The use of the natural gamma log in engineering geological investigations

The natural gamma log is widely used in both cased and uncased boreholes to identify changes in lithology down the length of a borehole. This is particularly important in the ground investigation process where 100% core recovery is often not achieved in the borehole programme. In this paper the use of the gamma log to provide additional information from the ground investigation boreholes is examined and illustrated by a number of case histories. It is shown that the gamma log can be used to study both the lithological variations within an individual borehole and changes in geological structure across a construction site. It is also demonstrated that a geological formation or sequence can be classified in terms of its natural gamma signature, which enables the geologist to observe its presence over large distances on a regional basis. The importance of the calibration of the gamma sonde and the use of the correct logging speed is emphasised in the paper. The successful calibration of the log against a quarry wall using a known observed geological structure as a reference is also described together with the use of the resulting information to obtain a geological log for boreholes drilled behind the quarry face. Its use in extrapolating between boreholes to detect and trace the presence of a particular geological formation to estimate its vertical and lateral extent for possible extraction is also discussed.     

中东T油田灰岩储层自然伽马能谱测井的应用

中东地区T油田主力含油储层受高放射性物质影响,导致利用常规自然伽马测井资料无法合理求取泥质含量。同时,由于岩芯分析资料较少,确定各主力含油储层的黏土类型就显得比较困难。针对这些问题,笔者基于自然伽马能谱测井中铀、钍、钾与地层中黏土矿物的密切关系,利用无铀伽马测井资料对泥质含量进行了合理计算,参考斯仑贝谢理论交会图版,利用钍与钾交会图法确定了黏土类型,通过制作钍与铀比值的直方图对沉积环境进行了研究,取得了较好的应用效果,为油田后期的开发提供了更加可靠的资料支持。     

基于自然伽马测井数据的铀资源评价方法研究

“煤铀兼探”“油铀兼探”是当今的研究热点,利用煤、油气田钻井的测井资料评价铀资源潜力是尚待解决的难题。以鄂尔多斯盆地彭阳铀矿区为例,开展基于自然伽马测井数据的铀资源评价方法探索。根据彭阳铀矿区砂岩型铀储层自然伽马异常响应显著的特性,通过对比分析9个验证孔中定量伽马和油田钻孔中自然伽马测井数据,研究彭阳铀矿区矿层定量伽马值的自然伽马测井回归模型,研发矿层平米铀量筛选计算程序。初步建立基于自然伽马测井信息的区域铀矿层识别和品位评价方法,研究成果精度与实测数据吻合,解决了难以高效利用常规煤、油气田测井资料进行铀矿层识别和品位评价的问题。该成果可为鄂尔多斯盆地铀资源调查和潜力评价提供有效的技术支持。      

自然伽马曲线应用于古气候、古环境研究——以柴达木盆地七个泉地区古近-新近纪地层为例

关于全球气候变化过程的研究一直是国内外关注的焦点,而将GR曲线应用于重建古环境、古气候方面的工作目前还处于尝试性阶段。本文在研究七23井GR曲线的基础上,利用水体盐度、古生物化石资料加以验证,发现GR曲线可以敏感地反映古气候、沉积环境的变迁。并据此完整恢复了研究区干旱气候→暖湿气候→干旱气候的4次波动,扇三角洲相与滨浅湖相的交替沉积,水体在湖盆扩张与收缩过程中浅→深→浅的变化。且在GR值下降→气候变干→水体变浅的普遍规律下,总结出波频高低和波幅大小的一系列组合可以较为详尽的反映沉积环境信息。同时GR曲线的突变有记录短时间内沉积环境及气候突变事件的能力,由此可提取出研究区与青藏高原隆升有关的古地理信息。故GR曲线能够成为恢复古环境、古气候的有用参考指标。     

