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71.
准噶尔盆地西北缘三叠系干旱型冲积扇储层内部构型特征 总被引：7，自引：0，他引：7
以克拉玛依油田一中区为例,综合现代沉积、岩芯、露头、密井网等资料,应用层次分析法深入解剖干旱型冲积扇内部构型。以冲积扇相带划分为基础,构建7~9级构型要素分级体系,明确构型要素的成因、规模及样式,建立精细的干旱型冲积扇构型模式。研究表明:①根据岩性组合、沉积构造等特征将冲积扇依次划分为槽流、片流、辫流及径流4个相带;②槽流带主体为宽带状槽流沉积体,由多期槽流砾石体垂向叠置而成,单期槽流砾石体顶部在间洪期受到小股牵引流侵蚀改造,发育网状的流沟系统;③片流带主体为扇状片流砂砾体,由多期片流朵体侧向—垂向复合而成,朵体顶部披覆的泥质夹层是稳定的渗流屏障;④辫流带主体为宽带状辫流水道,由洪水水道和间洪水道两种单一水道侧向复合而成,洪水水道规模较大、侧向迁移频繁、切割叠置关系复杂、物性较好,在油田注水开发过程中极易形成水窜通道,而间洪水道规模较小,侧向切叠程度较低、物性也较差;⑤径流带主体为漫流细粒沉积,在漫流细粒沉积的背景上发育径流水道,其水道规模小、物性差且易尖灭。 相似文献
72.
SIG中的元数据共享服务体系研究与实践 总被引：1，自引：0，他引：1
元数据是数字地球建设的关键技术之一，是建设信息化城市和实施空间信息网格基础设施的重要内容。本文基于Web服务对象及其标准，建立了分布、异构的网格环境下的元数据服务管理模型，包括基于Web服务的空间元数据共享服务体系、空间元数据服务与发布流程及其实现。最后，探讨了如何使用目前JAVA技术中比较流行的JDBC和懒加载技术开发空间元数据服务管理模型。 相似文献
73.
The Late Paleoproterozoic Athabasca Basin contains more than 1.5 km of predominantly sandy strata, most of which are of braided fluvial origin. In the eastern part of the basin, at McClean Lake, sandstones and minor conglomerates of the Read Formation at the base of the succession are preserved within a steep-walled valley system. They consist predominantly of meter-scale sheet elements, characterized by massive and flat-laminated fine- to very coarse-grained sandstone with minor discontinuous cobble and boulder conglomerate along lower set boundaries. These are interpreted as sheet-flood and stream-flood deposits of a terminal dry-land system, deposited in an arid climatic setting. Analysis of closely spaced drill-core indicates that late stage run-off was confined to small shallow channels, typically only a few tens of meters wide and a few meters deep. Overlying strata of the Bird Member of the Manitou Falls Formation are predominantly coarse- to very coarse-grained sandstones with abundant small-scale cross-stratification and minor granule and small pebble conglomerate. At McClean Lake, these appear to have been deposited as sheet-elements by semi-ephemeral to perennial braided rivers under more humid conditions. At Key Lake, 160 km to the southwest, architectural analysis of a 184 m wide section indicates that at least part of the Bird Member was deposited in deeper, sandy-braided rivers characterized by seasonally varied flow. The closest modern analogue is the South Saskatchewan River, in which large simple flow-transverse bedforms become exposed and dissected during falling stage, and act as nuclei for sand-flat development. The presence of numerous low-relief 4th order surfaces suggests continued reworking of bar-tops during rising stage. The incremental character of downstream accretionary elements suggests periodic migration of barforms during peak-flood stages, separated by periods of low flow. This indicates similarities with modern perennial braided systems, and is counter to the idea that all pre-Devonian fluvial systems should consist of stacked sheets formed by individual flood events. Thin gravel layers accumulated as lags on fourth order surfaces, with discontinuous mud layers suggesting deposition within temporary ponds in channel thalwegs after major floods. Strata in overlying units indicate a return to semi-perennial conditions. 相似文献
74.
AstroGrid是一个成熟并已广泛运用的英国虚拟天文台(VO-Virtual Observatory)项目。公共执行架构(Common Execution Architecture,CEA)作为其重要组成部分,通过构建一套合理的接口和框架实现对虚拟天文台天文应用执行过程的建模。详细介绍了AstroGrid CEA的实现原理、基本架构、接口分析和应用模型,并通过CEA实现中国科学技术大学光谱处理数据的发布,完成基于FITS格式的锥型检索服务,最后在此基础上就如何运用CEA进行完整的讨论。 相似文献
75.
Alessandro Ielpi Martin R. Gibling Arden R. Bashforth Corinne Lally Michael C. Rygel Saif Al‐Silwadi 《Sedimentology》2014,61(6):1659-1700
Vegetation is a major driver of fluvial dynamics in modern rivers, but few facies models incorporate its influence. This article partially fills that gap by documenting the stratigraphy, architecture and palaeobotany of the Lower Pennsylvanian Boss Point Formation of Atlantic Canada, which contains some of the Earth's earliest accumulations of large woody debris. Braided‐fluvial systems occupied channel belts of varied scale within valleys several tens of metres deep and more than 12 km wide, and their deposits predominantly consist of sandy and gravelly bedforms with subordinate accretionary macroforms, high flow‐strength sand sheets and rippled abandonment facies. Discrete accumulations of clastic detritus and woody debris are up to 6 m thick and constitute at least 18% of the in‐channel deposits; they represent lags at the base of large and small channels, fills of minor channels and sandy macroforms that developed in central positions in the upper parts of channel fills. Sandstones with roots and other remnants of in situ vegetation demonstrate that vegetated islands were present, and the abundance of discrete channel fills suggests that the formation represents an anabranching, island‐braided sandbed river, the earliest example documented to date. Although some sphenopsid and lycopsid remains are present, most woody fragments are derived from cordaitalean trees, and the evolution of this group late in the Mississippian is inferred to have exerted a significant influence on fluvial morphodynamic patterns. The formation records a landscape in which active channel belts alternated with well‐drained floodplains colonized by dense, mature forests and local patches of pioneering, disturbance‐tolerant vegetation. Lakes and poorly drained floodplains dominated by carbonate and organic deposition, respectively, were also present. A large supply of woody debris triggered channel blockage and avulsion, and active channel margins and islands within the channel belts were initially colonized by pioneer vegetation and subsequently stabilized by large trees. A similar alternation of stable and unstable conditions is observed in modern braided rivers actively influenced by vegetation. 相似文献