共查询到20条相似文献，搜索用时 31 毫秒
1.
D.P. Moseley J.K. Pringle R.B. Haslam S.S. Egan S.L. Rogers R. Gertisser N.J. Cassidy I.G. Stimpson 《Geology Today》2015,31(3):109-115
The geology of the Snowdonia National Park in North Wales comprises a mixture of Lower Palaeozoic shallow marine sediments, acidic igneous rocks and basic intrusions of the Welsh Basin that were subsequently deformed during the Caledonian Orogeny. Thin igneous intrusions are challenging to map due to variable surface exposures, their intrusive origin, structural deformation and burial by glacial sediments. This study used a combination of traditional geological techniques, near‐surface geophysical surveys and remote sensing to detect and map a buried dolerite sheet intrusion. Both simple and mathematical analysis of magnetic anomalies and numerical modelling allowed the dolerite position, depths and target widths to be determined. Results showed that calibrated magnetic surveys can characterize buried igneous bodies in such mountainous environments. 相似文献
2.
Rinita A. Dalan 《Geoarchaeology》2001,16(3):263-273
Investigations of magnetic susceptibility have been used to (1) define sites, activity areas, features, buried soils, and cultural layers, (2) build and correlate stratigraphic sequences, and (3) understand site‐formation and postdepositional processes. Archaeologists are limited in these endeavors, however, by the instruments available for field studies of susceptibility. A prototype instrument developed for archaeological application logs volume magnetic susceptibility down a small‐diameter (ca. 2.2 cm) core‐hole made with a push‐tube corer. Measurements can be made rapidly, approximately 10 times faster than collecting samples either by coring or from an exposed section, to depths of 1.6 m below the surface. The prototype logger was field‐tested on a mid‐Holocene stratigraphic section in southeastern North Dakota where it clearly distinguished various soils and sediments, including a buried occupation layer. © 2001 John Wiley & Sons, Inc. 相似文献
3.
Parr and Boyd (2002) used colorimetric analysis in combination with geophysical and geochemical techniques to estimate firing temperatures for archaeological daub from an Iron Age site in Thailand. They suggest that the daub was fired at high temperatures and, therefore, is indicative of kiln utilization and increased industrialization during that period in Thailand. They argue that the adoption of a multimethod analytical approach in which the combination of data derived from ICP‐MS, X‐ray diffraction, and magnetic susceptibility analyses of daub samples, coupled with microscopic and macroscopic examination of samples, enhances the accuracy of their interpretations. While they should be commended for attempting to substantiate their claims using many geophysical and geochemical techniques, their arguments are flawed by the misapplication of the techniques described and/or over‐interpretation of the data generated by such techniques. Therefore, Parr and Boyd's (2002:285) point about methodology (“that the combined interpretation of independent measures provides a better estimate of the original firing temperatures of the archaeological material than has hitherto been possible”) is made redundant by the lack of scientific rigor applied to the independent measures used for this study. © 2003 Wiley Periodicals, Inc. 相似文献
4.
Rakesh Kumar Mishra P N S Roy Virendra Kumar Singh Jai Krishna Pandey 《Journal of Earth System Science》2018,127(8):107
Coal mine fire is a serious problem in Jharia coal field, India. The coal mine fire can be detected with different techniques such as borehole temperature measurement, thermo-compositional analysis, remote sensing techniques, thermo-graphic measurement and geophysical methods. In this study, various geophysical methods were used to detect the surface and subsurface coal mine fires. Geophysical techniques used in the present study are apparent resistivity, self-potential (SP), magnetic method and thermography. Geophysical anomalies such as low SP value of \(-60\hbox { mV}\), high negative magnetic response and low apparent resistivity value helped us to detect and delineate the fire and non-fire areas laterally as well as depthwise. Furthermore, the thermography survey was carried out in the coal field using thermal imaging camera in order to substantiate the geophysical methods. This integrated approach was found to be more advantageous for the detection and delineation of surface and subsurface fire with respect to use of any specific techniques. Moreover, the level of threat towards the locality, national railway line was also assessed unambiguously using the above techniques. Hence, proper planning and implementation towards the mitigation of hazard can be achieved on the basis of the reported results. 相似文献
5.
