Structural state of detrital alkali feldspars     

LEE J. SUTTNER  ABHIJIT BASU 《Sedimentology》1977,24(1):63-74

The structural state of an alkali feldspar is determined by the nature of the distribution of Al and Si in the tetrahedral sites of the feldspar structure. This state is a function of a number of genetic controls including temperature, cooling rate, deformation, crystal size, and several chemical factors. Together these controls constitute a genetic regime. Identification of the structures of detrital feldspars may enable recognition of genetic regimes and be useful in provenance interpretation and mineral province definition. A 2-peak method of X-ray diffraction (XRD) determination as a variant of an earlier proposed 3-peak method of structural state determination is used in this study. Total analytical time for each determination is about 50–55 min per grain. Results of structural state identification of 126 detrital feldspars from Holocene stream sands derived from volcanic, plutonic and metamorphic rocks are presented in order to illustrate the application and potential of the technique. Detrital feldspars from the metamorphic rocks are all maximum microcline; those from the plutons range from orthoclase to microcline depending on the age of the pluton, whereas those from the volcanic rocks are sanidines.  相似文献   

ODP204航次天然气水合物的可能有利储层——浊积层   总被引：3，自引：1，他引：3  

龚建明  张莉  陈建文  Young-Joo LEE  王红霞  闫桂京 《现代地质》2005,19(1):21-25

为了解岩性在天然气水合物分布中的作用, 利用岩矿鉴定、扫描电镜和能谱法对ODP204航次的 4个站位 10个钻孔共计 115个沉积物样品进行分析, 发现沉积物中矿物成分基本相近, 以粘土矿物为主, 含少量以石英为主的陆源碎屑。样品中含有丰富的硅藻和有孔虫等微体化石, 可形成硅藻粘土—硅藻土、有孔虫硅藻土或凝灰质硅质生物粘土。石英碎屑大多呈棱角状, 粒径小、含量少, 同时, 样品中可见透镜体、团块或旋涡状层状结构以及杂乱堆积的斑杂构造。上述特征表明沉积物为含有大量深海或半深海的浊流沉积物或其夹层。由于钻井岩心中有相当部分的天然气水合物样品分布在上述沉积物中, 推断这些浊流沉积物很可能是ODP204航次天然气水合物的有利储层。  相似文献   

生态工法评估指标的建立   总被引：1，自引：0，他引：1       下载免费PDF全文

李锦育 《水科学进展》2005,16(3):361-367

基于集水区的尺度下,利用几种相关指标,以生物性与非生物性作一区隔,并进一步与生态工法施工准则加以结合,建立了一评估的方法论,探讨了工法施工之成效性。建立长期的河川水质监测计划,以了解在施工前、中及施工后的水质变动情形,避免工程对河川生态环境造成破坏。生态工法在指标的选择上应包含不同尺度的考量,以河川流域管理之完整性为主,藉由多样化的评估指标,提供决策者在拟定计划时能参考运用;另一方面也需运用生物指标的监测,提供具生态考量之工程规划参数,使工程施工能兼顾生态环境。  相似文献   

Contrast in Fluid M etallogeny between the Tianmashan Au-S Deposit and the Datuanshan Cu Deposit in Tongling, Anhui Province     

LEE Hyun Koo 《《地质学报》英文版》2003,77(1):116-124

A comprehensive contrast of ore-forming geological background and ore-forming fluid features, especially fluid ore-forming processes, has been performed between the Tianmashan and the Datuanshan ore deposits in Tongling, Anhui Province. The major reasons for the formation of the stratabound skarn Au-S ore deposit in Tianmashan and the stratabound skarn Cu ore deposit in Datuanshan are analyzed in accordance with this contrast. The magmatic pluton in Tianmashan is rich in Au and poor in Cu, but that in Datuanshan is rich in Cu and Au. The wallrock strata in Tianmashan contain Au-bearing pyrite layers with some organic substance but those in Datuanshan contain no such layers. Moreover, the ore-forming fluids in Tianmashan are dominantly magmatic ones at the oxide and sulfide stages, but those with high content of Cu in Datuanshan are mainly groundwater fluids. In addition, differences in compositional evolution and physicochemical condition variation of the ore-forming fluids result in gradual dispersion  相似文献   

NUMERICAL SIMULATIONS OF SCOUR AND DEPOSITION IN A CHANNEL NETWORK     

Hong-Yuan LEE  Hui-Ming HSIEH 《国际泥沙研究》2003,18(1)

1 INTRODUCTION Evolution of the river bed in alluvial channels has been studied by many researchers using analytical and numerical approaches. The use of analytical approach alone is insufficient for solving natural river engineering problems. With rapid growth in computer technology, numerical models have become a popular means for the study of mobile bed hydraulics. During the past decade, several numerical models have been developed. Most of the computer codes, such as HEC2SR (Si…  相似文献   

Systematic Revision of Trilobites from the Middle Ordovician (Darriwilian) Klimoli Formation of the Zhuozishan Area, Inner Mongolia, China     

LEE Seung-Bae  LEE Dong-Chan  WOO Jusun  ZHANG Xingliang 《《地质学报》英文版》2016,90(6):1955-1975

