西藏塔惹增地区上石炭统—下二叠统拉嘎组火山岩夹层的发现及其地质意义

冈底斯带广泛分布晚古生代火山岩地层。岩石学、地球化学特征表明,冈底斯带的构造属性在晚古生代已经发生转变。在冈底斯带中西部塔惹增地区晚石炭世—早二叠世拉嘎组中发现了火山岩夹层。根据岩石地球化学特征分析,该火山岩属岛弧环境,标志着晚古生代冈底斯发生首次造弧作用,该时期冈底斯中西部已经由被动大陆边缘向主动大陆边缘转化。     

冻融条件下浅层黄土中温度与水分的空间变化相关性

黄土高原是西北典型的季节性冻土区,在黄土斜坡冻结和融解过程中土体内的温度、水分变化显著,导致土体中含水量及地下水位发生相应的变化,诱发一系列的滑坡、崩塌等地质环境问题。选择甘肃永靖县黑方台黄土斜坡为研究区,原位监测冻结至融解过程中黄土的温度和含水量,研究冻融条件下黄土斜(边)坡冻结层温度和水分及变化特征及其关系。结果表明,本次监测点黄土冻结深度为52cm,黄土剖面温度表现为3个特征带:温度稳定传递带、温度变动带、温度交替显著带。温度在黄土斜(边)坡冻融过程中对水分具有控制性作用,含水量随温度变化划分为3个阶段:1小于2℃,含水量随温度呈现非线性递增趋势;22~6℃,含水量随温度呈现波动性下降;3大于6℃,水分由小幅增加直至稳定,温度影响权重减小。随着冻结土层完全融解,被冻结水分融解后向下运移,最终导致剖面含水量急剧增加,因此,冻结至融解过程中含水量发生急剧增加,是导致浅层黄土滑塌的重要因素。     

大气CO2浓度时空变化卫星遥感监测的应用潜力分析

GOSAT卫星观测反演大气CO2浓度精度已经提高到了1—2 ppm,而卫星数据能否准确地揭示全球和区域大气CO2浓度变化特征还缺乏充分的评价与分析。本文针对已经连续运行观测3年的GOSAT卫星,收集了来自美国NASA-OCO团队(ACOS)和日本环境研究所GOSAT团队(NIES)基于各自算法反演的两套大气CO2柱浓度数据,描述并分析了全球大气CO2时空变化特征。分析结果表明,从XCO2反演的绝对值结果来看ACOS总体上比NIES的高出约2 ppm左右,但从时空的相对变化上它们揭示了相近的大气CO2浓度时空变化特征。两套数据显示出全球平均大气CO2浓度在2010年—2012年的3年期间年增量分别为1.8 ppm和2.0 ppm;季节变化幅度,北半球最大4—6 ppm,南半球最大约2 ppm,这与地面观测结果基本一致。进一步将EDGAR 4.2人为排放总量格网化数据与GOSAT卫星观测反演的CO2浓度进行相关统计分析,结果指出两套数据对人为排放量有着微弱的响应。本文结果指出目前GOSAT卫星观测反演的XCO2可以检测出全球和区域大气CO2浓度的年变化、季节变化和区域空间变化的特征;GOSAT卫星10.5 km空间分辨率的观测虽难于检测出点源的浓度变化,但从区域上对人为排放的累积效应的监测显示了一定的应用潜力。     

Comparison of basin morphometry derived from topographic maps,ASTER and SRTM DEMs: an example from Kerala,India

The drainage network of a sixth-order tropical river basin, viz. Ithikkara river basin, was extracted from different sources such as Survey of India topographic maps (1: 50,000; TOPO) and digital elevation data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) (30 m) and Shuttle Radar Topography Mapping Mission (SRTM) (90 m). Basin morphometric attributes were estimated to evaluate the accuracy of the digital elevation model (DEM)-derived drainage networks for hydrologic applications as well as terrain characterization. The stream networks derived from ASTER and SRTM DEMs show significant agreement (with slight overestimation of lower order streams) with that of TOPO. The study suggests that SRTM (despite the coarser spatial resolution) provides better results, in drainage delineation and basin morphometry, compared to ASTER. Further, the variability of basin morphometry among the data sources might be attributed to spatial variation of elevation, raster grid size and vertical accuracy of the DEMs as well as incapability of the surface hydrologic analysis functions in the GIS platform.     

