Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan

The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration of approximately 450 km of seismic reflection data with available surface geologic, magnetostratigraphic, and exploration well data help in delineating different tectonic features in the Salt Range. These studies reveal a concealed duplex structure under the roof sequence, help to determine the footwall and hangingwall geometries of the leading edge at different successive evolutionary stages, estimate the lateral extent of a basement normal fault, constrain the ages of different structural features, and define lateral variations in the deformational style within the leading edge. The above mentioned features have been synthesized to document an out-of-sequence evolutionary model of the Salt Range. The newly recognized, concealed duplex structure extends more than 40 km along the strike and gradually progrades southward along a décollement that first ramps within the Salt Range Formation and then across the platform sequence and follows the shaley horizons of overlying Murree Formation near the contact. This duplex structure is terminated along the two lateral ramps in the east and west. The northern ramp in the footwall of the roof sequence is localized by a basement normal fault in the central Salt Range, and changes its position and characteristics in the eastern and western Salt Range. In the western Salt Range, it is located 15 km farther south and is entirely within the sedimentary sequence. These two segments are linked by a lateral ramp that developed over the western culmination wall of the lateral ramp associated with the underlying duplex structure. In the eastern Salt Range, however, the northern ramp first continues within the sedimentary sequence beyond the end of the basement normal fault and farther east it changes into an oblique ramp. This oblique ramp is truncated by another N-S trending lateral ramp farther to the east. The monoclinal structure of the Chambal Ridge marks the southernmost extension of this lateral ramp. Along this lateral ramp the roof sequence steps down and joins the basal décollement. Due to the down stepping of the roof sequence the structural style also changes from fault-bend fold to fault propagated fold geometry. Because in fault-bend fold geometry the major component of shortening was accommodated across the northern ramp, very little shortening occurred within the roof sequence. In contrast, all the shortening in the east has been distributed over a region in a prograde fashion. Therefore, the thrust wedge is internally deformed into a fault propagated fold geometry to provide a surface topographic slope necessary to maintain a critical taper. The concealed duplex structure is the earliest structure of the Himalayan thrust front that was formed during 9-7 m.y., and further suggests that out of sequence thrusting has occurred over a region of 150 km during the past 9 m.y. Due to the development of a basement normal fault at 7 m.y., the thrust acquired a high friction front and was unable to move forward. Crustal shortening was then taken up by the Main Boundary Thrust zone in the north, which was quite active during this time. Between 5-6 m.y., the thrust wedge started to ramp over the basement normal fault, facilitated by the development of a thick salt pad on the down-thrown side, during 7-6 m.y. The newly built topography due to the ramping of the thrust wedge resisted the southwards propagation of the roof sequence and caused further out-of-sequence thrusting in the north but was not sufficient to stop its southward progradation. It was followed by the major horizontal translation of the roof sequence over the roof sequence flat. This study also suggests that 13° counter clockwise rotation has occurred along the northern ramp and the concealed duplex structure. Recognition of the concealed duplex structure and better understanding of the footwall geometry of the roof sequence also generates new prospects of oil exploration in the Salt Range

Risk factors and causes of stillbirths among pregnant women in Pakistan

Background: Globally 3 million stillbirths occur per year, and Pakistan is ranked 3rd among the countries having the highest burden. Despite being a major public health problem, efforts to reduce this figure are insufficient.Objective: The aim of the study was to identify and measure the inequalities in stillbirth associated risk factors, causes and fertility risk behaviors.Methods: Data were derived from the Pakistan Demographic and Health Surveys (PDHS) 1990-2013. Inequalities on determi- nants were evaluated using rate differences and rate ratios; time trends computed with annualized reduction rate (ARR).Results: Overall ARR determined for stillbirth was -12.52 percent per annum. The high ARR were recorded for mothers age &lt;20, urban areas, educated mothers and for highest wealth quintile. The relative inequalities were most pronounced for wealth quintiles, education and age of mothers. Stillbirth causes were unexplained antepartum (33%), unexplained intrapartum (21%), intrapartum asphyxia (21%) and antepartum maternal disorders (19%). The high fertility risk behavior was found in mothers with age &gt;34 and birth order &gt;3.Conclusion: The study concluded that to achieve gain in child survival, there is need to promote antenatal care, birth spacing, and family planning programs in developing countries.Keywords: Perinatal mortality, stillbirth causes, delivery complications, Pakistan

Biological Monitoring of Blood Naphthalene Levels as a Marker of Occupational Exposure to PAHs among Auto-Mechanics and Spray Painters in Rawalpindi

