Strike-slip faulting as a trigger mechanism for overpressure release through piercement structures. Implications for the Lusi mud volcano,Indonesia

Piercement structures such as hydrothermal vent complexes, pockmarks, and mud volcanoes, are found in various geological settings but are often associated with faults or other fluid-focussing features. This article aims to investigate and understand the mechanisms responsible for the formation of piercement structures in sedimentary basins and the role of strike-slip faulting as a triggering mechanism for fluidization. For this purpose four different approaches were combined: fieldwork, analogue experiments, and mathematical modeling for brittle and ductile rheologies. The results of this study may be applied to several geological settings, including the newly formed Lusi mud volcano in Indonesia (Mazzini et al., 2007).     

Subsidence associated with the LUSI mud eruption,East Java,investigated by SAR interferometry

A mud volcano LUSI initiated its eruption on 29 May 2006, adjacent to a hydrocarbon exploration well in East Java. Ground subsidence in the vicinity of the LUSI eruptive vent was well recorded by a Synthetic Aperture Radar (SAR) PALSAR onboard the Japanese ALOS satellite. We apply an Interferometric SAR (InSAR) technique on ten PALSAR data scenes, acquired between 19 May 2006 and 21 May 2007, in order to obtain continuous maps of ground displacements around LUSI. Although the displacements in the area closest to the eruptive vent (spatial extension of about 1.5 km) are not detectable because of the erupted mud, all the processed interferograms indicate subsidence in an ellipsoidal area of approximately 4 km (north–south) × 3 km (east–west), centered at the main eruptive vent. In particular, interferograms spanning the first four months until 4 Oct. 2006 and the subsequent 46 days between 4 Oct. 2006 and 19 Nov. 2006 show at least about 70 cm and 80 cm of displacements away from the satellite, respectively. Possible causes of the subsidence, i.e., 1) loading effect of the erupted mud, 2) creation of a cylindrical mud conduit, and 3) pressure decrease and depletion of materials at depth, are investigated. The effects of the first two causes are found to be insufficient to explain the total amount of subsidence observed in the first six months. The third possibility is quantitatively examined using a boundary element approach by modeling the source of deformation as a deflating oblate spheroid. The spheroid is estimated to lie at depths of a few hundred to a thousand meters. The estimated depths are significantly shallower than determined from analyses of erupted mud samples; the difference is explained by presence of significant amount of inelastic deformation including compaction and downward transfer of material.     

Three-dimensional modeling of tidal circulation and mixing over the Java Sea

A combination of a three-dimensional hydrodynamic model and in-situ measurements provides the structures of barotropic tides, tidal circulation and their relationship with turbulent mixing in the Java Sea, which allow us to understand the impact of the tides on material distribution. The model retains high horizontal and vertical resolutions and is forced by the boundary conditions taken from a global model. The measurements are composed of the sea level at coastal stations and currents at moorings embedded in Seawatch buoys, in addition to hydrographic data. The simulated tidal elevations are in good agreement with the data for the K₁ and M₂ constituents. The K₁ tide clearly shows the lowest mode resonance in the Java Sea with intensification around the nodal point in the central region. The M₂ tide is secondary and propagates westward from the eastern open boundary, along with a counterclockwise amphidromic point in the western part. The K₁ tide produces a major component of tidal energy, which flows westward and dissipates through the node region near the Karimata Strait. Meanwhile, the M₂ tide dissipates in the entire Java Sea. However, the residual currents are mainly induced by the M₂ tide, which flows westward following the M₂ tidal wave propagation. The tidal mixing is mainly caused by K₁ tide which peaks at the central region and is consistent with the uniform temperature and salinity along the vertical dimension. This mixing is expected to play an important role in the vertical exchange of nutrients and control of biological productivity.     

IPv4/IPv6混合组网下P2P文件共享系统的设计与实现

IPv6作为下一代互联网的核心技术,必然会逐步取代IPv4。但在相当长的一段时期内,IPv6会与IPv4共存。利用Java的网络编程设计与实现了1种P2P文件共享系统。该系统能够布署在纯IPv4、IPv6网络上,也可以布署在IPv4/IPv6混合组网的网络上,因此实现了P2P文件共享系统在IPv4和IPv6网络上的无缝连接。     

基于plug-in的数据库查询系统

以设计具有良好扩展性的数据库查询系统为目标,应用xml、java反射机制及plug-in思想等技术,使系统有很强的扩展性,降低系统维护成本,延伸软件系统生命期。     

基于J2EE的数据通用性操作框架的研究与实现

数据操作是基于J2EE的多级应用开发中常见而又具有通用性的重要一部分，而框架技术的研究可以实现软件开发过程中的重用，提高软件开发效率和质量。通过对国内外成熟的开发框架进行研究，并综合各自的优点形成一套在开发中可以保证数据操作模块具有可重用、可扩展、稳定性好等优势的方案；同时结合电子政务中的一个应用实例给出了数据通用性操作框架技术在企业级开发中的具体实现。     

J2EE在电力系统工作票信息化管理中的应用--从C/S模式到B/S多层模式的转换

介绍了传统C／S模式在电力工作票管理信息系统中的应用及其问题，同时介绍J2EE多层分布式体系结构在工作票管理系统中应用的可行性。通过对传统C／S电力系统工作票管理系统的分析，提出将J2EE应用于工作票管理系统的思想并进行实践。     

Stylolites, porosity, depositional texture, and silicates in chalk facies sediments. Ontong Java Plateau – Gorm and Tyra fields, North Sea

Comparison of chalk on the Ontong Java Plateau and chalk in the Central North Sea indicates that, whereas pressure dissolution is controlled by effective burial stress, pore-filling cementation is controlled by temperature. Effective burial stress is caused by the weight of all overlying water and sediments as counteracted by the pressure in the pore fluid, so the regional overpressure in the Central North Sea is one reason why the two localities have different relationships between temperature and effective burial stress. In the chalk of the Ontong Java Plateau the onset of calcite-silicate pressure dissolution around 490 m below sea floor (bsf) corresponds to an interval of waning porosity-decline, and even the occurrence of proper stylolites from 830 m bsf is accompanied by only minor porosity reduction. Because opal is present, the pore-water is relatively rich in Si which through the formation of Ca–silica complexes causes an apparent super-saturation of Ca and retards cementation. The onset of massive pore-filling cementation at 1100 m bsf may be controlled by the temperature-dependent transition from opal-CT to quartz. In the stylolite-bearing chalk of two wells in the Gorm and Tyra fields, the nannofossil matrix shows recrystallization but only minor pore-filling cement, whereas microfossils are cemented. Cementation in Gorm and Tyra is thus partial and has apparently not been retarded by opal-controlled pore-water. A possible explanation is that, due to the relatively high temperature, silica has equilibrated to quartz before the onset of pressure dissolution and thus, in this case, dissolution and precipitation of calcite have no lag. This temperature versus effective burial stress induced difference in diagenetic history is of particular relevance when exploring for hydrocarbons in normally pressured chalk, while most experience has been accumulated in the over-pressured chalk of the central North Sea.     

基于J2EE和XML的分布式GIS研究

分布式对象技术和Web Services技术日臻成熟,在IT领域已经广泛使用。在地理信息系统领域,由于空间数据的特点,分布式地理信息系统的理论和实践还有待完善。论文首先分析了相关技术存在的问题,并在此基础上阐述了基于J2EE和XML的分布式GIS体系结构,最后对涉及的关键技术进行了分析。