Multiple overpressure systems and their relationship with hydrocarbon accumulation in the Qikou Depression of the Bohai Bay Basin,China     

Xue‐Bin Du  Xi‐Nong Xie  Yong‐Chao Lu  Liang Zhang  Wei Peng  Yun‐Peng Li 《Geological Journal》2015,50(4):465-476

Pressure measurements using drill stem tests and estimates from log data calculation indicate that three vertically stacked regional pressure compartments exist in the Qikou Depression of Bohai Bay Basin, N. China. The compartments comprise hydrostatic, upper weak, and lower overpressure systems. Laterally, overpressure (pressure coefficient > 1.2) occurs in the deeper areas and weakens gradually from the centre to the margin of the depression. The accumulation of oil and gas exhibits the interesting characteristics of oil‐bearing layers above gas‐bearing layers in the Qikou Depression. The pattern can be accounted for by the evolution of overpressure system, the maturity process of the source rock and the main fault activity. In the late Dongying Formation (Ed, 30 Ma), the lower overpressure system began to form shape, and the hydrocarbon sources generated a large volume of oil. However, because there was no migration pathway, the oil only accumulated in the original strata. In the late Guantao Formation (Ng, 12 Ma), the gas was generated, the upper overpressure system formed gradually, and the activity of the main fault gradually increased. Then, the overpressure pushed the early gathered oil to flow from the lower overpressure system into the upper overpressure system. Afterwards, the activity of the main fault decreased again and remains weak until now. Thus, later generated natural gas cannot keep migrating along the main fault and can only accumulate in the lower overpressure system. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

An analytical proof on certain determinants connected with the collinear central configurations in the n-body problem     

Zhifu Xie 《Celestial Mechanics and Dynamical Astronomy》2014,118(1):89-97

In this paper we give a short analytical proof of the inequalities proved by Albouy–Moeckel through computer algebra, in the cases $n=5$ and $n=6$ . These inequalities guarantee that, in the $n$ -body problem, the family of mass vectors making a given collinear configuration a central configuration is 2-dimensional. The induction techniques here may be used to prove the inequalities for general $n$ with more subtle estimation but currently the inequalities still remains unproved for $n\ge 7$ .  相似文献   

Eutectic metal + troilite + Fe‐Mn‐Na phosphate + Al‐free chromite assemblage in shock‐produced chondritic melt of the Yanzhuang chondrite     

Xiande Xie  Ming Chen  Shuangmeng Zhai  Fuya Wang 《Meteoritics & planetary science》2014,49(12):2290-2304

An assemblage with FeNi metal, troilite, Fe‐Mn‐Na phosphate, and Al‐free chromite was identified in the metal‐troilite eutectic nodules in the shock‐produced chondritic melt of the Yanzhuang H6 meteorite. Electron microprobe and Raman spectroscopic analyses show that a few phosphate globules have the composition of Na‐bearing graftonite (Fe_,Mn,Na)₃(PO₄)₂, whereas most others correspond to Mn‐bearing galileiite Na(Fe,Mn)₄(PO₄)₃ and a possible new phosphate phase of Na₂(Fe,Mn)₁₇(PO₄)₁₂ composition. The Yanzhuang meteorite was shocked to a peak pressure of 50 GPa and a peak temperature of approximately 2000 °C. All minerals were melted after pressure release to form a chondritic melt due to very high postshock heat that brought the chondrite material above its liquidus. The volatile elements P and Na released from whitlockite and plagioclase along with elements Cr and Mn released from chromite are concentrated into the shock‐produced Fe‐Ni‐S‐O melt at high temperatures. During cooling, microcrystalline olivine and pyroxene first crystallized from the chondritic melt, metal‐troilite eutectic intergrowths, and silicate melt glass finally solidified at about 950–1000 °C. On the other hand, P, Mn, and Na in the Fe‐Ni‐S‐O melt combined with Fe and crystallized as Fe‐Mn‐Na phosphates within troilite, while Cr combined with Fe and crystallized as Al‐free chromite also within troilite.  相似文献   

A large shock vein in L chondrite Roosevelt County 106: Evidence for a long‐duration shock pulse on the L chondrite parent body          下载免费PDF全文

Thomas G. Sharp  Zhidong Xie  Paul S. de CARLI  Jinping Hu 《Meteoritics & planetary science》2015,50(11):1941-1953

