Closed Basin Modes of a Dual Basin Harbour

Closed basin seiches have been studied in Port Kembla, Australia, a compound harbour comprising two basins linked by a narrow channel. Despite the irregular geometry, there are well defined closed basin resonances which may be excited by long waves incident on the harbour entrance. The March 2011 Japanese tsunami excited open-basin modes, but did not significantly excite closed-basin modes. This is attributed to the very low incident wave energy at those frequencies. While the direct forcing of a closed basin mode has been extensively studied, the indirect forcing via an independent open-basin mode found here has not been extensively studied. It was found that single basin modes are more readily excited than the higher dual basin harmonics and the role of the irregular geometry in inhibiting some modes is discussed. The non-linear generation of a higher frequency mode unrelated to the forcing mode is demonstrated.     

涉县盆地控盆构造晚第四纪活动特征

涉县断裂为太行山隆起区内涉县盆地的控盆构造,走向由NE转为近EW向,倾向NW/N,中部在井店东被EW向断裂错断,是控制涉县盆地的一组断裂。本文采用地质地貌调查、河流阶地分析和地质测年等方法,研究了涉县断裂晚第四纪活动特征。研究发现,涉县断裂带由多组断裂构成,带宽约200m,在清漳河两侧表现为山前的陡崖地貌、基岩破碎变形带,具有正断兼走滑特征,在基岩变形带上部发育走向NNE向和NWW向次级滑动面,次级滑动面错断第四系黄土,最新活动到晚更新世;断裂在盆地区通过,地表形成低缓陡坎,断裂错断Q2-3地层,表现为上陡下缓的正断层。通过对涉县断裂两侧清漳河河流阶地、夷平面和地层年龄综合分析,估算涉县断裂晚更新世以来平均垂直滑动速率为0.06～0.08mm/a,中更新世以来平均垂直滑动速率为0.22～0.34mm/a,垂直差异活动主要发生于中更新世期间。     

Coal-generated oil in Tuha Basin

The Turpan-Harmi (abbreviated to Tuha below) Basin is a typical basin of coal-generated oil accumulation in China. The Middle-Lower Jurassic coal measures are considered the main source beds. Hence, both desmocollinite and suberinite are considered the contributors for coal-generated oil. Principal geochemical features of the crude oil in the Tuha Basin are rich in alkanes (70%—80%), high pristane/phytane ratio (6—8), abundant heavy carbon isotope (δ¹³C PDB= -26%–-23%) and absolute GP sterane predominance. The hydrocarbon generation process from the coal series is characterized by multistages, early generation and early expulsion.     

Potential evapotranspiration changes in Lancang River Basin and Yarlung Zangbo River Basin,southwest China

ABSTRACT

Understanding potential evapotranspiration (PET) changes under climate change is of great importance for hydrological research. The trends of PET changes and their driving forces were investigated in the Lancang (LRB) and Yarlung Zangbo (YRB) river basins, southwest China, using diagnosis graphs and the Mann-Kendall test. Analysis of variance was applied to examine the contribution of different climatic variables to PET. The results show that: (i) there was a statistically significant increase in PET in the period of 1957–2015 in the LRB, while it showed a markedly decreasing trend in the YRB; (ii) PET in both basins is fairly sensitive to wind speed, relative humidity, solar radiation and maximum air temperature, and the interactions between wind speed and relative humidity are also important; and (iii) the increase in PET in the LRB is due mainly to the increase in maximum air temperature and decrease in relative humidity, while declines in wind speed and solar radiation are the main reasons for the decrease in PET in the YRB.     

