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91.
Geometric form of Haiyuan fault zone in the crustal interior and dynamics implications 总被引:1,自引:0,他引:1
The deep seismic reflection data on profile HY2 are reprocessed by the method of simultaneous inversion of velocity distribution
and interface position. By the travel-time inversion with the data of the diving wave Pg and fault plane reflection wave,
we determine the geometric form and velocity of Haiyuan fault zone interior and surrounding rock down to 10 km depth. The
measured data show that the amplitudes have strong attenuation in the range of stake number 37–39 km, suggesting the fault
zone has considerable width in the crustal interior. The results of this paper indicate that to the north of the fault zone
the crystalline basement interface upheaves gradually from southwest to northeast and becomes shallow gradually towards northeast,
and that to the south of the fault zone, within the basin between Xihua and Nanhua mountains, the folded basement becomes
shallow gradually towards southwest. The obliquity of the fault zone is about 70° above the 3 km depth, about 60° in the range
of the 3–10 km depths. From the results of this paper and other various citations, we believe that Haiyuan fault zone is in
steep state from the Earth’s surface to the depth of 10 km.
Foundation item: Joint Seismological Science Foundation of China (201001) and State Key Basic Research Development and Programming Project
(95-13-02-02).
Contribution No. RCEG200308, Exploration Geophysical Center, China Earthquake Administration. 相似文献
92.
Basin-fill sequences of Mesozoic typical basins in the Yanshan area, North China may be divided into four phases, reflecting lithosphere tectonic evolution from flexure (T3), flexure with weak rifting (J1+2), tectonic transition (J3), and rifting (K). Except the first phase, the other three phases all start with lava and volcaniclastic rocks, and end with thick coarse clastic rocks and/or conglomerates, showing cyclic basin development rather than simple cyclic rift mechanism and disciplinary basin-stress change from extension to compression in each phase. Prototype basin analysis, based on basin-fill sequences, paleocurrent distribution and depositional systems, shows that single basin-strike and structural-line direction controlling basin development had evidently changed from east-west to northeast in Late Jurassic in the Yanshan area, although basin group still occurred in east-west zonal distribution. Till Early Cretaceous, main structural-line strike controlling basins just turned to northeast by north in the studied area. 相似文献
93.
LIU Xiangwen YANG Guangming ZOU Huamin QU Jing & ZHAO Wenxia . Graduate School China University of Geosciences Wuhan China . Test Center China University of Geosciences Wuhan China . Physics Technology College Wuhan University Wuhan China . Test Center Zhongshan University Guangzhou China 《中国科学D辑(英文版)》2004,47(3)
Sakhaite was first discovered by Ostrovskaya, Pertsev and Nikitina at Siberia in the former Soviet Union. By using the X-ray diffraction technique, they proved that the crystal system of sakhaite was cubic (a = 1.464 nm), its possible space groups were Fm3m, F432, F43m, Fm3, F23, and its crystal chemical for-mula was Ca48Mg16(CO3)16(BO3)28Cl4(OH)8 4H2O[1]. Chichagov, Simonov and Belov studied the crystal structure of synthetic sakhaite and determined that its space group was F4132, … 相似文献
94.
山东省气候变化及其对冬小麦生产潜力的影响 总被引:11,自引:0,他引:11
利用全省 2 7个台站 1 96 1~ 1 998年的温度、降水、日照等基本气象要素资料 ,对山东省气候变化特点进行了分析 ,并对冬小麦生产潜力进行了计算、分析。结果表明 ,山东省年、季平均气温呈波动性增暖趋势 ,降水量呈减少趋势。气候变暖有利于生产潜力的提高 ,冬小麦气候生产潜力总的变化趋势是波动性的上升 ,但较光温生产潜力倾向率小 ,反映了小麦生育期内光、温、水的综合影响。 相似文献
95.
山西省主要河流流域面雨量预报业务流程 总被引:3,自引:1,他引:3
以T213、HLAFS模式、MM5中尺度模式输出的格点资料以及日本降水量格点资料为基础,将影响山西降水的天气动力模型归纳为诊断模型,从中引出多个能够全面反映降水模型特征的综合物理因子;根据各种数值模式输出的降水量预报性能和质量优劣特点,依据数值模式的形势场预报优于要素场预报的现实,构造在不同环流形势背景下,启动不同预报方程的面雨量预报业务流程,有效地遏止了在环流形势调整时预报输出不能快速响应的弱点,提高了点和面雨量预报的准确度。 相似文献
96.
从安徽气候变化看2003年洪涝和高温的必然性 总被引:6,自引:0,他引:6
利用近 50年温度和降水资料研究了安徽夏季气候变化特征 ,解释了 2 0 0 3年夏季洪涝、高温等极端气候事件出现的必然性。研究结果表明 :(1 )近 50年来安徽夏季温度呈下降趋势 ,降水则呈增加趋势 ,两者变化是相协调的。目前夏季温度处于较低的气候基本态 ,降水处于高基本态。 (2 )无论是温度还是降水 ,其变率都在 2 0世纪80年代中后期开始上升 ,目前均处于高气候变率时期。降水的“两高”(高基本态和高气候变率 )结合决定了 2 0 0 3年夏季洪涝出现的必然性 ;温度的较低基本态决定了“凉夏”背景 ,但由于基本态的回升和变率的加大 ,仍会出现像 2 0 0 3年夏季的若干高温天气。 (3)最大熵谱估计表明 ,安徽夏季降水变化的主周期为 2 5年 ,反映了降水的准两年振荡特征 相似文献
97.
