Integrative Geophysical Studies at the Novaya Kurya-1 Cemetery in the Kulunda Steppe

We outline the results of prospection studies at the Novaya Kurya-1 cemetery in the south of Western Siberia, using remote sensing methods such as aerial photography, ground-based magnetometry, high-precision aeromagnetic survey, electromagnetic profi ling, and electrotomography. Original techniques were used to construct relative relief maps, and an inversion of data from ground-based magnetic survey at various altitudes was carried out. The fi rst technique reduces the effect of natural relief, and highlights anthropogenic altitudinal anomalies, making the analysis of digital elevation models more effi cient. The second technique is helpful for assessing the thickness and depth of anomalous magnetic bodies or horizons, not only providing planigraphic information but enabling us to evaluate two- and threedimensional geometric properties of the detected objects. As a result of the analyses, at least 14 kurgans were identifi ed at the cemetery, six of which lack salient outward features. Structural details suggest that most of them date to the Early Scythian time (800–400 BC). On the basis of the interpretation of the results of highly effi cient prospection analyses using the UAV platform, offering the possibility of surveying a large area (about 25 ha), the boundaries of the site were determined. Several features were detected. To identify these, further studies are needed.

Drone Magnetometry in Mining Research. An Application in the Study of Triassic Cu–Co–Ni Mineralizations in the Estancias Mountain Range, Almería (Spain)

The use of drones in mining and geological exploration is under rapid development, especially in the field of magnetic field prospection. In part, this is related to the advantages presented for over ground surveys, allowing for high-density data acquisition with low loss of resolution, while being particularly useful in scenarios where vegetation, topography, and access are limiting factors. This work analyzes results of a drone magnetic survey acquired across the old mines of Don Jacobo, where Copper-Cobalt-Nickel stratabound mineralizations were exploited in the Estancias mountain range of the Betic Cordillera, Spain. The survey carried out used a vapor magnetometer installed on a Matrice 600 Pro Hexacopter. Twenty-four parallel survey lines were flown with a speed of 5 m/s, orthogonal to the regional strike of the geological structure, and mineralization with 50 m line separation and 20 m flight height over the ground was studied. The interpretation of the magnetic data allows us to reveal and model two high magnetic susceptibility bodies with residual magnetization, close to the old mines and surface mineral shows. These bodies could be related to potential unexploited mineralized areas whose formation may be related to a normal fault placed to the south of the survey area. Our geophysical survey provides essential data to improve the geological and mining potential of the area, allowing to design future research activities.

A Magnetic Survey of the Southwest Pacific Ocean

<p>The design and construction of a free precession proton magnetometer which give a reading of the field directly in gamma is described. This instrument has been used to obtain magnetic profiles across the Southwest Pacific Ocean during the 1963-65 summer Antarctic supply cruises of H.M.N.Z.S. Endeavour. The magnetic and bathymetric profiler obtained on these cruises have been analysed to determine the nature and structure of the oceanic crust in this region. The region is divided into four divisions. (l) The New Zealand Plateau, with an almost continental crustal thickness. (2) The Southwest Pacific Basin, at a depth of 3,000 fathoms. (3) The Pacific-Antarctic Ridge, pert of the world encircling mind-ocean ridge system. (4) The Ross Sea, an epicontinental sea across the Antarctic continental shelf. Subtraction of the regional field form the magnetic results has enabled a regional field map of the area to be drawn. Comparison with earlier results indicates a westward drift of the earth's field of approximately 0.25 degrees /yr. Some discussion of regional anomalies (~ 100 miles period) has been given. Because of the excellent correlation of magnetic anomalies from track to track across the basin it has been possible to draw an anomaly contour map of this part. This map illustrates the predominantly east-west trend of features over the basin. To the north the features parallel the edge of the New Zealand Plateau. To the south the features swing more towards the Pacific-Antarctic Ridge. A major discontinuity is indicated along a direction 9 degrees E of S meeting the Plateau just southwest of Antipodes Islands. If this discontinuity is extrapolated south to the ridge it meets it at approximately 180 degrees E, where the ridge turns N-E towards Easter Island. Across the ridge the magnetic pattern shows three distinct regions. Over the northern flanks large anomalies are evident but the correlation of anomalies from track to track is very poor. Further south, across the upper flanks, the magnetic records are very much subdued. The extent of this region varies appreciably from track to track. Over the axis of the ridge large, steep-sided anomalies are obtained. These correlate well over part of the region studied. The southern flanks of the ridge are hidden by the Balleny Plateau which seems to form a link between Antarctica and the ridge in this region. The bathymetry records obtained indicate a step-type formation over the ridge. A narrow median valley appears to exist along the axis of the ridge. Some preliminary experimentation has been carried out with continual seismic profiling techniques over the region. The equipment that has been developed and the preliminary results obtained with it are discussed.</p>

