Isotope geochemistry of Jeongok basalts,northernmost South Korea: Implications for the enriched mantle end-member component     

《Journal of Asian Earth Sciences》2014

South Korea separates two mantle source domains for Late Cenozoic intraplate volcanism in East Asia: depleted mid-ocean-ridge basalt (MORB) mantle-enriched mantle type 1 (DMM-EM1) in the north and DMM-EM2 in the south. We determined geochemical compositions, including Sr, Nd, Pb, and Hf isotopes for the Jeongok trachybasalts (∼0.51 to 0.15 Ma K–Ar ages) from northernmost South Korea, to better constrain the origin and distribution of the enriched mantle components. The Jeongok basalts exhibit light rare earth element (LREE)-enriched patterns ([La/Yb]_N = 9.2–11.6). The (La/Yb)_N ratios are lower than that of typical oceanic island basalt (OIB). On a primitive mantle-normalized incompatible element plot, the Jeongok samples show OIB-like enrichment in highly incompatible elements. However, they are depleted in moderately incompatible elements (e.g., La, Nd, Zr, Hf, etc.) compared with the OIB and exhibit positive anomalies in K and Pb. These anomalies are also prime characteristics of the Wudalianchi basalts, extreme EM1 end-member volcanics in northeast China. We have compared the geochemistry of the Jeongok basalts with those of available Late Cenozoic intraplate volcanic rocks from East Asia (from north to south, Wudalianchi, Mt. Baekdu and Baengnyeong for DMM-EM1, and Jeju for DMM-EM2). The mantle source for the Jeongok volcanics contains an EM1 component. The contribution of the EM1 component to East Asian volcanism increases toward the north, from Baengnyeong through Jeongok to Mt. Baekdu and finally to Wudalianchi. Modeling of trace element data suggests that the Jeongok basalts may have been generated by mixing of a Wudalianchi-like melt (EM1 end-member) and a melt that originated from a depleted mantle source, with some addition of the lithospheric mantle beneath the Jeongok area. In Nd–Hf isotope space, the most enriched EM1-component-bearing Jeongok sample shows elevation of ¹⁷⁶Hf/¹⁷⁷Hf at a given ¹⁴³Nd/¹⁴⁴Nd compared with OIB. Recycled pelagic sediments may explain the EM1-end-member component of northeastern Asian volcanism, possibly from the mantle transition zone.  相似文献   

Near-surface air temperature lapse rate in a humid mountainous terrain on the southern slopes of the eastern Himalayas     

Kattel  Dambaru Ballab  Yao  Tandong  Panday  Prajjwal Kumar 《Theoretical and Applied Climatology》2018,132(3-4):1129-1141

Theoretical and Applied Climatology - Based on climatic data from 18 stations on the southern slopes of the eastern Himalayas in Bhutan for the period from 1996 to 2009, this paper investigates...  相似文献   

Comparison of different phases of bismuth silicate nanofibers for photodegradation of organic dyes     

S. S. Batool  S. Hassan  Z. Imran  K. Rasool  M. Ahmad  M. A. Rafiq 《International Journal of Environmental Science and Technology》2016,13(6):1497-1504

Two different phases of bismuth silicate nanofibers [Bi₂SiO₅ and Bi₄(SiO₄)₃] were synthesized using electrospinning technique. BS nanofibers were tested for the photocatalytic degradation of methyl orange and safranin O dyes. Different phases of BS affect the photodegradation efficiency of nanofibers. Impressive enhancement in photocatalytic efficiency and BET surface area of Bi₄(SiO₄)₃ was observed over Bi₂SiO₅. A speedy reduction in dyes concentration was attributed to the rapid formation of oxygenated radicals by the capture of electrons and holes, generated in the BS nanofiber by UV irradiation. Therefore, the photocatalytic mechanism was elucidated using impedance spectroscopy at room temperature. The lower impedance value of Bi₄(SiO₄)₃ nanofibers had improved high-efficiency charge transfer capability. The cycling efficiency (30 times) and recovery characteristics pointed out that Bi₄(SiO₄)₃ nanofibers photocatalysts had high constancy, resilience, and regeneration ability.  相似文献   

Petrophysical parameters and modelling of the Eocene reservoirs in the Qadirpur area,Central Indus Basin,Pakistan: implications from well log analysis     

Miraj Khan  Mohammad Arif  Nowrad Ali  Mohammad Yaseen  Ammar Ahmed  Syed Mamoon Siyar 《Arabian Journal of Geosciences》2016,9(5):425

