Geochemistry,petrogenesis and tectonic implication of Early Cretaceous A-type rhyolites in Hailar Basin,NE China

Early Cretaceous A-type rhyolites of the Shangkuli Formation in the Hailar Basin of NE China exhibit geochemical characteristics of high silicon, alkali, Fe/Mg, Ga/Al, Zr, Pb, HFSEs, and REE contents but low Ca, Ba, Sr and Eu, which meet the criteria of typical reduced A-type granite.The A-type rhyolites are most probably derived from magmatic underplating and partial melting of quartz-feldspathic lower crust, with the lithospheric mantle material involved, due to the extensional deformation of the Erguna-Hulun Fault.Although the A-type rhyolites show A1-type trace elements characteristics, they were formed in a post-orogenic extension-al background together with the coeval widespread bimodal volcanic rocks, metamorphic core complexes, vol-canic fault basins and metallogenic province in the Sino-Russia-Mongolia border tract.This extension event was related to the collapse of thickened region of the continental crust after the closure of the Mongol-Okhotsk Ocean.     

Vertical characteristics of ozone variation over the Arctic Chukchi Sea region in 1999

1　ＩｎｔｒｏｄｕｃｔｉｏｎＡｒｃｔｉｃｃｌｉｍａｔｅａｎｄｅｎｖｉｒｏｎｍｅｎｔａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｉｎｔｈｅｇｌｏｂａｌｃｈａｎｇｅｓｙｓｔｅｍｓ(ＷＭＯ/ＵＮＥＰ 1 990 ;ＷＭＯ 1 991 ) .Ｏｂｓｅｒｖａｔｉｏｎｓａｎｄｍｏｄｅｌｉｎｇｒｅｓｕｌｔｓｉｎｄｉｃａｔｅｔｈａｔｔｈｅｇｌｏｂａｌｗａｒｍｉｎｇｗｉｌｌｂｅｅｎｈａｎｃｅｄｉｎｔｈｅｐｏｌａｒｒｅｇｉｏｎｓ ,ｅｓｐｅｃｉａｌｌｙｉｎｔｈｅＮｏｒｔｈＨｅｍｉ ｓｐｈｅｒｅ ,ｗｉｔｈａｐｒｅｄｉｃｔｅｄｗａｒｍｉｎｇｏｆａｂｏｕｔ…     

福建沿海地区形变-应变场的演变特征

利用福建沿海地区GPS基本网2003—2010年4期观测资料,运用GAMIT/GLOBK软件及块体整体旋转线性应变模型,得到了各站相对于整个块体的形变速度和块体上的应变图像。结果显示:福建沿海地区具有一致的东南向运动,大小在35 mm/a左右;邵武-河源断裂带附近的剪切应变较大,政和-海丰断裂带与永安-晋江断裂带交汇处剪切应变相对较小,长乐-诏安断裂带从南到北的剪切应变经历了一个南弱北强到南强北弱的变化过程,政和-海丰断裂带和永安-晋江断裂带交汇处最大和最小主应变由压应变转为张应变;福建地区从西北到东南沿海经历了由张到压-由压到张-由张到压的变化过程。     

浅析企业经济责任审计的难点与对策

领导干部任期经济责任审计,是审计机关接受干部管理部门委托,依据国家法律、法规,对党政机关、人民团体、事业单位的党政领导干部或企业领导人员任职期间经济责任履行情况进行的监督、评价和鉴证的活动。1986年底,审计署指定下发了《关于开展厂长离任审计工作几个问题的通知》,对厂长(经理)离任审计的范围、内容、程序和要求作了原则规定,为全面开展企业经济责任审计奠定了基础。实践证明,这项工作的开展,对加快企业经济体制改革、维护财经纪律、保证财产安全、强化干部监督、促进廉政建设等都起到了重要作用。同时,经济责任审计也存在一些…     

岩溶水型水源地保护区划分方法研究——以济南市曹楼水源地为例

对地下水水源地进行保护区划分将提高地下水的安全保障程度。岩溶水型水源地由于含水层的非均质、各向异性的特点,难以合理准确的划分水源地保护区。以济南市曹楼水源地为研究对象,在充分收集和分析水源地水文水质、地形地貌等资料的基础上,采用组合法划定水源地保护区,结合地形地质条件对保护区范围进行修正,保护水源地免受污染。利用组合法划分的水源地保护区加强了对上游补给区,尤其是地下水主径流带的保护,划分结果更符合实际。利用该方法能提高对水源地主要补给区的保护,保障地下水的可持续开发利用,为水源地的保护提供科学的依据和参考。     

