共查询到20条相似文献，搜索用时 468 毫秒
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地震波旅行时精度直接影响着地震反演、叠前偏移成像、层析成像等各领域研究成果的可靠性,因此,研究如何提高地震波旅行时精度是很有意义的。在双重网格技术的基础上,引入一种基于变网格差分格式的快速行进法(FMM)计算地震波旅行时,通过正演模拟均匀模型、存在高速异常体模型、Marmousi模型来分析变网格FMM的优势及适用性。研究结果表明:均匀模型背景下,变网格FMM与双重网格FMM优势相当,但是在存在高速异常体模型背景下,双重网格FMM可能违背波前扩展的规律,从而导致较大的误差,而变网格FMM则不存在这样的问题; Marmousi模型试算验证了变网格FMM能适应各种复杂模型。因此,该方法是一种有效提高走时计算精度和效率的方法,不仅增强了FMM法的适用性,而且扩展了变网格技术的应用范围。 相似文献
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《物探化探计算技术》2020,(2)
对于山地地震勘探而言,地形起伏,不能直接使用Herglotz-Wiechert公式反演近地表速度模型,这里采用不同于前人在炮域处理的思路,而是在CMP域建立了一组基于CMP浮动基准面对起伏地表上的炮检对走时和偏移距进行校正的公式,首先用本文提出的公式去除起伏地表对初至波的影响,然后应用Herglotz-Wiechert公式快速反演地形起伏地区近地表速度模型。该方法采用地震反射波的CMP浮动基准面校正思路,包含三个关键步骤:①产生CMP浮动基准面;②实测时距曲线的校正;③计算射线参数和速度-深度函数的计算。此方法无需射线追踪,无需初始模型,计算速度快,反演得到的模型具有和地震数据相同的水平分辨率,该模型可用于计算基准面静校正量,或用于叠前深度偏移速度场的表层建模,也可以作为回转初至波层析反演或全波形反演的初始模型。 相似文献
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在山区或地表复杂地区进行地震勘探,采用基于地表一致性假设的静校正将会严重影响勘探效果,该影响主要源于地表一致性假设存在着不合理因素。如较高的低速带、巨厚的低速带、基岩裸露、地形起伏较大等。为分析一致性假设静校正偏差产生的原因及大小．构建一地形起伏、基岩出露的复杂模型,通过正演其射线路径,对比其时距曲线与理论时距曲线的差异,以及二者静校正量误差大小。模型分析证实该差异与偏移距、地震波穿透深度及基准面高程之间存在直接的联系,据此提出了改进方法,如浮动基准面校正及分块静校正等。理论模型和实际地震资料试算表明,使用改进的方法可有效改善地震时间刮面同相轴聚焦效果及连续性。 相似文献
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准噶尔盆地南缘山地地表起伏剧烈、地下构造复杂且速度场纵横向变化大,地震数据原始单炮一致性差、信噪比低,这对山前带起伏地表地震成像造成了巨大挑战。为完善复杂条件下低信噪比山地资料的起伏地表处理技术,以提高山地资料地震成像精度,本文提出了保持炮检点一致性的浮动基准面处理方法。通过配套的时间域处理和深度域速度建模技术,实现了炮检点分离的浮动地表处理思路。基于南缘四棵树工区连片深度偏移生产中的实际应用,证明了该处理思路能够有效提高复杂构造成像质量,同时大大缩短处理项目周期,现已成为双复杂地区地震成像的主力技术手段,可以广泛推广到其它地区山前带起伏地表地震成像中。 相似文献
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针对城市区域沉积盆地三维地震动模拟问题,发挥边界元法处理无限域波动问题的独特优势和快速多极算法(FMM)处理大规模问题的特性,形成适用于宽频、高自由度模型的快速多极子间接边界元法(FMM-IBEM)。通过精度对比和效率验证发现,FMM-IBEM可精确高效地实现三维复杂场地地震动宽频模拟,同时大幅度降低存储量和计算量。采用该方法对某含起伏基岩面的三维复杂形状沉积盆地进行频域和时域分析,结果表明:入射频率、盆地形状和盆地内部的位置点对沉积盆地地表位移放大作用均有不同程度的影响;总体上低频域的放大作用高于高频域;频谱曲线呈现多个共振频段;沉积盆地中部和边缘处地表位移放大效应差别显著。重要工程选址宜避开沉积盆地中地震能量积聚区域。 相似文献
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井间地震走时波形层析成像方法 总被引：2，自引：1，他引：2
提出了井间地震走时波形顺序反演方法。该方法先利用井间地震走时反演得到速度模型的低频成分 ,然后用井间地震波形反演获得速度模型的高频成分。数值模型试验和实际应用结果表明 ,该方法反演稳健 ,提高了走时成像的分辨率 ,克服了波形成像易于陷入局部极小的缺陷 ,实现了快速高分辨率成像。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Emmanuel Skourtsos Daniel Vachard Alexandra Zambetakis-Lekkas Rossana Martini Louisette Zaninetti 《Comptes Rendus Geoscience》2002,334(12):925-931
Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931. 相似文献
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正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.) 相似文献
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正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.) 相似文献
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正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.) 相似文献
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正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus., 相似文献
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正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an 相似文献
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正20141266Fan Chaoyan(Guangdong Provincial Key Laboratory of Mineral Resources and Geological Processes,Guangzhou 510275,China);Wang Zhenghai On Error Analysis and Correction Method of Measured Strata Section with Wire Projection Method(Journal of 相似文献