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1.
文章对采自华北板块山东潍坊、河北唐山和辽宁大连的寒武系开腔骨类化石的新材料进行了研究,这些化石鉴定为 Chancelloria 属。辽宁大连地区的Chancelloria 产自寒武系第二统第四阶馒头组下部的黄绿色页岩;山东潍坊地区的 Chancelloria 产自苗岭统乌溜阶馒头组上部的黄绿色页岩和鼓山阶张夏组的深灰色中厚层灰岩;河北唐山地区的Chancelloria 产于芙蓉统江山阶长山组的薄层灰岩,该层位是目前Chancelloria 属在中国产出的最高层位,也是全球的最高层位之一。这 些来自华北寒武系第二统—芙蓉统的Chancelloria 骨片与早期的骨片相比,展现出骨片形态趋于规则、基面从浑圆趋于平 整、骨片整合度提升的特点,进一步印证了之前关于此类问题的研究结论。  相似文献   
2.
Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central China. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response to intensive neotectonism and climate change.  相似文献   
3.
北京北苑居住区第四系断层走向勘察   总被引:2,自引:0,他引:2  
介绍了北京北苑居住区第四系断层走向勘察的工作方法,提出了在平原地区进行岩土工程勘察时应注意发现地层在水平方向变化的问题,并根据区域性的地层对比划分两个工程地质区,用剖面追索法准确确定分区界线,并论证了该界线的形成与黄庄—高丽营隐伏断层的第四纪继承性活动有关  相似文献   
4.
Northeast China is an essential area for studying the strength of East Asian Summer Monsoon(EASM), due to its northernmost location in EASM domain. However, the lack of sufficient modern pollen data in this region hinders an effective interpretation of fossil pollen records and quantitative vegetation/climate reconstructions. Here, 44 surface pollen samples from forest, steppe, and meadow were used to explore pollen-vegetation-climate relationships. Cluster analysis, species indicator analysis, and principal components analysis, were used to identify the discontinuous and continuous trends in pollen dataset. In addition, correlation analysis and boosted regression trees were used to investigate primary explanatory variables, while coinertia analysis and redundancy analysis to examine pollen-vegetation and pollen-climate correlations respectively. Our results show that:(1) vegetation can be well represented by surface pollen assemblages, i.e. forest is characterized by a high proportion of tree pollen(70%) dominated by Betula(40%) along with Alnus, Larix, and Pinus, whereas Steppe by herb pollen(80%),dominated by Artemisia, Chenopodiaceae;(2) significant correlations exist between pollen assemblages and mean annual temperature and then mean annual precipitation;(3) pollen ratios of Artemisia/Chenopodiaceae and arboreal/non-arboreal can respectively be used as good indicators of humidity and temperature in Northeast China.  相似文献   
5.
宽频带超低频标准振动台的研究   总被引:1,自引:1,他引:0  
主要介绍了为中国地震局工程力学研究所振动计量实验室的技术升级项目研制的垂直和水平超低频振动台.水平振动台采用单导轨结构,大大提高了振动位移,达150mm(p-p),同时加宽了使用频率范围,可从0.01~250Hz ,而且加工、安装、调试、维护都十分方便.振动台取消了机械弹簧,代之以自动控制电弹簧,比原振动台的超低频性能大为改善,在控制方面,采用相对速度与绝对速度复合反馈技术.振动台的波形失真度,振级稳定性、横向振动比、低频背景噪声等各项技术指标达到或超过国际标准,为低频、超低频振动传感器的检定提供更精更准确的检定装置.  相似文献   
6.
采用细粒沉积岩宏观观察刻画与显微刻画的方法,探索基于湖相细粒沉积纹层类型及其结构特征作为关键指标的细粒岩岩相成因.提出了湖相细粒岩岩相的划分指标和原则,即以细粒沉积纹层作为细粒岩岩相划分的重要指标.用两级核心指标作为划分湖相细粒岩岩相及亚类的依据,分为一级指标和二级指标.一级指标为岩石组成类型,分为泥质岩类、灰岩类以及...  相似文献   
7.
目的:观察痛风方联合吲哚美辛治疗湿热蕴结型痛风的临床疗效。方法:将120例湿热郁结型痛风患者随机分为治疗组和对照组,每组各60例。治疗组采用痛风方联合吲哚美辛治疗,对照组单用吲哚美辛治疗。治疗2周后评定2组综合疗效,并比较2组治疗前后中医证候积分、白细胞(WBC)、血清尿酸(UA)、红细胞沉降率(ESR)、C-反应蛋白(CRP)水平。结果:总有效率治疗组为95.00%(57/60),对照组为81.67%(49/60),组间比较,差异有统计学意义(P<0.05);中医证候积分及UA、ESR、CRP水平治疗前后组内比较及治疗后组间比较,差异均有统计学意义(P<0.05);WBC水平治疗前后组内比较,差异有统计学意义(P<0.05),但治疗后组间比较,差异无统计学意义(P>0.05)。结论:痛风方联合吲哚美辛能改善湿热蕴结型痛风患者的中医症状,降低WBC、UA、ESR、CRP水平,且不良反应少。  相似文献   
8.
The X-ray fluorescence(XRF)core-scanned Rb/Sr ratios of lake sediments have been widely used as a proxy for chemical weathering intensity and past climate change.However,some factors could affect Rb/Sr ratios,causing misinterpretation and limiting its application.In this study,we present a high-resolution XRF core-scanned Rb/Sr record of core ZB13-C1 from the Zoige Basin in the eastern Tibetan Plateau.To validate its application,we correlated this record with the chemical index of alteration(CIA)and other paleoclimatic proxies.Our results showed that(1)the core-scanned Rb/Sr ratios and CIA were reliable proxies of chemical weathering intensity in fine-grained sedimentary sequences;(2)the low values of corescanned Rb/Sr ratios and CIA were significantly correlated with high total organic carbon content,arboreal pollen content,carbonate content,and C/N ratios,confirming its reliability as a proxy for the Asian summer monsoon intensity;(3)the corescanned Rb/Sr ratios at core depths of 25–0.3 and 56–47 m were unable to reliably reflect chemical weathering intensity due to both the grain-size effect and the low test accuracy.Our study highlights the need for mutual verification of multiple indicators before accurately applying Rb/Sr as a paleoclimatic proxy in other similar study areas.  相似文献   
9.
This paper presents an image analysis method for automated quantification of charcoal total area, focusing on the charcoal fractions less than 160 μm observed on 14 pollen slides from Grotta Reali samples. Four fire signals were recorded with 4 high values in the microcharcoal concentration curve. On the basis of modern microcharcoal study, mean length/width ratio of the microcharcoal particles was applied in an archeological context as an indicator of vegetal type (wood, grass or leaves). Therefore, the 4 fire signals were separated into two types: high concentration with high length/width ratio, and high concentration with low length/width ratio. Two fire signals might be interpreted as anthropic fire based on hearth or combustion areas, as inferred from archeological remains.  相似文献   
10.
本文介绍了941B型超低频测振仪的原理和技术性能.将无源电路补偿技术应用于优化设计的往复式小质量摆上,实现了测量量程和低频特性的扩展,克服了回转摆式低频测振仪簧片易损、需要调零、频带较窄的缺点.该仪器不仅可用来测量地面和工程结构的超低频振动的加速度、速度和位移,而且可用于爆破、冲击等较高频的振动测量.  相似文献   
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