常速叠加－DMO－叠后偏移等效叠前偏移   总被引：1，自引：0，他引：1       下载免费PDF全文

王振华 《地球物理学报》1994,(6)

常速叠加是根据给定的速度将炮检距空间的地震数据映射到叠加速度空间，在实际叠加速度位置形成叠加能量；速度变换是将叠加速度空间的能量数据映射到均方根速度空间，消除地层倾角对速度的影响，这实际上是一种ＤＭＯ方法；常速偏移是在每个均方根速度剖面上独立地进行波场归位，消除反射点位置对速度的影响．经过这三步处理获得最终叠前偏移结果．  相似文献   

Volcanic history of Mount Sidley,a major alkaline volcano in Marie Byrd Land,Antarctica     

K. S. Panter  W. C. McIntosh  J. L. Smellie 《Bulletin of Volcanology》1994,56(5):361-376

Mount Sidley is a complex, polygenetic stratovolcano composed primarily of phonolitic and trachytic lavas and subordinate pyroclastic lithologies at the southern extremity of the Executive Committee Range, a linear chain of volcanoes in central Marie Byrd Land, Antarctica. Detailed field investigation coupled with 14 high precision ⁴⁰Ar/³⁹Ar age determinations reveal a 1.5 million year life span between 5.7 and 4.2 Ma in which three major phonolitic central vent edifices (Byrd, Weiss and Sidley volcanoes) and their calderas were developed (5.7–4.8 Ma). This was followed (4.6–4.5 Ma) by the eruption of trachytic magmas from multiple vent localities further south, and then by small volume benmoreite-mugearite lavas and tephras around 4.4–4.3 Ma at the southern end of Mount Sidley. The final phase of activity was the eruption of basanite cones at approximately 4.2 Ma. The southward migration of volcanic activity was accompanied by distinct changes in magma composition and is best explained by the sequential release of magmas stored within an intricate system of conduits and chambers in the crust by tectonically driven (magma assisted?) fracture propagation. The style of volcanic migration at Mount Sidley is emulated on a larger scale by other volcanoes in the Executive Committee Range, in which progressive southward displacement of volcanic activity corresponds with significant petrological variations between major centers.  相似文献   

中国大陆强震序列次大地震及第三大地震的时间分布特征     

刁守中  华爱军  王红卫 《高原地震》1994,(4)

从地震现场早期地震趋势判断工作需要出发，本文对中国大陆地区１９６６年以来的４８个Ｍｓ≥６．０级地震序列的次大地震及第三大地震与主震（或最大地震）的时间间隔进行了统计分析。结果表明，强震序列的次大及第三大地震与主震（或最大地震）的时间间隔分布，总体上呈随机分布，其与主震（或最大地震）震级无关，而与序列类型有关。  相似文献   

莺歌海盆地泥底辟发育演化与油气运聚机制   总被引：35，自引：0，他引：35  

何家雄  黄火尧 《沉积学报》1994,12(3):120-129

第三系泥底辟是莺歌海盆地非常独特的地质体，其发育演化与烃类及流体的生、排、运、聚以及塑性泥的流动，均存在直接的成因联系。泥底辟是一个独立、完整的油气生、运、聚体系，或即油气运聚的封闭箱或封存箱，其烃类及流体运聚和塑性泥质物的流动均与该封闭体系（封闭箱）顶封闭层的形成与破坏密切相关，亦即顶封层的破裂刺穿与保存完整与否，直接控制了烃类及流体的运聚机制及模式和塑性泥的流动方式与形态特征。籍此，总结出两种不同的油气运聚机制及模式。  相似文献   

华南花岗岩中铀活化转移的地球化学证据   总被引：10，自引：2，他引：10  

章邦桐 《地球化学》1994,23(2):161-167

采用诱发裂变径迹法研究，发现华南产铀花岗岩副矿物中的铀沿微裂隙活化转移和交代蚀变矿物的自洁作用迫使载体矿物中的铀活化再分配的地球化学现象。与经过０．０５ｍＨＣ１溶液浸泡的花岗样品进行第二次诱发裂变径迹照射结果对比，确认为活化铀的存在，并具有易转移的特点。蚀变轩上岩取订及铅同位素组成研究提供了铀在热液蚀变过程中活化转移的佐证。γ能谱测量结果证实，花岗岩中的部分铀在风化作用过程中已活化转移而钍则基本存  相似文献   

Differentiating Between Subsystems and Typologies in the Analysis of Migration Regions: A U.S. Example*     

Kavita Pandit 《The Professional geographer》1994,46(3):331-345

Studies of migration regions are characterized by two separate conceptual approaches. The first views migration regions as clusters of highly interconnected spatial units (subsystems) while the other defines them as groups of spatial units with a similar geographic structure of flows (typologies). This paper highlights the theoretical and methodological distinctions between migration subsystems and typologies. An empirical analysis using U.S. migration data for 1940, 1960, and 1980 shows that although migration subsystems and typologies have both changed over time, each reveals a different dynamic of regional change and has different morphological characteristics.  相似文献   

油气二次运移的浮力驱动数学模型在辽东湾地区的应用          下载免费PDF全文

何生  何炳骏 《地球科学》1993,18(5):612-620

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低温环境中^2^1^0Pb的迁移性综述     

熊永良  翟裕生 《地质科技情报》1993,12(2):91-96

~(210)Pb的衰变半周期较短(25年),因而在近年来广泛用于现代沉积物的年龄测定。但是迄今对~(210)Pb的迁移性尚有不同认识。本文试图综合评述显示~(210)Pb在低温环境中迁移性的各种证据,并阐述控制~(210)Pb迁移性的各种条件,以便作为评估用~(210)Pb测定年龄方法精度的参考。  相似文献   

Adaptive adjustment of channel geometry     

R. J. Bennett 《地球表面变化过程与地形》1976,1(2):131-150

This paper constructs a model of channel geometry composed of three subsections: a steady-state submodel, a gradedstate submodel, and a stochastic error submodel. With the aid of this representation of the morphology of channels, the at-a-point changes in geometry can be reproduced by a simple recursive equation of autoregressive, moving-average form which is derived from methods used in the statistical analysis of time series. A set of height loss data for three Japanese rivers derived from Yatsu's (1955) paper is used to determine the effect of bed material changes on adaptations within the graded-state submodel of the channel. The results of analyzing the autocorrelation function, spectrum, and adaptive parameter shifts within this model can be used to infer that significant changes in the amplitude of height change variation, and a shift to higher frequency oscillations of bed forms are associated with the shift in bed material conditions.  相似文献   

Spectral analysis of earthquake migration in South America     

Jacques Delsemme  Albert T. Smith 《Pure and Applied Geophysics》1979,117(6):1271-1285

Earthquake migration along linear seismic belts is investigated by analyzing spacetime diagrams using spectral analysis. In order to sample the earthquakes in the space-time domain, they must first be convolved with a (sinx sint)/xt surface to obtain an unbiased and alias free twodimensional Fourier spectrum. Further enhancements are provided by selectively stacking patterns (a pattern is defined as the distribution of earthquakes in space and time before a particular earthquake), thereby reinforcing the similarities within the various patterns. With these techniques, it is possible to quantitatively estimate the migration rates (from theirspatial frequencies) and recurrence intervals (from theirtemporal frequencies) of large earthquakes in South America.Preliminary examination of the spectra for South America indicates that a low frequency peak occurs at approximately 2500 km and 27 years for earthquakes with magnitudes greater than 7.7. The results suggest a migration rate of approximately 95 km/yr from south to north and a recurrence interval of 27 years.  相似文献