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1.
Palaeolithic sites associated with the Eemian Interglacial (MIS 5e) are very rare in NW Europe, and especially in Northern France, where their preservation is restricted to very specific geological contexts, in association with carbonated tufa (Caours) or peat deposits (Waziers). In order to check the reliability of ESR/U-series method to date teeth recovered from archaeological levels in such specific geological environments, teeth were sampled on these two Middle Palaeolithic sites and systematic in situ dosimetry was performed using portable gamma spectrometer. The ESR/U-series ages obtained on the Caours site are very homogeneous allowing the calculation of a mean age equal to 125 ± 11 ka, in agreement with the geological age, mammal's association and other available geochronological data (U-series on tufa carbonate, TL on burnt flints, OSL on sediments), despite a relatively heterogeneous dosimetric environment (gamma dose rate ranging between ca 200–450 μGy/a). At Waziers, reducing (water logging) environment linked to the peat leads to very specific U-series data of the analysed teeth (U content lower than 0.1 ppm in all the dental tissues, evidence of leaching in some tissues), but the mean ESR/U-series age, 129 ± 4 ka, is also in agreement with the available geological and palaeoenvironmental data indicating that the dated teeth were associated with Late Glacial deposits prior to the climatic interglacial optimum. These two case studies then confirm the reliability of ESR/U-series method to date with good reliability and accuracy the archaeological levels linked to such relatively short climatic events (ca 10 ka).  相似文献   

2.
城市密集柏油公路网和坚硬水泥地面给地下遗址考古勘探造成了很大困难,传统的高密度电阻率法需要插置电极,无法在城市环境中使用。电容耦合式电阻率法采用非侵入式的方式,通过特制电极与大地形成电容器产生电流进行电法勘探,特别适合城市硬地表介质的条件。为了检验电容耦合式电阻率法在城市遗址考古勘探中的应用效果,在地处杭州市主城区的吴越捍海塘遗址进行了电容耦合式电阻率法探测试验,采集多个收发距的电法数据,对数据进行反演处理,将反演结果与考古发掘结果进行对比分析。结果表明,反演的电阻率图像推断结果与考古发掘结果基本吻合,电容耦合式电阻率法是城市遗址考古勘探的有效方法,具有广泛的应用前景。   相似文献   

3.
Recovering accurate data is important for both earthquake and exploration seismology studies, when data are sparsely sampled or partially missing. We present a method that allows for precise and accurate recovery of seismic data using a localized fractal recovery method. This method requires that the data are selfsimilar on local and global spatial scales. We present examples that show that the intrinsic structure associated with seismic data can be easily and accurately recovered by using this approach. This result, in turn, indicates that seismic data are indeed self-similar on local and global scales. This method is applicable not only for seismic studies, but also for any field studies that require accurate recovery of data from sparsely sampled datasets with partially missing data. Our ability to recover the missing data with high fidelity and accuracy will qualitatively improve the images of seismic tomography.  相似文献   

4.
Radio‐frequency electromagnetic tomography (or radio imaging method) employs radio‐frequency (typically 0.1–10 MHz) electromagnetic wave propagation to delineate the distribution of electric properties between two boreholes. Currently, the straight‐ray imaging method is the primary imaging method for the radio imaging method data acquired for mineral exploration. We carried out synthetic studies using three‐dimensional finite‐element modelling implemented in COMSOL Multiphysics to study the electromagnetic field characteristics and to assess the capability of the straight‐ray imaging method using amplitude and phase data separately. We studied four sets of experiments with models of interest in the mining setting. In the first two experiments, we studied models with perfect conductors in homogeneous backgrounds, which show that the characteristics of the electromagnetic fields depend mainly on the wavelength. When the borehole separations are less than one wavelength, induction effects occur; conductors with simple geometries can be recovered acceptably with amplitude data but are incorrectly imaged on the phase tomogram. When the borehole separations are longer than two wavelengths, radiation effects play a major role. In this case, phase tomography provides images with acceptable quality, whereas amplitude tomography does not provide satisfactory results. The third experiment shows that imaging with both original and reciprocal datasets is somewhat helpful in improving the imaging quality by reducing the impact of noise. In the last experiment, we studied models with conductive zones extended into the borehole plane with different lengths, which were not accurately recovered with amplitude tomography. The experiment implies that it is difficult to determine the extent of a mineralised zone that has been intersected by one of the boreholes. Due to the large variation of the wavelength in the radio‐frequency range, we suggest investigating the local electric properties to select an operating frequency prior to a survey. We conclude that straight‐ray tomography with either amplitude or phase data cannot provide high‐quality imaging results. We suggest using more general methods based on full electromagnetic modelling to interpret the data. In circumstances when computational time is critical, we suggest saving time by using either induction methods for borehole separations less than one wavelength or wave‐based methods (only radiation fields are considered) for borehole separation larger than two wavelengths.  相似文献   

