Depositional Environments and Diagenesis of the Kuldhar and Keera Dome Carbonates (Late Bathonian–Early Callovian) of Western India     

A.H.M. Ahmad  G.M. Bhat  M. Haris Azim Khan 《Journal of Asian Earth Sciences》2006,27(6):765-778

This paper describes 11 microfacies types in late Bathonian–Early Callovian carbonates of the Kuldhar Member of the Jaisalmer Formation (Rajasthan) and the Keera Golden Oolite Member of the Chari Formation (Kachchh Mainland) western India. The different microfacies associations reported in this study reflect an ideal shallowing upward sequence, representing a system of bioclastic bars developed on the lower ramp, evolving into an oolitic bar-to-bank system separating restricted lagoonal—from lower ramp environment. Four main types of cements, i.e. bladed, fibrous, syntaxial overgrowth and blocky cement (characterized in a few cases by ferroan calcite and anhydrite II) occur in these carbonates. The study also reveals that chemical compaction followed the two phases of early mechanical compaction that largely governed porosity of these limestones. However, micritization and neomorphism also contributed significantly in this respect. Diagenetic signatures in these carbonates suggest that marine phreatic and fresh water phreatic environments dominated, but deep burial diagenesis also played its role in shaping these rocks. The early and late diagenetic changes have been controlled by the depositional facies evolving in a basin riddled with rifting in an extensional tectonic regime forcing regional-scale sea level fluctuations.  相似文献   

Unplanned urbanization: Assessment through calculation of environmental degradation index     

Md. J. B. Alam  M. J. B. Alam  M. H. Rahman  S. K. Khan  G. M. Munna 《International Journal of Environmental Science and Technology》2006,3(2):119-130

Urbanization is an inevitable phenomena for the country like Bangladesh. The push and pull factors help to migrate people from rural area to urban area. As a result haphazard and unplanned urbanization create environmental degradation. Survey data reveals that inadequate solid waste disposal services, lack of adequate public water supply, traffic congestion, water logging, air pollution, noise pollution, hill cutting are the main problems in the city area. Concentration of dust as well as SOx, NOx exceeded the allowable limit at the selected points. Groundwater level of Sylhet city has a considerable lowering over the last few decades. It has lowered from 3380 mm below ground in 1982 to 7880 mm below ground. Sylhet is located in highly seismic risk zone but most of the buildings and other structures in this area are constructed without considering earthquake risk. Environmental degradation index was calculated based on economical condition of the country.  相似文献   

Studies on the transfer of mineral nutrients from feed, water, soil and plants to buffaloes under arid environments     

M.Y. Ashraf  A. Khan  M. Ashraf  S. Zafar 《Journal of Arid Environments》2006,65(4):632-643

Studies were conducted at a Livestock Farm in an arid region of Pakistan, to determine the uptake of mineral nutrients from the food of buffaloes. Samples of feed, water, forage, soil as well as blood, milk, urine, and faeces of the animals were collected and analysed for K⁺, Ca²⁺, and Fe²⁺ during summer and winter. The results showed that the concentrations of K⁺ and Ca²⁺ in plants were low, whereas that of Fe²⁺ was high. In animals, K⁺ was not found in the milk in significant amounts, rather it was excreted in the urine. The calcium taken in by the animals was used for the synthesis of milk, as a result of which low Ca²⁺ concentrations were detected in urine. Mineral nutrient concentrations (K⁺ and Ca²⁺) in forage plants and water were lower than the optimum requirement of the animals, as a result of which blood plasma contained lower amounts of minerals (K⁺ and Fe²⁺) than that of the normal animals or critical limits. From the findings of the present study, it can be concluded that the buffaloes raised at the livestock farm had a severe deficiency of mineral nutrients, particularly K⁺ in lactating and Fe²⁺ in both lactating and non-lactating animals. Feed supplements, that can overcome these deficiencies, should be used for the optimum growth, milk production and resistance to diseases.  相似文献   

Artificial neural network application to estimate kinematic soil pile interaction response parameters   总被引：1，自引：0，他引：1  

Irshad Ahmad  M. Hesham El Naggar  Akhtar Naeem Khan   《Soil Dynamics and Earthquake Engineering》2007,27(9):892-905