<p>Abstract</p> <p>Background</p> <p>Routine exposure to chemical contaminants in workplace is a cause for concern over potential health risks to workers. In Pakistan, reports on occupational exposure and related health risks are almost non-existent, which reflects the scarce availability of survey data and criteria for determining whether an unsafe exposure has occurred. The current study was designed to evaluate blood naphthalene (NAPH) levels as an indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) among automobile workshop mechanics (MCs) and car-spray painters (PNs). We further determined the relationship between blood NAPH levels and personal behavioural, job related parameters and various environmental factors that may further be associated with elevated risks of occupational exposures to PAHs.</p> <p>Methods</p> <p>Sixty blood samples (n = 20 for each group i.e. MC, PN and control group) were collected to compare their blood NAPH levels among exposed (MCs and PNs) and un-exposed (control) groups. Samples were analyzed using high pressure liquid chromatography (HPLC). Data regarding demographic aspects of the subjects and their socioeconomic features were collected using a questionnaire. Subjects were also asked to report environmental hygiene conditions of their occupational environment.</p> <p>Results</p> <p>We identified automobile work areas as potential sites for PAHs exposure, which was reflected by higher blood NAPH levels among MCs. Blood NAPH levels ranged from 53.7 to 1980.6 μgL^-1and 54.1 to 892.9 μgL^-1among MCs and PNs respectively. Comparison within each group showed that smoking enhanced exposure risks several fold and both active and passive smoking were among personal parameters that were significantly correlated with log-transformed blood NAPH levels. For exposed groups, work hours and work experience were job related parameters that showed strong associations with the increase in blood NAPH levels. Poor workplace hygiene and ventilation were recognized as most significant predictors related to differences among workplaces that may enhance the extent of exposure to chemical contaminants.</p> <p>Conclusions</p> <p>It appeared that chemical exposure at the workplace may be influenced by multiple environmental factors, but poor workplace hygiene and duration of exposure (long work hours) were the most important factors. Smoking and negligence of workers regarding self protection were among some of the important personal behaviours than can be addressed with better training. There is also a need to improve workplaces hygiene and to rationalize work hours to minimize health risks. Since smoking was an important confounding factor that supplemented most of the actual occupational exposure, a study based on non-smoker subjects is needed to separate out the effects of smoking and other confounding factors that may obscure measurements of actual extent of occupational exposure.</p

Risk factors and causes of stillbirths among pregnant women in Pakistan

Background: Globally 3 million stillbirths occur per year, and Pakistan is ranked 3rd among the countries having the highest burden. Despite being a major public health problem, efforts to reduce this figure are insufficient. Objective: The aim of the study was to identify and measure the inequalities in stillbirth associated risk factors, causes and fertility risk behaviors. Methods: Data were derived from the Pakistan Demographic and Health Surveys (PDHS) 1990-2013. Inequalities on determinants were evaluated using rate differences and rate ratios; time trends computed with annualized reduction rate (ARR). Results: Overall ARR determined for stillbirth was -12.52 percent per annum. The high ARR were recorded for mothers age &lt;20, urban areas, educated mothers and for highest wealth quintile. The relative inequalities were most pronounced for wealth quintiles, education and age of mothers. Stillbirth causes were unexplained antepartum (33%), unexplained intrapartum (21%), intrapartum asphyxia (21%) and antepartum maternal disorders (19%). The high fertility risk behavior was found in mothers with age &gt;34 and birth order &gt;3. Conclusion: The study concluded that to achieve gain in child survival, there is need to promote antenatal care, birth spacing, and family planning programs in developing countries. DOI: https://dx.doi.org/10.4314/ahs.v19i1.24 Cite as: Afshan K, Narjis G, M Q. Risk factors and causes of stillbirths among pregnant women in Pakistan. Afri Health Sci. 2019;19(1). 1507-1516. https://dx.doi.org/10.4314/ahs.v19i1.2

Displacement transfer from fault-bend to fault-propagation fold geometry: An example from the Himalayan thrust front

