Heavy Minerals Concentration along the Baluchistan Coast,Pakistan from Gadani to Phornala     

M. A. Chaudry  M. Q. Memon  M. Danish 《Marine Georesources & Geotechnology》2013,31(1):73-83

Sorting and concentration of a variety of heavy minerals along the coast between Gadani and Phornala, Baluchistan, are facilitated by the coincidence of the periods of maximum turbulence and wave activity, maximum percipitation, and sediments discharge. Sediment samples from different intertidal zones between Gadani and Phornala were collected for grain size analysis and petrographic/petrological study. Variations in grain size and mineral assemblage in the intertidal zones have been noted. Concentration of dark color heavy minerals has been noted in fine grain sediments, light color minerals are ubiquitous. The sediments exhibit wide ranges of sorting.  相似文献   

Potential Risk Assessment of Metal Consumption in Food Crops Irrigated with Wastewater          下载免费PDF全文

Muhammad U. Khan  Said Muhammad  Riffat N. Malik 《洁净——土壤、空气、水》2014,42(10):1415-1422

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基于子带干涉测量技术的巴基斯坦地震形变获取研究          下载免费PDF全文

庾露  单新建  宋小刚  屈春燕 《地球物理学报》2016,59(4):1371-1382

2013年9月24日发生在巴基斯坦俾路支省(Balochistan)境内阿瓦兰县(Awaran)的MW7.7级地震,在地表产生了最大达10m的滑动量.利用TerraSAR-X短波雷达数据获取的InSAR同震形变场产生了密集且大范围的干涉条纹,给后续的相位解缠带来困难.而子带干涉法是一种无需或只需进行少量相位解缠,即可获得绝对相位差的新方法.其主要思路是通过缩减带宽以增长波长,从而减少干涉条纹数,降低解缠难度或不需解缠直接得到绝对相位差.但由于带宽的缩减,导致噪声的增大和旁瓣带来的额外干扰,使干涉图质量下降,因此在子带干涉参数选取、噪声滤波以及处理流程等方面需要特殊处理,特别是子带的中心频率和带宽的选取会很大程度地影响测量精度.首先选取典型DEM实验区,以干涉图相干性和误差为评价指标,利用逐步参数选取法,研究相关参数对子带干涉测量的影响,制定最优的参数方案,认识参数选取的原则和方法.在此基础上,将子带干涉应用于巴基斯坦地震的同震形变场获取.最后,将子带干涉、Landsat 8光学影像的交叉频谱相关法、offset-tracking、常规DInSAR获取的同震形变场进行比较,并与模型拟合的形变场进行对比分析.结果表明,子带干涉虽然会受失相干的影响,其提取的形变场范围相较于Landsat 8和offset-tracking有所缺失,但在共同覆盖的区域其精度和噪声水平更优,相比较于常规DInSAR,更适用于条纹密集和形变量大的地区.  相似文献   

Timing of metamorphism and deformation in the Swat valley,northern Pakistan:Insight into garnet-monazite HREE partitioning     

Kyle P.Larson  Asghar Ali  Sudip Shrestha  Mathieu Soret  John M.Cottle  Rafique Ahmad 《地学前缘(英文版)》2019,10(3):849-861

New metamorphic petrology and geochronology from the Loe Sar dome in the Swat region of northern Pakistan place refined constraints on the pressure, temperature and timing of metamorphism and deformation in that part of the Himalayan orogen. Thermodynamic modelling and monazite petrochronology indicate that metamorphism in the area followed a prograde evolution from ～525 ± 25 ℃and 6 士 0.5 kbar to ～610 ± 25 ℃ and 9 士 0.5 kbar, between ca. 39 Ma and 28 Ma. Partitioning of heavy rare earth elements between garnet rims and 30-28 Ma monazite are interpreted to indicate coeval crystallization at peak conditions. Microtextural relationships indicate that garnet rim growth post-dated the development of the main foliation in the area. The regional foliation is folded about large-scale N-S trending fold axes and overprinting E-W trending folds to form km-scale domal culminations. The textural relationships observed indicate that final dome development must be younger than the 30-28 Ma monazite that grew with garnet rims post-regional foliation development, but pre-doming-related deformation. This new timing constraint helps resolve discrepancy between previous interpretations,which have alternately suggested that N-S trending regional folds must be either pre-or post-early Oligocene. Finally, when combined with existing hornblende and white mica cooling ages, these new data indicate that the study area was exhumed rapidly following peak metamorphism.  相似文献   

ENVIRONMENTAL HEALTH RISKS AND GENDER IN THE KARAKORAM‐HIMALAYA,NORTHERN PAKISTAN*     

SARAH J. HALVORSON 《Geographical review》2002,92(2):257-281

ABSTRACT. Many mountain peoples face water and environmental health problems. At particular risk is the health of women and of children who live in remote and marginalized mountain areas. Environmental health concerns are often associated with the waterborne parasitic and endemic diseases responsible for much child morbidity and mortality in the Karakoram‐Himalaya of northern Pakistan. Poor environmental health and water‐quality conditions affect child survival, and challenges to viable local interventions are severe. Transformations in women's productive and reproductive work have health consequences for children, and gender and household dynamics shape and mediate women's responses to environmental health risks. Significantly, these findings draw attention to the need for improved water and health policy, especially policy that recognizes different gender and child‐care roles in mountainous regions of the developing world.  相似文献   