Archaeologists dealing with earthen forms must distinguish those constructed by humans from those with a natural origin. Geophysical techniques can help identify culturally loaded soils and sediments. We suggest that intrinsic changes in geophysical properties, due to cultural loading, can serve as fingerprints in determining whether a mound or other earthen form is natural or culturally constructed. Culturally emplaced soils might be identified through anomalous values in geophysical properties or through unusual spatial or stratigraphic complexity. The identification of this “lumpiness” in geophysical properties may involve geophysical techniques quite different from those employed in traditional archaeogeophysical surveys. Experiments at three prehistoric mound sites (the Cahokia Mounds State Historic Site, Effigy Mounds National Monument, and the Hopeton Earthwork) illustrate a number of these techniques including studies of the anisotropy (directionality) of geophysical properties, seismic Rayleigh (surface) waves, and magnetic susceptibility. © 2002 Wiley Periodicals, Inc. 相似文献
6.
The magnetic method is the oldest and one of the most widely used geophysical techniques for exploring the earth’s subsurface.
It is a relatively easy and inexpensive tool to employ, being applicable to a wide variety of subsurface exploration problems
involving horizontal magnetic property variations occurring from near the base of the crust to within the uppermost meter
of soil. Successful applications of the magnetic method require an in-depth understanding of its basic principles and careful
field work, data reduction, and interpretation. Commonly, interpretations are limited to qualitative approaches which simply
map the spatial location of anomalous subsurface conditions, but under favourable circumstances the technological status of
the method will permit more quantitative interpretations involving specification of the nature of the anomalous sources. No
other geophysical method provides critical input to such a wide variety of problems. However, seldom does the magnetic method
provide the complete answer to an investigation problem. As a result, it is generally used in concert with other geophysical
and geological data to limit its interpretational ambiguities. 相似文献
7.
Mashael M. AlSaud 《Arabian Journal of Geosciences》2008,1(2):129-136
Aeromagnetic data covering an area of about 40,000 km2 at the west central Arabian Shield, Saudi Arabia has been collected and interpreted to provide structural map of the area.
A number of normalized derivatives were used to help interpret the signature of magnetic data so that weak and small amplitude
anomalies can be amplified relative to the stronger and larger amplitude anomalies. The interpretations obtained from these
geophysical techniques of the field data demonstrated a strong correlation between magnetic anomalies and mapped subsurface
geology. Based upon the variation in magnetic lineaments, shape amplitude, and trend structural map of the west central Arabian
Shield on Saudi Arabia were obtained. 相似文献
8.
Óscar Pueyo Anchuela Antonio M. Casas‐Sainz Emilio L. Pueyo Andrés Pocoví Juan Andrés Gil Imaz 《地学学报》2013,25(4):307-314
Magnetic susceptibility in rocks is the sum of the contributions of different magnetic particles (paramagnetic, diamagnetic and ferromagnetic s.l.). These contributions can be measured at variable temperatures or at variable fields (hysteresis loops). Both are time‐consuming techniques that cannot be routinely used in magnetic fabrics analysis. In this study, we propose a simplified method to determine the ferro‐ and paramagnetic contributions to the susceptibility, based on the discrete measurement of susceptibility at two different fields (near 0 and 2.5 T). The results obtained in samples from the Southern Pyrenees and Ebro Basin indicate that the ferromagnetic contribution vary considerably within homogeneous susceptibility values and within the expected range of paramagnetic values. Standard bulk susceptibilities higher than 200 10?6 SI contribute significantly to the ferromagnetic fraction (>50% on average). 相似文献
9.
