Allende(CV3)陨石中一种特殊蠕虫状橄榄石集合体的矿物岩石学特征及其成因探讨

在通过对Allende(CV3)碳质球粒陨石的4个光薄片中发现的5个特殊蠕虫状橄榄石集合体(AOA)的岩石学和矿物化学特征研究,证实它们的矿物组合以富橄榄石和霞石为特征,可见少量的金属硫化物。橄榄石颗粒Fa(Fe/(Fe Mg)原子百分比)值范围在34.1 mol%～42.2 mol%,百分标准平均方差(PMD)值为6.1,表明这些颗粒达到了一定的热力学平衡。AOA可能属于星云直接凝聚形成,AOA和细粒CAI(FTA和富尖晶石-辉石型CAI)可能代表了太阳星云从高温到低温连续凝聚的产物。认为AOA的蚀变作用发生在太阳星云中,霞石和铁橄榄石可能是后期水化蚀变的产物,霞石可能替代了AOA中原始的矿物——钙长石和黄长石等。AOA可能在星云中还经历了热蚀变作用的过程,橄榄石和霞石颗粒均具有高的FeO质量分数(29.1%～34.4%,4.04%～9.70%),表明蚀变反应发生在高逸氧度的星云环境下。     

摄影地质快速编录的关键技术研究

针对现行水电工程、地下工程施工地质编录方法的不足,进行了摄影地质快速编录技术与方法的研究。在数字相机量测化改造的基础上,综合应用近景摄影测量、图像处理和GIS技术,设计开发了基于数字相机的摄影地质编录信息系统。该系统以高边坡、大洞室为对象,具有数字摄影、正射影像制作、图像镶嵌、编录要素提取与产状量测、编录成果CAD制图等功能,实现了数据采集、机助处理与成图的一体化作业模式,提高了地质编录的工作效率和成图精度,为施工地质编录提供了新的手段与途径。     

A survey of natural aggregate properties and characteristics important in remote sensing and airborne geophysics

Natural aggregate is vital to the construction industry. Although natural aggregate is a high volume/low value commodity that is abundant, new sources are becoming increasingly difficult to find and develop because of rigid industry specifications, political considerations, development and transportation costs, and environmental concerns. There are two primary sources of natural aggregate: (1) exposed or near-surface bedrock that can be crushed, and (2) deposits of sand and gravel. Remote sensing and airborne geophysics detect surface and near-surface phenomena, and may be useful for detecting and mapping potential aggregate sources; however, before a methodology for applying these techniques can be developed, it is necessary to understand the type, distribution, physical properties, and characteristics of natural aggregate deposits.The distribution of potential aggregate sources is closely tied to local geologic history. Conventional exploration for natural aggregate deposits has been largely a ground-based operation, although aerial photographs and topographic maps have been extensively used to target possible deposits. Today, the exploration process also considers factors such as the availability of the land, space and water supply for processing, political and environmental factors, and distance from the market; exploration and planning cannot be separated.There are many physical properties and characteristics by which to judge aggregate material for specific applications; most of these properties and characteristics pertain only to individual aggregate particles. The application of remote sensing and airborne geophysical measurements to detecting and mapping potential aggregate sources, however, is based on intrinsic bulk physical properties and extrinsic characteristics of the deposits that can be directly measured, mathematically derived from measurement, or interpreted with remote sensing and geophysical data. On the cover: Northward view of alluvial fans along San Luis Valley, southcentral colorado. This image was created in the U.S. Geological Survey (USGS) Remote Sensing laboratory by digitally draping SPOT panchromatic satellite data resampled to 30 meters pixels resolution over the 124,000 USGS DEM of the Bonanza, Whle Hill, Bushnell Peak, Graveyard Guich, Klondike Mine, and Villa Grove quadrangles.     

南海北部地壳的深地震地质结构探测

１９９３年５月，中国科学院南海海洋研究与日本东京大学地震研究所等单位合作南海北部共同开展了综合地球物理测量实验，本文介绍了其中的海底地震仪海上资料采用，室内资料处理，根据资料的初步处理解释结果，文中分析了测区的地壳地质结构。     

黄土塬区二维地震施工技术初步研究

某勘探区位于宁夏回族自治区南部固原市,具黄土高原地貌特征：黄土冲沟发育,地形切割剧烈,部分沟壁近乎直立,地形总体北低南高,最大高差大568m。该区基岩少有裸露,大多数被第四系所覆盖,盖层厚度一般大于100m,地震激发条件属Ⅲ类区,原始资料存在严重的静校正问题。该区目的层主频率为30Hz,通过试验,采用井深20m、药量3kg及多井组合激发,同时增加排列长度,提高覆盖次数等野外技术措施,改善资料品质。     

