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171.
Hafiz U. Rehman Tahseenullah Khan Hao‐Yang Lee Sun‐Lin Chung Mamoru Murata M. Qasim Jan 《Island Arc》2019,28(6)
We report Permian (ca. 272 Ma ±5.4 Ma) felsic dykes that intrude into the Neoproterozoic (ca. 750 Ma) magmatic suite of the Nagar Parkar Igneous Complex (NPIC), the western extension of the Malani Igneous Suite (MIS). The NPIC consists of Neoproterozoic basement amphibolites and granites (riebeckite–aegirine gray granites and the biotite–hornblende pink granites), all of which are intruded by several generations of mafic and felsic dykes. Granitic magmatism occurred in the Late Neoproterozoic (ca. 750 Ma) due to the subduction‐, followed by the rift‐related tectonic regime during the breakup of the Rodinia supercontinent. U–Th–Pb zircon and monazite CHIME age data of 700–800 Ma from the earlier generation porphyritic felsic dykes suggest the dyke intrusion was coeval or soon after the emplacement of the host granites. Our findings of Permian age orthophyric felsic dykes provide new insights for the prevalence of active tectonics in the MIS during late Paleozoic. Textural features and geochemistry also make the orthophyric dykes distinct from the early‐formed porphyritic dykes and the host granites. Our newly obtained age data combined with geochemistry, suggest the existence of magmatism along the western margin of India (peri‐Gondwana margin) during Permian. Like elsewhere in the region, the Permian magmatism in the NPIC could be associated with the rifting of the Cimmerian micro‐continents from the Gondwana. 相似文献
172.
In this paper, we present a numerical simulation of a water jet impacting a new aeronautical material Ti555-03 plate.The Computational Fluid Dynamics(CFD) behavior of the jet is investigated using a FV(Finite Volume) method.The Fluid–Structure Interaction(FSI) is studied using a coupled SPH(Smoothed Particle Hydrodynamics)-FE(Finite Element) method. The jets hit the metal sheet with an initial velocity 500 m/s. Two configurations which differ from each other by the position(angle of inclination) of the plate relatively to the axis of revolution of the jet inlet are investigated in this study. The objective of this study is to predict the impact of the fluid produced at high pressure and high speed especially at the first moment of impact. Numerical simulations are carried out under ABAQUS. We have shown in this study that the inclination of the titanium alloy plate by 45° stimulates the phenomenon of recirculation of water. This affects the velocity profile, turbulence and boundary layers in the impact zone. The stagnation zone and the phenomenon of water recirculation are strongly influenced by the slope of the plate which gives a pressure gradient and displacement very important between the two configurations. Fluctuations of physical variables(displacement and pressure) prove the need for a noise and vibratory study. These predictions will subsequently be used for the modeling of the problem of an orthogonal cut in a high-speed machining process assisted by high-pressure water jet. 相似文献
173.
M.R. Khan C.A.J.M. de Bie H. van Keulen E.M.A. Smaling R. Real 《International Journal of Applied Earth Observation and Geoinformation》2010
Governments compile their agricultural statistics in tabular form by administrative area, which gives no clue to the exact locations where specific crops are actually grown. Such data are poorly suited for early warning and assessment of crop production. 10-Daily satellite image time series of Andalucia, Spain, acquired since 1998 by the SPOT Vegetation Instrument in combination with reported crop area statistics were used to produce the required crop maps. Firstly, the 10-daily (1998–2006) 1-km resolution SPOT-Vegetation NDVI-images were used to stratify the study area in 45 map units through an iterative unsupervised classification process. Each unit represents an NDVI-profile showing changes in vegetation greenness over time which is assumed to relate to the types of land cover and land use present. Secondly, the areas of NDVI-units and the reported cropped areas by municipality were used to disaggregate the crop statistics. Adjusted R-squares were 98.8% for rainfed wheat, 97.5% for rainfed sunflower, and 76.5% for barley. Relating statistical data on areas cropped by municipality with the NDVI-based unit map showed that the selected crops were significantly related to specific NDVI-based map units. Other NDVI-profiles did not relate to the studied crops and represented other types of land use or land cover. The results were validated by using primary field data. These data were collected by the Spanish government from 2001 to 2005 through grid sampling within agricultural areas; each grid (block) contains three 700 m × 700 m segments. The validation showed 68%, 31% and 23% variability explained (adjusted R-squares) between the three produced maps and the thousands of segment data. Mainly variability within the delineated NDVI-units caused relatively low values; the units are internally heterogeneous. Variability between units is properly captured. The maps must accordingly be considered “small scale maps”. These maps can be used to monitor crop performance of specific cropped areas because of using hypertemporal images. Early warning thus becomes more location and crop specific because of using hypertemporal remote sensing. 相似文献
174.
M. A. Khan 《洁净——土壤、空气、水》1998,26(1):40-44
Wadi el Majanin, one of the largest hydraulic structures in Libya was studied for ecophysiological aspects in relation to ambient environment. The waterbody is alkaline (pH=7.2) and characteristic of hydrogen-carbonate (144.8 mg L–1 CaCO3) system. Vertical extinction coefficients (> 4.8) indicate very high (biogenic) turbidity. Conspicuous variations of a quantitative kind in algal development (e.g., Pediastrum bloom) together with abundant diatom populations (chlorococcales-diatom assemblage), apart from very common occurrence of cyanobacteria and euglenoids show eutrophic water condition. Winter-summer alternation induced pronounced seasonal variability in the rates of in situ planktonic algal photosynthetic activities (285.7...1305 mg m–3 d–1 C). Dark fixation activity, attributed largely to bacterial production, oscillated by order of 2-fold magnitude, characterized by summer maxima (47.6 mg m–3 d–1 C). Size-fractional analysis established that smaller forms (< 60 μm), broadly regarded nanno-phytoplankton, frequently dominated (c. 70%) overall algal productivity. 相似文献
175.
