Clift P.D.,University of Aberdeen |
Clift P.D.,CAS South China Sea Institute of Oceanology |
Carter A.,Birkbeck College London |
Giosan L.,Woods Hole Oceanographic Institution |
And 8 more authors.
Geology | Year: 2012
The Harappan Culture, one of the oldest known urban civilizations, thrived on the northwest edge of the Thar Desert (India and Pakistan) between 3200 and 1900 BCE. Its demise has been linked to rapid weakening of the summer monsoon at this time, yet reorganization of rivers may also have played a role. We sampled subsurface channel sand bodies predating ca. 4.0 ka and used U-Pb dating of zircon sand grains to constrain their provenance through comparison with the established character of modern river sands. Samples from close to archaeological sites to the north of the desert show little affinity with the Ghaggar-Hakra, the presumed source of the channels. Instead, we see at least two groups of sediments, showing similarities both to the Beas River in the west and to the Yamuna and Sutlej Rivers in the east. The channels were active until after 4.5 ka and were covered by dunes before 1.4 ka, although loss of the Yamuna from the Indus likely occurred as early as 49 ka and no later than 10 ka. Capture of the Yamuna to the east and the Sutlej to the north rerouted water away from the area of the Harappan centers, but this change significantly predated their final collapse.
East A.E.,U.S. Geological Survey |
Clift P.D.,Louisiana State University |
Carter A.,University of London |
Alizai A.,Geological Survey of Pakistan |
Vanlaningham S.,Oregon State University
Journal of Sedimentary Research | Year: 2015
Sediment production and its subsequent preservation in the marine stratigraphic record offshore of large rivers are linked by complex sediment-transfer systems. To interpret the stratigraphic record it is critical to understand how environmental signals transfer from sedimentary source regions to depositional sinks, and in particular to understand the role of buffering in obscuring climatic or tectonic signals. In dryland regions, signal buffering can include sediment cycling through linked fluvial and eolian systems. We investigate sediment-routing connectivity between the Indus River and the Thar Desert, where fluvial and eolian systems exchanged sediment over large spatial scales (hundreds of kilometers). Summer monsoon winds recycle sediment from the lower Indus River and delta northeastward, i.e., downwind and upstream, into the desert. Far-field eolian recycling of Indus sediment is important enough to control sediment provenance at the downwind end of the desert substantially, although the proportion of Indus sediment of various ages varies regionally within the desert; dune sands in the northwestern Thar Desert resemble the late Holocene-Recent Indus delta, requiring short transport and reworking times. On smaller spatial scales (1-10 m) along fluvial channels in the northern Thar Desert, there is also stratigraphic evidence of fluvial and eolian sediment reworking from local rivers. In terms of sediment volume, we estimate that the Thar Desert could be a more substantial sedimentary store than all other known buffer regions in the Indus basin combined. Thus, since the mid-Holocene, when the desert expanded as the summer monsoon rainfall decreased, fluvial-eolian recycling has been an important but little recognized process buffering sediment flux to the ocean. Similar fluvial-eolian connectivity likely also affects sediment routing and signal transfer in other dryland regions globally. © 2015, SEPM (Society for Sedimentary Geology).
Jouanne F.,French National Center for Scientific Research |
Awan A.,Geological Survey of Pakistan |
Madji A.,Geological Survey of Pakistan |
Pecher A.,Joseph Fourier University |
And 5 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2011
The 8 October 2005 Kashmir earthquake ruptured an out-of-sequence Himalayan thrust known as the Balakot-Bagh thrust. The earthquake's hypocenter was located at a depth of 15 km on the ramp close to a possible ramp/flat transition. In the weeks following the earthquake a GPS network was installed to measure postseismic displacement. The initial measurements in November 2005 were followed by other campaigns in January and August 2006, in March and December 2007, and in August 2008 and 2009. Two hypotheses were tested: post-seismic displacements controlled by viscous relaxation of the lower crust or by afterslip along a flat north of the ramp affected by the main shock. A single Newtonian viscosity for the different periods cannot be determined by numerical simulations of viscous relaxation, which may indicate that the viscosity of the lower crust is non-Newtonian or that viscous relaxation does not control postseismic displacements. Numerical simulations using dislocations in a uniform elastic half-space indicate afterslip north of the ramp of the earthquake along a flat connected to the ramp. Slip along the northwestern portion of the flat accrued to about 285 mm between November 2005 and August 2006, while slip along the southeastern portion accrued to 130 mm over the same time period. Residual misfit of the observed and predicted displacements clearly indicated that afterslip is a better explanation for the observations than the hypothesis of viscous relaxation. The time evolution of the afterslip was found to be consistent with that predicted from rate-strengthening frictional sliding. © 2011 by the American Geophysical Union.