Six artificial neural network (ANN) models are developed to predict various response parameters of kinematic soil pile interaction. These responses include (1) kinematic response factors for free and fixed head piles in homogenous soil layer to derive foundation input motion (2) normalized bending moment at fixed head of pile in homogenous soil layer (3) normalized kinematic pile moment at the interface of two soil layers of sharply different soil stiffnesses. These ANN models represent simple solutions that can be implemented in a simple calculator capable of matrix operation and bypass the site response analysis and the complex wave diffraction analysis. The data required for ANN training is generated using beam on dynamic Winkler formulation (BDWF). Fifty percent of the data is used to train the ANN models while remaining 50% is used to test the ANN models. The trained ANN models show good agreement with BDWF results.  相似文献   

The occurrence of vanadium in nature: its biogeochemical cycling and relationship with organic matter—a case study of the Early Cambrian black rocks of the Niutitang Formation,western Hunan,China     

Awan  Rizwan Sarwar  Liu  Chenglin  Yang  Shangfeng  Wu  Yuping  Zang  Qibiao  Khan  Ashar  Li  Guoxiong 《中国地球化学学报》2021,40(6):973-997

Acta Geochimica - Vanadium in the black rocks has economic and environmental impacts. In sediments, it is broadly disseminated as a multivalent metal element mainly sensitive to redox settings....  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   

Chemometric evaluation of heavy metals distribution in wastewater irrigated soil of peri-urban area     

H. Ullah  N. U. Khan  F. Ali  A. Khan  I. Zeb  M. J. Khan 《International Journal of Environmental Science and Technology》2018,15(12):2519-2530

Characterization of content and source of heavy metals in soils are necessary to establish quality standards on a regional level. In relation to this, two zones, (sampling zone-1) and (sampling zone-2) depending on nature and intensity of wastewater disposal along the peri-urban area of Peshawar, Pakistan were selected. Thirty-six samples of wastewater and topsoil each were collected to determine the content of Pb, Cr, Cd, Cu, Zn, Ni, Fe and Mn, and physico-chemical parameters like pH, electrical conductivity, total solids, total dissolved solids, total suspended solids, and organic matter. Analytical determinations were performed by atomic absorption spectroscopy after microwave sample digestion in acid solution. Chemometric techniques which include hierarchical cluster analysis, principal component analysis, correlation analysis, and tukey test were applied. Concentrations of physico-chemical properties in wastewater and soil were higher in sampling zone-2. Concentrations of six heavy metals in wastewater and two in soil exceeded permissible limits of World Health Organization (Guidelines for drinking water quality, 4th edition, 2011), European Union (Heavy metals in wastes, European commission on environment. http://ec.europa.eu/environment/waste/studies/pdf/heavymetalsreport, 2002). Hierarchical cluster analysis grouped eight heavy metals into two clusters for wastewater and five clusters for soils. Principal component analysis describes four factors possessing Eigenvalues greater than 1.0 and explained the cumulative total variance of 84% with factor 1, having positive loading of anthropogenic metals (Cd, Cu, and Ni). Significant correlation was found between anthropogenic metals like Ni and Cd in water and between Cu and Cr in soil. Further research in other agricultural lands in peri-urban region would improve the basis for proposing such soil quality standards.  相似文献   

Magnetic tracing of sediment dynamics of mudbanks off southwest coast of India     

F. Badesab  V. Gaikwad  T. R. Gireeshkumar  O. Naikgaonkar  K. Deenadayalan  S. V. Samiksha  P. K. Dinesh Kumar  V. J. Loveson  S. D. Iyer  A. Khan  P. B. Udayakrishnan  A. Sardar 《Environmental Earth Sciences》2018,77(17):625

In this study, we utilized environmental magnetic in combination with sedimentological and hydrodynamic data to investigate the formative processes of mudbanks along southwest coast of India. We document the linkages between enrichment of silt-sized magnetic particles and formation processes of mudbanks along Alappuzha coast. A trend of increasing magnetite concentration and coarsening in magnetic grain size is observed at mudbank stations M2 and M3, while the mud-deficient station (M1) showed an opposite trend. A strong relationship between magnetic and physical grain size for all samples implies that the magnetic particle size and clastic grain size are largely adjunct. Analysis of rock magnetic and grain size data of surficial and suspended sediments from non-mudbank (M1) and two mudbank stations (M2, M3) reflect the differential sediment partitioning and transport regimes which controlled the formation of mudbanks along Alappuzha coast. Two plausible mechanisms responsible for the formation of mudbanks are identified: grain size-selective entrainment is the dominant process during pre-monsoon; weaker hydrodynamics (waves and bottom currents) favors accumulation of silt-sized (fine and coarse) magnetic and non-magnetic fractions resulting in the formation of magnetically low-enriched sediment bed of mixed grain sizes. At the onset of monsoon, wave-induced energetic bottom currents enhance the suspension of entire sediment bedload at stations M2, M3 to form fluid mud. Concurrently, mineral-density-based selective fractionation allows the settling of coarse silt-sized magnetic particles, while the fine magnetic silt-size particles accumulate forming thick fluid mud as a suspension load resulting in the formation of mudbanks. An observed increase in magnetic susceptibility and coarsening in magnetic grain size of surficial sediments at mudbank stations (M2, M3) during monsoon period supports the interpretation. Our findings are summarized in a conceptual model which can be very well applied to investigate sediment dynamics associated with mudbank formation in coastal and shelf sedimentary systems.  相似文献   