A large shock‐induced melt vein in L6 ordinary chondrite Roosevelt County 106 contains abundant high‐pressure minerals, including olivine, enstatite, and plagioclase fragments that have been transformed to polycrystalline ringwoodite, majorite, lingunite, and jadeite. The host chondrite at the melt‐vein margins contains olivines that are partially transformed to ringwoodite. The quenched silicate melt in the shock veins consists of majoritic garnets, up to 25 μm in size, magnetite, maghemite, and phyllosilicates. The magnetite, maghemite, and phyllosilicates are the terrestrial alteration products of magnesiowüstite and quenched glass. This assemblage indicates crystallization of the silicate melt at approximately 20–25 GPa and 2000 °C. Coarse majorite garnets in the centers of shock veins grade into increasingly finer grained dendritic garnets toward the vein margins, indicating increasing quench rates toward the margins as a result of thermal conduction to the surrounding chondrite host. Nanocrystalline boundary zones, that contain wadsleyite, ringwoodite, majorite, and magnesiowüstite, occur along shock‐vein margins. These zones represent rapid quench of a boundary melt that contains less metal‐sulfide than the bulk shock vein. One‐dimensional finite element heat‐flow calculations were performed to estimate a quench time of 750–1900 ms for a 1.6‐mm thick shock vein. Because the vein crystallized as a single high‐pressure assemblage, the shock pulse duration was at least as long as the quench time and therefore the sample remained at 20–25 GPa for at least 750 ms. This relatively long shock pulse, combined with a modest shock pressure, implies that this sample came from deep in the L chondrite parent body during a collision with a large impacting body, such as the impact event that disrupted the L chondrite parent body 470 Myr ago.  相似文献   

A type of new conserved quantity deduced from Mei symmetry for Appell equations in a holonomic system with unilateral constraints     

贾利群  解银丽  张耀宇  杨新芳 《海洋学报(英文版)》2010,29(11)

A type of new conserved quantity deduced from Mei symmetry of Appell equations for a holonomic system with unilateral constraints is investigated. The expressions of new structural equation and new conserved quantity deduced from Mei symmetry of Appell equations for a holonomic system with unilateral constraints expressed by Appell functions are obtained. An example is given to illustrate the application of the results.  相似文献   

Using three-dimensional discrete spherical Fourier descriptors based on surface curvature voxels for pollen particle recognition     

谢永华  Michael OhEigeartaigh 《海洋学报(英文版)》2010,29(11)

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Analyzing qualitative and quantitative changes in coastal wetland associated to the effects of natural and anthropogenic factors in a part of Tianjin,China     

Zhenglei Xie  Xuegong Xu  Lei Yan 《Estuarine, Coastal and Shelf Science》2010,86(3):379-386

Natural and anthropogenic factors in coastal wetland changes are widely discussed in wetland studies. Previous literatures have demonstrated that many factors may cause wetland change and argued that the global climate change and nutrient enrichment may become the most important ones in the next 50 years. Through field investigation, with the help of remote sensing technology and geographic information system, this research discusses the wetland change in Tianjin under the great pressure of rapid economic development, population growth, and sea-level rising. These findings include: (1) the wetland area expanded from 466.50 km² to 658.38 km² between 1987 and 1998, but it shrank to 550.5 km² by the year of 2006. (2) The results show that the groundwater has not been contaminated while the surface water has been polluted. (3) The questionnaire survey shows that the social environment in some specific ways impedes the protection of natural reserve. In order to achieve the harmony between human and nature, feasible countermeasures on how to keep ecological balance should be immediately taken. Consequently, natural conservation and sustainable economic development will be realized.  相似文献   

Simulating and mapping the risk of surge floods in multiple typhoon scenarios: a case study of Yuhuan County,Zhejiang Province,China   总被引：1，自引：0，他引：1  

Mengya?Li  Wei?Wu  Jun?WangEmail author  Zhumei?Che  Yali?Xie 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(3):645-659

