Cenozoic fault control on ‘deep lead’ palaeoriver systems,Central Highlands,Victoria

Basaltic eruptions across the Central Highlands of Victoria have sealed in-place Early to middle Cenozoic palaeodrainage systems (also known as deep leads). The basal gravels of the deep leads have been mined extensively in the past for their rich placer-gold deposits. Detailed mapping of the distribution of all palaeorivers has been carried out using drilling results and modern aeromagnetic/radiometric surveys. The palaeochannel isopachs (including basalt and sediment) do not thicken in a modern downvalley direction. Instead, deeper depressions alternate with shallower areas. The variations in thickness, and parts of the palaeochannel courses, are controlled by a series of east-northeast-trending basement highs. The basement highs are caused by a set of east-northeast-trending (Otway Basin-style) faults visible on radar shuttle imagery in the Central Highlands. They have not previously been recognised in regional geological mapping. Most published fault trends are north – south oriented, parallel to the strike of the Palaeozoic basement rocks. Exceptions occur at Ballarat where there is an orthogonal east-northeast set mapped in underground quartz reef workings that show right-lateral strike-slip movements. The east-northeast faults show half-graben block-style rotational movement on basement, creating north- and south-facing fault scarps along the horst ridges. Where palaeochannels overlie the grabens, valleys broadened, infill thickens, and locally drainage directions may change. When the drainage cuts through the horsts, steeper incised valleys result, and this is where, in the historical past, some gold leads were ‘lost’. The initial timing of the block movement pre-dates at least the Early Oligocene to Late Miocene ages of the basal palaeovalley sediments, as shown by revised palynological dating. In places, the modern drainage divide coincides with east-northeast-trending faults. In the Ballarat area, an earlier divide accentuated by the aeromagnetic palaeodrainage mapping occurs up to 25 km south and appears to pre-date the earliest basalt flows at around 7.0 Ma. This evidence suggests the divide can change position through time by differential movements along east-northeast faults and transferral of maximum uplift to adjacent blocks.     

Advances in the study of the Crop Evapotranspiration in Changing Environment

Significant changes in the regional energy process, water recycling and the biological process have taken place due to the climate change and human activities, and the regional agriculture has been affected by these changes. It is therefore a key issue for the regional agricultural water resource management to accurately monitor and evaluate the change of crop evapotranspiration under a changing environment. The development of the evapotranspiration theory was first reviewed, and then, the driven mechanisms and the research progress of crop evapotranspiration were illustrated. The suitability of the current monitoring method and evaluation model of the evapotranspiration in the crop evapotranspiration research under climate change were analyzed. After that, the current studies of the agricultural water resources management of “ET-based” were reviewed, and finally, the research tendency of the crop evapotranspiration on the theory, methods and application management in the future were prospected.     

四川甘孜-理塘金成矿带成矿时代与构造活动的裂变径迹研究

通过对甘孜-理塘金矿带内6个金矿区的11个磷灰石和锆石的裂变径迹数据分析,并对磷灰石数据进行热历史模拟,分析讨论了甘孜-理塘金矿带的成矿时代、构造热历史和构造事件.锆石裂变径迹结果显示金成矿时代主要为82～140Ma,属早白垩世成矿,并由南往北成矿时代具有变小的趋势,其中南段为124 ～ 140Ma,中段107Ma,北段约82Ma.磷灰石年龄亦具有同样趋势,矿石年龄为14 ～ 27Ma,围岩为88～ 95 Ma.金矿带自燕山期以来,主要经历3个演化阶段,200～ 140Ma处于退火带中,为缓慢降温期,140 ～ 30Ma为相对平缓降温阶段,30Ma以来为快速降温期.从南到北降温速率依次加快,从锆石封闭温度250℃降至磷灰石封闭温度100℃的平均速率分别为1.46℃/Ma、1.67℃/Ma和2.21℃/Ma,对应的隆升速率为48.7m/Ma、55.7m/Ma和73.7m/Ma;从100℃降至地表温度的速率为3.15℃/Ma、5℃/Ma和6.07℃/Ma,对应的隆升速率为104.9m/Ma、166.7m/Ma和202.4m/Ma.甘孜-理塘带的大规模陆内隆升主要在3Ma内,平均20℃/Ma,667m/Ma,属于快速隆升,隆升量约2km.     

