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11.
通过分析3种传统数据模型的特点,得出它们在管理地理复杂对象方面的局限性,从而引出了面向对象数据模型。本文利用面向对象数据模型中的各种操作,以基本地理对象为基础构建复杂地理对象,并且在VC 6.0平台上实现了面向对象几何数据模型。 相似文献
12.
扬子地块西南缘下震旦系火成岩系研究 总被引：10，自引：0，他引：10
研究区的天宝山组和苏雄组、开建桥组酸性、中酸性火山岩、火山碎屑岩同属下震旦系。它们及同期形成的花岗岩形成于后造山构造环境中,并非与裂谷活动有关。它们皆为S型,其源岩为太古界。 相似文献
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Mohammad Qausar 《Pure and Applied Geophysics》1989,131(4):703-713
The attenuation properties of eight rheological models have been studied theoretically. The expressions forQ have been obtained by using dissipated and stored energies and/or complex modulus for each model. The dependence ofQ on frequency has been demonstrated. The three-element elastic model appears to be the best one to represent the viscoelastic nature of the earth's material for a finite value ofQ. 相似文献
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The recognition of terminal fluvial systems, otherwise termed 'terminal fans' or 'distributary fluvial fan systems', preserved in the ancient rock record is based primarily on the recognition of facies characteristics indicative of a progressive downstream decrease in: (i) fluvial discharge; (ii) channel depth and width; (iii) lateral and vertical connectivity of channel-fill elements; and (iv) evidence for channellized flow and a systematic increase in: (i) evidence for sheetflood deposition; (ii) aeolian and/or playa deposits; and (iii) channel bifurcation. However, despite these criteria having been applied previously to a variety of outcrop successions, there is still no unifying facies model that adequately accounts for the complex stratigraphic architectural relationships expected for such systems, based on the varied styles of fluvial activity and system interaction known from modern examples. Moreover, few previous studies have given significant consideration to the long-term temporal evolution of terminal fluvial fans. These issues are addressed by this study of the Permian (Leonardian/Artinskian) Organ Rock Formation of the Paradox Basin, South-east Utah. A detailed stratigraphic framework based on 84 sedimentary logs demonstrates proximal to distal variations in sedimentary style. Integration of these data with high-resolution architectural panels depicting the geometry and facies characteristics of individual fluvial elements has enabled the development of a series of depositional models that account for both the spatial and temporal evolution of the system and which are representative of: (i) initial progradation of the fluvial system into the Paradox foreland basin; (ii) retreat of the fluvial system and expansion of a distal aeolian dune system; (iii) the final phase of fluvial progradation following aeolian dune deflation; and (iv) the final retrogradation of the fluvial system back towards the hinterland. 相似文献
16.
辽南早元古宙辽河群变质岩系中的金矿床为变质热液成因金矿床,矿床的形成与吕梁期变质变形作用关系密切。金矿化带的展布与金矿体的产出受韧性剪切带控制。剪切带内岩石具有明显的动态性组构特征,直接赋矿围岩为辽河群盖县组糜棱岩化千枚岩、变砂岩及云母石英糜棱岩等。韧性剪切带为含矿流体的运移提供通道。作者定义这类金矿床为变质热液型含金剪切带金矿床。 相似文献
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Subaerial unconformities are used widely for palaeoenvironmental and palaeogeographic reconstructions, sequence stratigraphy and petroleum reservoir assessments. Recognition and interpretation of these unconformities, particularly those with associated palaeosols, may be problematic in Lower and Middle Palaeozoic carbonate successions because of the collective effect of limited land plant development, superficial similarities between some pedogenic and marine features, and overprinting by later diagenesis. The isolated Judy Creek reef complex in the Lower Frasnian Swan Hills Formation in west‐central Alberta, Canada, contains two subaerial unconformities, R0.5 and R4, which formed as a consequence of relative sea‐level falls of at least regional scale. Deposits beneath these unconformities have distinctive palaeosol and palaeokarst features. The lower unconformity, R0.5, occurs at the top of a progradational reefal phase of stromatoporoid rudstones–floatstones and peloidal packstones–grainstones and has been recognized in at least one other isolated Swan Hills reef complex (Snipe Lake). Palaeosol–palaeokarst profiles beneath this unconformity extend as deep as ca 2 m below the unconformity. These profiles are characterized by the presence of small rhizoliths, laminar calcretes, ferroan dolomite glaebules, desiccation cracks, breccias, green shale and solution vugs. The upper unconformity, R4, occurs at the top of a backstepping phase of reef growth and has been correlated widely between isolated reefs and carbonate banks on both the western and eastern shelves of the Central Alberta Basin. Palaeosol–palaeokarst profiles, extending as deep as ca 9·5 m beneath the R4 unconformity, are distinguished by abundant, sub‐horizontal desiccation cracks filled with green shale, occurring in peloidal wackestones–packstones. Comparison of the R0.5 and R4 profiles indicates that the major intrinsic controls on the development and modification of the profiles are parent‐material lithology, particularly the prior degree of induration and particle size; the low topographic relief at the top of the reef interior; and limited vegetation of the exposed reef top due to unfavourable growth conditions and geographic isolation. In addition to climate, the major extrinsic controls are the extent of relative sea‐level fall, estimated to be 2·5 to 3 m and 13 to 14 m associated with the R0.5 and R4 unconformities, respectively, and the degree of shoreface erosion during the ensuing marine transgression, estimated to be up to 3 m. This study highlights the complex interplay of mainly physical and chemical processes influencing the formation of subaerial unconformities in carbonate environments during the Devonian, before major evolutionary innovations among vascular land plants led to more intense pedogenesis. 相似文献
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内蒙古正镶白旗宝力根套海井田为一个新发现的全隐蔽井田,井田含煤地层为侏罗系中、下统阿拉坦合力群,是一套典型的内陆湖泊、河流、三角洲陆相含煤建造。井田为四条正断层所围限的矩形断块,含煤地层的形成严格受构造因素控制,与其所处特殊构造地理位置有关。含煤区处于隆起带的凹陷内,西北及西南为古隆起带,呈直角包围宝力根套海井田,形成有利的聚煤场所—交角构造区。井田与邻区实例对比分析表明:地台内隆起带的凹陷区聚煤的构造控煤模式是该区域的普遍成煤规律,煤易在盆地次边缘沉积,交角构造区更有利于聚煤。通过区域构造特征分析,提出了找煤方向。 相似文献
20.
Xiao L.-L.Jiang Z.-S. 《矿物岩石地球化学通报》2010,(4):339-347
Amphibolites, one of the kinds of Precambrian basement rocks, are exposed in the south-middle Zanhuang Metamorphic Complex, central-south segment of the Trans-North China Orogen. These metamorphic rocks were carefully studied through field investigations and petrographical and geochemical analyses. It was found that protoliths of the Zanhuang amphibolites are calc-alkaline and tholeiitic rocks with a large range of ΣREE (41.38 × 10-6 -232.55 × 10-5 ) and weak LREE enrichment. The multi-element variation results showed that K, Rb and Ba were relatively concentrated, Nb and Ta were of evident depletion while Ti was of weak depletion. Geochemical characteristics and various relevant geochemical discrimination diagrams showed that the Zanhuang amphibolites were formed in volcanic arcs of continental margin similar to the current continental margin, which was resulted from the subduction between the Western Block and the Eastern Block. 相似文献