天然黑钨矿可见光催化活性的实验研究

天然半导体矿物具有优良的日光催化特性。本研究选取天然钨酸盐作为研究对象,对武鸣、栗木、崇义3个不同矿区的天然黑钨矿进行了矿物学及光催化实验探究。利用X射线衍射、拉曼光谱、红外光谱、电子探针微区分析对天然样品的结构与成分进行分析,鉴定其主要矿物相为黑钨矿(Fe,Mn)[WO4],从武鸣、栗木到崇义矿区,Fe/Mn摩尔分数比从7.1、0.9到0.3依次降低。利用紫外可见漫反射测得武鸣、栗木、崇义地区样品禁带宽度分别为1.5、1.6和1.7eV,说明其具有良好的可见光响应。在pH为7的条件下用质量浓度为1g/L的样品对5mg/L的有机染料亚甲基蓝(MB)进行光催化实验(含0.01mol/L H2O2 ),结果表明武鸣地区黑钨矿实验组降解MB的效果最佳,3h后其效率分别是栗木、崇义地区样品的1.1倍和1.6倍。电子顺磁共振谱检测结果显示,反应过程中均产生氧化性羟自由基(·OH),其中效果最好的武鸣黑钨矿产生的·OH信号更强;不同自由基捕获实验证明·OH在光催化反应过程中起主要作用。进一步选取武鸣黑钨矿开展光催化降解机制研究,实验结果显示:光照下黑钨矿与H2O2共存的实验组对MB的脱色降解率可达99%(3h),只有黑钨矿的对照组降解7%的MB,只有H2O2 的对照组降解31%的MB;黑暗条件下,同时添加黑钨矿与H2O2的对照组对MB的去除率为34%。不同H2O2 浓度条件下黑钨矿降解MB符合准一级动力学方程,说明降解过程与催化剂含量无关,H2O2 更多的是充当电子受体。分析认为,不同产地黑钨矿日光催化效率与矿物铁含量呈正相关,与禁带宽度呈负相关,推测其反应机理是光催化与芬顿反应协同产生的·OH将MB氧化降解。本研究为开发利用天然矿物治理环境污染提出了新方法。     

On the natural floatability of sulfides

A system is presented in which an atmosphere containing less than 10^?6 mole fraction oxygen and water containing less than 5 ppb oxygen can be maintained. Flotation of chalcocite, chalcopyrite, galena, pyrite and sphalerite in this system reveals that these minerals are naturally floatable under these conditions.     

Modeling the natural degradation of earthworks

Stratigraphic, topographic, and ground‐penetrating radar data obtained from a ca. 1800‐year‐old embankment and adjacent ditch at the Hopewell Mound Group (Chillicothe, Ohio) are used to validate the archaeological application of a simple finite‐differences diffusion model employed frequently to assess geomorphic change in natural landscapes. Although diffusion models have been used to describe the topographic degradation of landforms in a variety of geomorphic terrains, the approach has not been applied to ancient earthworks in an archaeological context. The results of this study indicate that a variety of initial earthwork forms can result in the sinusoidal profile apparent on the current landscape. Using the model results to interpret the field data, we suggest that the initial embankment form was steeper and the adjacent ditch was deeper. As a result of natural degradation processes, the earthwork widened and flattened over time. These results have broad implications for any study aimed at: (1) assessing the function of original earthwork forms, (2) determining the formation processes of complicated stratigraphies or artifact assemblages, (3) estimating the time and labor investment required for construction, or (4) identifying the socio‐political structures necessary to build earthworks. © 2005 Wiley Periodicals, Inc.     

Microorganisms and the natural environment

Microorganisms are potentially capable of carrying out chemical transformations of organic and inorganic materials on a large scale. Their activity involves many reactions which may participate in geobiological formations. The microorganisms are affected by the environment and the environment has an influence on the microbial population. The presence or absence of certain compounds is critical for microbiological growth. As no pure strain of organisms exists in nature in complete isolation, it is necessary to consider the effect of individual biological systems on each other. Microorganisms are known for their ability to adjust themself to changes in the environment. This adjustment can demonstrate in reversible non-heriditary adaptive processes or more permanent heriditary forms, mutation.

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Zusammenfassung Mikroorganismen sind in der Lage, organische und anorganische Verbindungen in großem Maßstab umzuformen. Ihre Teilnahme an geologischen Prozessen spielt möglicherweise eine große Rolle. Mikroorganismen werden durch ihre Umwelt beeinflußt und wirken ihrerseits wieder zurück auf diese. Die An- oder Abwesenheit bestimmter Verbindungen wirkt entscheidend auf das mikrobiologische Wachstum. Da einzelne Organismen in der Natur nicht isoliert existieren können, müssen die Wechselwirkungen biologischer Systeme betrachtet werden. Die Fähigkeit sich an Veränderungen der Umwelt anzupassen, ist eine bekannte Fähigkeit der Mikroorganismen. Diese Anpassungsfähigkeit kann in reversiblen oder in nichtreversiblen erblichen Veränderungen (Mutationen) zum Ausdruck kommen.