在黄土高原-阿拉善高原区域沿接近降水量最大梯度线方向系统采集了表土(包括沙漠和土壤)样品,详细研究了其环境磁学、粒度和有机质含量等环境替代指标的变化特征.结果表明,整个断面表土中的强磁性矿物主要为磁铁矿和磁赤铁矿,并含有赤铁矿.阿拉善高原表土中磁性矿物颗粒多为多畴(MD),总体含量偏低,磁性矿物中硬磁组分含量较高;黄土高原区表土中磁性颗粒多为准单畴(PSD),总体含量偏高,磁性矿物中软磁组分含量较高.进一步分析发现,在干旱地区,频率磁化率与降水有良好的相关性,而常用的磁化率不能较好地反映降水量变化.本研究指示在干旱地区应用单一磁化率指标解释环境变化需要谨慎. 相似文献
10.
George A. Brook L. Bruce Railsback Alec C. Campbell Lawrence H. Robbins Michael L. Murphy Greg Hodgins Joseph McHugh 《Geoarchaeology》2011,26(1):61-82
Geophysical techniques have been widely employed for the noninvasive location of burial sites in archaeological and forensic investigations. This approach has met with varying degrees of success, depending on factors such as equipment choice, survey methodology, burial type, and geological setting. This paper reports the results of a multitechnique geophysical survey carried out immediately prior to the salvage excavation of two Indigenous burials from an eolian dune in coastal South Australia. Ground‐penetrating radar was not successful in defining the location of the burials owing to the disturbed nature of the local stratigraphy. Magnetic field intensity and apparent magnetic susceptibility surveys identified discrete anomalies that coincided with the location of skeletal material revealed during excavation, which we hypothesize to be due to burning or ochre use during funerary practices. Despite the spatial association of these features, subsequent laboratory analyses of the mineralogy and magnetic properties of sediments collected from the site failed to find a definite cause of the anomalies. Nevertheless, the association between them and the primary interment locations has implications for archaeological surveys carried out in the Australian coastal zone, as it highlights the potential of magnetic field intensity and apparent magnetic susceptibility geophysical techniques undertaken with a more refined survey methodology to afford a noninvasive, culturally appropriate means through which to detect Indigenous burials. This approach may prove particularly useful in areas with disturbed stratigraphy where ground‐penetrating radar is less effective. © 2010 Wiley Periodicals, Inc. 相似文献
11.
Ian Moffat Lynley A. Wallis Mark W. Hounslow Katrina Niland Kate Domett George Trevorrow 《Geoarchaeology》2010,25(5):645-665
Geophysical techniques have been widely employed for the noninvasive location of burial sites in archaeological and forensic investigations. This approach has met with varying degrees of success, depending on factors such as equipment choice, survey methodology, burial type, and geological setting. This paper reports the results of a multitechnique geophysical survey carried out immediately prior to the salvage excavation of two Indigenous burials from an eolian dune in coastal South Australia. Ground‐penetrating radar was not successful in defining the location of the burials owing to the disturbed nature of the local stratigraphy. Magnetic field intensity and apparent magnetic susceptibility surveys identified discrete anomalies that coincided with the location of skeletal material revealed during excavation, which we hypothesize to be due to burning or ochre use during funerary practices. Despite the spatial association of these features, subsequent laboratory analyses of the mineralogy and magnetic properties of sediments collected from the site failed to find a definite cause of the anomalies. Nevertheless, the association between them and the primary interment locations has implications for archaeological surveys carried out in the Australian coastal zone, as it highlights the potential of magnetic field intensity and apparent magnetic susceptibility geophysical techniques undertaken with a more refined survey methodology to afford a noninvasive, culturally appropriate means through which to detect Indigenous burials. This approach may prove particularly useful in areas with disturbed stratigraphy where ground‐penetrating radar is less effective. © 2010 Wiley Periodicals, Inc. 相似文献
12.
