Comment on “Dextral transpression and late-Eocene magmatism in the trans-Himalayan Ladakh Batholith (North India): implications for tectono-magmatic evolution of the Indo-Eurasian collisional arc”     

Lloyd T. White  Gordon S. Lister  Talat Ahmad  Marnie A. Forster 《International Journal of Earth Sciences》2013,102(3):969-972

  相似文献   

Mapping rubber trees based on phenological analysis of Landsat time series data-sets     

Janatul Aziera binti Abd Razak  Noordin bin Ahmad  Maher Ibrahim Sameen 《国际地球制图》2018,33(6):627-650

This study proposes a strategy for accurate mapping of rubber trees through the analysis of Landsat time series datasets. The phenological dynamics of rubber trees were derived from the Normalized Difference Vegetation Index (NDVI) to verify the three important phenological metrics of rubber trees; defoliation, foliation and their growing stages. A decade (2006–2015) ago, Landsat time series NDVIs were used to study the strength of relationship between rubber trees, evergreen trees and oil palm trees. Two important results that could discriminate these three types of vegetation were found; firstly, a weak relationship of NDVIs between rubber trees and evergreen trees during the defoliation period (r² = 0.1358) and secondly between rubber trees and oil palm trees during the growing period (r² = 0.2029). This analysis was verified using Support Vector Machine to map the distribution of the three types of vegetation. An accurate mapping strategy of rubber trees was successfully formulated.  相似文献   

Evaluation of magma mixing in the subvolcanic rocks of Ghansura Felsic Dome of Chotanagpur Granite Gneiss Complex,eastern India     

Gogoi  Bibhuti  Saikia  Ashima  Ahmad  Mansoor  Ahmad  Talat 《Mineralogy and Petrology》2018,112(3):393-413

Mineralogy and Petrology - The subvolcanic rocks exposed in the Ghansura Felsic Dome (GFD) of the Bathani volcano-sedimentary sequence at the northern fringe of the Rajgir fold belt in the...  相似文献   

Assessing Lateral Continuity within the Yammama Reservoir in the Foroozan Oilfield, Offshore Iran: An Integrated Study     

Payam HASSANZADEH  Ahmad Reza RABBANI  Ardeshir HEZARKHANI  Saeed KHAJOOIE 《《地质学报》英文版》2018,92(6):2405-2415

Located in Iranian sector of the Persian Gulf, Foroozan Oilfield has been producing hydrocarbons via seven different reservoirs since the 1970s. However, understanding fluid interactions and horizontal continuity within each reservoir has proved complicated in this field. This study aims to determine the degree of intra-reservoir compartmentalization using gas geochemistry, light hydrocarbon components, and petroleum bulk properties, comparing the results with those obtained from reservoir engineering indicators. For this purpose, a total of 11 samples of oil and associated gas taken from different producing wells in from the Yammama Reservoir were selected. Clear distinctions, in terms of gas isotopic signature and composition, between the wells located in northern and southern parts of the reservoir (i.e. lighter δ13C1, lower methane concentration, and negative sulfur isotope in the southern part) and light hydrocarbon ratios (e.g. nC7/toluene, 2,6-dmC7/1,1,3-tmcyC5 and m-xylene/4-mC8) in different oil samples indicated two separate compartments. Gradual variations in a number of petroleum bulk properties (API gravity, V/Ni ratios and asphaltene concentration) provided additional evidence on the reservoir-filling direction, signifying that a horizontal equilibrium between reservoir fluids across the Yammama Reservoir is yet to be achieved. Finally, differences in water-oil contacts and reservoir types further confirmed the compartmentalization of the reservoir into two separate compartments.  相似文献   

2D and 3D rockfall hazard analysis and protection measures for Saptashrungi Gad Temple,Vani, Nashik,Maharashtra – A case study     

