No water, no plate tectonics: convective heat transfer and the planetary surfaces of Venus and Earth

We consider the influence of water on the near-surface rheology of Venusian and terrestrial rocks and hence the way their heat transfer processes have been able to shape their planetary surfaces. We suggest that Earth is now unique in having plate-like surface movements at velocities characteristic of ‘deep’ material in self-regulating convective states (～ few cm/year) only because liquid water is there available to facilitate mechanical failure of its lithosphere (sic). The relative absence of free water on Venus is thought to more than compensate for the effect of higher temperatures on the deformability of its surface rocks and is interpreted as the reason for an absence of Earth-like platetectonics and the distinctive distributions of volcanism and seismicity accompanying such a process for > 109 years. The characteristics of Venusian volcanism in its post plate-tectonic era are now expected to be similar to Earth's intraplate (‘hotspot’) volcanism.     

On the relationship between Indian Ocean Dipole events and the precipitation of Pakistan

This study investigated the relationship between the Indian Ocean Dipole (IOD) and the precipitation of Pakistan using data for the period of 1958–2010. The long-term evolution of the IOD index did not show interannual patterns similar to those of the annual precipitation of Pakistan. No linkage between the co-occurring trends of the IOD and the precipitation was traced during the period of investigation. The correlation between the IOD and the precipitation of Pakistan indicated a noteworthy impact over the monsoonal regions, especially the coastal area and the western region of Pakistan, which showed a significant positive correlation between the IOD index and annual and summer precipitation. A significant positive relationship was also revealed between the precipitation of the Balochistan Plateau and the IOD index for the summer monsoon season. No connection was observed between the IOD and the precipitation of the northern regions and the upper Indus Plain of Pakistan. Positive phases of the IOD have been noted to occur along with surplus precipitation during active monsoon conditions. The southeasterly wind moves from the Arabian Sea and transports additional moisture from the Arabian Sea to the coastal and southwestern parts of Pakistan during positive phases of the IOD.

     

Brick kiln exhaust as a source of polycyclic aromatic hydrocarbons (PAHs) in the surrounding soil and plants: a case study from the city of Peshawar, Pakistan

The purpose of the present study was to investigate the effects of brick kiln exhaust on the quantity of polycyclic aromatic hydrocarbons in surrounding soils and plants. In Pakistan, a big problem is the rapid conglomeration of the brick kilns in out skirt of nearly all urban centers to cope with the rapid construction work in big cities. A huge amount of low-grade coal, rubber, tires is used in non-scientific manner. The study was conducted in the City of Peshawar the capital of Kyber Pakhtunkhwa where many brick kilns are located in the periurban areas. Soil and medicinal plants samples were collected from different locations around the bricks kiln and were analyzed for selected polycyclic aromatic hydrocarbons (PAHs), i.e., benzo(a)pyrene, anthracene, chrysene, flourene, flouranthene, phenanthrene, naphthalene, and acenapthylene. Quantitative and qualitative analysis was carried out by UV spectrophotometer and high-performance liquid chromatography. Benzo[a]pyren and Chrysene were found to be the most abundant compounds. The total load of PAHs in the central location was found to be 0.4014 mg/kg. General trend of PAHs distribution was such that the concentration of individual PAHs was found to increase with depth clearly indicating their absorption in the soil. PAHs concentration increased with the distance up to 300 m and then gradual decreased which showed their movement with the water and air. The PAHs load was found high in the leaves as compared to stem and roots. This high load in the aerial parts indicated their excretion route as well as air deposition.     

连云港淤泥质海床上波浪衰减研究──实验、观测及理论模型比较和评价

本文对连云港淤泥质海床波浪衰减问题通过室内实验、现场观测和理论模拟进行了综合研究，重点介绍了四种典型理论模型（粘性模型、粘弹性模型、宾汉模型及多孔介质模型），并通过与实验和现场观测结果的全面综合比较，对这些理论模型用于研究连云港地区波浪衰减规律的适用性进行了分析讨论。本文最后指出，针对连云港实际情况今后需要着重研究和发展波浪与淤泥底相互作用的非线性理论模型。     

Receiver function analysis for seismic structure of the crust and uppermost mantle in the Liupanshan area,China

A portable broadband seismic array was deployed from the northeast Tibetan Plateau to the southwest Ordos block, China. The seismic structure of the crust and uppermost mantle of the Liupanshan area is obtained using receiver function analysis of teleseismic body waves. The crustal thickness and Poisson’s ratios are estimated by stacking the weighted amplitudes of receiver functions. Our results reveal complex seismic phases in the Liupanshan area, implying intense deformation at the boundary between the Tibetan Plateau and the Ordos block. The average crustal thickness is 51.5 km in the northeast Tibetan Plateau, 53.5 km in the Liupan Mountain and 50 km in the southwest Ordos block, resulting in a concave Moho beneath the Liupan Mountain. The Poisson’s ratio of the Liupanshan area varies between 0.27–0.29, higher than the value of 0.25–0.26 to the east and west of the Liupan Mountain, suggesting partial melting in the lower crust. The variance in Poisson’s ratio across the Liupan Mountain indicates notable changes in the crustal composition and mechanical properties, which may be formed by the northeastward flow of the Tibetan lower crust during the India-Eurasia collision.

     

隧道工程物探方法结果的综合解释

本文以陈庄隧道工程勘察为例,讨论了运用综合工程物探方法进行隧道勘测的可行性,阐述了查明风化层分层、断层、地下水分布等的野外工作方法和技术,并对各种物探方法所得的结果进行了单独解释和综合解释,从而避免了单一物探方法的多解性,提高了解释结果的可靠性,经钻孔资料验证,效果良好。另外,对在隧道开挖过程中可能遇到的断层、塌陷等情况也做了讨论。     

浪作用下海洋底床动态响应的研究

有关波浪作用下的底床动态响应越来越引起人们的重视。本文从海洋土的特点出发，针对各向同性底床和各向异性底床，详细论述了在线性波加载下，波浪衰减和底床动态响应这两方面的研究现状，在分析和比较已有研究成果的基础上，对今后的研究方向提出了自己的看法。     

Determination of Rock Fracture Toughness <Emphasis Type="Italic">K</Emphasis><Subscript>IIC</Subscript> and its Relationship with Tensile Strength

Hydraulic fracture propagation is greatly influenced by mode-II fracture toughness since this is one of the factors which determine whether a fracture diverts. Direct measurement of rock fracture toughness is constrained by high cost, limited number of available cores and long turn around time. Therefore, to overcome these constrains, it is necessary to develop an effective mode-II fracture toughness test which can be used in a prediction analysis for deep rock formations. Consequently, a mode-II fracture toughness test system was designed for rocks using the straight-notched Brazilian disc (SNBD) test methodology. In the experiment, this system was used to test 20 rock samples from the WG oilfield. This enabled a fracture toughness prediction model to be established, based on an analysis of the test data. H341 acoustic, density and gamma-ray logging data were used to predict horizontal stresses and rock tensile strength. When combined with the mode-II fracture toughness prediction model, continuous values were predicted, which were successfully confirmed by field fracturing practices. It was confirmed, therefore, that this successful method met the need of providing continuous fracture toughness data during field fracturing operations.