein, P.; Liu, C.; Tan, K.; Yu, Y.; Zhang, T.; Fang, J.
Global warming or the increase of the surface and atmospheric temperatures of the Earth, is increasingly discernible in the polar, sub-polar and major land glacial areas
. The Himalayan and Tibetan Plateau Glaciers, which are the largest glaciers outside of the Polar Regions, are showing a large-scale decrease of snow cover and an extensive glacial retreat. These glaciers such as Siachen and Gangotri are a major water resource for Asia as they feed major rivers such as the Indus, Ganga and Brahmaputra. Due to scarcity of ground measuring stations, the long-term observations of atmospheric temperatures acquired from the Microwave Sounding Unit (MSU) since 1979–2008 is highly useful. The lower and middle tropospheric temperature trend based on 30 years of MSU data shows warming of the Northern Hemisphere's mid-latitude regions. The mean month-to-month warming (up to 0.048±0.026°K/year or 1.44°K over 30 years) of the mid troposphere (near surface over the high altitude Himalayas and Tibetan Plateau) is prominent and statistically significant at a 95% confidence interval. Though the mean annual warming trend over the Himalayas (0.016±0.005°K/year), and Tibetan Plateau (0.008±0.006°K/year) is positive, the month to month warming trend is higher (by 2–3 times, positive and significant) only over a period of six months (December to May). The factors responsible for the reversal of this trend from June to November are discussed here. The inequality in the magnitude of the warming trends of the troposphere between the western and eastern Himalayas and the IG (Indo-Gangetic) plains is attributed to the differences in increased aerosol loading (due to dust storms) over these regions. The monthly mean lower-tropospheric MSU-derived temperature trend over the IG plains (dust sink region; up to 0.032±0.027°K/year) and dust source regions (Sahara desert, Middle East, Arabian region, Afghanistan-Iran-Pakistan and Thar Desert regions; up to 0.068±0.033°K/year) also shows a similar pattern of month-to-month oscillation and six months of enhanced and a statistically significant warming trend. The enhanced warming trend during the winter and pre-monsoon months (December–May) may accelerate glacial melt. The unequal distribution of the warming trend over the year is discussed in this study and is partially attributed to a number of controlling factors such as sunlight duration, CO2 trends over the region (2003–2008), water vapor and aerosol distribution
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Places do well when they promote transformations along the dimensions of economic geography: higher densities as cities grow; shorter distances as workers and businesses migrate closer to density; and fewer divisions as nations lower their economic borders and enter world markets to take advantage of scale and trade in specialized products
. WDR 2009 argues that the three dimensions of transformation-density, distance, and division-are essential for development and should be encouraged
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