WGS-84&CGCS2000坐标基准转换参数的初步求取

针对WGS-84CGCS2000坐标基准差异问题,分析了用于估计基准转换参数的Bursa模型及其求解方法,初步尝试求取WGS-84CGCS2000的坐标基准转换参数。算例采用了中国区域内含有CGCS2000坐标值,同时安装有GPS接收机的21个观测站,并针对点位的区域分布问题,提出利用重心化的Bursa模型求解转换参数的思路,且得到一组较好的转换结果。     

Geology and tectonics of Neoproterozoic salt diapirs and salt sheets in the eastern Willouran Ranges,South Australia

Allochthonous salt structures and associated primary and secondary minibasins are exposed in Neoproterozoic strata of the eastern Willouran Ranges, South Australia. Detailed geologic mapping using high‐quality airborne hyperspectral remote‐sensing data and satellite imagery, combined with a qualitative structural restoration, are used to elucidate the evolution of this complex, long‐lived (>250 Myr) salt system. Field observations and interpretations at a resolution unobtainable from seismic or well data provide a means to test published models of allochthonous salt emplacement and associated salt‐sediment interaction derived from subsurface data in the northern Gulf of Mexico. Salt diapirs and sheets are represented by megabreccias of nonevaporite lithologies that were originally interbedded with evaporites that have been dissolved and/or altered. Passive diapirism began shortly after deposition of the Callanna Group layered evaporite sequence. A primary basin containing an expulsion‐rollover structure and megaflap is flanked by two vertical diapirs. Salt flowed laterally from the diapirs to form a complex, multi‐level canopy, now partly welded, containing an encapsulated minibasin and capped by suprasalt basins. Salt and minibasin geometries were modified during the Late Cambrian–Ordovician Delamerian Orogeny (ca. 500 Ma). Small‐scale structures such as subsalt shear zones, fractured or mixed ‘rubble zones’ and thrust imbricates are absent beneath allochthonous salt and welds in the eastern Willouran Ranges. Instead, either undeformed strata or halokinetic drape folds that include preserved diapir roof strata are found directly below the transition from steep diapirs to salt sheets. Allochthonous salt first broke through the diapir roofs and then flowed laterally, resulting in variable preservation of the subsalt drape folds. Lateral salt emplacement was presumably on roof‐edge thrusts or, because of the shallow depositional environment, via open‐toed advance or extrusive advance, but without associated subsalt deformation.     

港口城市空间格局、发展趋势及借鉴——以南非德班为例

港城空间结构一直是港口城市发展的重要内容,经济全球化背景下的国际港口普遍呈现由贸易和物流综合中心向港口及港际联盟发展的态势。南非与中国同属于发展中国家,南非德班属于非洲的门户型港口城市且处于向港际联盟发展的阶段,就港城关系来看德班港在城市中发挥主导作用且呈继续上升的趋势。因此本文选取德班港为主要研究案例,运用文献综述、专题地图分析及数据比较法,从港口对城市城乡结构、土地利用的空间布局、产业集聚及城市交通的影响方面分析,总结发展中国家处于此阶段的门户型港口城市内部空间布局结构特点,并对港城空间结构的发展提出建议。     

图解法和矩值法计算西台吉乃尔盐湖沉积物粒度参数的差异

柴达木盆地西部的西台吉乃尔盐湖既是研究成盐演化的典型湖泊,也是一个重要的盐湖资源产地。盐湖沉积物的粒度组成记录了湖泊沉积环境和动力条件的变化,对于理解盐湖的形成演化具有指示意义。目前有关盐湖沉积物粒度参数(平均粒径、标准偏差、偏度和峰度)计算的报道较少。采用Beckman Coulter LS 13320激光粒度仪测定了西台吉乃尔盐湖沉积剖面(XT剖面,240 cm厚)121个样品的粒度组成,并对图解法和矩值法计算出来的粒度参数进行了比较。分析结果表明,1)图解法和矩值法得出的平均粒径和标准偏差非常一致,二者可以相互替代;2)两种方法得出的偏度和峰度存在显著差别,二者不可替代;3)矩值法计算整体考虑了样品粒度的频率分布特征,得到的粒度参数比图解法更全面。