New morphologic information permits systematic revision of trilobites from the Middle Ordovician Klimoli Formation of the Zhuozishan area, Ordos Basin, Inner Mongolia. The new assemblage is composed of 10 species of the Raphiophoridae, Nileidae, Asaphidae, and Telephinidae.? An asaphid, aff. Mioptychopyge lashachungensis (previously Paraptychopyge lashachungensis) displays an intermediate morphology between the Chinese nobiliasaphine genera Mioptychopyge and Zhenganites. The pygidial doublure is regarded as the most significant character to differentiate Symphysurus klimoliensis (previously Nileus klimoliensis) of the Nileidae from such closely allied taxa as Poronileus. A nileid, cf. Peraspis kujandensis displays typical nileid morphology, unlike the type species, Peraspis lineolata, which might turn out to be an asaphid. Ampyx gongwusuensis sp. nov. of the Raphiophoridae is the first record of the genus in the Zhuozishan area and reveals morphologic details that might be employed to resolve Ampyx taxonomy in China. Morphologic differences between A. gongwusuensis and Abulbaspis ordosensis might represent a case of sexual dimorphism.  相似文献   

TRANSIENT EM ANALOGUE MODELLING FOR KOREAN TREASURE HUNTING WITH THE SIROTEM SYSTEM1     

SANG KYU LEE  G. BUSELLI 《Geophysical Prospecting》1988,36(8):976-994

The inductive transient electromagnetic method (TEM) shows good potential for the detection of metallic relics of historical interest, such as buried antique bells, Buddhist idols, or precious metal nuggets. The effectiveness of the method was investigated with analogue models, using transmitter-receiver loop configurations with sizes or receiver spacings slightly different from those usually applied in earth resources exploration with the Sirotem system. The analogue modelling results show that the location and depth of the buried treasure may be obtained from the Sirotem data. A solid metallic object such as an antique bell could be detected to a depth about 12 times greater than its size, and treasure consisting of separate metallic objects, such as gold nuggets, could be detected to a depth 5 times its linear dimensions with a transmitter current of ? 20 A. In scaling down the dimensions of a target, its conductivity should be increased in order to preserve the same TEM conditions found in the field. However, since the buried treasure consists of gold or copper objects, it is not possible to properly scale the conductivity. Hence, in the field, the depth detection limit is expected to be greater than that derived from analogue modelling.  相似文献   

Ripple formation in combined transdirectional steady and oscillatory flow     

J. S. LEE YOUNG  J. F. A. SLEATH 《Sedimentology》1990,37(3):509-516

Measurements are described of the geometry of ripples formed on beds of sand exposed to a steady current at right angles to an oscillatory flow. Four different sands were studied. The oscillation was produced by an oscillating tray set into the bed of a steady-flow flume. It was observed that straight-crested ripples formed by oscillatory flow would usually develop a ‘serpentine’ form when the superimposed steady current exceeded a certain limit. For amplitudes of the tray velocity U_∞ less than about 0.38 m s^-1 this limit corresponded to U_∞/ū_*c>31, where ū_*c is the shear velocity measured just upstream of the oscillating tray. It is suggested that the serpentine form is caused by the interaction of vortices carried back and forth between adjacent ripples. On this assumption, the wavelength of the serpentine form would be proportional to the product of period of oscillation and near-bed steady current velocity. The present measurements appear to support this hypothesis although there is also evidence that the wavelength is influenced by preferred spacing patterns between vortices. The measurements also show the ratio of the amplitude of the serpentine form to its wavelength to be approximately constant. Empirical relationships are derived relating ripple geometry to flow and sediment properties. It is observed that the influence of Reynolds number and sediment properties on the geometry is very weak. It is suggested that this is typical of ripples formed with relatively low sediment transport rates. It is also found that, under the present experimental conditions, the ripple spacing in the direction of oscillation is almost independent of the magnitude of the steady current and in close agreement with the wavelengths previously measured in an oscillating water tunnel. This suggests that the additional inertia effects associated with oscillating tray rigs were not sufficient to affect bed geometry under the present test conditions.  相似文献   

INTERPRETATION OF VLF-EM IN-PHASE DATA USING CURRENT DENSITY PSEUDOSECTIONS1     

R. D. OGILVY  A. C. LEE 《Geophysical Prospecting》1991,39(4):567-580

The interpretation of VLF-EM surveys in terms of buried conductors can be assisted by the application of a linear filter to the observed in-phase component of the vertical magnetic field. One such scheme is examined critically by using the calculated response from a variety of synthetic models to compute theoretical current density pseudosections. The results confirm that this filter technique provides a useful complementary tool for studying the third (i.e. depth) dimension. For single, steeply dipping plates (> 45°) diagnostic information may be derived concerning the depth, size, lateral location, and direction of dip, since the current density maxima seems always to occur within the conductor or at least within one data interval. However, there are some limitations which do not appear to be widely recognized. For single plates the angle of dip cannot be resolved by the current density transformation. Pattern distortions can occur where targets are in close proximity, where the cross-sectional form of the conductor is complex or where the dip is shallow (< 45°). In these latter cases the current density maxima may not occur within the conductive structure and therefore cannot be used to infer depth of burial and/or conductor shape with the same degree of confidence.  相似文献   

THE EFFECT OF A SUPERPARAMAGNETIC LAYER ON THE TRANSIENT ELECTROMAGNETIC RESPONSE OF A GROUND*     

T. LEE 《Geophysical Prospecting》1984,32(3):480-496

A thin superparamagnetic layer on the earth's surface greatly affects the transient electromagnetic response of a conducting ground. The effect of the layer is most evident for singleloop transient electromagnetic data where transient voltages decay as 1/t. Even when a separate transmitter and receiver are used, the effect of the superparamagnetic layer is still pronounced. In this case the effect of the 1/t term in the equation is much less. More dominant now is a 1/t² term. The effect of the superparamagnetism can readily be seen in the analytical expressions for the apparent resistivities. If the presence of the superparamagnetic layer is not recognized, then the apparent resistivities decrease with time rather than approach the true value of the host rock.  相似文献