Source Sector Contributions to Aerosol Levels in Pakistan

Urban air pollution in Pakistan is a serious challenge and it causes significant damage to human health and ecosystems. This paper presents a modelling study using the Weather Research and Forecasting Model coupled with Chemistry(WRF-Chem) to simulate the spatial distributions and temporal variations of aerosol concentrations over Pakistan, focusing on contributions of domestic emission sectors(transport, industry, residential, and energy) to mass concentrations of sulfate(SO2–4), nitrate(NO–3), ammonium(NH+4), black carbon(BC), and organic carbon(OC) during the months of January, April, July, and October in 2010. Sensitivity studies indicate that, averaged over January, April, July, and October of 2010, energy and industry sectors have the largest contributions to SO2–4 concentrations, each of which contributes about 10%?20% to SO2– 4over the polluted eastern Pakistan. The contributions from residential and transport sectors to NO–3 concentrations reach 40%?50% in central Pakistan. The residential sector has the highest contribution of 50%–80% to BC and OC loading in northeastern and southern Pakistan. Examination of sector contributions to aerosol levels in Lahore, the most polluted city in Pakistan, suggests that reductions in emissions in the residential sector should be an efficient measure for improving particulate matter air quality in this region.     

Stratigraphic and palaeoenvironmental framework of the Early Permian sequence in the Salt Range, Pakistan

The Early Permian Gondwana regime succession of the Nilawahan Group is exposed only in the Salt Range of Pakistan. After a prolonged episode of non-deposition that spanned much of the Palaeozoic, the 350?m thick predominantly clastic sequence of the Nilawahan Group records a late glacial and post-glacial episode in which a range of glacio-fluvial, marine and fluvial environments evolved and accumulated. The Early Permian succession of the Salt Range has been classified into four formations, which together indicates a changing climatic regime during the Early Permian in the Salt Range region. The lower-most, Tobra Formation unconformably overlies a Cambrian sequence and is composed of tillite, diamictite and fresh water facies, which contain a floral assemblage (Gangamopteris and Glossopteris) that confirms an Asselian age. The Tobra Formation is overlain by marginal marine deposits of the Dandot Formation (Sakmarian), which contain an abundant brachiopods assemblage (Eurydesma and Conularia). Accumulation of the Dandot Formation was terminated by a regional sea-level fall and a change to the deposition of the fluvial deposits of the Warchha Sandstone (Artinskian). The Warchha Sandstone was deposited by high sinuosity meandering, avulsion prone river with well developed floodplains. This episode of fluvial sedimentation was terminated by a widespread marine transgression, as represented by the abrupt upward transition to the overlying shallow marine Sardhai Formation (Kungurian). The Early Permian Gondwana sequence represented by the Nilawahan Group is capped by predominantly shallow shelf carbonate deposits of the Tethyan realm. The sedimentologic and stratigraphic relationship of these four lithostratigraphic units in the Salt Range reveals a complex stratigraphic history for the Early Permian, which is mainly controlled by eustatic sea-level change due to climatic variation associated with climatic amelioration at the end of the major Gondwana glacial episode, and the gradual regional northward drift to a lower latitude of the Indian plate.     

Integration of Sequence Stratigraphic Analysis and 3D Geostatistical Modeling of Pliocene–Pleistocene Delta,F3 Block,Netherlands

This research is focused on the analysis of the sequence stratigraphic units of F3 Block, within a wave-dominated delta of Plio–Pleistocene age. Three wells of F3 block and a 3D seismic data, are utilized in this research. The conventional techniques of 3D seismic interpretation were utilized to mark the 11 surfaces on the seismic section. Integration of seismic sequence stratigraphic interpretation, using well logs, and subsequent 3D geostatistical modeling, using seismic data, aided to evaluat...     