The Eocene rock units of the Qadirpur field, Central Indus Basin (Pakistan), are investigated petrophysically for their detailed reservoir characterization. The different petrophysical parameters determined include the following: true resistivity, shale volume, total porosity, effective porosity, density and neutron porosity, water and hydrocarbon saturation, bulk volume of water, lithology, gas effect, P-wave velocity, movable hydrocarbon index and irreducible water saturation and integrated with different cross-plots. The Eocene reservoirs are excellent with high effective porosity (2–32 %) and hydrocarbon saturation (10–93 %). Among these, the Sui Upper Limestone is an overall a poor reservoir; however, it has some hydrocarbon-rich intervals with high effective porosity and better net pay. All the net pay zones identified show low and variable shale volume (5–30 %). The secondary porosity has added to the total and effective porosities in these reservoirs. The main contributors to the porosity are the chalky, intercrystalline and vuggy/fracture types. The thickness of the reservoirs zones ranges from 4.5 to 62 m. These reservoirs are gas-producing carbonates with almost irreducible water saturation (0.002–0.01) and are likely to produce water-free hydrocarbons. The lower values of moveable hydrocarbon index (0.07–0.9) show that the hydrocarbons are moveable spontaneously to the well bore. The proposed correlation model shows that the reservoirs have an inclined geometry and are a part of an anticlinal trap.  相似文献   

Defining the 3D geometry of thin shale units in the Sleipner reservoir using seismic attributes     

《Marine and Petroleum Geology》2016

Defining the 3D geometry and internal architecture of reservoirs is important for prediction of hydrocarbon volumes, petroleum production and storage potential. Many reservoirs contain thin shale layers that are below seismic resolution, which act as impermeable and semi-permeable layers within a reservoir. Predicting the storage volume of a reservoir with thin shale layers from conventional seismic data is an issue due to limited seismic resolution. Further, gas chimneys indicative of gas migration pathways through thin shale layers, are not easily defined by conventional seismic data. Additional information, such as borehole data, can be used to aid mapping of shale layers, but making lateral predictions from 1D borehole data has high uncertainty. This paper presents an integrated workflow for quantitative seismic interpretation of thin shale layers and gas chimneys in the Utsira Formation of the Sleipner reservoir. The workflow combines the use of attribute and spectral analysis to add resolution to conventional seismic amplitude data. Detailed interpretation of these analyses reveals the reservoirs internal thin shale architecture, and the presence of gas chimneys. The comprehensive interpretation of the reservoirs internal structure is used to calculate a new reservoir storage volume. This is done based on the distribution of sand and interpreted shale layers within the study area, for this active CO₂ storage site.  相似文献   

Agent-based simulation for biogas power plant potential in Schwarzwald-Baar-Kreis,Germany: a step towards better economy     

Hafiz Ali Imran  Dietrich Schröder  Bilal Ahmed Munir 《国际地球制图》2017,32(1):59-70

Over the past decade, political framework in the energy sector all over the world has provoked a strong focus on the production of renewable energies. The study focuses on agent-based modelling approach to identify the suitable and economical distribution of biogas power plants over time in the area of interest. For sufficient supply of biomass (silage maize) on a regional basis to run biogas power plants economically and smoothly, different thematic layers with defined rules for Agent Analyst used to simulate the future installations of power plants. In conjunction with ArcGIS, the Agent Analyst software generates simulations that prove the robustness of the model in finding the suitable location of power plants. The resultant location from the model is analysed in different aspects. The designed methodology could be implemented in other areas with minor edits as per requirement of the area.  相似文献   

The impact of weather variations on maize yields and household income: Income diversification as adaptation in rural China     

《Global Environmental Change》2017

Climate change is threatening global food production and could potentially exacerbate food insecurity in many parts of the world. China is the second largest maize producer. Variations in maize yields in China are likely to have major implications for food security in the world. Based on longitudinal data of 4861 households collected annually between 2004 and 2010, we assess the impact of weather variations on maize yields in the two main producing regions in China, the Northern spring maize zone and the Yellow-Huai Valley summer maize zone. We also explore the role of adaptation, by estimating the response of Chinese farmers in both regions, in particular in terms of income diversification. With the use of household and time fixed effects, our estimates relate within-household variations in household outcomes (maize yields, net income, land and input use) to within-location variations in weather conditions. Temperature, drought, wet conditions, and precipitations have detrimental effects on maize yields in the two maize zones. The impact is stronger in the Northern spring maize zone where one standard deviation in temperature and drought conditions decreases maize yields by 1.4% and 2.5%, respectively. Nonetheless, such impact does not seem to translate into a significant fall in total net income. Adaptation seems to be key in explaining such a contrast in the Northern spring maize zone where the largest impact is estimated. On the contrary, we find a lower impact in the other region, the Yellow-Huai Valley summer maize zone but such impact is likely to intensify. The lack of adaptation observed in that region results into detrimental impacts on net farm and total income. Enhancing adaptative behaviors among Chinese farmers even further is likely to be key to future food security in China and in the rest of the world.  相似文献   

Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018     

《山地科学学报》2020,17(3):572-587

Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude(ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area≥ 20 km2 each, situated in the Chitral region(Hindukush Mountains) were investigated in this study. Digital Elevation Model(DEM) and available cloud-free continuous series of Landsat and Sentinel satellite images from minimum snow cover season were used to monitor the variability in the studied glaciers by keeping the status of glaciers in year 2001 as a reference. The annual climatic trends of mean temperature and total precipitation from Chitral weather station were detected using the nonparametric Mann-Kendall's test. Results revealed a general increase in the ELA, decrease in the glacier mass balance and the retreat of snout position.Average upward shift in the ELA for the entire study area and data period was ～345 ± 93 m at a rate of～13 m.a~(-1) from the reference year's position i.e.～4803 m asl. Estimated mean mass balance for the entire study area indicated a decline of-0.106 ± 0.295 m w.e. a~(-1). Periods of snout retreat and advance in different glaciers were found but the mean value over the entire study area was a retreat of-231 ± 140 m.No obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.  相似文献   

Litter decay in rangeland sites with varying history of human disturbance: a study with Hazargangi Chiltan mountain     

Imran KHAN  Shamim GUL  Sarfraz AHMAD  Gul Bano REHMAN  Agha Waqar YUNUS  Iram GUL  Imran ALI  Ali AKBAR  Muhammad ISLAM 《山地科学学报》2020,17(4):898-906

Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human disturbances such as collection of wood for fuel purpose and livestock grazing. Removal of vegetation of rangelands has a significant negative impact on soil organic matter(SOM). This research evaluates litter decomposition in three sites of Hazarganji Chiltan mountain with varying history of human disturbances(unprotected site, young protected site and old protected site). Twigs of Pistacia khinjuk with approximately equal weight and length were placed in litter bags of mesh size 2 mm and were buried in 0-5 cm depth in three sites in January. Half of the twigs of each site received rain simulation in April, August, October, November and January while the other half of the twigs were subjected under natural conditions for 15 months. Twigs from each plot of each treatment of each site were collected from soil after every rain simulation in the previous month of experiment and were processed for weight loss assessment. Results showed that weight loss of twigs by decomposition was significantly higher in the soil of unprotected site as compared to other two sites and there was no difference between rain simulation and control treatments except that loss of weight of twigs of unprotected site was higher under control than rain simulation condition. To confirm that SOM was the major controlling factor for the decomposition of litter decay, soils of each site were collected and burned to remove SOM;thereafter, burned soil samples were mixed with homogenous powder of oven-dried native plants, incubated for 6 months and were provided with dissolved organic matter of the soils of each site. Results showed that there was no difference in the decomposition of litter between soils under controlled laboratory condition, which confirmed that SOM was a major controlling factor for the litter decay in soil under field conditions. The pyrosequencing analysis of the DNA of soils collected from three sites revealed the presence of bacterial species Thermovum composti.  相似文献   

Effect of climate change on overland flow generation: a case study in central Germany          下载免费PDF全文

Muhammad Rehan Anis  Michael Rode 《水文研究》2015,29(11):2478-2490

The impact of global climate change on runoff components, especially on the type of overland flow, is of utmost significance. High‐resolution temporal rainfall plays an important role in determining the hydrological response of quick runoff components. However, hydrological climate change scenario analyses with high temporal resolution are rare. This study investigates the impact of climate change on discharge peak events generated by rainfall, snowmelt, and soil‐frost induced runoff using high‐resolution hydrological modelling. The study area is Schäfertal catchment (1.44 km²) in the lower Harz Mountains in central Germany. The WaSiM‐ETH hydrological model is used to investigate the rainfall response of runoff components under near future (2021–2050) and far‐distant future (2071–2100) climatic conditions. Disaggregated daily climate variables of WETTREG2010 SRES scenario A1B are used on a temporal resolution of 10 min. Hydrological model parameter optimization and uncertainty analysis was conducted using the Differential Evolution Adaptive Metropolis (DREAM_(ZS)) uncertainty tool. The scenario results show that total runoff and interflow will increase by 3.8% and 3.5% in the near future and decrease by 32.85% and 31% in the far‐distant future compared to the baseline scenario. In contrast, overland flow and the number and size of peak runoff will decrease moderately for the near future and drastically for the far‐distant future compared to the baseline scenario. We found the strongest decrease for soil‐frost induced discharge peaks at 79.6% in the near future and at 98.2% in the far‐distant future scenario. It can be concluded that high‐resolution hydrological modelling can provide detailed predictions of future hydrological regimes and discharge peak events of the catchment. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献