等离子体层嘶声对槽区电子的弹跳共振散射效应

等离子体波动与带电粒子的共振相互作用一直是磁层物理学的研究热点.作为一种常见的宽频、右旋极化等离子体波动, 等离子体层嘶声在地球磁层电子的损失过程中起到了重要作用.其中, 嘶声波对电子的回旋共振散射被认为是辐射带槽区形成的主要机制, 而人们对嘶声波与电子的弹跳共振机制的理解却相对匮乏.本文旨在细致研究嘶声波与槽区电子的弹跳共振相互作用, 明确其对槽区电子动态演化过程的影响.研究发现, 嘶声波与电子的弹跳共振可以造成槽区电子在高投掷角(80°~90°)处明显的投掷角扩散.相比于低能(＜~100 keV)电子, 嘶声波引起的高能(＞~100 keV)电子的弹跳共振效应明显更强.槽区电子的弹跳共振投掷角扩散系数对于L-shell、地磁活动条件和共振阶数都有着很强的依赖性.随着L-shell的增大和地磁活动的增强, 嘶声波对电子的弹跳共振散射效应显著增强.对于低能电子, 共振阶数对总散射系数的贡献随阶数的升高而增大; 而对于低L-shell处的高能电子, 共振阶数对总散射系数的贡献随阶数的升高而呈现先增大后减小的趋势.嘶声波与槽区电子的弹跳共振相互作用可以有效地将高投掷角电子散射到较低的投掷角上, 进而在回旋共振机制的协助下将它们散射到损失锥中.因此, 未来在地球槽区电子动力学建模过程中有必要考虑等离子体层嘶声对电子的弹跳共振散射效应.

     

Devonian integrative stratigraphy and timescale of China

The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian stratigraphers include further subdivision of these standard stages, strictly constrained absolute ages for the boundaries, and precise neritic-pelagic and marine-terrestrial correlations using multidisciplinary stratigraphy methods. Establishment of high-resolution Devonian integrative stratigraphy framework and timescale of China would play an important role in improving regional and international correlation, facilitating the recognition of important stratigraphic levels in different paleogeographic settings, and understanding the evolution pattern of biota, paleoclimate and paleoenvironment during this critical interval. Based on well-studied bio-and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.Up to date, few studies have been conducted on the astronomical cyclostratigraphy and high-resolution radioactive isotope dating in Devonian of China, which should be our main focuses in the near future.     

Radiolarian fauna from the Chiungchussuan Shuijingtuo Formation(Cambrian Series 2) in Western Hubei Province,South China

Little is known regarding characteristics and evolution of radiolarian fossils in the early Cambrian due to its rarity and poor preservation. Here we report a new radiolarian fauna from the Cambrian Shuijingtuo Formation corresponding to the Chiungchussuan Stage(Cambrian Series 2) in western Hubei, China. It contains over 300 radiolarian tests and these fossils belong to 4 morphotypes, including Paraantygopora porosa gen.et sp. nov., Braunosphaera sinensis gen.et sp. nov., Tetrasphaera? sp. and incertae spherical radiolarians. In taxonomy, Spumellaria predominates in the fauna and comprises 92% of the total. In shell structure, about 73% of all specimens are similar to the early Ordovician radiolarian fossils, with the shell walls characterized by perforated plate structures. The spherical radiolarians with latticed shells constitute another feature of the early Cambrian radiolarian fauna. The radiolarian fauna reported here contains many fossil specimens and covers different taxonomical taxa. These specimens usually consist of distinctive concentric multi-layers with complex structure. These characteristics indicate that Radiolaria had already thrived during the Cambrian Chiungchussuan Stage(Series 2, Stage 3), which may have occurred synchronously with the explosion and prosperity of macrobiota recorded in the strata deposited in shallower water condition.     