煤炭高密度空间采样地震勘探方法研究及应用效果

高密度空间采样地震勘探技术在野外采用单点激发、单点接收,可有效避免野外组合时差对高频的影响及组合产生的接收各向异性问题,并有利于室内对规则干扰进行压制。通过开展高密度空间采样试验,对高密度勘探技术中空间采样密度与分辨率的关系,高密度激发技术、静校正、高保真室内组合方法、噪声压制方法及三维去噪最小数据集抽取方法等关键技术进行了总结。以HNDJ区的高密度地震勘探项目为例,高密度地震勘探获得的新剖面,其各煤层的反射特征都比过去普通三维资料有明显提高,特别是Td波。对该区的高密度空间采样数据利用多种地震属性对断层进行识别,新发现6～8m的断层2条,尤其2m断距的断层显示的也非常清晰,实例表明高密度空间采样地震勘探技术,可提高地震勘探的成像精度。     

A multi‐asperity plastic‐contact crack plane model for geomaterials

A mechanistic constitutive model for fully formed cracks in geomaterials, such as concrete and rock, is presented. A three‐dimensional characterisation of the crack morphology is employed in which the crack surface is idealised as a series of conical teeth and corresponding recesses of variable height and slope. Based on this geometrical characterisation, an effective contact function is derived to relate the contact stresses that develop on the sides of the teeth to the net stresses on a crack plane. Plastic embedment and frictional sliding are simulated using a local plasticity model in which the plastic surfaces are expressed in terms of the contact surface function in cylindrical relative displacement space. Finally, the performance of the model is assessed against several sets of experimental data from direct shear tests, and it is concluded that the model is able to capture key characteristics of the behaviour of fully formed cracks in geomaterials. Copyright © 2012 John Wiley & Sons, Ltd.     

低剂量水泥稳定粒料基本性能

我国长久以来使用的半刚性基层发展到今天已广泛采用水泥稳定粒料基层,低剂量水泥稳定粒料基层与此类似但减少了水泥用量,从经济上和防止反射裂缝两个方面改善了水泥稳定粒料基层的性能。首先从级配角度出发,分析了级配对水泥稳定粒料强度的影响,规定了各级级配的控制点。然后从水泥稳定粒料基层强度与水泥用量的关系出发,按相同的集料级配,针对不同的水泥用量绘制了其最大干密度和含水量的关系曲线。最后按抗压强度和CBR值对比了不同水泥剂量间及与级配碎石的强度变化情况,验证了低剂量水泥稳定碎石基层应用的可能性。     

Benthic control upon the morphology of transported fine sediments in a low‐gradient stream

The structure of fluvial sediments in streams has environmental implications to contaminant fate, nutrient budgeting and the carbon flux associated with fine particulate organic matter (FPOM). However, the influence of sediment structure is lacking in environmental predictive models. To this end, the present study links field‐based results of sediment aggregate structure to seasonal biological functions in the surface fine‐grained laminae (SFGL) of a low‐gradient stream. Fluvial sediment collection, microscopy and image analysis are used to show that aggregates collected over a 20 month time period support the concept that aggregate structure can vary seasonally in low‐gradient streams where temporarily stored sediment is prominent. Results show that the structure of the transported aggregates is more irregular in the summer with the structure being elongated about the long axes. In the winter, the aggregate structure is compacted and more spherical. Statistical analysis and results suggest that heterotrophic and autotrophic biological activity within the SFGL exhibits seasonal control upon the morphology of transported sediments. Implications of this research are highlighted through calculations of the reactive surface area of the transported suspended sediment load. The surface area of transported sediment is estimated to be 40% greater in the summer as compared to the winter time period, which implies that (i) the affinity of sediments to sorb contaminants is higher in summer months and (ii) the downstream reactivity of FPOM in large rivers, lakes and estuaries is not just a function of microbial drivers but also the seasonally dependent structure of transported FPOM derived from low‐order streams. Copyright © 2013 John Wiley & Sons, Ltd.     

陇东巨厚黄土塬区地震勘探数据采集方法研究

陇东巨厚黄土塬区,由于表层地震激发条件复杂多变,潜水面深,反射波衰减强烈,导致目的层反射波难以分辨,为此在陇东地区的多个地震勘探项目中有针对性的进行了多井组合、井深对比、检波器组合等一系列试验及分析研究。结果表明在黄土塬地区可使用中密度成型炸药,多井组合激发,且井越深记录质量越好;检波器采用9串2并或9串线形组合,组内距2m,可有效压制随机干扰;观测系统须根据不同地貌条件进行选择,在黄土塬上宜采用多道、小炮间距、小偏移距、高覆盖等直线观测系统;而在黄土沟、坡中,可采用弯线观测系统,并适当减少道数及覆盖次数、增大炮间距及偏移距等;在沟塬过渡段为避免出现空白段,应采用变观系统。