5.
The study area is located at S. Agata (Gera Lario), a small center at the northern end of Como Lake, near the junction of Valchiavenna and Valtellina Valleys. This site played a strategic role since ancient times, providing the control on the communications routes to both the Como Lake and the Spluga and Septimer alpine passes. Since the end of the last century archaeological findings are reported in literature, also supported, from the early XI century, by archival documents confirming the existence of the `Olonium' settlement, an administrative and fiscal center of primary importance, as well as a parish amongst the most influential in the Como Lake area. Within an area of 45,000 m2 an electrical survey has been carried out in conjunction with magnetic and GPR investigations. These studies have indicated the presence of a number of sub-areas characterized by significant anomalies defined by the overlapping of the results obtained from two or more geophysical methods. In two of such sub-areas, excavation tests have been conducted, which have brought to light a number of archaeological findings of interest. In one of the two sub-areas, which is characterized by the superimposition of electrical and radar anomalies, a deposit of large pebbles has been found. The origin of this deposit has not been ascertained, whether it is of fluvial origin, related to the deviation of the Adda river in the Pian di Spagna region in Roman times, or it is part of reclamation works, still of Roman times, of paleolacustrine marshes. The overlapping stratigraphy, however, suggests the development of fluvial channels between Roman and Low-Medieval times. In the other sub-area, excavations were carried out on sites defined by electrical and radar anomalies, and confirmed by the results from magnetic survey. The excavations brought to light, below the fluvial deposits, a large medieval edifice, which could be identified as the S. Stefano church abandoned in 1444. The church is built on earlier structures, amongst which an apse with a single aisle has been interpreted as a paleochristian sacellum.  相似文献   

6.
During the last two decades, extensive road-construction works in Northern France have allowed the discovery of numerous Middle Palaeolithic sites. Geological and multidisciplinary studies performed on these localities allowed the establishment of a precise chronostratigraphical and biostratigraphical framework of regional significance, which could be correlated to the global marine palaeoclimatic scale. Each human occupation layer has been linked to this regional framework, thus providing a stratigraphical age-control for the Middle Palaeolithic human settlements of this area.At the same time, a program of geochronological studies was developed using TL, OSL, U-series, ESR and, as often as possible, ESR/U-series methods. Hence, bones and teeth recovered from archaeological sites of Savy, Ault, Caours, Gentelles and La Celle-sur-Seine, were analyzed and the results compared to the chronostratigraphical ages. The age results are generally in good agreement with the geological data while bones and dental tissues display in some cases U-series ages higher that the EU-ESR ones, suggesting U-loss phenomena.  相似文献   

7.
The integrated use of electrical resistivity tomography (ERT) and ground penetrating radar (GPR) measurements, and in particular the joint analysis of 2D and 3D data, can represent a valid solution for target identification at complex archaeological sites. A good example, in this respect, is given by the case study of a Phoenician–Punic necropolis in the archaeological site of Nora, in southern Sardinia (Italy), where GPR and ERT measurements were collected before site excavation. In this specific case, the mix of soil and air in the buried chambers, as well as the orientation and the complex spatial distribution of these structures into the sandstone bedrock, generated a number of anomalies difficult to interpret only using 2D results. Only the integration of all GPR and ERT data in a 3D view, and the comparison with archaeological evidence after the excavation, allowed a solid interpretation of geophysical anomalies visible in the 2D sections. Overall, this case study demonstrates the efficiency of the combined use of GPR and ERT acquisitions and shows how, in general, only the joint analysis of 2D data and in a 3D view can help the interpretation of the real distribution of the buried archaeological remains at similar archaeological complex sites.  相似文献   