Effect of Temperature on the Acoustic Reflection Characteristics of Seafloor Surface Sediments

Because the sound speeds of seawater and seafloor sediment both increase with temperature,the influence of tempera-ture on the bottom reflection characteristics of seafloor sediments needs to be investigated.Based on the calculation of the temperature-controlled experimental measurement data of typical seafloor surface sediment samples,the temperature-dependent acoustic characteristics,including acoustic impedance,acoustic impedance ratio between surface sediment and seawater,and reflection coefficient,were analyzed.The effective density fluid model was used to analyze and explain the reflection coefficient variation of surface sediments with temperature and predict the dispersion characteristics.Results show that the acoustic impedance of the seabed sediment increases with temperature,whereas the acoustic impedance ratio and acoustic reflection coefficient slightly decrease.The acoustic impedance,acoustic impedance ratio,and acoustic reflection coefficient of sandy,silty,and clayey sediments vary similarly with tem-perature variation.Moreover,the influence of temperature on these acoustic characteristics is independent of detection frequencies.     

Identification of paralytic shellfish toxin-producing microalgae using machine learning and deep learning methods

Journal of Oceanology and Limnology - Paralytic shellfish poisoning (PSP) microalgae, as one of the harmful algal blooms, causes great damage to the offshore fishery, marine culture, and marine...     

南京地区新近纪砂砾层的沉积环境演变

南京地区分布着一套新近纪的松散砂砾沉积,曾被统称为雨花台砾石层。依据岩性、层序、沉积构造等特征,我们解译了4个地点砂砾层的沉积环境。研究发现,洞玄观组的沉积环境类似于曲流河沉积,六合组类似于砂质辫状河沉积,雨花台组则属于砾质辫状河沉积。沉积环境的不同印证了前人的观点,即这些砂砾层是不同时期形成。古流向显示,从中新世到更新世早期本区的流域格局与目前的大体一致。而河流沉积环境的演化,却指示河道的坡降具有不断增大的趋势。我们认为这可能是全球海平面不断下降导致侵蚀基准面降低所引起的,而差异性的构造运动似乎不是主要的驱动因素。     

Coupled convection and tidal dissipation in Europa’s ice shell

We performed 2D numerical simulations of oscillatory tidal flexing to study the interrelationship between tidal dissipation (calculated using the Maxwell model) and a heterogeneous temperature structure in Europa’s ice shell. Our 2D simulations show that, if the temperature is spatially uniform, the tidal dissipation rate peaks when the Maxwell time is close to the tidal period, consistent with previous studies. The tidal dissipation rate in a convective plume encased in a different background temperature depends on both the plume and background temperature. At a fixed background temperature, the dissipation increases strongly with plume temperature at low temperatures, peaks, and then decreases with temperature near the melting point when a melting-temperature viscosity of 10¹³ Pa s is used; however, the peak occurs at significantly higher temperature in this heterogeneous case than in a homogeneous medium for equivalent rheology. For constant plume temperature, the dissipation rate in a plume decreases as the surrounding temperature increases; plumes that are warmer than their surroundings can exhibit enhanced heating not only relative to their surroundings but relative to the Maxwell-model prediction for a homogeneous medium at the plume temperature. These results have important implications for thermal feedbacks in Europa’s ice shell.To self-consistently determine how convection interacts with tidal heating that is correctly calculated from the time-evolving heterogeneous temperature field, we coupled viscoelastic simulations of oscillatory tidal flexing (using Tekton) to long-term simulations of the convective evolution (using ConMan). Our simulations show that the tidal dissipation rate resulting from heterogeneous temperature can have a strong impact on thermal convection in Europa’s ice shell. Temperatures within upwelling plumes are greatly enhanced and can reach the melting temperature under plausible tidal-flexing amplitude for Europa. A pre-existing fracture zone (at least 6 km deep) promotes the concentration of tidal dissipation (up to ∼20 times more than that in the surroundings), leading to lithospheric thinning. This supports the idea that spatially variable tidal dissipation could lead locally to high temperatures, partial melting, and play an important role in the formation of ridges, chaos, or other features.     

射电脉冲星的偏振特性与逆康普顿散射（ICS）模型

大量射电脉冲星的偏振观测－包括红偏振和圆偏振，个别脉冲的生直偏振模式，累积脉冲的消偏振现象等－为辐射区的物理状态和辐射提供了非常确切的观测事实，但现有理论对大从观测事实尚无法给出完整的说明，综述了脉冲星的偏振观测特征，并利用逆康谱顿散射模型对这些特性进行了解释。