Composition,Structure and Regeneration Dynamics of Olea ferruginea Royle Forests from Hindukush Range of Pakistan

The abundance of Olea ferruginea in Malakand Division has been significantly reduced across its distribution range due to anthropogenic pressure in the recent past. A number of initiatives were taken for grafting this species to obtain better seeds for oil production, without the basic information on their ecology and management. To address this knowledge gap, we quantified the composition, structure and regeneration dynamics of Olea ferruginea forests in Malakand Division, Hindukush range of Pakistan. In the present study, five communities dominated by Olea ferruginea were identified using Ward's agglomerative cluster analysis.Total tree density ranged from 153-2602 plants/ha, and basal area from 19.55 to 2353 m2 ha-1 with Olea having a relative density of 51% to 87% and basal area of 48% to 93%, respectively. The density of juveniles of the dominant and subordinate tree species were generally low which reflect their narrow distribution in the study area. Size-class distributions of O. ferruginea disclosed a bell-shaped pattern, indicating that forests were heavily exploited by local inhabitants in previous periods and recently by armed forces owing to security risks in the study area. The age(mean max. 300±34 years) and annual increment(3.2±1.2 years/cm) indicates that the species is long lived and generally slow growing among the different broad leaved species studied so far. However, the oldest trees can be found by the exploration of large diameter trees in the area. In addition, we found a stable linear relationship between the age and diameter(r2 = 0.779), indicating that diameter is a good predictor of age for this broad leaved species. In view of its relatively slow growth, longevity and positive ring-width characteristics O. ferruginea seems to be a suitable choice for dendroecological and dendrochronological studies in lesser Himalayan and Hindukush ranges of Pakistan. The results obtained from this study may help in understanding the composition, structure and regeneration dynamics of other subtropical broad leaved species.     

Petrogenesis of Mafic Garnet Granulite in the Lower Crust of the Kohistan Paleo-arc Complex (Northern Pakistan): Implications for Intra-crustal Differentiation of Island Arcs and Generation of Continental Crust

We report the results of a geochemical study of the Jijal andSarangar complexes, which constitute the lower crust of theMesozoic Kohistan paleo-island arc (Northern Pakistan). TheJijal complex is composed of basal peridotites topped by a gabbroicsection made up of mafic garnet granulite with minor lensesof garnet hornblendite and granite, grading up-section to hornblendegabbronorite. The Sarangar complex is composed of metagabbro.The Sarangar gabbro and Jijal hornblende gabbronorite have melt-like,light rare earth element (LREE)-enriched REE patterns similarto those of island arc basalts. Together with the Jijal garnetgranulite, they define negative covariations of La_N, Yb_N and(La/Sm)_N with Eu^* [Eu^* = 2 x Eu_N/(Sm_N + Gd_N), where N indicateschondrite normalized], and positive covariations of (Yb/Gd)_Nwith Eu^*. REE modeling indicates that these covariations cannotbe accounted for by high-pressure crystal fractionation of hydrousprimitive or derivative andesites. They are consistent withformation of the garnet granulites as plagioclase–garnetassemblages with variable trapped melt fractions via eitherhigh-pressure crystallization of primitive island arc basaltsor dehydration-melting of hornblende gabbronorite, providedthat the amount of segregated or restitic garnet was low (<5wt %). Field, petrographic, geochemical and experimental evidenceis more consistent with formation of the Jijal garnet granuliteby dehydration-melting of Jijal hornblende gabbronorite. Similarly,the Jijal garnet-bearing hornblendite lenses were probably generatedby coeval dehydration-melting of hornblendites. Melting modelsand geochronological data point to intrusive leucogranites inthe overlying metaplutonic complex as the melts generated bydehydration-melting of the plutonic protoliths of the Jijalgarnet-bearing restites. Consistent with the metamorphic evolutionof the Kohistan lower arc crust, dehydration-melting occurredat the mature stage of this island arc when shallower hornblende-bearingplutonic rocks were buried to depths exceeding 25–30 kmand heated to temperatures above c. 900°C. Available experimentaldata on dehydration-melting of amphibolitic sources imply thatthickening of oceanic arcs to depths >30 km (equivalent toc. 1·0 GPa), together with the hot geotherms now postulatedfor lower island arc crust, should cause dehydration-meltingof amphibole-bearing plutonic rocks generating dense garnetgranulitic roots in island arcs. Dehydration-melting of hornblende-bearingplutonic rocks may, hence, be a common intracrustal chemicaland physical differentiation process in island arcs and a naturalconsequence of their maturation, leading to the addition ofgranitic partial melts to the middle–upper arc crust andformation of dense, unstable garnet granulite roots in the lowerarc crust. Addition of LREE-enriched granitic melts producedby this process to the middle–upper island arc crust maydrive its basaltic composition toward that of andesite, affordinga plausible solution to the ‘arc paradox’ of formationof andesitic continental-like crust in island arc settings. KEY WORDS: island arc crust; Kohistan complex; Jijal complex; amphibole dehydration-melting; garnet granulite; continental crustal growth