Sadiq Malkani M.,Geological Survey of Pakistan
Disaster Advances | Year: 2010
Dinosaurs from Sulaiman basin of Pakistan are found just below the Cretaceous Tertiary (K-T) boundary. After K-T boundary no dinosaurs are reported from Pakistan. Hiese dinosaurs were the huge land animals at that time and were the ruler of continents but became extinct due to natural disasters. The extinction of dinosaurs at the K-T boundary represents a big disaster as well as big bioevent and geoevent. Past is past but alerts for present and future natural disaster advances and prevention especially for earthquakes and land slidings.
Firdous R.,Geological Survey of Pakistan |
Devlin J.F.,University of Kansas
Groundwater Monitoring and Remediation | Year: 2015
Diluting granular iron with sand is a common practice performed to minimize clogging and to reduce the cost of permeable reactive barrier (PRB) installations. This study used a pore-scale image analysis technique and a reanalysis of previously published data to test the hypothesis of Bi etal. (2009) that the mixing of 15% by weight sand with a commercial, platy-grained iron medium opens the pore space between grains, exposes more reactive grain surface to flowing water, and leads to a more reactive medium (i.e., promoting faster transformation rates per unit volume of medium) than 100% by weight granular iron. Four mixing ratios (100, 85, 75 and 50% iron by weight) were compared on the basis of two morphological parameters measured in section: (1) total grain area, which correlates with the total amount of iron present, and (2) grain perimeter, which is governed by both the mobile solution-available surface and the total amount of iron present. As expected, grain areas exposed in section were highest for 100% iron packings and decreased with increasing sand content. The estimated iron grain effective perimeters (i.e., accessible to mobile water) for 85% iron-by weight mixtures were similar to 100% iron and decreased in 75 and 50% iron mixtures. The section confirmed that the presence of 15% sand by weight opened up the pore structure, likely improving the mobile-water to iron contact. The analysis of kinetic column experimental data indicated that the same trend was present in the sorption capacity term in the Kinetic Iron Model (KIM) equation, providing corroborating evidence that the iron surface availability was higher in the 85% iron medium than the 100% iron medium on a per gram of iron basis. © 2016, National Ground Water Association.
Chandio T.A.,Geological Survey of Pakistan |
Khan M.N.,University of Karachi |
Sarwar A.,Fuel Research Center
Environmental Monitoring and Assessment | Year: 2015
The fluoride level in drinking water is an important parameter and has to be controlled in order to prevent dental and skeletal fluorosis. The objective of this study is to assess fluoride content and other water quality parameters in the samples taken from open wells, tube wells, and karezes of Mastung, Mangochar, and Pringabad areas of Balochistan province. A total number of 96 drinking water samples out of 150 were found unfit for human consumption. Area-wise analysis show that the samples from 39 sites from Mastung, 12 from Mangochar, and 13 from Pringabad were found in the risk of dental fluorosis of mild to severe nature. However, 12 sampling sites from Mastung, 8 from Mangochar, and 2 from Pringabad were identified as the risks of mottling and skeletal fluorosis or other bone abnormalities. The highest concentration of F− has been observed as 14 mg L−1 in Mastung. Correlation analysis show that fluoride solubility in drinking water is pH dependent; and the salts of Ca2+, Na+, K+, Cl−, and SO42− contribute to attain the favorable pH for dissolution of fluoride compounds in drinking water. Principal component analysis shows that the geochemical composition of the rocks is only responsible for groundwater contamination. On the basis of the results, defloridation of the identified sampling sites and continuous monitoring of drinking water at regular basis is recommended at government level to avoid further fluorosis risks. © 2015, Springer International Publishing Switzerland.
Bebej R.M.,Olivet Nazarene University |
ul-Haq M.,Geological Survey of Pakistan |
Zalmout I.S.,University of Michigan |
Gingerich P.D.,University of Michigan
Journal of Mammalian Evolution | Year: 2012
The archaeocete family Remingtonocetidae is a group of early cetaceans known from the Eocene of India and Pakistan. Previous studies of remingtonocetids focused primarily on cranial anatomy due to a paucity of well-preserved postcranial material. Here we describe the morphology of the known vertebral column in Remingtonocetus domandaensis based largely on a single well-preserved partial skeleton recovered from the upper Domanda Formation of Pakistan. The specimen preserves most of the precaudal vertebral column in articulation and includes seven complete cervical vertebrae, ten partial to complete thoracic vertebrae, six complete lumbar vertebrae, and the first three sacral vertebrae. Cervical centra are long and possess robust, imbricating transverse processes that stabilized the head and neck. Lumbar vertebrae allowed for limited flexibility and probably served primarily to stabilize the lumbar column during forceful retraction of the hind limbs. Vertebral evidence, taken together with pelvic and femoral morphology, is most consistent with interpretation of Remingtonocetus domandaensis as an animal that swam primarily by powerful movement of its hind limbs rather than dorsoventral undulation of its body axis. © 2012 Springer Science+Business Media, LLC.
