Geology, Geochemistry and Tectonic Significance of Mafic-ultramafic Rocks of Mesoproterozoic Phulad Ophiolite Suite of South Delhi Fold Belt, NW Indian Shield

A thick sequence of mafic-ultramafic rocks, occurs along a major shear zone (Phulad lineament), running across the length of Aravalli Mountain Range for about 300 kms. It has been suggested, that this sequence may represent a fragment of ophiolite or a rift related metavolcanic suite made up of basalts and fractionated ultramafics. The geological and tectonic significance of the complex is assessed using field relationships, petrography and geochemistry. Structurally, the lowest part of the complex comprises a discontinuous band of plastically deformed harzburgite (mantle component) followed by layered cumulus gabbroic rocks (crustal component). A complex of non-cumulus rocks comprising hornblende schists, gabbros, sheeted dykes and pillowed basalts structurally overlies layered gabbros. Huge bodies of diorite intrude volcanics.

Geochemical classification suggests that all non-cumulus mafic rocks are sub-alkaline basalts except one variety of dykes which shows mildly alkaline character. The sub-alkaline rocks are tholeiite to calc-alkaline with boninite affinity. Tectono-magmatic variation diagrams and MORB normalised patterns suggest a fore arc tectonic regime for the eruption of these rocks.

The mafic rocks of Phulad Ophiolite Suite are zoned across the strike in terms of their distribution from west to east. The hornblende schists and basalts are exposed at the westernmost margin followed by gabbros and dykes. The alkaline dyke occurs at the easternmost part. The rocks of Phulad suite are juxtaposed with shallow water sediments in the east followed by platformal sediments and then continental slope sediments in the further east indicating gradual thickening of the crust from west to east and an eastward subduction. The geochemical interpretation presented in this study, together with discussion of lithological association is used to decipher the tectonic evolution of the Mesoproterozoics of NW Indian shield.     

Vulnerability and adaptability of wheat production in different climatic zones of Pakistan under climate change scenarios

Ten wheat production sites of Pakistan were categorized into four climatic zones i.e. arid, semi-arid, sub-humid and humid to explore the vulnerability of wheat production in these zones to climate change using CSM-Cropsim-CERES-Wheat model. The analysis was based on multi-year (1971–2000) crop model simulation runs using daily weather series under scenarios of increased temperature and atmospheric carbon dioxide concentration (CO₂) along with two scenarios of water management. Apart from this, sowing date as an adaptation option to offset the likely impacts of climate change was also considered. Increase in temperature resulted in yield declines in arid, semi-arid and sub-humid zone. But the humid zone followed a positive trend of gain in yield with rise in temperature up to 4°C. Within a water regime, increase in CO₂ concentration from 375 to 550 and 700 ppm will exert positive effect on gain in wheat yield but this positive effect is significantly variable in different climatic zones under rainfed conditions than the full irrigation. The highest response was shown by arid zone followed by semi-arid, sub-humid and humid zones. But if the current baseline water regimes (i.e. full irrigation in arid and semi-arid zones and rainfed in sub-humid and humid zones) persist in future, the sub-humid zone will be most benefited in terms of significantly higher percent gain in yield by increasing CO₂ level, mainly because of its rainfed water regime. Within a CO₂ level the changes in water supply from rainfed to full irrigation shows an intense degree of responsiveness in terms of yield gain at 375 ppm CO₂ level compared to 550 and 700 ppm. Arid and semi-arid zones were more responsive compared to sub-humid and humid zones. Rise in temperature reduced the length of crop life cycle in all areas, though at an accelerated rate in the humid zone. These results revealed that the climatic zones have shown a variable intensity of vulnerability to different scenarios of climate change and water management due to their inherent specific and spatial climatic features. In order to cope with the negative effects of climate change, alteration in sowing date towards cooler months will be an appropriate response by the farmers.     