We propose a scenario-based method for simulating and mapping the risk of surge floods for use by local authorities concerned with public safety and urban planning in coastal areas. Focusing on the triad of hazard, vulnerability and adaptation capability, we estimate the comprehensive risk and display its spatial distribution using the raster calculation tool in ArcGIS. The detailed methodology is introduced via a case study of Yuhuan, an island county in Zhejiang Province, China, which is frequently affected by typhoon storm surges. First, we designed 24 typhoon scenarios and modeled the flood process in each scenario using the hydrodynamic module of MIKE 21. Second, flood depth and area were used for hazard assessment; an authorized indicator system of land use categories and a survey of emergency shelters were used for vulnerability and adaptation capability assessment, respectively; and a quantified model was used for assessment of the comprehensive risk. Lastly, we used the GIS raster calculation tool for mapping the risk of storm surges in multiple typhoon scenarios. Our principal findings are as follows: (1) Seawalls are more likely to be overtopped or destroyed by more severe storm surges with increasing typhoon intensity. (2) Most of the residential areas with inadequate emergency shelters are highly vulnerable to flood events. (3) As projected in the risk mapping, if an exceptional typhoon with a central pressure of 915 or 925 hPa made a landfall in Yuhuan, a wide range of areas would be flooded and at high risk. (4) Determining optimal strategies based on identification of risk-inducing factors is the most effective way of promoting safe and sustainable development in coastal cities.  相似文献   

Aerosol properties over an urban site in central East China derived from ground sun-photometer measurements     

Qi Liu  WeiDong Ding  Lei Xie  JinQiang Zhang  Jun Zhu  XiangAo Xia  DongYang Liu  RenMin Yuan  YunFei Fu 《中国科学:地球科学(英文版)》2017,60(2):297-314

Sun-photometer measurements at Hefei, an urban site located in central East China, were examined to investigate the variations of aerosol loading and optical properties. It is found that aerosol optical thickness (AOT) keeps higher in winter/spring and gets relatively lower in summer/autumn. The large AOT in winter is caused by anthropogenic sulfate/nitrate aerosols, while in spring dust particles elevate the background aerosol loading and the excessive fine-mode particles eventually lead to severe pollution. There is a dramatic decline of AOT during summer, with monthly averaged AOT reaching the maximum in June and soon the minimum in August. Meanwhile, aerosol size decreases consistently and single scattering albedo (SSA) reaches its minimum in July. During summertime large-sized particles play a key role to change the air from clean to mild-pollution situation, while the presence of massive small-sized particles makes the air being even more polluted. These complicated summer patterns are possibly related to the three key processes that are active in the high temperature/humidity environment concentrating on sulfate/nitrate aerosols, i.e., gas-to-particle transformation, hygroscopic growth, and wet scavenging. Regardless of season, the increase of SSA with increasing AOT occurs across the visible and near-infrared bands, suggesting the dominant negative/cooling effect with the elevated aerosol loading. The SSA spectra under varying AOT monotonically decrease with wavelength. The relatively large slope arises in summer, reinforcing the dominance of sulfate/nitrate aerosols that induce severe pollution in summer season around this city.  相似文献   

A study of parameter uncertainties causing uncertainties in modeling a grassland ecosystem using the conditional nonlinear optimal perturbation method     

GuoDong Sun  DongDong Xie 《中国科学:地球科学(英文版)》2017,60(9):1674-1684

In this paper, we apply the approach of conditional nonlinear optimal perturbation related to the parameter (CNOP-P) to study parameter uncertainties that lead to the stability (maintenance or degradation) of a grassland ecosystem. The maintenance of the grassland ecosystem refers to the unchanged or increased quantity of living biomass and wilted biomass in the ecosystem, and the degradation of the grassland ecosystem refers to the reduction in the quantity of living biomass and wilted biomass or its transformation into a desert ecosystem. Based on a theoretical five-variable grassland ecosystem model, 32 physical model parameters are selected for numerical experiments. Two types of parameter uncertainties could be obtained. The first type of parameter uncertainty is the linear combination of each parameter uncertainty that is computed using the CNOP-P method. The second type is the parameter uncertainty from multi-parameter optimization using the CNOP-P method. The results show that for the 32 model parameters, at a given optimization time and with greater parameter uncertainty, the patterns of the two types of parameter uncertainties are different. The different patterns represent physical processes of soil wetness. This implies that the variations in soil wetness (surface layer and root zone) are the primary reasons for uncertainty in the maintenance or degradation of grassland ecosystems, especially for the soil moisture of the surface layer. The above results show that the CNOP-P method is a useful tool for discussing the abovementioned problems.  相似文献