     

On the origin of natural sapphire color

An attempt has been made to interpret natural sapphire optical absorption spectra with regard to the exchange-coupled pairs of iron impurities in their ferric and ferrous states. Level schemes have been calculated for Fe³⁺-Fe³⁺ and Fe²⁺-Fe²⁺ pairs of all the orders, their symmetry being observed. The selection rules are discussed. EPR and infrared spectroscopy information has been used to assist the optical spectroscopy data. The sapphire color has been interpreted as a function of Fe²⁺/Fe³⁺ ratios and of the presence of their pairs in the stone. The various types of charge compensation in Fe²⁺→Al³⁺ isomorphism are discussed.     

The variability of the natural abundance of U

The possibility that the atomic ratio ²³⁵u/²³⁸U may be slightly variable due to natural nuclear chain reactions such as have been identified in Gabon, West Africa, has prompted a re-examination of very precise gas mass spectrometric isotopic ratio data from a number of laboratories. Two modal values of the isotopic ratio exist in the data. Their relative difference, 0.03%, is statistically significant. The lower mode is due principally to ores from the Colorado Plateau. This difference was recognized in 1963 by the U.S. Atomic Energy Commission but the substantiating data have not been openly published. Insufficient data presently exist to attribute this difference to chemical differentiation of the uranium isotopes, presumably in the ‘sandstone’ type deposits of the Colorado Plateau, or to dilution with Precambrian ore deposits, depleted in ²³⁵U by nuclear reactions.     

To the infrared spectroscopy of natural uranyl phosphates

An interpretation based on site and factor symmetry analysis has been given of infrared spectra of the natural layered uranyl phosphates metaautunite, metatorbernite, metauranocircite I and II, saléeite and sabugalite, of the deuteroanalogues of metaautunite, metatorbernite and metauranocircite II and of the Raman spectrum of metatorbernite. The principal correlation relationships for the analysis of virbrational spectra G _M (symmetry of free ion) ? G _S (site symmetry) ? G _F (factor symmetry) have been described. The results have been correlated with data from X-ray structure analysis.     

Observations of the flux of very-high-energy gamma rays from the blazar 3C 66A

Measurements of the flux of very-high-energy (>1 TeV) gamma rays from the blazar 3C 66A obtained over four years are presented. The mean flux over the four-year period was (2.8±0.4)×10^?11 cm^?2 s^?1. There is a correlation between the season-averaged flux of very-high-energy gamma rays and the observed optical radiation.     

Time-clustering of natural hazards

Natural hazards can be represented as point processes that are characterized by the occurrence times of the events and their intensities. It is crucial to investigate the correlation properties of these processes in order to gain a deep knowledge of the dynamical mechanisms which underlie hazardous phenomena. To this end, suitable methodologies must be developed to perform these correlation analyses on processes, which are described as point-like processes. The concept of time-clustering implies a time-structured organization of these processes, and is in direct opposition to the pure randomness typical of Poissonian processes in which the events are uncorrelated. This article reports several examples of natural hazards within the framework of time-clustering.     

地球自然灾害发生原因初探

本文根据应力与应变原理对地球上自然灾害发生的原因进行了分析研究，根据灾害发生原因的不同，将其分为一般灾害和特殊灾害两种类型。本文还介绍了每种灾害类型的特点，危险及其相互关系，通过综合研究，掌握了地球上各种自然灾害发生的原因后，人类对各种灾害的预防工作就会变被动为主动。     

天然矿物材料在复合材料中的应用价值

本文介绍了复合材料的特殊工业意义、发展前景及天然矿物在复合材料中的利用价值。天然矿物和复合材料的关系及应注意的问题。     

Croatia — the land and natural features

As both Middle-European and Mediterranean country, the Republic of Croatia is composed of several regional units. Every single natural and geographical unit is not specific only in terms of its general natural features, but also by its role in linking Croatia with the rest of the world. Additional peculiarity of these geographic units is their complementary value, which gives good prerequisites for successful economic development of the country.In Pannonian section of Croatia prevail natural features close to those in other Central-European countries. Namely, this section of Croatia participates in Danube catchment area, linking Croatia with the rest of Central Europe. Dinaric Alps are typical mountainous area; in north-western part of the range (i.e. in the region of Gorski Kotar) they are very narrow, making thus possible a comparatively easy communication between Pannonian part of Croatia and the Adriatic coast. Coastal region of Croatia — stretching along the most of (north)eastern coast of the Adriatic — is predominantly characterised by Mediterranean natural features. Due to its size and share in total area of the country, territorial waters of the Adriatic sea can be accepted as the fourth natural and geographic unit of Croatia.