This paper estimates the coefficients of volume compressibility from variation in compressible layer thickness and changes in piezometric heads by using detail ground surface surveys and a multilayer monitoring well at a selected site (Shigang) within the Choshui River alluvial fan in west Taiwan. The paper integrates various types of in situ monitoring tools, including leveling surveys, continuous global position system (GPS) stations, multilevel layer compression and groundwater pressure head-monitoring wells, to investigate the situation and progress of the subsidence problem in the region. The results from the cross-analyses of the measured data show that surface settlement caused by the compression of strata is between the depths of 60 and 210 m where the clayey stratum within 120-180 m was most pronounced and contributes up to 53% of the total compression. The results indicate that the clayey stratum is under normal consolidation. The results also reflect the fact that 20% of settlement contribution comes from the sandy stratum within 90-120 m; the elasto-plastic behavior of this sandy stratum is clear. The coefficients of volume compressibility of the clayey and sandy stratum analysed from the stratum's compression records; they were 6.38×10−8 and 5.71×10−9 m2/N, respectively. Ultimately, this parameter estimation would permit to control and predict land subsidence based on change in pressure head which are related to groundwater extraction. 相似文献
98.
The Zhangjiakou–Penglai seismotectonic zone (ZPSZ) lies in the northern part of North China and extends along the Zhangjiakou–Beijing–Tianjin–Bohai Bay–Penglai–Yellow Sea. It is about 900 km long and some 250 km wide in a northwest direction. The great Sanhe-Pinggu (MS=8.0) earthquake occurred on September 1679 and the Tangshan (MS=7.8) earthquake on July 1976 caused serious economic and life losses. According to some differences in crust structure and regional tectonic stress field, the ZPSZ is divided into western and eastern segment by the 117°E line for study on long-term seismic hazard analysis. An analysis of Gutenberg–Richter's empirical relation of earthquake-frequency and time process of historic and recent earthquakes along the eastern and western segments shows that the earthquake activity obeys a Poisson process, and these calculations indicate that the earthquake occurrence probability of MS=6.0–6.9 is 0.77–0.83 in the eastern segment and the earthquake occurrence probability of MS=7.0–7.9 is 0.78–0.80 in the western segment of the ZPSZ during a period from 2005 to 2015. 相似文献
99.
Ninad R. Bondre Raymond A. Duraiswami Gauri Dole 《Journal of Earth System Science》2004,113(4):809-817
The nature and style of emplacement of Continental Flood Basalt (CFB) lava flows has been a matter of great interest as well
as considerable controversy in the recent past. However, even a cursory review of published literature reveals that the Columbia
River Basalt Group (CRBG) and Hawaiian volcanoes provide most of the data relevant to this topic. It is interesting to note,
however, that the CRBG lava flows and their palaeotopographic control is atypical of other CFB provinces in the world. In
this paper, we first present a short overview of important studies pertaining to the emplacement of flood basalt flows. We
then briefly review the morphology of lava flows from the Deccan Volcanic Province (DVP) and the Columbia-Oregon Plateau flood
basalts. The review underscores the existence of significant variations in lava flow morphology between different provinces,
and even within the same province. It is quite likely that there were more than one way of emplacing the voluminous and extensive
CFB lava flows. We argue that the establishment of general models of emplacement must be based on a comprehensive documentation
of lava flow morphology from all CFB provinces. 相似文献
100.
Pollution history and recovery of a boreal lake exposed to a heavy bleached pulping effluent load 总被引:4,自引:0,他引:4
Juhani Hynynen Arja Palomäki Jarmo J. Meriläinen Allan Witick Keijo Mäntykoski 《Journal of Paleolimnology》2004,32(4):351-374
We examined the effects of heavy pulp mill discharges on the Lake Lievestuoreenjärvi ecosystem and the later recovery of diatom and chironomid communities from age-dated short core samples. Beginning in 1927 the lake received a heavy effluent load from a sulphite pulp mill. Except for the recession during the Second World War and the temporary closure of the mill from 1967 to 1971, the industrial load, containing large quantities of nutrients, organic matter and toxic compounds, increased continuously. In the early 1980s, laboratory documents were falsified by the directors of the mill and the systematic illegal effluent overload led to a collapse of the whole lake ecosystem. In 1985, the outdated plant was finally closed down. Based on the assessment of chemical properties and biological remains of the sediment, we distinguished five developmental phases in the ecological state of the lake. In the pre-industrial phase, the pelagic and profundal benthic communities were dominated by species preferring ultraoligotrophic or oligotrophic lakes. Concomitant with the increasing discharge and deposition of chlorine compounds, resin acids, and mercury, as well as strong acidity and hypolimnetic and epilimnetic anoxia, the ecological status changed in a short period from excellent to bad. Finally, in the early 1960s, the majority of the lake was virtually dead and the aquatic life survived only in the uppermost littoral zone. Since 1985, a fast recovery in the water quality has led to a strong, but temporary eutrophy in pelagic communities. The main peak of eutrophication was caused by the invasion of a species new to the lake,Aulacoseira granulata var.angustissima. Later, the pelagic communities shifted towards oligotrophy, but the original, pre-industrial status has not been re-established. The profundal benthic communities have not achieved the pre-industrial structure, but at present indicate mesotrophy. 相似文献