澧水流域矿山开采与诱发地震

从澧水流域矿山开采现状入手,通过对几个矿震的剖析,总结了该区矿震的几个特点。结合地震地质条件,对澧水流域未来矿山诱发地震形势作了分析,对矿山诱发地震的监测与防治工作提出了建议。     

怀来盆地的构造应力场

１９９５年７月２０日在北京西北的怀来盆地发生了一次ＭＬ＝４．１地震。在此主震之后该地区小震活动变得十分活跃。在１９９５年７月１日至１９９６年６月３０日期间，中－欧合作怀来数字地震台网记录并精确定位了这个地震序列的４５０多个地震。余震的震源分布表明，余震主要分布在两个共轭的断层上。在盆地南部边缘的余震震源位于走向５０°、倾向南东，倾角８０°的断层上，而盆地北部边缘的余震震源则位于走向１５０°、几乎竖直的断层上。用Ｐ波初动符合资料得到了主震的震源机制解。根据余震震源的分布，确定走向３７°、倾角４０°、滑动角－１５４°的节面为主震的断层面，另一节面走向２８７°、倾角７４°、滑动角－５３°。利用怀来数字地震台网的记录资料，分析了怀来地区近期地震活动性和构造应力场。结果表明，怀来盆地的主压应力轴的方位角为２３６°，倾角４８°，与主压应力轴近水平、北东东向的华北地区的构造应力场一致，表明了ＭＬ（＝４．１地震序列是在怀来盆地北东东向挤压、北北西向拉张的构造应力作用下发生的。处于上述两条共轭断层文汇处的怀来县城附近地区近期小震活动较少，表现出断层闭锁区的特征。怀来盆地潜在的地震危险性应予以特别关注，但其近期的微震活动并未显     

残留盆地研究综述

从残留盆地的概念、残留盆地形成的古生代体制特点、中新生代的演化环境和成因等方面论述了残留盆地形成的理论依据；结合油气资源的勘探状况强调了残留盆地研究的现实意义。从残留盆地的四个主要研究内容论述了残留盆地的研究现状，并对存在的问题进行了探讨。     

渤海盆地的现今扩张运动

关于渤海盆地的扩张,前人已有很多研究成果.但是,对渤海盆地现今扩张的主方向,扩张的速率和笵围迄今还不清楚,本文试图探讨之.根据中国地壳运动观测网络GPS网1998~2004年的观测结果,建立了渤海盆地周围地区相对于欧亚板块的速度场.将该区划分为8个块体,建立了各块体的速度模型,得到该区的水平形变速度场和应变场.分析形变速度场和应变场的空间变化,发现渤海及周围地区呈现明显的NW-SE方向的双向扩张运动,扩张速率为2.5±1.8 mm/a.NW-SE与NE-SW方向扩张范围分别为310 km与 410 km.渤海盆地扩张的范围与华北地壳最薄的区域基本一致,这表明上地壳的扩张变形与上地幔的隆升密切相关,岩石圈减薄和岩浆上涌使上地壳发生拉张变形,使渤海地区发育成一个拉张盆地.     

南海北部珠江口与琼东南盆地构造-热模拟研究

珠江口盆地和琼东南盆地位于南海北部的大陆边缘,本文在此地区选取了13条典型剖面,进行了构造沉降史和热史的模拟,初步探讨了其新生代以来的构造-热演化历史.其研究结果表明:珠江口盆地存在两次热流升高过程,分别为始新世(56.5～32 Ma)和渐新世(32～23.3 Ma).琼东南盆地存在三期加热和两期冷却过程,始新世盆地热...     

地震动残差分析盆地附加放大效应:日本关东盆地为例

我国地震动预测及地震危险性分析通常仅考虑局部场地浅层岩土层对地震动的放大效应,不能考虑较大范围的地质条件影响,如沉积盆地厚沉积层对地震动的附加放大效应通常被忽略,造成盆地内地震动及地震危险性预测结果普遍被低估。本文以地震动观测记录数据充足的日本关东盆地为例,采用地震动残差分析方法评估盆地附加放大效应,分析覆盖层厚度、盆地内空间位置、震级、震源距对地震动放大效应的影响,建立关东盆地附加放大效应经验评估模型。分析表明:关东盆地附加放大效应与反应谱周期相关,整体上从短周期的1.0逐渐增大至周期为5s时的1.5,附加放大效应与覆盖层厚度相关性较小,主要受盆地空间位置和震源距的影响;盆地北部边缘及西北部地区附加放大效应更强烈,盆地南部附加放大效应较小,这可能与盆地边缘效应密切相关。本文建立的关东盆地附加放大效应经验模型略高于BSSA14和ASK14模型的放大效应预测。相关研究结果可用于我国地震动预测、下一代地震动区划图修订等。     