Quantification of the urban heat island under a changing climate over Anatolian Peninsula

The Anatolian Peninsula is located at the confluence of Europe, Asia, and Africa and houses 81 cities of which 79 of them have population over 100,000. We employed some criteria to select the cities from the 81 cities. After accomplishing all the criteria, eight cities were remaining for the study. Nonparametric Mann–Kendall test procedure was employed for the urban and rural stations of these cities to detect the long-term change in temperature trends. Statistical analysis of daily minimum temperatures for the period between 1965 and 2006 suggest that there is no statistically significant increase in rural areas. In contrast to the findings of the previous studies, however, all the urban sites and difference between urban and rural pairs show significant increase in temperatures, a strong indication for the existence of urban heat island (UHI) affect over the region. Regional Climate Model was also utilized to assess the changes in temperature by the end of century for the region. The findings suggest that an increase of up to 5°C is possible. Climate change effects enforced with UHI have the potential to cause serious problems for the entire region and hence needs to be studied thoroughly.     

Place-based or sector-based adaptation? A case study of municipal and fishery policy integration

Place-based adaptation planning is an approach to address cross-sectoral and multi-level governance concerns as well as to build local adaptive capacity in vulnerable resource-dependent communities facing the adverse impacts of climate change. In contrast, sector-based adaptation planning focuses on addressing climate change impacts on individual economic sectors (e.g. fisheries or forestry) or sub-sectors (such as lobsters or timber). Yet, linking sectoral approaches with local adaptation policies is challenging. More effort is needed to identify opportunities for complementary adaptation strategies and policy integration to foster multiple benefits. In this article, we use a case study of fishery sector resources and municipal adaptation planning in Nova Scotia to demonstrate how meaningful entry points could catalyse policy integration and lead to co-benefits across multiple levels and stakeholder groups. Drawing on a fisheries systems and fish chain framework, we identify and assess several entry points for policy integration across sector- and place-based adaptation domains within coastal habitats, as well as harvesting, processing, and marketing sectors. The analysis highlights the multiple benefits of integrating local municipal adaptation plans with multi-scale resource sectors especially towards monitoring ecosystem changes, protecting essential infrastructure, and securing local livelihoods.

POLICY RELEVANCE

Climate change is having a growing impact on coastal communities around the world, with consequences for sea-level rise, critical habitats, essential infrastructure, and multiple economic sectors and industries. This Canadian case study demonstrates how municipal adaptation initiatives can be complementary to sector-based adaptation at both local and regional levels through various entry points across commodity production chains. Policy integration across place-based and sector-based adaptation processes should lead to multiple benefits such as conserving marine biodiversity, protecting essential infrastructure, and securing livelihoods. Our analysis, which focuses specifically on the fishery sector and coastal communities, shows that these co-benefits may arise particularly in such coastal-marine systems and provide policy lessons to terrestrial systems and other sectors.     

A comprehensive study on the surface chemistry of particulate matter collected from Jeddah,Saudi Arabia

In this work, the X-ray Photoelectron Spectroscopy (XPS) technique is utilized to analyze the surface chemical composition of particulate matter (PM) which was collected from various locations at Jeddah, Saudi Arabia. The main elements found on the surface of PM are carbon (C), oxygen (O) and silicon (Si) with combined percentage of 89.4–94.9 while traces of nitrogen (N), calcium (Ca), aluminum (Al), sodium (Na), chlorine (Cl), manganese (Mg), and sulfur (S) were also present. The analyzed XPS chemical state of C, O and Si was further used to determine their bonding with other elements occurring over the surface of PM. Carbon was found in the form of carbides (18.86%), fluorides (2.39%) and carbonates (78.75%); oxygen was observed as oxides (21.05%) and hydroxides (73.42%) of other metals; and silicon was detected as silicones (12.16%), nitrides (82.53%) and silicates (5.25%). The particle size of a PM is also of great concern for health issues, and thus has been investigated by the Field Emission Scanning Electron Microscope (FESEM). The Energy Dispersive X-ray Spectroscopy (EDS) was employed for cross verification of detected elements by XPS.     

Provenance, diagenesis, tectonic setting and geochemistry of Tawil Sandstone (Lower Devonian) in Central Saudi Arabia

The Tawil Sandstone (Lower Devonian) in Central Saudi Arabia overlies the Sharwara Member of the Tayyarat Formation (Silurian) and succeeded conformly by the Shaiba Member of the Jauf Formation. Petrographical data reveal that the Tawil Sandstone comprises 96% quartz, 3% feldspar, and 1% rock fragments and all samples are classified as quartz arenites. The presence of well sorted, altered to fresh feldspar, and discriminate function analysis suggests that the sediments have been subjected to substartial reworking resulting in a high level of maturity. Modal analysis data (Q–F–L) suggest a stable cratonic provenance for the sediments and accumulation in a passive margin basin is indicated (binary plot of SiO₂ vs K₂O/Na₂O). Diagenetic features include dissolution of feldspar and rock fragments, compaction, reduction of the existing pore space through rearrangements, and rotation and fragmentation of grains resulting in dissolution of quartz grains and cementation.     

