论双侧造山带——以桐柏—大别造山带为例

从双侧造山带的几何学和力学模式出发,详细地讨论了桐柏—大别造山带的构造特征。在综合地质和地球物理资料基础上,提出一个解释桐柏—大别造山带漂浮体及花状构造的运动学模式。强调指出,具有两个不同变形楔状体的桐柏—大别造山带,是由华北及扬子克拉通间在印支—燕山期斜向碰撞造成的。     

郯庐断裂带中南段的岩石圈精细结构

郯庐断裂带是中国东部规模最大的构造活动带,有着复杂的形成演化历史,对中国东部的区域构造、岩浆活动、矿产资源的形成和分布以及现代地震活动都有重要控制作用.2010年在郯庐断裂带中南段的江苏宿迁市附近,采用深地震反射探测方法对郯庐断裂带及其两侧地块的岩石圈结构进行了解剖.结果表明,该区莫霍面和岩石圈底界均向西倾,其中,地壳厚度约为31~36km,岩石圈厚度约为75~86km,且岩石圈厚度在郯庐断裂带下方出现突变.郯庐断裂带在剖面上表现为由多条主干断裂组成的花状构造,其内部发育有断陷盆地和挤压褶皱,具有伸展、挤压和走滑并存的构造形迹,暗示郯庐断裂带的形成和演化经历了多期复杂的构造活动.这一断裂带错断了近地表沉积层,向下切割莫霍面和岩石圈地幔,属岩石圈尺度的深大断裂构造系统.软流圈高温高压热物质沿断裂带的上涌、岩浆底侵或热侵蚀作用造成岩石圈出现拉张伸展和岩石圈减薄,并可能使岩石圈组构及其物质成分发生改变.本项研究结果不但可进一步加深对郯庐断裂带深、浅部结构的认识,而且还可为分析研究华北克拉通东部的深部过程和浅部构造响应提供资料约束.     

南汀河西支断裂深浅构造特征——来自深地震反射剖面的证据

云南省西南部,发育一组由不同断裂组成的北东向断裂构造带,沿这些断裂数十年来相继发生过多次强震.本文以其中的南汀河西支断裂为研究对象,采用深地震反射剖面方法,获得了断裂及两侧地壳精细结构和构造图像.探测结果表明:研究区纵向上,分为上、下两层地壳结构,总厚度约为31.25~35.6 km;横向上,以南汀河西支断裂为界,两侧反射特征差异较大,分别以弧状或倾斜反射波组为主·测线经过地区,莫霍面反射特征较为清晰,为2-3个反射同相轴组成的反射条带.南汀河西支断裂为一个由5条分支断层组成的断裂带,呈花状结构,反映了一种走滑挤压的应力状态.断裂带下方,存在一条切穿下地壳及莫霍面并延伸至上地幔的深大断裂·这种深、浅断裂共存的构造格局是控制南汀河地区地震孕育和发生的重要因素之一.     

浅层地震勘探与联合钻孔探测揭示丽江-小金河断裂隐伏段复杂花状构造特征

丽江-小金河断裂是川滇菱形块体内部重要的边界断裂,前人根据其断错地貌特征确定其为左旋走滑断层,并认为其左旋断错了SN向的丽江盆地。本文对丽江-小金河断裂丽江盆地隐伏段开展了浅层地震勘探与钻孔探测,通过地层岩性分析建立跨断层的钻孔联合剖面,揭示丽江-小金河断裂斜穿了丽江盆地,隐伏段整体形式为不对称正花状构造,表现为断展褶皱和逆冲断层,但主断层顶部表现为局部拉张,断错了晚第四纪地层。     

