汶川地震震前与同震断层滑移的比较分析

本文利用GPS观测的1999-2007年汶川震前3期地表变形数据和2008年汶川同震地表变形数据,结合地震位错理论,通过高斯变换和坐标旋转建立断层模型,运用遗传算法,反演了龙门山断裂带断层震前3期和同震滑动参数。结果表明龙门山断层震前3期平均走滑位移为-5.39mm,倾向位移为2.66mm,与同震断层滑移相比较,发现震前断层的滑移趋势与同震断层滑移一致,均为逆冲兼右旋的挤压运动。比较震前3期逆冲方向的滑移量,发现逆冲滑移有加速的现象。并根据震前和同震的断层滑动量估算了汶川地震复发周期。     

东北印度洋沉积岩芯热释光与古气候变化

孟加拉深海扇中扇的MD77181和下扇的MD81345岩芯沉积物天然热释光变化与古气候变化有明显的对应关系,岩芯记录的时间跨度约300 ka BP.将两支岩芯的热释光测量结果与δ18O、CaCO3含量和磁化率结果对比后发现,热释光强度与磁化率变化存在显著的一致性.它们与间冰期和冰期气候变化的对应关系表现为:间冰期,风化作用减弱,输入海洋的陆源性矿物减少,对碳酸盐的稀释作用低于冰期,热释光和磁化率同时降低.此时,热释光强度随碳酸盐含量的增加而增大,说明沉积物热释光主要来自于碳酸盐矿物的贡献,表现为海进沉积环境特征.在冰期,陆地风化作用加强,输入海洋的陆源性矿物增加,对碳酸盐的稀释作用增强,热释光强度随陆源物的增多而增强,热释光和磁化率同时增大.说明沉积物热释光主要来自陆源矿物,表现为海退沉积环境特征.     

《活动断层的地震地表永久位移研究》简介

震害调查表明近场的结构破坏不仅由地震动引起,地表破裂或永久位移引起的破坏也占很大比重。近年来的汶川地震、集集地震、昆仑山口地震、土耳其伊兹米特地震等都引起了大规模的地表破裂,其可能对道路、桥梁、隧道、大坝、输油（气）管网、通讯电缆等大型工程造成严重破坏,导致巨大人员伤亡和资产损失。另外,目前各类抗错动构件的实际应用也促使地震地表永久位移与地震动一样,成为工程结构的地震输入。因此,活动断层的地震地表破裂研究已经成为地震工程中关注的焦点课题之一,地表永久位移的分布特征对防震减灾具有十分重要的工程意义和理论价值。     

An Overview of Paleo-AO/NAO Studies

The discovery of decadal variability of North Atlantic Oscillation (NAO) and the introduction of Arctic oscillation (AO) concept have initiated a series of paleo-AO/NAO related studies since the mid-to-late 1990s. The progress and new findings of paleo-AO/NAO works after that time were comprehensively reviewed. The new results from the observations and modelings at four key timescales were summarized in detail: ①the reconstructions of the AO/NAO annual index over the past millennium; ②the debate on AO/NAO’s trend since early Holocene; ③the weakening of AO/NAO’s amplitude during the Last Glacial Maximum; and ④the anomalous positive phase of AO/NAO during the Last Interglacial. In addition, the possible mechanism for different timescales of AO/NAO is also summarized. Furthermore, the distinction between AO/NAO’ was mean state and amplitude, which were not explicitly separated in previous studies, were comprehensively discussed. Considering the current uncertainties related to paleo-AO/NAO studies, we encourage the community to search for more proxies having longer-than-10,000-year length with annual resolution around AO/NAO highly correlated regions. Another, we encourage long-term transient modeling on AO/NAO can be performed in order to improve our understanding of the dynamics and interaction between AO/NAO’s high-frequency variability and the climatological background, so as to further improve AO/NAO’s predictability on global warming context.     

