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The catastrophic Shikotan earthquake of October 4 (5), 1994, occurred in the Pacific Ocean. Its focus was located 80 km eastward of Shikotan Island. The stress state of the Earth’s crust in this area was estimated by the method of the cataclastic analysis of the whole range of the earthquake mechanisms. The performed reconstruction of the parameters of the current stress state of the Earth’s crust and the upper mantle in the area of the Southern Kuril Islands made it possible to establish that this area is characterized, on the one hand, by the presence of extensive areas of steady behavior of the stress tensor parameters and, on the other hand, by the presence of local sections of anomalously fast changes in these parameters. 相似文献
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In the year of 2011, a super-large molybdenum deposit was discovered in the Shapinggou area, Jinzhai county, Anhui Province by the Bureau of Geology and Mineral Exploration of Anhui Province, with its reserve more than 2.2 million ton, just next to the Klimax molybdenum deposit (>3.3 million ton) in Colorado. It has ranged the world’s second largest molybdenum deposit, with potential economic value up to 100 billion dollars.
Geological surveys suggest orebodies from the Shapinggou porphyry molybdenum deposit extend 1000 m long by up to 900 m wide. A drillhole intersects one orebody as thick as 945 m, with 0.2 wt% Mo. This entire deposit suggests 332+333 ore reserve as 1.275 billion ton and Mo metal reserve as 2 million ton; this does not include the reserves of the east-west ends. Based on the current exploration work, a total Mo metal reserve of 2.2 million ton can be accomplished. The Shapinggou molybdenum deposit is characterized by its large scale, high grade, concentrated orebodies and high economic value.
The Shapinggou porphyry molybdenum deposit is the largest metal deposits during the 50 years’ prospecting history in Anhui Province. Its discovery rewrites China’s history of “no large-scale deposit in the eastern Dabie Mountains”, and validates that the Qinling-Dabie orogenic belt is the most significant Au-Mo metallogenic belt. 相似文献
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As top predators, marine mammals and seabirds play an important role in structuring marine ecosystems, and their trophic role have become a major issue. In this study, we quantify the trophic impact of marine mammals and seabirds in the Río de la Plata estuary based on a previous trophic mass balance model of this estuary. The model comprised 37 functional groups: 3 species of marine mammals (2 cetaceans: Tursiops truncatus, Pontoporia blainvillei and 1 pinniped: Otaria flavescens), 1 coastal bird group comprising 11 species, 17 fish, 12 invertebrates, 2 zooplanktons, 1 phytoplankton, detritus, and 5 fishing fleets. Model results showed that seabirds, O. flavescens and P. blainvillei, are apex predators, with high levels of niche overlap among them, suggesting competition for similar resources such as fish species. Marine mammals and seabirds produce negative effects on commercially important species, while, at the same time, indirect positive effects (increase of the biomass) were also detected in some groups related to trophic cascade effects. 相似文献
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The Qilian Mountains water conservation forest in Gansu province is an important ecological barrier surrounding the oasis in China’s Hexi Corridor. The water they provide is the basis for the existence and sustainable socioeconomic development of those oases. As a result of unsustainable use of the water conservation forest until the 1980s, the oasis ecosystems of the Hexi region were seriously damaged, and the oasis areas experienced deterioration of their ecological environment. In this paper, Landsat images were used to monitor the temporal and spatial changes in area of water conservation in Qilian Mountains of China’s Gansu province and to assess the effect on water conservation by analyzed relationship between water conservation forest area, climatic data and hydrological data. The results showed that the forest covered 15.1% of the study area in 2007 and has followed different trends during the study period. From 1978 to 1990, the forest area decreased; however, from 1990 to 2007, the forest area increased, with a faster rate of increase from 1990 to 2000, and the rate of increase averaged 2,733.89 ha per year since 1990. The water conservation forest appears to play an important role in flood control, runoff regulation, the prevention of soil erosion, and water conservation; and these benefits increase with an increasing area of forest. 相似文献
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Afshin Qishlaqi Farid Moore 《中国地球化学学报》2006,25(B08):214-214