8.
In this work a new algorithm for the fast and efficient 3D inversion of conventional 2D surface electrical resistivity tomography lines is presented. The proposed approach lies on the assumption that for every surface measurement there is a large number of 3D parameters with very small absolute Jacobian matrix values, which can be excluded in advance from the Jacobian matrix calculation, as they do not contribute significant information in the inversion procedure. A sensitivity analysis for both homogeneous and inhomogeneous earth models showed that each measurement has a specific region of influence, which can be limited to parameters in a critical rectangular prism volume. Application of the proposed algorithm accelerated almost three times the Jacobian (sensitivity) matrix calculation for the data sets tested in this work. Moreover, application of the least squares regression iterative inversion technique, resulted in a new 3D resistivity inversion algorithm more than 2.7 times faster and with computer memory requirements less than half compared to the original algorithm. The efficiency and accuracy of the algorithm was verified using synthetic models representing typical archaeological structures, as well as field data collected from two archaeological sites in Greece, employing different electrode configurations. The applicability of the presented approach is demonstrated for archaeological investigations and the basic idea of the proposed algorithm can be easily extended for the inversion of other geophysical data.  相似文献   

9.
— In the recent years, geophysical methods have been applied successfully in archaeological studies. In this article we have studied the application of wavelet transform to magnetic data in order to estimate boundaries of various synthetic examples and real data. Enhanced Horizontal Derivative (EHD) method is also applied as an alternative method for boundary estimation. The performance of wavelet transform and the EHD method are evaluated using magnetic data of the Sarissa-Kusakli archaeological site. All boundary results are mutually compared. Based on these comparisons, we conclude that the wavelet transform provides reasonable results.This work was supported by the TUBITAK under Project YDABCAG-100Y021.Received: 23 October 2001  相似文献   

10.
Discovered accidently during factory building construction works, the Middle Palaeolithic site of Biache-Saint-Vaast (Pas-de-Calais, France) was excavated from 1976 to 1982 by a team of Lille University directed by Alain Tuffreau. An abundant archaeological and paleontological material, including two human skulls, was there recovered from fossil alluvial deposits of the Scarpe River. In order to determine the ages of these remains, the ESR/U-series method was applied on bone and teeth. As the U-series data obtained of the main part of the analyzed tissues do not allow the use of the classical US-ESR model, the recently proposed AU-ESR model, taking into account if necessary U-leaching from some of the tissues, was used to calculate combined ESR/U-series ages for these samples. The obtained ages suggest a MIS7 attribution to the faunal remains and permit an age of ca 240 ka to be assigned for the human remains and associated archaeological material, in accordance with the stratigraphic data and the large mammal associations.  相似文献   

11.
Muro Leccese (Lecce) contains one the most important Messapian archaeological sites in southern Italy.The archaeological interest of the site arises from the discovery of the remains of Messapian walls, tombs, roads, etc. (4th–2nd centuries BC) in the neighbourhood. The archaeological remains were found at about 0.3 m depth.At present the site belongs to the municipality, which intends to build a new sewer network through it. The risk of destroying potentially interesting ancient archaeological structures during the works prompted an archaeological survey of the area. The relatively large dimensions of the area (almost 10,000 m2), together with time and cost constraints, made it necessary to use geophysical investigations as a faster means to ascertain the presence of archaeological items. Since the most important targets were expected to be located at a soil depth of about 0.3 m, a ground-penetrating radar (GPR) survey was carried out in an area located near the archaeological excavations. Unfortunately the geological complexity did not allow an easy interpretation of the GPR data.Therefore a 3D electrical resistivity tomography (ERT) scan was conducted in order to resolve these interpretation problems.A three-way comparison of the results of the dense ERT measurements parallel to the x axis, the results of the measurements parallel to the y axis and the combined results was performed.Subsequently the synthetic model approach was used to provide a better characterization of the resistivity anomalies visible on the ERT field data.The 3D inversion results clearly illustrate the capability to resolve in view of quality 3D structures of archaeological interest. According to the presented data the inversion models along one direction (x or y) seems to be adequate in reconstructing the subsurface structures.Naturally field data produce good quality reconstructions of the archaeological features only if the x-line and y-line measurements are considered together. Despite the increased computational time required by the 3D acquisition and 3D inversion schemes, good quality results can be produced.  相似文献   