GIS-based landslide susceptibility evaluation using fuzzy-AHP multi-criteria decision-making techniques in the Abha Watershed,Saudi Arabia     

Javed Mallick  Ram Karan Singh  Mohammed A. AlAwadh  Saiful Islam  Roohul Abad Khan  Mohamed Noor Qureshi 《Environmental Earth Sciences》2018,77(7):276

Landslides are natural geological disasters causing massive destructions and loss of lives, as well as severe damage to natural resources, so it is essential to delineate the area that probably will be affected by landslides. Landslide susceptibility mapping (LSM) is making increasing implications for GIS-based spatial analysis in combination with multi-criteria evaluation (MCE) methods. It is considered to be an effective tool to understand natural disasters related to mass movements and carry out an appropriate risk assessment. This study is based on an integrated approach of GIS and statistical modelling including fuzzy analytical hierarchy process (FAHP), weighted linear combination and MCE models. In the modelling process, eleven causative factors include slope aspect, slope, rainfall, geology, geomorphology, distance from lineament, distance from drainage networks, distance from the road, land use/land cover, soil erodibility and vegetation proportion were identified for landslide susceptibility mapping. These factors were identified based on the (1) literature review, (2) the expert knowledge, (3) field observation, (4) geophysical investigation, and (5) multivariate techniques. Initially, analytical hierarchy process linked with the fuzzy set theory is used in pairwise comparisons of LSM criteria for ranking purposes. Thereafter, fuzzy membership functions were carried out to determine the criteria weights used in the development of a landslide susceptibility map. These selected thematic maps were integrated using a weighted linear combination method to create the final landslide susceptibility map. Finally, a validation of the results was carried out using a sensitivity analysis based on receiver operator curves and an overlay method using the landslide inventory map. The study results show that the weighted overlay analysis method using the FAHP and eigenvector method is a reliable technique to map landslide susceptibility areas. The landslide susceptibility areas were classified into five categories, viz. very low susceptibility, low susceptibility, moderate susceptibility, high susceptibility, and very high susceptibility. The very high and high susceptibility zones account for 15.11% area coverage. The results are useful to get an impression of the sustainability of the watershed in terms of landsliding and therefore may help decision makers in future planning and mitigation of landslide impacts.  相似文献   

Microfacies analysis and diagenetic fabric of the Lockhart Limestone exposed near Taxila,Margalla Hill Range,Punjab, Pakistan     

Mohibullah Khan  Mumtaz Ali Khan  Birkhez Aslam Shami  Muhammad Awais 《Arabian Journal of Geosciences》2018,11(2):29

The microfacies analysis and diagenetic fabric of the Lockhart Limestone are studied in an outcrop section exposed in the Margalla Hill ranges. The Lockhart Limestone is predominantly composed of medium to thick bedded, nodular and occasionally brecciated, highly fossiliferous limestone with thin interbeds of marl and shale. On the basis of detailed petrographic investigations, four microfacies have been identified including bioclastic packstone, wackestone (siliciclastic bioclastic rich sub-microfacies), wackestone-packstone, and mud-wackestone. Based on the microfacies analysis, the Lockhart Limestone is interpreted to have been deposited in the fore-shoal mid-ramp, mid-ramp, and outer ramp depositional environments. The Paleocene age has been assigned to the Lockhart Limestone based on age diagnostic foraminifera, i.e., Miscellanea, Lockhartia, and Ranikothalia. The diagenetic fabric of the Lockhart Limestone is characterized by several diagenetic features such as micritization, neomorphism (aragonite to calcite transformation and development of microspar), compaction, pressure dissolution (microstylolites), and cementation (calcite-filled microfractures). Such diagenetic features are developed in marine, meteoric, and burial diagenetic settings. The Paleocene Lockhart Limestone of Pakistan shows analogous features to that of the Paleocene Zongpu Formation (Member-3) of the Gamba-Tingri Basin of southern Tibet based on the outcrop features, microscopic fabric, and depositional environment.  相似文献