近20年来湖南公路网络优化与空间格局演变

基于最短路径模型,以经济权重可达性和经济潜力指数为主要指标,对近20年湖南公路网络演化和空间格局进行分析。结果表明:1984~2004年,湖南公路网络通达性呈现以长株潭为核心的同心圈层结构,呈现"中心-外围"向外递减,到2004年等值线密度趋于平缓,显示以长株潭为强极,外围湘北(岳阳)、湘南(郴州)为次极和湘西(怀化和吉首)为弱极的空间结构;20年来,湖南省内部可达性绝对差距逐步缩小,相对差距逐步加大,经济发展潜力以长株潭为核心沿主要交通轴线呈指状递减。可达性和经济结构相关分析表明,湖南空间结构由1980年代的低级无序状态变为2004年的多核不均衡集聚扩散状态,未来需要大力优化湘西地区可达性和加快经济的发展,促进空间格局向均衡有序的方向发展。     

水文地质分析方法在建水区域地下水宏观异常分析中的应用

通过对云南省建水县多次地下水宏观异常实例的分析,提出充分了解当地水文地质情况,掌握不同地质条件下地下水的运移规律以及不同类型地下水的物理、化学特征等基本知识,可以对地下水宏观异常是否属于由构造活动引起的地震异常作出判断。     

Early Cretaceous porphyry copper mineralization in Northeast China: the Changfagou example

The Changfagou Cu deposit is a newly discovered porphyry deposit located in the southern Jilin Province of Northeastern China, on the northeastern margin of the North China Craton. To better understand the formation of the Cu deposit, we report the zircon U–Pb and molybdenite Re–Os dating, and Sr-, Nd-, and Hf- isotopic data of the granite porphyry. LA-ICP-MS dating of zircon grains from two mineral zones in the granite porphyry yield ages of 115.7 ± 0.8 and 115.3 ± 0.6 Ma, which is interpreted as the emplacement age of the granite porphyry. The molybdenite Re–Os model ages of 112.5 to 113.8 Ma, an isochron age of 113.3 ± 1.3 Ma, and a weighted mean model age of 113.0 ± 0.7 Ma, which represents the age of the Cu mineralization quite well. The Changfagou granite porphyry samples lack amphibole and muscovite, and are compositionally characterized by high SiO₂, high Na₂O+K₂O, and low P₂O₅, enriched in some Rb, Th, U, and Pb, and depleted in Nb, Ta, Ti, P, and Eu. Mineralogical and geochemical features suggest that the Changfagou granite porphyry samples are slightly peraluminous and are of highly fractionated I-type granitoids. The granitic rocks also have relatively high (⁸⁷Sr/⁸⁶Sr)_i (0.71199 to 0. 71422), and both low εNd(t) (?14.56 to ?13.19) and εHf(t) values (?14.916 to ?8.644), which suggest that Changfagou granite porphyry are derived from mixed sources of crustal and mantle, and diagenesis and mineralization were possibly related to the switch in subduction direction of the Palaeo-Pacific Plate in the late phase of Early Cretaceous.     

瓦片金字塔模型技术的研究与实践

海量栅格数据的简化与压缩是近年来三维GIS领域的研究热点。本文在研究瓦片金字塔技术的前提下,基于线性四叉树结构,采用重采样、分层分块的方法构建了海量栅格数据的瓦片金字塔模型,并以该模型为基础设计实现了一个Web3DGIS平台。实验证明,本文设计的平台能够满足海量地形及影像数据的实时三维可视化要求。     

基于GIS的测量控制点管理信息系统的设计与实现

随着城市建设项目的迅速增加,测绘部门在城区内建立的控制点也正在逐步加密.控制点被破坏的可能性逐渐增加,其资料的更新也变得异常频繁.采用传统手工方式对控制点资料进行管理已不能满足信息化测绘工作的需要.为此,本文在.NET开发平台的基础上利用ArcGIS Server和ArcSDE相关技术设计并构建了测量控制点管理信息系统.该系统实现了测量控制点地图发布、控制点高效查询、控制点在线编辑等功能,有效地完善了对测量控制点的信息化管理.     

湖南柿竹园钨多金属矿床成矿机理的实验研究

作者在深入柿竹园钨多金属矿床野外地质工作的基础上，采用矿区燕山期花岗岩和泥盆系灰岩作为试料，在含ｐＨ＝４．０的０．３ＭＮａＣｌ＋０．７ＭＫＦ水溶液的高压釜中持续了１２０小时的交代作用。实验的结果表明了：在４００～７００℃的温度和２５０×１０５～９００×１０５Ｐａ的压力下，形成的交代岩及其钨、锡、钼、铋矿物基本上与矿区的矽卡岩及其矿石矿物共生组合相吻合，揭示了湖南柿竹园矽卡岩型钨多金属矿床成矿的机理