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991.
992.
东方震群历时273天,共发生ML≥1.0级地震557次,最大震级为4.5级。介绍了对该震群跟踪分析与预报的过程和方法,震群各活动阶段的判断以及相应的地震对策依据。 相似文献
993.
模式识别在强余震等早期综合判别中的应用研究 总被引:1,自引:0,他引:1
本文利用所收集到的29个6级以上地震序列,探讨将模式识别CORA-3算法用于5级以上强余震或震群或再发生更大地震的前震-主震-余震型地震序列早期综合判断的可能性及具体方法。文中参与学习和训练的25个地震序列中,8个I类序列全部被正确识别,17个II类序列中有16个被正确识别,只有1个被误判为I类,预报评分V值达0.92。对于留作外推的4个地震序列中,2个II类序列全部被正确识别,2个I类序列,1个 相似文献
994.
SequenceStratigraphicFeaturesofMesozoic-CenozoicNonmarineSedimentsinEasternChina¥XuHuaida;WeiKuisheng(DepartrmentofEnergyReso... 相似文献
995.
According to the alternation of terrestrial beds and transgressive beds, the sedimentary sequence of the South Yellow Sea since the Olduvai subchron can be divided into 15 stratigraphical intervals. According to the facies analysis, there are 7 transgressive beds and one bed with transgression marks, and classical transgressive-regressive facies sequence also appears in the major transgressive beds.Palaeogeographic evolution in the shelf area involved 4 periods: (1) 1.70-0.5 Ma B. P. was the stage for the development of the Palaeo-Yangtze River alluvial plain and delta. Tide influenced -river channel sediments formed during the Olduvai have been found in borehole QC2. The river mouth was located near 124°E and during the transgressive stage from 0.97-0.73 Ma B.P. to the east of 122.2°E, a large-scale undersea delta was formed. In the regressive stage, the shelf area became an alluvial plain. (2) 0.50-0.75 Ma B.P. was a multi-transgressive fluctuation stage during which 3 transgressive beds (HVI, HV, H 相似文献
996.
997.
黔西纳雍煤系地层中潮汐沙脊的发现 总被引:1,自引:0,他引:1
发现并分析了黔西纳雍县生拱地区龙潭组中段一个潮汐沙脊的沉积层序。研究了组成潮汐沙脊砂岩的沉积构造和岩石学特征,并通过主砂体图再现了潮汐沙脊的平面展布。 相似文献
998.
B.J. Keely J.S. Sinninghe Damst S.E. Betts Ling Yue J.W. de Leeuw J.R. Maxwell 《Organic Geochemistry》1993,20(8)
Principal components analysis (PCA) has been used to investigate changes in concentrations of the components of the hydrocarbon fractions extracted from 71 marl samples, selected to cover two total organic carbon (TOC) maxima in the lower part of the Salt IV formation, a Lower Oligocene evaporitic sequence from the Mulhouse Basin, France. The analysis indicates that the fractions can be ascribed as lying between two end member distributions. The changes in these distributions are gradual, suggesting that they resulted from fairly gradual changes in the depositional palaeoenvironment. These changes are related to increased algal productivity associated with the evolution of a restricted lacustrine environment through to one with a greater marine influence. Systematic variations in the concentrations of selected components relative to the TOC profile point to a repeated sequential evolution in the biological assemblage during deposition of the sequence. 相似文献
999.
Liu Zhaojun Wang Dongpo Liu Li Liu Wanzhu Wang Pujun Du Xiaodi Yang Guang Changchun University of Earth Sciences Changchun Jilin Sun Sheping 《《地质学报》英文版》1993,67(2):167-180
The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional fracturing, fault subsidence, fault downwarping, downwarping and shringkage, resulting in the deposition of terrstrial facies nearly 10,000 m thick. There are different depositional sequences in these stages: the depositional period of the Early Cretaceous Shahezi and Yincheng Formations is the development stage of the down-faulted basin, forming a volcanic rock-alluvial fan-fan delta-lacustrine (intercalated with episodic turbidites)-swamp facies sequences; the period of the Early Cretaceous Dengluku Formation is the transformation stage of fault subsidence into fault downwarping of the basin, forming a sequence mainly of alluvial plain-lacustrine facies; the depositional period of the Early Cretaceous Quantou Formation-Late Cretaceous Nenjiang Formation is the downwarping stage of the basin, forming an alluvial plain-delta-lacustrine facies sequence; the period of the Late Cretaceous Sifangtai Formation-Mingshui Formation is the shringkage stage of the basin, forming again a sequence mainly of alluvial plain-alluvial fan and small relict lacustrine facies. These vertical depositional sequences fully display the sedimentary characteristics of a failed continental rift basin. Many facts indicate that the two large-scale lake invasions, synchronous with the global rise of sea level, which took place in the downwarping stage of the basin development, led to the connection between the lake and sea. 相似文献
1000.