M. K. Ansari  M. Ahmad  Rajesh Singh  T. N. Singh 《Journal of the Geological Society of India》2018,91(1):47-56

The Saptashrungi gad temple (SGT) situated on basaltic hills belongs to Deccan volcanic of Upper Cretaceous to Lower Eocene, is one among the 51 Shakti Peeths and most holy place for pilgrims. Rockfall is a major problem in the past and causing danger to the lives of the villagers settled at the toe of the SGT hill as well as the pilgrims who perform parikrama along the tracks. On the evening of 16 April 2011, an old woman died due to rockfall at SGT hill when she was performing parikrama, moreover, two persons got injured during the deliverance process of this old woman from the continuous rockfall activity. The problem of rockfall could be linked to rainfall, jointing, weathering, man-made or the compounding of all. In this research, the rockfall hazard analysis at SGT hill is assessed using both 2D and 3D rockfall programs along the two parikrama paths: Parikrama Path 1 (or the Badi Parikrama Path ‘BPP’), and Parikrama Path 2 (or the Chhoti Parikrama Path ‘CPP’). Also, the study area of the SGT hill has been divided into eight zones (Zone#01 to Zone#08), based on field observations, orientations of joint sets and hill slope faces and eighteen topographic profiles (AA' to RR') have been taken from these eight zones for rockfall analysis. A detailed topographic survey along with field investigation has been carried out along the temple for ascertaining the nature of rock, discontinuity orientations, and slope geometry. DEM has been generated using topographic profile in ArcGIS to facilitate the 3D rockfall analysis. Maximum rock block sizes are taken into the analysis and run-out distance, bounce height, kinetic energy and velocity of the basaltic blocks are evaluated separately. Based on the analyzed data, the rockfall hazard zone map has been prepared and site having potential rockfall risks have been identified. Finally, wire/net meshing has been proposed after removal of unstable blocks as a stabilization and protection measures.It is worth mentioning here that for the first time rockfall hazard assessment was made in such detail for a site. Suggestions made are implemented by the State Government for the protection of the temple as well as the life of pilgrims performing the parikrama from the rockfall.  相似文献   

Provenance,tectonic setting,source weathering and palaeoenvironmental implications of Middle-Upper Jurassic rocks of Ler dome,Kachchh, western India: Inferences from petrography and geochemistry     

Asma A. Ghaznavi  Imran Khan  M.A. Quasim  A.H.M. Ahmad 《Chemie der Erde / Geochemistry》2018,78(3):356-371

The Middle-Upper Jurassic sandstones and shales of Ler dome (Chari and Katrol Formations), Kachchh, western India, have been analyzed for modal, bulk mineralogy and geochemistry to deduce their provenance, tectonic setting, source area weathering and palaeoenvironmental conditions. The detrital modes of Ler dome sandstones indicate that they were emanated from recycled orogen (uplifted shoulders of rift) and stable cratonic source in passive margin setting. Rapid deposition of sediments from a granitic source area can be predicted from feldspar abundance. A highly mature heavy mineral assemblage characterized in the form of high Zircon-Tourmaline-Rutile (ZTR) index also endorses these findings. The X-ray diffraction patterns (XRD) and scanning electron microscope (SEM) data show the presence of clay minerals depicting moderate to extensive chemical weathering in an oxidizing environment with periodic cycles of transgression and regression. The chemical index of weathering, chemical index of alteration and plagioclase index of alteration suggest moderate to high and low to moderate weathering conditions for sandstone and shales, respectively, that took place in low to moderate relief. We postulate that Ler dome sediments are derivative of the eroded and weathered parts of the Aravalli craton located on east and northeast of the basin and the Nagarparkar Massif placed to the north and northwest.  相似文献   

Geochemistry and petrogenesis of Biabanak-Bafq mafic magmatism: Implication for the evolution of central Iranian terrane     

Monireh Poshtkoohi  Talat Ahmad  Ashwini Kumar Choudhary 《Journal of Earth System Science》2018,127(5):72

Precambrian magmatism in the Biabanak-Bafq district represents an extensive sequence of mafic magmatic rocks. Major, trace and rare earth elements reveal that the low-Ti basement mafic rocks are magnesium tholeiite and low-Ti cover a mafic rock belongs to Fe-tholeiite, whereas, the high-Ti alkaline mafic rocks, as well as dolerites, show much more Fe–Ti enrichment. Primitive mantle normalized trace element patterns show a relative enrichment of LREE and LILE and depletion of HFSE, but have an equally distinct continental signature reflected by marked negative Nb, Sr, P, and Ti anomalies. The composition of the intrusive rocks is consistent with fractional crystallization of olivine ± clinopyroxene ± plagioclase, whereas variations in the Sr and Nd isotope compositions suggest heterogeneous sources and crustal contamination. Low-Ti group samples contain a crustal signature in the form of high La/Yb, Zr/Nb, and negative \(\varepsilon \hbox {Nd}\) values. In contrast, high-Ti mafic magmatic rocks display an increase in La/Yb with a decrease in Proterozoic alkaline rocks recognized across the central Iran. The presence of diverse mafic magmatic rocks probably reflects heterogeneous nature of sub-continental lithospheric mantle (SCLM) source. The mafic magmatism largely represents magmatic arc or rift tectonic setting. It is suggested that the SCLM sources were enriched by subduction processes and asthenospheric upwelling.  相似文献   

Correction: Impact of excessive groundwater pumping on rejuvenation processes in the Bandung basin (Indonesia) as determined by hydrogeochemistry and modeling     