At present, most, if not all zinc is being produced from the mineral sphalerite. With the exception of its piezoelectricity and in some cases its density, sphalerite has no salient physical properties to routinely allow its direct detection by geophysical methods. Although the mineral usually occurs with other sulfides, which do respond to various geophysical techniques, detection of zinc‐bearing deposits is often difficult. In this paper, physical property measurements from numerous, mainly Australian, deposits are presented, together with examples from various geophysical surveys. The results are used to suggest the most effective geophysical technique for the direct detection of the different types of zinc‐bearing deposits. Induced polarisation is probably the most effective technique for unmetamorphosed sediment‐hosted deposits and for carbonate‐hosted deposits, whereas electromagnetics is usually the most appropriate method to use for volcanic‐hosted deposits and for sediment‐hosted deposits that have been strongly metamorphosed. Magnetics is the best technique for skarn and ‘Cobar‐style’ deposits. However, it must be emphasised that usually more than one geophysical technique is required before a prospect can be considered to have been thoroughly explored. 相似文献
13.
在云南厂口隧洞工程施工中,根据不同地质问题,采用高密度电法、洞地间地震波CT和超前预报三种物探方法进行探测,探测结果均对地质灾害有较明确的反映,说明作为基本技术手段的物探方法在隧洞超前探测中能发挥重要作用。 相似文献
14.
Karst aquifers supply a significant fraction of the world's drinking water. These types of aquifers are alsohighly susceptible to pollution from the surface with recharge usually occurring through fractures and solution openings at the bedrock surface. Thickness of the protective soil cover, macropores and openings within the soil cover, and the nature of the weathered bedrock surface all influence infiltration. Recharge openings at the bedrock surface, however, are often covered by unconsolidated sediments, resulting in the inadvertent placement of landfills, unregulated dump sites, tailing piles, waste lagoons and septic systems over recharge zones. In these settings surface geophysical surveys, calibrated by a few soil cores, could be employed to identify these recharge openings, and qualitatively assess the protection afforded by the soil cover. In a test of this hypothesis, geophysical measurements accurately predicted the thickness of unconsolidated deposits overlying karstic dolomite at a site ab 相似文献
15.
Donald J. Stierman 《Environmental Geology》1984,6(1):11-20
At the Stringfellow Class I waste-disposal site near Riverside, California, the influence of variations in groundwater chemistry
and saturation on electrical measurements made from the surface was tested Spontaneous potential, D C electrical sounding,
dipole-dipole resistivity profiles, and mise-a-la-masse measurements were employed to investigate the sub-surface migration
of the acidic fluids deposited in this site between 1956 and 1972 Mise-a-la-masse exploration conducted at the downstream
edge of the site detected a major anomaly which, on excavation, proved to be the signature of a previously unsuspected leak
from the surface disposal ponds on the site Downstream from the site, a dipole-dipole profile and electrical soundings correlate
well with electrical conductivity of groundwater obtained from monitoring wells This study demonstrates that geophysical methods
may be used to search for and map leaks from toxic chemical waste dumps 相似文献
16.
Ó. Pueyo Anchuela P. Frongia F. Di Gregorio A. M. Casas Sainz A. Pocoví Juan 《Environmental Earth Sciences》2017,76(5):230
Dispersion of pollutants from mining areas can result in risks to human health. The dynamic interaction of geological processes can generate complex situations that favor enrichment in toxic elements by sedimentary and diagenetic mechanisms. In order to explore the distribution of iron-rich minerals in coastal and river sediments, a geophysical campaign was performed along the outlet of the Piscinas and Naracauli Rivers that drain two abandoned mining areas in SW Sardinia. Both rivers flow into the Mediterranean Sea, a bay where fluvial, marine, and eolian processes interact. The geophysical campaign comprised magnetometry and ground-penetrating radar surveys. Magnetic properties were controlled by means of magnetic susceptibility measurements along the beach and dune areas, through sampling of surface sediments, natural outcrops and trenches, and considering different grain size intervals. Results indicate enrichment in ferromagnetic minerals at the leeside of dunes and berms. Sedimentological interpretation is supported by means of ground-penetrating radar. Due to both sedimentary and diagenetic processes, the 100- to 300-μm fraction of fine sands exhibits high susceptibility. Implied tenors of toxic elements in the magnetite may represent a serious hazard to environmental and health security. The results inferred from magnetic anomalies support the applicability of the geophysical approach in order to locate high concentrations of iron-rich particles both at surface and below ground and the usefulness of joint evaluation of magnetic susceptibility and ground-penetrating radar in order to characterize the sedimentary and geomorphology-controlled magnetite distribution. 相似文献
17.