This preliminary work reported here dealt with potential impacts of wastewater irrigation on soils and crops sampled along the Koshk River canal in the suburban area of Shiraz City, Iran. It also attempts to assess the extent of heavy metal contamination in soils and crops and human exposure risk. For this purpose, samples including soils and plants were collected from two wastewater irrigated sites and a tubewell-irrigated site (marked by A, B and C). Concentrations of the six heavy metals Ni, Pb, Cd, Zn, Cr and Cu were determined by AAS. Physical and chemical properties of soil samples were also determined. The PLIs and CF for soils and HQ (Hazard quotient) for some vegetables were calculated. The results showed that organic matter content increased from 22% to 30 % in wastewater-irrigated soils as compared to tubewell water irrigated and admixture water irrigated ones. The soil pH was raised by 2 units as a result of wastewater irrigation at site A compared to sites B and C. Wastewater irrigation also result in relatively high concentrations of Ni, Pb and Zn (275.5, 441.3 and 177 mg/kg, respectively) in wastewater irrigated soils over tubewell water irrigated soils. These levels are higher than the maximum permissible limits in unpolluted soils, indicating that a degree of contamination has occurred. This was confirmed by calculated PLIs and contamination factors in soil samples, The results also showed some crops cultivated at sites A and B contained high levels of Ni and Cd beyond the maximum permissible concentrations and those cultivated at site C. The concentrations of these heavy metals are within or very close to the critical levels. HQ indices and daily intake calculated in respect of metal contents in some vegetables (spinach, lettuce and celery) showed that toxic risk due to Cd in these vegetables and crops was greater than one. This study generally concludes that although the content of heavy metals did not reach toxic level, extensive use of untreated wastewater drawn from the Koshk River has obviously increased the contamination of Ni and Pb in soils and Cd in some vegetables cultivated along the canal, causing potential health risk in the long-term scense for consumers or local residents. 相似文献
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Krupenin M. T. Kuznetsov A. B. Chervyakovskaya M. V. Gulyaeva T. Ya. Konstantinova G. V. 《Geology of Ore Deposits》2021,63(4):324-340
Geology of Ore Deposits - Based on Sm–Nd data, a crustal source of iron-ore fluid was substantiated and the probability of age estimation for hydrothermal–metasomatic siderite of the... 相似文献
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The Shexian gneissic granodiorite in southern Anhui trends NE 55° from Shexian in the west to Guitoujian in the east with
a length of 22 km and an outcrop area of 32 km. It was considered formerly to be Caledonian on the basis of a biotite K-Ar
age of 474 Ma (1982). However, new evidence indicates that it may be Early Jinning in age as shown by: (1) it is found intruding
into the Mid-Proterozoic Shangxi Group and is unconformably overlain by the Sinian Xiuning Formation, and (2) a zircon U-Th-Pb
age of 928 Ma is obtained for the pluton.
The pluton is composed of plagioclase (An=27.37%), K-feldspar(14%), biotite(16%) and quartz(32%). Accessory minerals are ilmenite
(150g/T), xenotime (15g/T). garnet(25g/T), monazite(10g/T), zircon (20g/T) and apatite (104g/T). Petrochemical characteristics
of the intrusion are:(l) Al-enrichment (A/NKC=1.30); (2) H2O enrichment (H2O= 1.74%); and (3) low oxidation index (f ’=0.10). It belongs to the continental crust transformation type as evidenced by: (1) MF and Mg/Y values of biotite are 0.41
and 0.31 respectively; (2) (87Sr/86Sr)=0.71119; (3) δ Eu=0.52; and (4) A/NKC=130. The Shexian pluton is therefore considered as a product of melting of phyllite
at depth in the light of similarities in trace element and REE contents with the phyllite of the Banxi Group. Calculations
of REE batch partial melting indicate that it may have resulted from 75% melting of the Banxi phyllite. 相似文献
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V. A. Petrov O. V. Andreeva V. V. Poluektov D. V. Kovalenko 《Doklady Earth Sciences》2017,472(2):159-162
The evolution of the geological structure in the Southern Argun’ Region is studied in terms of changing geodynamic conditions of the Proterozoic, Caledonian, and Variscan Tectonomagmatic Cycles, which also under Mesozoic tectonomagmatic activation led to the formation of latite igneous rocks enriched in Au, Cu–Mo, Pb–Zn–Ag, volcanic and plutonic complexes of the caldera structures with Mo–U, Pb–Zn, and fluorite ores, and rare-metal granites with a Sn–W–Li–Ta spectrum. 相似文献
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Gregory P. Marchildon Suren Kulshreshtha Elaine Wheaton Dave Sauchyn 《Natural Hazards》2008,45(3):391-411
Agriculture in the southern Great Plains of Canada has been particularly vulnerable to prolonged episodes of drought. Using
climate data and a precipitation minus potential evapotranspiration index, the extent of the region’s exposure to drought
is examined. Between 1914 and 1917, the Dry Belt was particularly vulnerable to drought, whereas after 1928, a much larger
region known as the Palliser Triangle covering most of southern Alberta and Saskatchewan was much more exposed to drought.