四川盆地潜在震源区的细致划分

四川盆地包括川中台拱和川东陷褶束的范围，具有相对稳定的大地构造环境.鉴于该地区地震活动水平相对较低、发震构造不甚明确的特点，在编制1990年版中国地震烈度区划图时，划分的潜在震源区面积也相对较大.本文在总结四川盆地中强地震（Ms=4.7-5.7）发震构造条件的基础上，用地震构造类比原则对四川盆地的潜在震源区进行了重新划分.确定潜在震源区边界时，充分考虑了背斜轴走向、背斜构造的影响带宽度、小震活动密集条带和余震的分布范围.得到了四川盆地更加细致的潜在震源区划分方案.这对于低地震活动水平地区的潜在震源区的细化研究具有一定参考意义。     

大同断陷盆地及其大震危险性

以最新研究成果，全面、系统地阐述了大同断陷盆地的地貌特征、晚新生代地层、火山与玄武岩、主要活动断裂、新构造单元与地震活动的空间分布、大同－阳高两次地震的地震构造。在此基础上探讨了今后10年左右的时间内，大同断陷盆地的地震危险性。     

Seafloor spreading history of the Agulhas Basin

Data gathered by recent “Islas Orcadas” cruises reveal the seafloor spreading pattern for a region south of the Agulhas/Falkland fracture zone system. The presence of a magnetic anomaly bight about the Agulhas Plateau indicates that the Agulhas Plateau may have developed at the site of a tectonic plate triple junction during the Late Cretaceous. A westward jump in the seafloor spreading center during the Late Maestrichtian (anomaly 34?31) reduced the offset across the Falkland/Agulhas fracture zone system and resulted in the formation of two conjugate aseismic ridges here described as the Meteor and Islas Orcadas Rises. The magnetic lineation pattern in the Agulhas Basin suggests that a tectonic plate (Malvinas Plate) existed during Campanian to Maestrichtian times. Relative rates of motion are calculated for Antarctica, South America, and Africa for the Late Cretaceous.     

Mesozoic magnetic lineations in the Mozambique Basin

East-west-trending Mesozoic magnetic anomalies M2 through M22 have been identified in the northern Mozambique Basin. These anomalies are best matched by sea floor created at 50°S trending N120°E and spreading at a rate of around 1.5 cm/yr. The northward increase in age inferred from the identifications of these anomalies are compatible with observed decrease in the “reliable” heat flow values from 1.4 to 1.1 μcal/cm² s to the north in the basin. The anomalies terminate in the southern part of the Mozambique Channel against a magnetic quiet zone to the north. Both the Mozambique Basin anomalies and those recently observed off Antarctica are strong evidence in favour of a Gondwanaland reconstruction that places Dronning Maud Land against southern Mozambique, and a late Jurassic or older separation between Africa and Antarctica.     

汶川地震盆地效应的思考与建议

通过实地考察及资料搜集,统计分析了汶川地震中地貌以及局部场地条件对震害的影响。根据受灾城市所在地理位置的不同,将城市分为盆地内部（成都）、盆地边缘（都江堰、绵竹、江油、什邡）、盆地外部（北川）3类,分别统计了震害情况,分析了震害原因。发现在这次地震中盆地效应尤其明显,盆地边缘震害比较严重;盆地中部震害较轻;山区的震害比平原的严重,尤其是在两个距离比较近的山体之间的地区,除了地震灾害之外,滑坡、泥石流等次生灾害也很严重。最后对建筑抗震设计提出了几点建议。