John Callahan Frank Hearn Stephen Heron Dennis Schumaker Samuel Swanson 《Journal of Geochemical Exploration》1978,10(1):53-61
A soil geochemical survey for Ni plus magnetic and radiometric surveys were used to outline a small dunite body on Rich Mountain, North Carolina. The dunite body is poorly exposed and is enclosed by garnet-bearing amphibolite of the Ashe Formation. Of the geophysical techniques used, the magnetic survey gives a better definition of the known extent of the body than the radiometric survey. However, the 400-ppm Ni contour from the soil program appears to best define the dunite and suggests that it extends farther to the north and east than was indicated from geologic mapping. Though HF digestion yields higher Ni values than HNO3 + HCl digestion, the patterns are the same. The Mn content of the soil at the Rich Mountain locality probably could also be used to outline the dunite body. 相似文献
18.
岩溶路基注浆质量综合物探检测方法与评价研究 总被引：1，自引：0，他引：1
为研究岩溶路基注浆质量综合物探检测方法及相关检测评价标准,在南广铁路全线的岩溶路基中选取具有代表性的试验区段,对电阻率法、瞬态面波法和电磁波CT法等物探检测方法的特性和检测评判标准展开了现场试验研究。根据上述物探检测方法的适用性和经济性,提出了一种在不同工程条件下多种物探检测方法优化组合的综合物探检测方法。并通过统计分析注浆合格的岩溶路基注浆前后电阻率、面波波速及电磁波吸收系数变化规律,初步得出了上述3种检测方法的注浆质量检测评价标准:电阻率法检测合格标准为溶洞注浆前后电阻率变化率大于20%,卵石土层电阻率变化率大于10%; 瞬态面波法检测合格标准为注浆后土体波速大于20.6h+130.3,溶洞波速大于17.1h+236.9; 电磁波CT法检测合格标准为溶洞注浆前后电磁波吸收系数差值大于0.4dB m-1,卵石土层电磁波吸收系数差值大于0.1dB m-1。 相似文献
19.
David Simpson Alexander Lehouck Marc Van Meirvenne Jean Bourgeois Erik Thoen Jelier Vervloet 《Geoarchaeology》2008,23(2):305-319
In archaeological prospection, geophysical sensors are increasingly being used to locate buried remains within their natural context. To cover a large area in sufficient detail, an electromagnetic induction sensor can be very useful, measuring simultaneously the electrical conductivity and the magnetic susceptibility of the soil (e.g., Geonics EM38DD). In this study, an 8 ha field containing a Medieval manor was mapped in a submeter resolution, using a mobile sensor configuration equipped with a GPS. As different soil features can yield analogous responses, the interpretation of geophysical maps can be ambiguous. Therefore, soil auger observations were laid out along two perpendicular transects to provide vertical profiles across the sensor measurements. This information greatly enhanced the interpretation of the anomalies obtained by the sensor. Both natural and anthropogenic features were delineated, which clearly presented a moated site along a former tidal channel. © 2008 Wiley Periodicals, Inc. 相似文献
20.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(6):541-543
A non-conventional way of utilizing magnetic susceptibility — soil kappametry — was tested in the area of a major metallurgical plant VSŽ Košice (East Slovakia). Magnetic susceptibility values above background in soil samples indicate higher concentrations of heavy metals in soil, i.e. the soil kappametry can be used as a preliminary quick and inexpensive method for detection of higher heavy metal contents in soils. 相似文献