Geochemistry of the sandstones of Punagarh basin: Implications for two source terranes and Arabian - Nubian connection of Aravalli craton?

Sandstones of Punagarh basin of Trans Aravalli region, NW Indian shield were analyzed for their major and trace element contents in conjunction with petrographic modes. The Punagarh basin comprises four formations (Sojat, Bambolai, Khamal and Sowania), amongst which the Sojat Formation in uncoformable contact with overlying formations, is significantly older and enjoys separate status as rest of the formations constitute Punagarh Group. Petrographic attributes suggest that Sojat sandstones contain distinct modal abundances like high content of quartz and low content of feldspar, mica, matrix, rock fragments and cement. In general there is a decrease in the average modal abundance of quartz and mica with concomitant increase of feldspar, chert and rock fragments from base to top in Punagarh sandstones. Sojat sandstones are also geochemically distinct as they possess high SiO₂/Al₂O₃, Th/U and Cr/Th ratios coupled with lowest Na₂O/K₂O ratio and Zr content, least fractionated LREE, more fractionated HREE and largest Eu* anomaly compared to Punagarh sandstones. The weathering indices suggest intense chemical weathering for Sojat sandstones and low to moderate for Punagarh sandstones. Compositionally all the sandstones of the Punagarh basin come under the category of quartzarenite. Compared to PAAS and UCC, both suite of sandstones are generally depleted in REE, HFSE (with exception of Zr, Hf and Ta), and enriched in ferromagnesian trace elements particularly Cr and Co. The chemical data indicate that the sediments were derived from the source(s) of mixed felsic - mafic composition, with the former being dominant. The source rocks were granites, TTG, basalts, and rhyolites. The Sojat sandstones owe their source form Archean crust while Punagarh sandstones got detritus from Mesoproterozic crust. Immobile element ratios and REE abundances of Sojat sandstones closely match with Paleoproterozoic metagreywackes of Ghana of African craton while Punagarh sandstones show near geochemical characteristic with Gogunda, Kumbalgarh and Vindhyan quartzites of Aravalli craton. This geochemical similarity of Sojat sandstones provides credence to the hypothesis that Trans–Aravalli region of India had been an integral part of Arabian - Nubian shield. The chemical data advocate the deposition of these sandstones in a tectonic setting comparable to modern back arc setting.     

Economic significance of colonial invasions in Khejuri-Hijli coastal sector of Purba Medinipur district,West Bengal: A geographical review

Khejuri- Hijili coastal area, now extends over the Khejuri police station, is situated in the southeastern part of the district of Purba Medinipur of West Bengal, on the western bank of the Hugli river. Between 21°47'42"N-22°4'N latitudes and 87°45'4"E-88°18"E longitudes the area covers about 267.97 sq. km. At the confluence of the rivers Bhagirathi-Hugli and the Bay of Bengal, Hijili emerged as an island from the estuarine surroundings around 1400-1500 A.D. afterward the island became covered with natural mangroves. Gradually it became the abode of fishermen. To gather some primary data, household survey by different questionnaire, topographic survey was done. Secondary data are mainly produced by assembling historical charts, maps, literatures for the specified work of the area concerned. Historical records including documents, survey notes, maps and photographs provided valuable information about the study area. Remains of early structures, monuments, and office buildings have been vigilantly watched and written reports and research articles have been carefully studied for sequencing the socio-economic history of the area. Later on accuracy assessment was performed by comparing two sources of information: classification of map derived from old records and maps and the ground truth information. The output obtained by performing the above steps includes land use and other maps and charts. These outputs were then analyzed to detect the historical significance of Khejuri-Hijili sector of the Hugli estuary and its sequential deterioration. These changes in the study area that were identified from classified maps, charts and diagram were tabulated.