地震时程分析的时频联合缩减法

为了减少动态时程法的计算开销,根据地震时程记录的能量在时间-频率域内主要集中在特定时间段和低频分量中的特点,用离散小波变换,变采样率重构时程记录,以达到在时程计算时减少积分步数,节约计算时间的目的。通过有限元数值实验,表明该法可有效缩短计算时间,同时计算误差不超过5%,在工程范围内可以接受。     

深埋公路隧道在双向地震动作用下的最大动力反应分析

为了解地震对深埋公路隧道的影响,以有限元软件MIDAS/GTS对武罐高速公路小石村隧道深埋段进行了单向、双向地震动作用和自重作用下的数值分析.地震动输入采用隧址区经过基线校正的50年10％超越概率的加速度时程.结果表明:双向地震作用对隧道结构的影响明显大于单向地震作用;隧道拱脚和拱顶处为地震作用下的最危险部位;纵向与竖向地震力的共同作用对隧道结构的影响最大.地震对深埋隧道的影响不可忽略.     

Kirchhoff型偏移理论的研究历史、研究现状与发展趋势展望——与光学绕射理论的类比、若干新结果、新认识以及若干有待于解决的问题

对Kirchhoff型偏移理论的研究历史、研究现状以及在今后一段时间内的发展趋势进行了简要的回顾和评述,并对加权函数、偏移孔径、子波拉伸、振幅畸变、垂向与横向分辨率等问题进行了相对详尽的讨论。还对若干有待于解决的问题进行了探讨,并对笔者在近几年内所取得的一些与Kirchhoff型偏移理论有关的新认识和新结果进行了介绍。为了充分地顾及反射地震成像和光学成像之间的渊源关系,采用了一种新的讨论方式,即首先对Kirchhoff绕射理论的主要内容进行概略的回顾,然后再通过类比的方式引入Kirchhoff型偏移成像的基本概念和基本方程。在过去的几十年中,在Kirchhoff型偏移理论研究方面已经取得了重大进展,一个完整的理论体系已经形成。尽管如此,仍有一些遗留的或新出现的理论问题有待于解决,例如加权等时面分布叠加偏移的输出场分析和模型空间中的最优偏移孔径等等。由于Kirchhoff型偏移理论的研究对象是加权绕射叠加而不是加权等时面分布,也由于GPU/CPU协同计算技术的出现已经使得加权绕射叠加的计算量问题不再形成瓶颈,所以在今后的发展中Kirchhoff型偏移在理论和实践上将达到统一,即将在实现上从加权等时面分布回归到加权绕射叠加。与此同时,在今后一个时期内的研究重点将会与Green函数的数学表述、局部相关反射信号（locally coherent events）的表示和处理、广义加权绕射叠加以及在模型空间中定义的最优偏移孔径等问题有关。     

Zircon U–Pb ages of plutonic rocks in the southern Abukuma Mountains: Implications for Cretaceous geotectonic evolution of the Abukuma Belt

Plutonic rocks in the southern Abukuma Mountains include gabbro and diorite, fine‐grained diorite, hornblende–biotite granodiorite (Ishikawa, Samegawa, main part of Miyamoto and Tabito, Kamikimita and Irishiken Plutons), biotite granodiorite (the main part of Hanawa Pluton and the Torisone Pluton), medium‐ to coarse‐grained biotite granodiorite and leucogranite, based on the lithologies and geological relations. Zircon U–Pb ages of gabbroic rocks are 112.4 ±1.0 Ma (hornblende gabbro, Miyamoto Pluton), 109.0 ±1.1 Ma (hornblende gabbro, the Hanawa Pluton), 102.7 ±0.8 Ma (gabbronorite, Tabito Pluton) and 101.0 ±0.6 Ma (fine‐grained diorite). As for the hornblende–biotite granodiorite, zircon U–Pb ages are 104.2 ±0.7 Ma (Ishikawa Pluton), 112.6 ±1.0 Ma (Tabito Pluton), 105.2 ±0.8 Ma (Kamikimita Pluton) and 105.3±0.8 Ma (Irishiken Pluton). Also for the medium‐ to fine‐grained biotite granodiorite, zircon U–Pb ages are 106.5±0.9 Ma (Miyamoto Pluton), 105.1 ±1.0 Ma (Hanawa Pluton) and the medium‐ to coarse‐grained biotite granodiorite has zircon U–Pb age of 104.5 ±0.8 Ma. In the case of the leucogranite, U–Pb age of zircon is 100.6 ±0.9 Ma. These data indicate that the intrusion ages of gabbroic rocks and surrounding granitic rocks ranges from 113 to 101 Ma. Furthermore, K–Ar ages of biotite and or hornblende in the same rock samples were dated. Accordingly, it is clear that these rocks cooled down rapidly to 300 °C (Ar blocking temperature of biotite for K–Ar system) after their intrusion. These chronological data suggest that the Abukuma plutonic rocks in the southern Abukuma Mountains region uplifted rapidly around 107 to 100 Ma after their intrusion.     