12.
Archaeoseismology can provide a useful chronological tool for constraining earthquakes and documenting significant evidence that would otherwise be lost. In this paper, we report a case of surface faulting on ancient man-made structures belonging to the archaeological site of Santa Venera al Pozzo situated along the eastern flank of Mt. Etna volcano in eastern Sicily (southern Italy), which is affected by well-developed tectonic faults. Geological surveys highlight a set of fractures affecting the archaeological ruins, suggesting the occurrence of a capable fault zone across the area. An integrated geophysical survey was carried out in order to identify the main subsurface tectonic discontinuity ascribable to the fault zone. The information derived from different geophysical techniques, such as electrical resistivity tomography, seismic refraction tomography, ground-penetrating radar, and magnetic surveys allowed us to infer that the fractures observed at the surface could have been produced by coseismic rupture. They are conceivably linked to a strong earthquake that probably occurred in the Roman period, around mid-end of the third-century AD; time constraints are inferred through the dating of buildings of the archaeological site.  相似文献   

13.
This paper is an extension of a previous study, in which the principles of self-potential ground surface tomography were outlined. The new arguments which are here set forth are the proper accounting for the topographic effects and a robust approach to global 3D tomography. The 2D case is initially considered in order to facilitate a full understanding of the new method. In order to gauge the topographic distortions, the concepts of slope effect and surface regularization are introduced, as suitable means to compute point by point correction factors of the measured self-potential data, prior to the recognition of the tomographic images of the primary and induced electric sources underground. The tomographic approach is then developed by introducing again the concepts of the scanning function and of the charge occurrence probability function, which were amply dealt with in the previous paper. The new approach to 3D global tomography means here the composition of charge occurrence probability functions related to any two orthogonal surface components of the natural electric field, in order to account fully for the total surface component of the self-potential field and hence to elicit the greatest amount of information. Two field examples are presented to show the full effectiveness of the proposed method. They refer, respectively, to a near-surface investigation for archaeological purposes and to a very deep investigation in an active volcanic area.  相似文献   

14.
The characterization of heterogeneity in hydraulic conductivity (K) is a major challenge for subsurface remediation projects. There are a number of field studies that compare the K estimates obtained using various techniques, but to our knowledge, no field‐based studies exists that compare the performance of estimated K heterogeneity fields or the associated characterization costs. In this paper, we compare the costs of characterizing the three‐dimensional K heterogeneity and its uncertainty estimates of a glaciofluvial aquifer‐aquitard sequence at a 15 m × 15 m × 18 m field site situated on the University of Waterloo campus. We compare geostatistical analysis of high resolution permeameter K data obtained from repacked core samples in five boreholes and hydraulic tomography analysis of four pumping tests consisting of up to 41 monitoring points per test. Aside from the comparison of costs, we also assess the performance of each method by predicting several pumping tests. Our analysis reveals that hydraulic tomography is somewhat more costly than the geostatistical analysis of high resolution permeameter K data due to the higher capital costs associated with the method. However, the equipment may be reused at other sites; hence these costs may be recovered over the life of the equipment. More significantly, hydraulic tomography is able to capture the most important features of the aquifer‐aquitard sequence leading to more accurate predictions of independent pumping tests. This suggests that more robust remediation systems may be designed if site characterization is performed with hydraulic tomography.  相似文献   

15.
遥感与地球物理考古探测数据类型多样,然而各种探测数据因缺少综合管理和分析平台,使综合分析更加困难,从而限制了考古探测技术应用效果。在了解遥感与地球物理考古探测技术的基础上,本文对当前遥感地球物理考古探测数据管理系统进行逻辑和业务需求分析,构建基于ArcGIS Engine开发引擎和Visual Studio 2017平台的遥感与地球物理考古探测数据综合管理系统。系统通过分层次设计功能模块,实现考古探测数据的编辑、解释、分析以及数据之间的交互和管理。实际应用表明,对于遥感地球物理考古探测技术与地理信息技术相结合的思路和研究,能够提升遥感与地球物理考古探测数据的综合分析能力,促进考古探测技术的有效应用。   相似文献   