Alizai A.,Geological Survey of Pakistan
Journal of Himalayan Earth Sciences | Year: 2013
This paper presents the latest seismicity data from the Karachi Arc and illuminates recent activity within the greater Karachi metropolitan area. Since the epicenter locations cover the entire Karachi Arc, the whole structure seems to be currently active with hypocenters located in a depth range of (0-500) kilometers. Most of these, however, are shallow (10-50 kilometers). Many of the epicenters are located within or near the Karachi neighborhoods plagued by recurrent earthquake activity. That explains why the people are so tormented. Coastal areas in southern Karachi are also exposed to tsunami threats from earthquakes along the shorelines or from within the Arabian Sea. This study also provides the first outcrop evidence of wrench nature of the southern boundary of Karachi Arc. The photographed fault, named Makli Fault here, is located 2 kilometers south of Makli (about 6 kilometers southwest of Thatta) in the Sindh province and appears to be part of a system that extends westwards through Karachi, where it is hidden under the concrete and urban sprawl. Geomorphic observations suggest that faults belonging to this system might have locally deflected the Malir and Lyari River channels and also created accommodation space for deposition of such coarse clastics as the Korangi Conglomerate. Progressive folding and shear-related drag - along the southern wrench boundary of Karachi Arc - as it moved eastward during the Neogene - probably resulted in the formation of large SW plunging folds - such as the Monghopir anticline and the adjacent syncline. The limbs of both of these folds are also torn by prominent NW oriented Riedel shears with enhanced drag-related wrench offsets. More fieldwork is urgently needed to map active faults in Karachi and develop a better understanding of the tectonic threats.
PubMed | University of Karachi, Geological Survey of Pakistan, University of Wisconsin - Stevens Point and Applied Chemistry Research Center
Type: | Journal: The Science of the total environment | Year: 2015
Groundwater samples (n=152) were collected in the Thar Desert of the Umarkot Sub-District, Pakistan to evaluate the geochemical controls on the occurrence of high fluoride (F(-)) levels within the study area. Fluoride concentrations range from 0.06 to 44.4 mg/L, with mean and median values of 5.22 and 4.09 mg/L, respectively; and roughly 84% of the samples contain fluoride concentrations that exceed the 1.5mg/L drinking water standard set by WHO. The overall groundwater quality reflects the influences of silicate mineral weathering and evaporation. Fluoride originates from the weathering of minerals derived from Type-A granite and possibly anion exchange (OH(-) for F(-)) on clays and weathered micas under high pH conditions. High fluoride levels are associated with Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. Depleted calcium levels in groundwater allow higher fluoride concentrations to occur before the solubility limit for fluoride is reached.
PubMed | Geological Survey of Pakistan
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2015
The fluoride level in drinking water is an important parameter and has to be controlled in order to prevent dental and skeletal fluorosis. The objective of this study is to assess fluoride content and other water quality parameters in the samples taken from open wells, tube wells, and karezes of Mastung, Mangochar, and Pringabad areas of Balochistan province. A total number of 96 drinking water samples out of 150 were found unfit for human consumption. Area-wise analysis show that the samples from 39 sites from Mastung, 12 from Mangochar, and 13 from Pringabad were found in the risk of dental fluorosis of mild to severe nature. However, 12 sampling sites from Mastung, 8 from Mangochar, and 2 from Pringabad were identified as the risks of mottling and skeletal fluorosis or other bone abnormalities. The highest concentration of F(-) has been observed as 14 mg L(-1) in Mastung. Correlation analysis show that fluoride solubility in drinking water is pH dependent; and the salts of Ca(2+), Na(+), K(+), Cl(-), and SO4(2-) contribute to attain the favorable pH for dissolution of fluoride compounds in drinking water. Principal component analysis shows that the geochemical composition of the rocks is only responsible for groundwater contamination. On the basis of the results, defloridation of the identified sampling sites and continuous monitoring of drinking water at regular basis is recommended at government level to avoid further fluorosis risks.