Statistical forecast of temperature dynamics within month on the basis of hydrodynamic model outputs
A method of a long-term forecast of smoothed temperature dynamics within month with a zero lead time for some Russian sites is considered. A procedure of a search for optimum predictors and a regression-analog prediction scheme are described. Hydrodynamic forecasts for the first ten days of the prognostic month are used as a predictor. Results of the prediction scheme verification on independent data with the use of hydrodynamic model outputs are discussed. Ways to improve the prediction scheme are suggested. 相似文献
176.
Hydrodynamics and petroleum migration in the Upper Ordovician Red River Formation of the Williston Basin 总被引:1,自引:0,他引:1
D.K. Khan B.J. Rostron Z. Margitai D. Carruthers 《Journal of Geochemical Exploration》2006,89(1-3):179
Simulations of petroleum migration within the Red River petroleum system of the Williston Basin show that petroleum generation and secondary migration preceded the onset of an active hydrodynamic regime that persists to the present day. Furthermore: (1) a better understanding of the eastern limit of the mature source rock area, which is largely facies controlled, is required to reduce exploration risk east of the Nesson Anticline, (2) the Red River play types that have been prosperous in southeastern Saskatchewan should extend considerable distances to the north, as well as throughout central Saskatchewan and western Manitoba, Canada, and (3) accumulations that may have developed in the southwest of the basin have likely been flushed and redistributed subsequent to the onset of hydrodynamics. 相似文献
177.
The occurrence of the genus Aquilapollenites in Upper Cretaceous and Neogene sediments of northwestern Pakistan is reported here. Aquilapollenites amplus, Aquilapollenites reductus, and Aquilapollenites sp. occur in the Maastrichtian palynomorph assemblage from an outcrop sample of the Mir Ali section, northern Waziristan. Aquilapollenites medeis in the Neogene Murgha Faqir Zai Formation of the Pishin Basin, Balochistan, is considered a reworked Cretaceous specimen. The Upper Cretaceous sediments of the Asian plate on the Tethys margin are considered to be the source of Aquilapollenites spp. in these samples. 相似文献
178.
The propagation of plane magnetogasdynamic shock waves in an optically-thin grey atmosphere of non-uniform density has been discussed by the use of the similarity method, by use of Planck's diffusion approximation. The distribution of pressure, density, magnetic field, velocity, temperature, and radiation flux have been illustrated through graphs. The numerical integration has been done on a DEC-1090 computer under a RKGS programme. 相似文献
179.
In NW Himalayas, the suture zone between the collided Indian and the Karakoram plates is occupied by crust of the Cretaceous Kohistan Island\|Arc Terrane [1] . Late Cretaceous (about 90Ma) accretion with the southern margin of the Karakoram Plate at the site of the Shyok Suture Zone turned Kohistan to become an Andean\|type margin. The Neotethys was completely subducted at the southern margin of Kohistan by Early Tertiary, leading to collision between Kohistan and continental crust of the Indian plate at the site of the Main mantle thrust.More than 80% of the Kohistan terrane comprises plutonic rocks of (1) ultramafic to gabbroic composition forming the basal crust of the intra\|oceanic stage of the island arc, and (2) tonalite\|granodiorite\|granite composition belong to the Kohistan Batholith occupying much of the intermediate to shallow crust of the terrane mostly intruded in the Andean\|type margin stage [2] . Both these stages of subduction\|related magmatism were associated with volcanic and sedimentary rocks formed in Late Cretaceous and Early Tertiary basins. This study addresses tectonic configuration of Early Tertiary Drosh basin exposed in NW parts of the Kohistan terrane, immediately to the south of the Shyok Suture Zone. 相似文献
180.
A joint analysis of river runoff and meteorological forcing in the Karakoram,upper Indus Basin 下载免费PDF全文
Satellite‐geodetic altimetry investigations in the Karakoram have indicated slight mass gain or loss of the glaciers during the early part of 21st century. Equivalent discharge in the upper Indus Basin due to these mass changes has been estimated at 5 to 10% of mean annual flow. However, satellite altimetry and geodetic glacier mass estimates in the extreme topography of the Karakoram have not yet been counter‐validated by hydrological analysis. Therefore, we present a first cross validation of three to five decades of river flow data from the three major watersheds in the Karakoram, with matching series of monthly precipitation, temperature, and evaporation provided by six atmospheric reanalysis products for 1979–2014. The analyses suggest that in most cases river flows have been increasing steadily from the end of the 1960s and 1970s to the middle of the 1990s and have stabilized or are in decline since then. Hunza watershed in Karakoram West shows consistently declining flows over the first half of the analysis period and stable flows during the second half for most of the summer melting season, suggesting mass accumulation. Rising river flows in the Shyok and Shigar watersheds, followed by stabilizing or slightly declining flows from 1995 onward, can be explained by consistently increasing precipitation during the first half of the analysis period, and successive stabilization or minor decline thereof. Flow data do not necessarily suggest considerable loss or gain of glacial mass in the Karakoram during the late 90s and early 2000s as suggested by satellite‐based altimetry studies. 相似文献