Mapping the geochemistry of the northern Rub' Al Khali using multispectral remote sensing techniques

Spatial variations in sand sea geochemistry relate to mixing of different sediment sources and to variations in weathering. Due to problems of accessibility, adequate spatial coverage cannot be achieved using field surveys alone. However, maps of geochemical composition produced from remotely sensed data can be calibrated against limited field data and the results extrapolated over large, inaccessible areas. This technique is applied to part of the Rub' Al Khali in the northern United Arab Emirates. Trend surface analysis of the results suggests that the sand sea at this location can be modelled as an east–west mixing zone of two spectral components: terrestrial reddened quartz sands and marine carbonate sands. Optical dating of these sediments suggests that dune emplacement occurred rapidly around 10 ka BP , when sea level was rising rapidly. The spatial distribution of mineralogical components suggests that this phase of dune emplacement resulted from coastal dune sands being driven inland during marine transgression, thereby becoming mixed with rubified terrestrial sands. Copyright © 2001 John Wiley & Sons, Ltd.     

Assessment of sea water inundation along Daboo creek area in Indus Delta Region,Pakistan

Indus Deltaic Region (IDR) in Pakistan is an erosion vulnerable coast due to the high deep water wave energy. Livelihood of millions of people depends on the fisheries and mangrove forests in IDR. IDR consists of many creeks where Daboo is a major creek located at southeast of the largest city of Pakistan, Karachi. Unfortunately, there has been no detailed study to analyze the damages of sea water intrusion at a large temporal and spatial scale. Therefore, this study is designed to estimate the effects of sea water inundation based on changing sea water surface salinity and sea surface temperature (SST). Sea surface salinity and SST data from two different surveys in Daboo creek during 1986 and 2010 are analyzed to estimate the damages and extent of sea water intrusion. Mean salinity has increased 33.33% whereas mean SST decreased 13.79% from 1987 to 2010. Spatio-temporal analysis of creek area using LANDSAT 5 Thematic mapper (TM) data for the years 1987 and 2010 shows significant amount of erosion at macro scale. Creek area has increased approximately 9.93% (260.86 m² per year) which is roughly equal to 60 extensive sized shrimp farms. Further Land Use Land Cover (LULC) analyses for years 2001 and 2014 using LANDSAT 7 Enhanced Thematic Mapper Plus (ETM+) has indicated 42.3% decrease in cultivated land. Wet mud flats have spread out at the inner mouth of creek with enormous increase of 123.3%. Significant sea water intrusion has increased the area of barren land by 37.9%. This also resulted in overall decrease of 6.7% in area covered by mangroves. Therefore, this study recorded a significant evidence of sea water intrusion in IDR that has caused serious damages to community living in the area, economical losses. Additionally, it has also changed the environment by reducing creek biological productivity as reported by earlier studies over other regions of the world.     

Desertification in the Arab Region: analysis of current status and trends

The total area of the Arab Region is about 14·2 million km², 90% of it lies within arid, semi-arid and dry sub-humid areas. The area is characterized by harsh environment, fragile ecosystems and limited water resources and arable lands. Throughout its long history these lands were the main source of grain and animal production.By the end of this century and in spite of the national, regional and international efforts to combat desertification and mitigate the effect of drought and desiccation, desertification is still one of the major environmental problems in the Arab Region. The rapid increase in population by some 3% annually, considered among the highest worldwide, along with the changing of consumption patterns and life styles, resulting in increasing food demand, have hastened land degradation in this arid environment.Land degradation in the Arab Region due to misuse is widespread and is proceeding at accelerating rates. Failures of resource management policies are aggravated by overgrazing, overexploitation of water and land resources, overcultivation of marginal lands, deforestation, and the use of inappropriate technologies.This paper attempts to provide:

• A synthesis and analysis of the status of desertification in the Arab Region.

• Identification of the major causes and trends of land degradation.

• Highlighting the limitations and constraints on combating desertification in the Arab Region.

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

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.     

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

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.     