中国明、清时期黄河和京杭大运河地图的特征与价值

黄河是中华民族的母亲河,而京杭大运河则担负着河运的重要职责,其重要性决定了古代关于黄运工程及其治理的地图数量繁多。本文旨在通过对大量明、清时期黄河、京杭大运河水利地图的梳理,对明、清时期水利地图的载体形式、表现形式和绘制特点进行剖析,并探讨其在地理学、地图学、水利学方面的应用价值和研究价值。明、清时期的黄河、京杭大运河地图,从载体形式来分,主要分为水利典籍（志书、图说）附图和绘本舆图2类：前者多为示意性地图,画法比较简单,只起到辅助说明水利典籍的作用;后者多采用山水形象画法绘制,多为长卷展开景物再现式地图,其主要特点是形象直观。其采用的“对景法”地图表现形式（即所绘黄河、京杭大运河两岸各类地物要素均朝向河流中心线）,容易引起读者的视觉共鸣,轻松构筑被描画事物的整体画面。从表现形式和绘制特点来看,明、清时期还出现了另外2类地图：计里画方类地图和经纬度实测地图,但由于其实用性和艺术性不如山水形象画法地图,因此,这2类地图在明、清并没有得到广泛普及。但从功能和价值而言,不论是长卷展开式古地图、计里画方类古地图,还是经纬度实测地图,对于古地图史、历史地理学、古代水利研究,对如今的地图、水利、地理学研究等,都是不可多得的历史瑰宝。     

单层球面网壳结构的柱顶隔震研究

以带下部混凝土支承结构的单层联方型球面网壳为研究对象,针对工程实际中支承刚度过强的情形,提出了柱顶隔震的方法,从而改善了整体结构的抗震性能。非线性时程分析表明,多遇地震作用下LRB能在一定程度上降低支座反力,且使支座反力分布趋于均匀,降低了支座设计的要求;罕遇地震作用下LRB支座基本进入塑性状态,支座反力维持在屈服力附近,与原结构相比有大幅度的降低,支座滞回曲线饱满,同时上部网壳的塑性发展程度大大减轻,基本保持为弹性,取得了良好的减震效果。     

北部湾涠洲岛珊瑚礁的研究历史、现状与特色

分析多年来涠洲岛珊瑚礁的研究成果,得出以下认识：1）近20多年来涠洲岛活珊瑚覆盖率呈快速下降趋势,北部活珊瑚覆盖率由2005年的63.70%下降到2010年的12.10%,东南部由1991年的60.00%下降到2010年的17.58%,西南部由1991年的80.00%下降到2010年的8.45%;2）处于相对高纬度区域的涠洲岛珊瑚礁,是研究全球气候变暖背景下珊瑚向高纬度或相对高纬度海域迁移的珊瑚避难所这一假说的理想区域;3）涠洲岛的珊瑚礁直接发育于火山基岩之上,是检验达尔文关于环礁成因假说的理想场所;4）涠洲岛珊瑚礁主要受到极端气候事件与人类活动的双重影响,是研究珊瑚礁响应人类活动和极端气候事件的天然实验室。因此,涠洲岛珊瑚礁除了与其他珊瑚礁一样具备重要的资源、生态与环境特征之外,还具有独特的科学研究价值,需要引起高度重视并进行有效保护,为南海珊瑚的北向迁移创造条件。