短时气压干扰下TJ-Ⅰ、TJ-Ⅱ型体应变观测频谱对比分析

短时气压干扰是形变观测中常见且显著的影响因素之一。本文选取易县地震台2015年3月1日至12月31日的TJ-Ⅰ型和TJ-Ⅱ型体应变观测分钟数据为研究对象,对受气压干扰的主测项与钻孔气压观测值进行对比分析,利用小波变换方法分别提取出高、低气压环境干扰下两台仪器观测值在不同频段的频谱特征,结果显示:对于短时气压干扰,TJ-Ⅰ型与TJ-Ⅱ型体应变均与气压变化发生同步响应;在高气压干扰下,两套体应变主测项及其辅助气压测项分别在其小波6阶细节上的变化同步且相关系数接近;对于低气压干扰,TJ-Ⅱ型体应变主测项与其钻孔气压测项在高频6阶的节相关系数更大,说明TJ-Ⅱ型体应变更易于在高阶细节部分识别低气压干扰。     

Kinetic study of the hydrocarbon generation from Upper Paleozoic coals in Ordos Basin

When organic matter during geological processes is affected by a variety of factors such as paleotemperature, and time, complicated chemical reactions will occur, finally resulting in the generation of petroleum and natural gas. These reactions leading to…     

南北地震带应力场演变的数值模拟研究

应用有限元方法,考虑主要地质构造情况,就粘弹介质状态下南北地震带及其相邻区域的应力场时空演变过程进行了数值模拟研究．计算了10万零10年累积载荷作用下模型的应力场演变,发现在周边板块不断推挤作用下,当整个南北带的应力松弛趋于稳定后,带上应力场的总体扰动大小取决于印度-澳大利亚板块、菲律宾板块和太平洋板块的共同作用．南北地震带上呈现出的“地震南北呼应”现象,就是区域应力场达到平衡态后,整个南北带对外载荷(板块边界力)作用的总体反应．     

基于同步挤压小波变换的烃类识别技术

利用频谱分解得到的频率能量数据体进行属性提取,是烃类检测的常用手段之一.同步挤压小波变换能够提供高分辨率的时频谱,具有较好的应用潜力.本文以同步挤压小波变换为基础,提出了一套烃类检测方法,包括低频阴影检测、流体流动性估计以及高频能量衰减等,通过自适应选取优势频段,实现了多属性联合高精度刻画烃类的分布范围.实际资料处理结果与现有钻井情况吻合,具有较好的实用性,实现了对储层位置的高精度描述,对指导油气田开发具有重要的理论意义和实用价值.     

深地震反射剖面揭示的天津地区张渤带地壳精细结构

穿过天津地区张渤带的长86 km、NE向深地震反射剖面揭示了该区清晰的地壳精细结构图像和断裂的深浅构造特征,为研究张渤地震构造带的深部孕震环境和构造模式提供了地震学证据,对探讨晚中生代以来华北裂陷盆地的深部动力学过程及演化具有重要意义.结果表明,天津地区张渤带地壳以结晶基底反射T_G为界,分为上下两部分;上地壳反射波组丰富,分层特征明显,界面起伏形态清楚,清晰地刻画出冀中坳陷新生代沉积分层、箕状沉积凹陷的底界、潮白河断裂、蓟运河断裂及丰台—野鸡坨断裂的几何结构;地壳内部结晶基底（T_G）至Moho之间,显示出近于"反射透明"的地震波场特征,无明显震相,这与华北其他地区的深地震反射剖面结果明显不同;地壳厚度为30.0~34.5 km,总体变化趋势为中段地壳厚而南北端相对较薄,Moho在横向上显示出明显的不均匀和横向间断特征,在Moho被错断处存在两个明显的反射事件R_A和R_C,R_A可能是软流圈热物质上涌的侧向残留物,叠层状反射震相R_C则表现出壳幔过渡带特征;剖面揭示了2条错断Moho的超壳深大断裂（F_D1和F_D2）和9条上地壳断裂,深大断裂应是软流圈热物质上涌,造成上地幔隆起而形成的,上地壳断裂与地壳垂直运动及侧向引张力有关;超壳深断裂（F_D1和F_D2）为本区深部热物质的上涌与能量交换提供了通道,而与之对应的地壳浅部断裂（F₃和F₉）,则为能量调整提供了可能的条件,断裂邻近区域可能是未来发生强震的地区,值得注意.     

带暗支撑剪力墙中暗支撑型式及其合理设计研究

提出了钢筋混凝土带暗支撑剪力墙,进行了5个剪力墙板模型抗震性能试验,重点分布了暗支撑的型式及其合理的设计参数,提出了供抗震设计参考的建议。     

西藏当雄6．6级地震应急行动及灾害特征

2008年10月6日西藏当雄县发生了6．6级地震。震后,各级政府和地震部门迅速启动了地震应急预案,周密安排和部署地震应急处置与救灾行动。简要介绍了当雄6．6级地震的应急行动和灾害特征,提出了减轻地震灾害、提高地震应急能力应注意的几个问题。