The probability distributions and fractal dimension of sunspot cycles associated with ENSO phenomena

Various methods have been used to secure the certainty of significant relations among the sunspot cycles and some of the terrestrial climate parameters such as temperature, rainfall, and ENSO. This study investigates the behavior of ENSO cycles and mean monthly sunspot cycles. Sunspot cycles range from 1755 to 2016 whereas, ENSO cycles range from 1866 to 2012. In this regard, the appropriateness of distributions is investigated with the help of Kolmogorov-Smirnov D, Anderson-Darling, and chi-square tests. It is found that most of the sunspot cycle follows generalized Pareto distribution whereas, generalized extreme value distribution was found appropriate for ENSO cycles. Probability distribution is used to analyze the behavior of each sunspot cycle and ENSO cycle separately. Probability distribution indicates the tail behavior of each cycle; tail explored correlation cycles. Furthermore, self-similar and self-affine fractal dimension methods are used to compute Hurst exponents to determine the persistency of the available data. Fractal dimension has an ability to study the complexity involved in sunspot and ENSO cycles. The fractal dimension and Hurst exponent describe persistency (smoothness) and complexity of data. Hurst exponent measures long-term behavior of time series, making it more helpful for forecasting. This is the measure of regularity or irregularity (chaos) of the time function in the form of their persistency or anti-persistency, respectively. Hurst exponents are computed using rescaled range analysis method and box counting methods. Both these methods are suitable for long-term forecasting. The results of this study confirm that during the period 1980–2000, ENSO cycles were very active. Simultaneously, ENSO was active for the periods 1982–1983, 1986–1987, 1991–1993, 1994–1995, and 1997–1998; these periods include two strongest periods of the century viz., 1982–1983 and 1997–1998. Sunspot cycles and ENSO cycles both were found to be persistent. Self-similar fractal dimensions exhibited a better persistency and a better correlation as compared to self-affine fractal dimension. This research is a part of a larger research project investigating the correlation of sunspot cycles and ENSO cycles, and the influence of ENSO cycles on variations of the local climatic parameters which in turn depends on solar activity changes.     

Erratum to: A spatio-temporal three-dimensional conceptualization and simulation of Dera Ismail Khan alluvial aquifer in visual MODFLOW: a case study from Pakistan

The Gour Oumelalen area exposes Paleoproterozoic (1.9 Ga) marbles and calc-silicate granulites. Some marbles show a specific mineralogy characterized by the presence of a highly aluminous clinopyroxene with Al₂O₃ content exceeding16 wt%. This clinopyroxene shows a marked zoning with a hedenbergitic core rimmed by fassaite. Phase relations are expressed by spectacular reaction textures in calc-silicate granulites as Opx + Cpx + Pl + H₂O  == > Grt + Qtz ± Am and Cpx + Ilm + Pl ± Mt = > Grt + Qtz + Spn. In olivine-bearing marbles, clinopyroxene and dolomite occur around olivine and calcite. According to thermodynamic modeling in the Na₂O–CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O–TiO₂–Fe₂O₃ (NCFMASHTO) system, the first stage of metamorphism is located at 800 °C and 6–7 kbar, which is followed by an increase in pressure at 9–10 kbar and 800 °C and an isobaric cooling at 680 °C. The deduced anticlockwise P–T path is consistent with a granulitic metamorphism occurring in an active continental margin context.

     

Latest Pleistocene and Holocene dune construction at the north-eastern edge of the Rub Al Khali, United Arab Emirates

Optical dating of two dune profiles developed in linear dunes in Ras Al Khaimah, United Arab Emirates, has been used to establish the timing and rate of dune accretion. One section at Awafi was over 17 m high, while that at Idhn was over 40 m high. The Awafi dune appears to have accumulated very rapidly ≈10 000 years ago, with a vertical accumulation rate of about 3·3 m ka⁻¹. The Idhn dune appears to have accumulated over the past 1000 years, with 20 m of sediment accumulating in a time period of about 270 years. The Awafi dune may have accumulated in response to the transgression of the Persian Gulf by rising sea levels in late Pleistocene and Holocene times. The Idhn dune may have accumulated rapidly because of intensified human activity, a short-lived climatic event, or because it may periodically be reactivated after erosion by fluvial action at its base.     

Using a naive Bayes classifier to explore the factors driving the harmful dinoflagellate Karenia selliformis blooms in a southeastern Mediterranean lagoon

Ocean Dynamics - The blooms of the toxic dinoflagellate Karenia selliformis can be predicted with accuracy derived from knowledge of the main forcing variables. A naive Bayes classifier modeling...