16.
We estimate velocity anisotropy factors from seismic traveltime tomographic data and apply a correction for anisotropy in the inversion procedure to test possible improvements on the traveltime fit and the quality of the resulting tomographic images. We applied the anisotropy correction on a traveltime data set obtained from the investigation of the foundation structure of a monumental building: a Byzantine church from the 11th century AD, in Athens, Greece. Vertical transverse isotropy is represented by one axis of symmetry and one anisotropy magnitude for the entire tomographic inversion grid. We choose the vertical direction for the symmetry axis by analysing the available data set and taking into account information on the character of the foundations of the church from the literature and past excavations. The anisotropy magnitude is determined by testing a series of values of anisotropy and examining their effect on the tomographic inversion results. The best traveltime fit and image quality are obtained with an anisotropy value (Vmax/Vmin) of 1.6, restricted to the high velocity structures in the subsurface. We believe that this anisotropy value, which is significantly higher than the usual values reported for near‐surface geological material, is related to the fabric of the church foundations, due to the shape of the individual stone blocks and the layout of the stonework. Inversion results obtained with the correction for anisotropy indicate that both the traveltime fit and the image quality are improved, providing an enhanced reconstruction of the velocity field, especially for the high‐velocity features. Based on this enhanced and more reliable reconstruction of velocity distribution, an improved image of the subsurface material character was made possible. In particular, the pattern and state of the church foundations and possible weak ground material areas were revealed more clearly. This improved subsurface knowledge may assist in a better design of restoration measures for monumental buildings such as Byzantine churches.  相似文献   

17.
An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious veneration. Finally, both ERT and GPR have been conducted during a week of intensive overnight surveys that provided detailed information on subsurface existing structures. The ERT method has been applied using different techniques and arrays, ranging from standard Wenner–Schlumberger 2D sections to full 3D electrical imaging with the advanced Maximum Yield Grid array. Electrical resistivity data were recorded extensively, making available many thousands of apparent resistivity data to obtain a complete 3D image after a full inversion. In conclusion, some significant buried structures have been revealed providing conclusive information for archaeologists. GPR results provided additional information about shallowest structures. The geophysical results were clear enough to persuade religious authorities and archaeologists to conduct selected excavations in the most promising areas that confirmed the interpretation of geophysical data. In conclusion, the significant buried structures revealed by geophysical methods under the cathedral were confirmed by archaeological digging as the basement of the impressive Roman Temple that headed the Provincial Forum of Tarraco, seat of the Concilium of Hispania Citerior Province.  相似文献   

18.
Within the framework of the studies focusing on the Pleistocene peopling of the Americas, our French-Brazilian team has undertaken a pluridisciplinary research on different archaeological sites, inside and in the neighborhood of the Serra da Capivara National Park, in Brazilian Nordeste. The present study regards an archaeological site, Vale da Pedra Furada, situated in the Piauí state in Brazil. The results of technological and functional studies suggest the existence of different successive human occupations during the Pleistocene in this region. Moreover, the geological and geomorphological studies shed new light on our understanding of sedimentary processes and confirm that the levels were not subject to any significant post-depositional processes. This is also confirmed by macro- and micro-analysis of quartz artefact surfaces. The chronological study has recently been completed employing both radiocarbon and luminescence techniques; radiocarbon dates were obtained on charcoal, multi-grain and single-grain OSL ages on sedimentary quartz grains. The results obtained with the different methods are consistent with each other: the most recent archaeological level is dated to around 8 ka and the oldest to 24 ka, indicating the open-air site of Vale da Pedra Furada to be a succession of human occupations beginning from OIS 2. These results are discussed in the context of some archaeological sites studied in the Serra da Capivara National Park of the last few decades.  相似文献   

19.
为了合理地设计熊家冢古墓的后续考古发掘工作,需要对其主冢和陪冢的位置和墓室埋深等进行地球物理探测。电阻率层析成像具有无损性的优点,利用该技术对熊家冢古墓的主冢和陪冢进行了试验性探测。在探测中,分别布设了展布南北和东西的2条测线来控制主冢和陪冢。根据反演后的电阻率图像,估算了主冢和陪冢的位置和尺寸,为古墓的后续考古挖掘工作设计提供了基本参数。   相似文献   

20.
2D高密度电法在古墓葬勘探中应用较多,但二维剖面解释局限性愈发突出。以2D平行或等角度放射状测线为基础的拟3D高密度电法能够一定程度上给出三维信息,但对地表条件要求较高,灵活性稍差。3D高密度电法能够给出详细的3D探测信息,但施工效率偏低,且难以适应复杂地表环境。为解决复杂地表环境古墓葬探测问题,提出了一种多方位拟3D高密度电法技术,并在一个位于密集竹林中的大型古墓葬调查中进行了应用研究。结合地表条件布设多个方位的2D高密度电法测线,将多个方位的2D反演数据合并为拟3D数据体,进行可视化解释获得了内部结构的3D信息。结果表明,该技术能够适应复杂环境,拟三维数据不仅能补充二维解释缺失的信息,且与钻探结果基本吻合。   相似文献   

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