Sodium sulphate weathering and the disintegration of Mohenjo-Daro,Pakistan     

A. S. Goudie 《地球表面变化过程与地形》1977,2(1):75-86

In Pakistan various brick building structures are currently disintegrating in the Indus Valley. These include the Harappan site of Mohenjo-Daro. The environment of this site is described, the nature and speed of the disintegration problem is outlined, and the cause of disintegration is discussed Weathering occurs in association with the development of salt efflorescences and some bricks disintegrate only a few years after being laid down. Chemical and X-ray diffraction analyses show that the predominant salt is the sodium sulphate mineral thenardite. The reasons for its effectiveness are discussed. They include its high solubility, the rapid change of solubility with temperature, and its hydration characteristics.  相似文献   

Seismicity variations in the Makran region of Pakistan and Iran: Relation to great earthquakes     

Richard C. Quittmeyer 《Pure and Applied Geophysics》1979,117(6):1212-1228

Teleseismic activity in the Makran region of southeastern Iran and southwestern Pakistan prior to the great earthquake (M_s=8) of 1945 can be characterized in terms of two stages. First, during the period 30 (or more) to 10 years prior to the main event, the frequency of occurrence of moderate to large earthquakes was relatively high in the region between the impending rupture zone and the volcanic arc to the northwest. These events probably occurred near the down-dip limit of seismic activity within the subducted slab. Second, activity was concentrated along the coast during the ten years immediately preceding the great earthquake and most of this activity was confined to the vicinity of the epicenter of the 1945 earthquake. These patterns are similar in some respects to those observed prior to some large earthquakes in other parts of the world.Three observations concerning the pre-1945 seismicity suggest it was associated with the preparation for rupture of the zone that eventually broke during the great earthquake in 1945: (1) The activity before 1945 is located either within the 1945 rupture zone or between this zone and the volcanic arc to the northwest; (2) No activity of similar magnitude and occurrence rate is observed elsewhere along the Makran plate boundary; and (3) The region that was active prior to 1945 has been relatively quiet since the decline in aftershock activity associated with the 1945 shock. The current quiescence may be related to the release of stress during the 1945 earthquake.Recent seismicity in the region west of that affected prior to 1945 suggests that this western region may be the site of the next large earthquake. Events along the coast are grouped at both ends of a seismically quiet zone, producing a distribution similar to the donut pattern identified by Mogi. In addition, one moderate-magnitude earthquake occurred within the subducted slab to the northwest of the donut pattern along the coast. This moderate-magnitude earthquake, the first to occur in the region immediately west of the 1945 rupture zone since the advent of instrumental recording, may be analogous to the activity of stage one associated with the 1945 earthquake. While by no means providing conclusive evidence of an impending earthquake, the characteristic patterns identified in the recent seismicity indicate that this region should be closely monitored in the future.Lamont-Doherty Geological Observatory Contribution Number 2853.  相似文献   

Detectability and reliability analysis of the local seismic network in Pakistan     

M.Qaisar T.Mahmood S.A.Khan 《地震学报(英文版)》2003,16(1):59-66

The detectability and reliability analysis for the local seismic network is performed employing by Bungum and Husebye technique.The events were relocated using standard computer codes for hypocentral locations.The de-tectability levels are estimated from the twenty-five years of recorded data in terms of 50%,90%and 100% cumu-lative detectability threshokls,which were derived from frequency-magnitude distribution.From this analysis the 100%level of detectability of the network is ML=1.7 for events which occur within the network.The accuracy in hypocentral solutions of the network is investigated by considering the fixed real hypocenter within the network.The epicentral errors are found to be less than 4km then the events occur within the network.Finally.the prob-lems faced during continuous operation of the local network,which effects its detectability,are discussed.  相似文献   

巴基斯坦地方地震台网的检测能力和可靠性分析   总被引：1，自引：0，他引：1       下载免费PDF全文

M.Qaisar  T.Mahmood  S.A.Khan  许忠淮 《地震学报》2003,25(1):55-61

利用Bungum和Husebye的方法，分析了地方地震台网的检测能力和可靠性．用标准的计算机定位程序重新测定了地震位置．根据25年的地震记录，分别由震级-频度关系导出的50%、90%和100%的累积检测率估计了检测水平．对台网内地震，相应于100%检测率的震级下限为ＭＬ＝1.7．用台网内固定的实际震源，研究了台网对震源位置的测定精度．对网内地震，震中测定误差小于4 km．最后讨论了台网连续工作时可能会遇到的影响检测能力的一些问题．   相似文献   

Biogeochemical Study of Tamarix Aphylla from Lasbela Area and Its Application in Prospecting of Ore Deposits     

SHAHIDNASEEM  M.QADEERUDDIN 《中国地球化学学报》1995,14(4):303-312

Biogeochemical investigation of Tamarix aphylla,a plant species, of the Las-bela area has been made.This area mainly consists of ophiolites associated with sed-imentary rocks of Jurassic and Cretaceous age .Quantitative estimations of important biogenic trace elements such as Fe,Mn,Pb,Zn,Cu,Cr,Ni, and Co have been carried out .Anomalous concentrations of these elements in plant species of certain regions can be used to locate possible occurrences of ore deposits in the area.The comparative strdy also reveals appreciable variations in the composition of trace elements in plants.The possible causes of variation in the constitrents of Tamarix aphylla from different localities have been discussed in the light of bed rock nature, mo-bility of element and average abundance in the plant.  相似文献