These droughts provoked major institutional adaptation, in particular the establishment of the Special Areas Board by the
Government of Alberta, and the creation of the Prairie Farm Rehabilitation Administration by the Government of Canada. Both
organizations have proved to be relatively permanent public adaptations to the natural hazard of drought in the region. Moreover,
these earlier experiences with prolonged drought as well as institution-building may be of value in helping the residents
of the Palliser Triangle adapt to predicted climate changes in the future as well as anticipate some of the barriers to effective
institutional adaptation. 相似文献
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Autumn Oczkowski Scott Nixon Steve Granger Abdel-Fattah M. El-Sayed Mark Altabet Richard McKinney 《Estuaries and Coasts》2008,31(6):1130-1142
The present study reports nitrogen and carbon stable isotope data (δ15N and δ13C) from four large (63–400 km2), shallow (∼1 m) coastal lagoons on Egypt’s Nile Delta. While the lagoons all receive sewage and agricultural drainage, the
magnitude of loading varies. In this preliminary survey, we document wide variability in the δ15N and δ13C isotope values of major fish groups among these lagoons. There were no consistent or significant differences among the major
groups of fish, including carp, catfish, mullet, and tilapia. There was a strong positive correlation (R
2 = 0.84) between the average δ15N values of fish muscle and estimated water residence time among the lagoons. This preliminary evidence suggests that nitrogen
cycle transformations may be more important than primary N source differences in determining N isotopic ratios of organisms
in the lagoons. The δ13C results point to the probable importance of autochthonous particulate organic matter rather than terrestrial detritus or
marine plankton in the diets of resident fish populations in the lagoons. 相似文献
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CHEN Qu 《地下水科学与工程》2014,2(2):54-61
Climate change issues has been discussed and argued for decades. It has been widely recognized that climate change will bring more serious issues to environment vulnerable areas than other areas. Southern Australia is one of the typical examples of vulnerable areas where water deficiency is enhanced by climate change. Although, this area has been successfully adapted with drought environment for decades, those shortcomings of strategies are highlighted by climate change events. In the interests of sustainable water management, Southern Australia’s experiences on possible anticipatory adaptation approaches, especially on mitigation of risks and costs of drought could be expected to provide recommendations to planning and management actions in the future 相似文献
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正The Junggar Basin in the northern part of Xinjiang is the second largest inland basin in China.It is located between the Altai and Tianshan Mountains,which is bounded by the Junggar bounded Mountain in the northwest,the Altai Mountains in the northeast and the North Tianshan Mountains in the south.It belongs to a triangular close inland basin,and extends 700 km in EW 相似文献
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G. L. Leitchenkov Yu. B. Guseva V. V. Gandyukhin S. V. Ivanov L. V. Safonova 《Geotectonics》2014,48(1):5-23
The Southern Indian Ocean comprises large sedimentary basins of the Riiser-Larsen Sea (western sector); the Cosmonauts, Cooperation (Commonwealth), Davis seas (central sector); and the Mawson-d’Urville seas (eastern sector). The main tectonic provinces of the Southern Indian Ocean (Antarctica) have been outlined as a result of comprehensive interpretation of the geophysical data. Special attention is paid to determining the boundary between the rifted continental and oceanic crust. The basin of the Riiser-Larsen Sea was formed in the Early Jurassic under the action of the Karoo mantle plume. The intrusive complex, as a remote manifestation of the mantle plume, occurs along the inner boundary of the marginal rift. Opening of the ocean in the basin of Riiser-Larsen Sea started about 160 Ma ago and was characterized by rearrangement of plate motion and intense volcanic activity at the early stage. In the basin of the Cosmonauts, Cooperation, and Davis seas, the final stage of rifting was accompanied by the rise of the lithospheric mantle and by intrusive magmatism. The opening of the ocean started here 134 Ma ago. Emplacement of the Kerguelen plume resulted in jumping of ridges and detachment of continental crustal blocks from the Indian margin with the formation of the Kerguelen Plateau (microcontinent). The basin of the Mawson-d’Urville seas has evolved under conditions of long-term rifting since the Late Jurassic and is characterized by an extended zone of mantle unroofing. Breakup of the lithosphere between Australia and Antarctica developed asynchronously over a time interval of 95–65 Ma ago with propagation of MOR from the west eastward. The research was carried out using a great body of geophysical information (~140000 km of CDP seismic profiling, more than 250 stations of seismic refraction sounding, and more than 250000 km of magnetic and gravity profiles) obtained by expeditions from many countries over more than 30 years. 相似文献
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We analyze autocorrelations and power spectra of the time series of monthly mean data characterizing sea surface temperature anomalies in the equatorial Pacific in the years 1920–2013 and show that the rhythms of El Niño–Southern Oscillation can be interpreted as the responses of the climate system to the external quasi-periodic forcing generated by the motions of the Earth’s pole. We conclude that the ENSO phenomenon has no prediction limits.
相似文献20.
《Geoforum》2015
Street vending faces uncertain state responses in contemporary Chinese cities, though it plays an important role in sustaining the livelihood of urban migrants. Building on the critical perspective that understands informality as a production of the state, this paper explores the nature of the regulation of street vending in Guangzhou since 1949. The state’s regulatory practices are characterized by what we call historical ambivalence and geographical ambivalence, which refer to the inconsistency in policies, which fluctuate between soft and hard approaches over time, and the mix of contradictory regulatory measures applied in different urban spaces, respectively. Ambivalence is generated because the state addresses street vending in ways that attain the overarching objective of urban policies. In particular, the exclusion of street vendors in present-day China is not historically natural but driven and sustained by the government’s pursuit of a good city image favorable for attracting capital in the context of intensifying inter-urban competition. The definition of informality is not a neutral classification. Rather, declaring when and to what extent an informal practice is tolerable depends on what the state desires in a specific historical circumstance. 相似文献