Experimental and theoretical study of stability of dense hydrous magnesium silicates in the deep upper mantle

Fluid-undersaturated experiments were conducted to determine the phase relations in the simplified peridotite system MgO-SiO₂-H₂O (MSH) at 11.0-14.5 GPa and 800-1400 °C. Stability relations of dense hydrous magnesium silicates (DHMSs) under fluid-undersaturated conditions were experimentally examined. From the fluid-absent experimental results, we retrieved thermodynamic data for clinohumite, phase A, phase E, and hydrous wadsleyite, consistent with the published data set for dry mantle minerals. With this new data set, we have calculated phase equilibria in the MSH system including dehydration reactions. The dehydration reactions calculated with lower water activities of 0.68-0.60 match the fluid-present experiments of this study above 11.0 GPa and 1000 °C, indicating that considerable amounts of silicate component were dissolved into the fluid phase. The calculated phase equilibria illustrate the stability of the post-antigorite phase A-bearing assemblages. In the cold subducting slab peridotite, phase A + enstatite assemblage survives into the transition zone, whereas phase A + forsterite + enstatite assemblage forms hydrous wadsleyite at a much shallower depth of about 360-km. The slab is subducted with no dehydration reactions occurring when entering the transition zone. The phase equilibria also show the high temperature stability of phase E. Phase E is stable up to 1200 °C at 13.5 GPa, a plausible condition in the mantle of relatively low temperature, i.e., beneath subduction zones. Phase E is a possible water reservoir in the mantle as well as wadsleyite and ringwoodite.     

空间数据挖掘进展

空间数据挖掘是解决海量空间数据利用瓶颈的技术之一。本文综述空间数据挖掘的研究与应用进展。首先,分析空间数据挖掘的缘起。其次,研究空间数据挖掘的本质及其特点。再次,基于理论技术,分类总结空间数据挖掘的研究和应用的成果,并探讨其研究方向。最后,总结全文。     

时空信息云平台下数据管理及可视化方法

针对智慧城市时空信息云平台中海量时空数据的管理和可视化问题,该文提出了一种时空索引建立及时空数据可视化方法。时空索引机制将时间、空间与专题属性作为同等重要的维度,兼顾了三者的查询效率,实现对时空数据的快速有效提取。时空数据可视化表达方法提出了时间轴动画、多时态对比、对象状态回溯等可视化方式,实现时空数据的动态交互式表达。该方法在"智慧常州时空信息云平台"项目中进行了实现,证明这种时空数据组织管理方法可较高效地实现数据的检索调度,且具有较强的可操作性;基于此的时空数据可视化方法亦具备较佳的时空对象动态表达效果。     

Inversion of near-field waveform data for earthquake source rupture process (Ⅱ): Inversion of Chi Chi earthquake source, 20 September, 1999, Taiwan

The Chi Chi earthquake (Mw7.6) occurred at 17:47 UTC on Sept. 20,1999 (01:47 September 21, 1999, local time) in central Taiwan. CWB located the epi- center at (120.82°E; 23.85°N) and the focal depth 8 km. Chi Chi earthquake is the best documented earth- quake ever recorded. The abundance and quality of its near-source observations present an unparalleled op- portunity for studying the rupture history from a close distance. More than 400 free field digital accelerome- ters with 3-compon…     

GIS新引擎——“真图”数据解决方案

提出了一种基于移动测量系统技术的"真图"数据解决方案。一方面极大地丰富了GIS数据源,另一方面通过相应的真图影像数据管理软件及开发包扩展GIS功能,为各行业应用提供了地理信息数据解决方案。     

我国地理空间数据的安全政策研究

本文首先列举了近几年发生的几起典型的境外组织、机构和人员对我国进行的非法测绘案件,分析了空间数据的重要性以及公众对空间数据安全的认识误区,提出了制定我国空间数据安全政策的建议。     

基于CTP制版环境下原图数据输出与管理

CTP制版技术在地图印刷中得到广泛应用,改变了传统地图制印生产工艺,文章分析了CTP制印环境对出版地图质量的影响,提出了对原图数据传输进行有效检控措施,做好图文色彩输出管理,提高印刷成图质量。     

快速建立地下水网点数据库方法及管理软件简介

为快速准确建立相应数据库,编制了数据库管理软件。通过对四川石棉地震重点监视区地下水网点水位和气压４０余万组数据的处理实践,效果很好,并已在有关单位推广应用。