传统节庆在地方认同建构中的意义——以广州“迎春花市”为例

节庆是地理学研究地方认同的一个重要视角。广州“迎春花市”与广府人“年卅晚行 花街”的传统民俗密不可分。一年一度的地方民俗节庆“迎春花市”作为广府地区的特质文 化形式, 在塑造地方认同中具有独特意义。本文基于新文化地理学视角, 采用问卷调查、参 与式观察、深度访谈等方法来搜集数据, 对问卷数据利用SPSS17.0进行频数统计、描述性统 计分析、数据质量分析、因子分析和单因子方差分析, 对访谈记录、网络资料等定性资料进 行文本分析。结果显示:(1)地方认同形成过程包含认知、情感和意向三个心理过程, 迎春 花市在这三个层面上都对地方认同的建构有积极作用。特别是, 政府尊重民意举办花市之举 措有利于促进地方认同的建构;(2)广州世居居民、父辈移居广州者、己辈定居者三类群体 对迎春花市的认同过程存在一定差异。尽管, 节庆能很好地将不同群体整合进更大的社区, 但是新来者要成为“本地人”,建立起地方认同仍需假以时日。这些发现将有助于理解广州不 同文化身份市民的文化融合及地方认同的形成原因     

基于眼动实验方法的城市开敞空间视觉研究 ——广州花城广场案例

以广州花城广场为案例,通过设计以认知地图、照片拍摄以及眼动实验环节的视觉研究方法,对花城广场的空间感知进行分析。结果表明：1）通过分析认知地图以及眼动数据可以发现,认知地图中高频率出现的要素和眼动实验得出的参与者感兴趣要素相一致,花城广场的建筑物、边界、场所和区域是参与者比较感兴趣的要素,以上要素在眼动实验中首次进入时间短,在认知地图中出现频率高;2）通过分析注视点注视时间热点图,可以得出在城市开敞空间的规划中应注重建筑物、构筑物、装置和场地的合理结合,注重空间层次和空间秩序,注重营造场所的规划设计结论。在应用上,照片拍摄、眼动实验等视觉的神经科学研究方法的使用可以为城市开敞空间的规划设计提供公众参与的新思路。     

Nanjinganthus is an angiosperm,isn’t it?

Nanjinganthus is an Early Jurassic angiosperm recognized based on the study of over 200 specimens. However, some other authors have misinterpreted these fossils. Here the authors try to remedy the problems, by pointing out the logical pitfalls in these publications and underscoring a long-used, workable criterion for early angiosperms. The paper explains the cons and pros of this criterion, hoping to bring palaeobotany and plant taxonomy back to a consistent and practical track. Nanjinganthus is an angiosperm.     

Structural architecture of the northern composite terrane, the Eastern Ghats Mobile Belt, India: Implications for Gondwana tectonics

New data from structural mapping and tectonic evaluation in the northern parts of the Eastern Ghats Mobile Belt (EGMB-north) involving the interpretation of satellite images, field traverses, critical outcrop mapping and kinematic studies of macro- as well as microstructures of the shear zone rocks together with the geometry and disposition of Gondwana basins led to, for the first time, the elucidation of post-Grenvillian structural architecture of the terrane. This helps in assessing the sequence of successive tectonothermal events that were responsible for the origin and progressive evolution of the Permo-Carboniferous coal bearing sediments along the Mahanadi rift that forms significant in the reconstruction models of east Gondwana.The composite terrane of high-grade metamorphic rocks (EGMB-north), strikes E–W in contrast to the regional NE–SW trend of the EGMB. The structural architecture obtained from this study is controlled by the boundary shear zones and associated link shear zones. The dextral kinematic displacements along the Northern Boundary Shear Zone (NBSZ) as well as the Mahanadi Shear Zone (MSZ) and Koraput–Sonapur–Rairakhol Shear Zone (KSRSZ) were derived from multi-scale field based structural observations. A N–S structural cross-section presents a crustal-scale ‘flower structure’ across the composite terrane exposing different domains displaying distinctive internal structures with widely varying different geological evolution history and strain partitioning, separated by crustal-scale shear zones. Deep seismic imaging and gravity signatures support ‘flower structure’ model. The pervasive first formed gneissic fabrics were continuously reworked and partitioned into a series of E–W, crustal-scale shear zones.The Neoproterozoic regional dextral transpressional tectonics along the shear zones and their repeated reactivation could be responsible for initiation and successive evolution of Gondwana basins and different episodes of sedimentation. Available geochronological data shows that the structural architecture presented here is post-Grenvillian, which has been repeatedly reactivated through long-lived transpressional tectonics. The composite terrane is characterized by all the typical features of an oblique convergent orogen with transpressional kinematics in the middle to lower crust. The kinematic changes from transpression to transtensional stresses were found to be associated with global geodynamics related to the transformation from Rodinia to Gondwana configuration.