The leading edge of the ENE-trending Himalayan thrust front in Pakistan exhibits along-strike changes in deformational style, ranging from fault-bend to fault-propagation folds. Although the structural geometry is very gently deformed throughout the Salt Range, it becomes progressively more complex to the east as the leading edge of the emergent Salt Range Thrust becomes blind. Surface geology, seismic reflection, petroleum well, and chronostratigraphic data are synthesized to produce a 3-D kinematic model that reconciles the contrasting structural geometries along this part of the Himalayan thrust front. We propose a model whereby displacement was transferred, across a newly-identified lateral ramp, from a fault-bend fold in the west to fault-propagation folds in the east and comparable shortening was synchronously accommodated by two fundamentally different mechanisms: translation vs. telescoping. However, substantially different shortening distribution patterns within these structurally contrasting segments require a tear fault, which later is reactivated as a thrust fault. The present geometry of this S-shaped displacement transfer zone is a combined result of the NW–SE compression of the lateral culmination wall and associated tear fault, and their subsequent modification due to mobilization of underlying ductile salt.Keywords: Lateral culmination wall, Displacement transfer, Fault-propagation fold, Pakistan, Salt Range, Fault-bend foldKeywords: Lateral culmination wall, Displacement transfer, Fault-propagation fold, Pakistan, Salt Range, Fault-bend fol

Ulnar dimelia variant: a case report

We report a case of ulnar dimelia, commonly called mirror hand, in a 2-month-old female child who had restriction of elbow flexion and forearm rotation. There was no facial or other internal organ malformation. Radiographs revealed seven triphalangeal digits with double ulnae (one following the other) and absent radius. To the best of the authors’ knowledge, this is the first report of this mirror hand deformity in which fingers are symmetrical while duplicated ulnae are not

Introduction of channel catfish Ictalurus punctatus (Rafinesque) in Pakistan and its performance during acclimatization and pond culture.

Abstract.-Two thousand fingerlings of channel catfish Ictalurus punctatus were imported from Thailand in a bid to introduce this fish in Pakistan. Five percent mortality occurred during transportation. Experiments were designed to observe catfish acclimatization in tanks or raceways for which five hundred fingerlings (average weight 10.86±1.20g) were placed in five tanks of 2000-liter water capacity and another 500 fingerlings (average weight, 10.56±0.68g) were kept in five raceways of 5000-liter water capacity each. The fish were fed on imported diet for a period of 75 days. Mean weight gain of 27.22±1.75 g and 31.5±1.04 g and surv~7.5% and 95.9% were recorded in tanks and raceways, respectively. For studying growth of fish two stocking densities (3,000 and 3,500/ha) were maintained in ponds (0.04 ha) from December 2003 -November 2004. The weight gain was significantly higher in low stocking density (1,263.3 ± 60.9 g) compared with high stocking density (1,184.9±57.1 g). Fish production and survival between two stocking densities was not different (P&gt;0.05)

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This multidisciplinary study integrates remote sensing, stratigraphy, siliciclastic and carbonate sedimentology, tectonics, and petrography of the Nisai, Khojak and Sharankar Formations to reveal the Paleogene depositional, diagenetic and deformational history of the Katawaz Basin. Study of Landsat Thematic Mapper (TM) digital data shows that maximum discrimination of different rocks is achieved in bands 5, 4, and 2 in red, green and blue, respectively. Maximum spectral contrast of Nisai limestone lithofacies uses band ratios 7/5(R), 4/3(G)and 3/2(B). Laboratory spectral measurements suggest Nisai lithofacies are best discriminated in lower wavelength regions (TM bands 1, 2, 3, and 4). Late Paleocene to early Oligocene Nisai Formation records carbonate platform, slope and basinal deposition. Newly formed structural highs and lows, due to emplacement of ophiolites on the western passive margin of Indo-Pakistan subcontinent, controlled deposition and thickness of Nisai lithofacies. Revised age of the ophiolite emplacement, based on benthic forams, is early Paleocene. Siliciclastic Khojak Formation includes newly identified upper continental slope, prodelta, delta front, lower and upper delta plains lithofacies. These lithofacies represent prograding fluvial-dominated, wave-modified Katawaz delta that axially fed Khojak submarine-fan turbidites to the southwest. Sandstone detrital modes and paleocurrent analysis suggest derivation from the early Himalayan orogen and longitudinal dispersal down the basin axis. Decrease in quartz, and increase in total lithics from bottom to top reflect gradual uplift and unroofing of the early Himalaya. Diagenetic relationships suggest complex paragenetic sequence of chlorite-quartz-calcite cementation. Himalaya-derived molasse, delta, and turbidite fan sediments are related in time and space. Molasse sedimentation began in late Paleocene, when early Himalayan orogenic highlands formed. However, sedimentation on the modern Indus delta-fan began in the early Miocene. This age-range discrepancy implies that a major portion of the Himalayan marine record is missing. Khojak strata are that missing record. The Katawaz remnant ocean closed, scissors fashion, by the end of early Miocene and the Katawaz-Khojak complex was incorporated to the Indo-Pakistan subcontinent. The Himalaya-Katawaz system is a Paleogene analogue to the Carboniferous Appalachian-Black Warrior-Ouachita system