Taufiq  Ahmad  Hosono  Takahiro  Ide  Kiyoshi  Kagabu  Makoto  Iskandar  Irwan  Effendi  Agus J.  Hutasoit  Lambok M.  Shimada  Jun 《Hydrogeology Journal》2018,26(4):1263-1279

In the Bandung basin, Indonesia, excessive groundwater pumping caused by rapid increases in industrialization and population growth has caused subsurface environmental problems, such as excessive groundwater drawdown and land subsidence. In this study, multiple hydrogeochemical techniques and numerical modeling have been applied to evaluate the recharge processes and groundwater age (rejuvenation). Although all the groundwater in the Bandung basin is recharged at the same elevation at the periphery of the basin, the water type and residence time of the shallow and deep groundwater could be clearly differentiated. However, there was significant groundwater drawdown in all the depression areas and there is evidence of groundwater mixing between the shallow and deep groundwater. The groundwater mixing was traced from the high dichlorodifluoromethane (CFC-12) concentrations in some deep groundwater samples and by estimating the rejuvenation ratio (R) in some representative observation wells. The magnitude of CFC-12 concentration, as an indicator of young groundwater, showed a good correlation with R, determined using ¹⁴C activity in samples taken between 2008 and 2012. These correlations were confirmed with the estimation of vertical downward flux from shallower to deeper aquifers using numerical modeling. Furthermore, the change in vertical flux is affected by the change in groundwater pumping. Since the 1970s, the vertical flux increased significantly and reached approximately 15% of the total pumping amount during the 2000s, as it compensated the groundwater pumping. This study clearly revealed the processes of groundwater impact caused by excessive groundwater pumping using a combination of hydrogeochemical methods and modeling.

  相似文献   

Efficient removal of Evans blue dye by Zn–Al–NO<Subscript>3</Subscript> layered double hydroxide     

M. Shamim  K. Dana 《International Journal of Environmental Science and Technology》2018,15(6):1275-1284

Evans blue (EB) dye has been successfully removed from aqueous solution through chemisorption process with synthetic layered double hydroxides (LDH) [Zn_1?x Al _x (OH)₂NO₃·nH₂O, x = 0.2–0.33]. Detailed evaluation of dye adsorption characteristics in aqueous medium has been studied for different layer charged hydroxides. The objective of the study was efficient removal of a dye by LDH and understanding the structure–property relationship of the LDH on its adsorption behaviour. Highest Langmuir monolayer adsorption capacity (Qt) of 113.64 mg g^?1 was observed for highest layer charge x = 0.33, and it is higher than previously reported values for the LDH-EB dye system. Under optimized condition, 99% of EB dye is removed from aqueous solution within 60 min at 313 K. The monotonous increase in Qt value with increasing layer charge is correlated with layer charge density (LCD) and lower particle size of the synthetic LDH. The variation in Qt among different layer charged materials is marginal (3.46–4.17%) with respect to the respective anion exchange capacity (AEC) of LDH NO₃. The limited contribution of AEC surmises the occurrence of surface-only adsorption and absence of intercalation as validated by the XRD analysis. The spontaneity of the EB dye removal increases with increasing temperature and LCD. The chemisorption nature of the adsorption reaction is well supported by the thermodynamics values.  相似文献   

Investigating the removal of ethylbenzene from aqueous solutions using modified graphene oxide: application of response surface methodology     

A. Azizi  A. Torabian  E. Moniri  A. H. Hassani  H. Ahmad Panahi 《International Journal of Environmental Science and Technology》2018,15(12):2669-2678

This research focused on the application of response surface methodology (RSM) for the removal of ethylbenzene by the graphene oxide grafted with polymethyl vinyl ketone and aniline (GO-MVK-ANI) from wastewater. The adsorbent was prepared through polymerization of graphene oxide with methyl vinyl ketone using ammonium persulfate initiator and further modification by aniline. The synthesized material was characterized via Fourier transform infrared resonance spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Brunauer–Emmett–Teller analysis. RSM was used to minimize the number of experiments and investigate the effect of three selected parameters (contact time, initial pH and adsorbent dose) on the removal efficiency of ethylbenzene. Additionally, the affecting parameters were optimized based on the selected target (ethylbenzene removal efficiency). The results show that 73% ethylbenzene could be adsorbed with initial ethylbenzene concentration of 20 mg/l under the optimum conditions (the contact time of 11 min, pH of 5.64 and adsorbent dose of 3.75 g/l). In this paper, high R ²-value (97.18%) for ethylbenzene removal and a good agreement with adjusted R ²-value (94.65%) indicated that the model was successful and the results demonstrated a reasonable proportion of the experimental and the predicted results.  相似文献