A Magnetic Survey of the Southwest Pacific Ocean

<p>The design and construction of a free precession proton magnetometer which give a reading of the field directly in gamma is described. This instrument has been used to obtain magnetic profiles across the Southwest Pacific Ocean during the 1963-65 summer Antarctic supply cruises of H.M.N.Z.S. Endeavour. The magnetic and bathymetric profiler obtained on these cruises have been analysed to determine the nature and structure of the oceanic crust in this region. The region is divided into four divisions. (l) The New Zealand Plateau, with an almost continental crustal thickness. (2) The Southwest Pacific Basin, at a depth of 3,000 fathoms. (3) The Pacific-Antarctic Ridge, pert of the world encircling mind-ocean ridge system. (4) The Ross Sea, an epicontinental sea across the Antarctic continental shelf. Subtraction of the regional field form the magnetic results has enabled a regional field map of the area to be drawn. Comparison with earlier results indicates a westward drift of the earth's field of approximately 0.25 degrees /yr. Some discussion of regional anomalies (~ 100 miles period) has been given. Because of the excellent correlation of magnetic anomalies from track to track across the basin it has been possible to draw an anomaly contour map of this part. This map illustrates the predominantly east-west trend of features over the basin. To the north the features parallel the edge of the New Zealand Plateau. To the south the features swing more towards the Pacific-Antarctic Ridge. A major discontinuity is indicated along a direction 9 degrees E of S meeting the Plateau just southwest of Antipodes Islands. If this discontinuity is extrapolated south to the ridge it meets it at approximately 180 degrees E, where the ridge turns N-E towards Easter Island. Across the ridge the magnetic pattern shows three distinct regions. Over the northern flanks large anomalies are evident but the correlation of anomalies from track to track is very poor. Further south, across the upper flanks, the magnetic records are very much subdued. The extent of this region varies appreciably from track to track. Over the axis of the ridge large, steep-sided anomalies are obtained. These correlate well over part of the region studied. The southern flanks of the ridge are hidden by the Balleny Plateau which seems to form a link between Antarctica and the ridge in this region. The bathymetry records obtained indicate a step-type formation over the ridge. A narrow median valley appears to exist along the axis of the ridge. Some preliminary experimentation has been carried out with continual seismic profiling techniques over the region. The equipment that has been developed and the preliminary results obtained with it are discussed.</p>

Magnetic Mapping and Seismoacustic Investigations in the Altinum Submerged Archaeologic Site

The roman fortress from Macuca Hill, identifi ed by Romanian archaeologists, until now, as the garrison Altinum, northof Oltina village, northeast of Oltina Lake, has no observable features to be ascribed to late Roman period. On the eastern bank of the lake the team in charge with the archaeological research in Capul Dealului site made land surveys on the northern slopes of Macuca Hill, looking to the Danube’s Island Ostrovu Iepuraçu (Rabbit’s Island), some hundred meters north of the timber and earth playing-card fort described a century ago by Pamfi l Polonic. The archaeologists from Constanta found in 2006 survey convincing remains of a monumental stone wall, hidden in the forest. If the remains depend of a fortress, or of a harbor facility, only the seimoacustic and magnetometric investigation research will answer. In this work we present the results of a multidisciplinary study for characterising the archaeological site of Altinum (Dobrudja, Southern Romania). The investigation has been performed by means of the integrated use of two different high resolution and no invasive geophysical techniques: magnetic mapping, and sidescansonar measurements. The integrated approach allows us to detect submerged archaeological structures. In particular, our results helped to define spatial pattern of the submerged remains, to define the geometry of the anthropogenic settlements and to obtain detailed information about the composition and the manufacturing processes of different building materials. Magnetic prospecting represents one of the widest employed tools in the geophysical research applied to the archaeological studies. This technique provides a great amount of high-resolution magnetic data in a very small time: up to ten measurements per second. Moreover, because the magnetic equipment is a portable instrument assembled by the user, it may be used in every configuration for investigation the submerged archaeological site. Sidescansonar profiling is widely applied to support the magnetometric investigation and archaeological prospection. In particular, three-dimensional modelling of sidescansonar surveys are increasing in popularity, in fact 3D models are much more valuable for archaeological feature interpretation. However, to obtain a higher horizontal and vertical resolution, a sub-metre line spacing is generally needed, making the 3D acquisition more expensive in time in respect of magnetic measurements. The magnetic survey on the waterhas been carried out using a caesium vapour marine magnetometer G-882 GEOMETRICS and proton magnetometer G-856 for diurnal variations of the natural magnetic field. The sidescansonar system (Klein Sonar Pro) has two working frequencies (445 KHz and 900 KHz). The 445 KHz frequency was used for discover submerged walls and other archaeological structure. The integration between these two techniques allowed us to define the geometry and the depth of a buried structures.

Airborne Magnetometry to Identify Metallic Debris to Support Dredging and Search Activities at the Brumadinho Disaster Site – A Case Study

This paper describes the procedures and results of an airborne magnetic survey using Unmanned Aerial Vehicle (UAV) conducted to support Search and Rescue (S&R) teams after the failure of a mining tailing dam at the Corrego do Feijão Mine, in the state of Minas Gerais, Southeast Brazil. The accident claimed 270 lives, practically destroying all the mine’s infrastructure. After the accident, the use of a fast, efficient, and cost-effective method to locate preferential sites for the rescue team to work was critical. Due to the difficulty of direct access to the impacted area, and since most of the affected infrastructure consisted of metallic materials, an airborne magnetometer was the logical choice. First, some performance tests were conducted in order to define the survey configurations, such as flight altitude, transect spacing and anomaly’s detectability threshold. After that, task priorities were set, and the survey area divided in small blocks according to their morphological characteristics using aerial photos of the impacted area. The results showed that the system was able to detect all relevant anomalies. The correlation of the anomalies with aerial photogrammetry helped to discard false anomalies, making the whole operation much more efficient. This increased the effectiveness of the S&R teams as well as the planning of the dredging operations by defining the preferential locations for the interventions.

A Novel Noise Reduction Method of UAV Magnetic Survey Data Based on CEEMDAN, Permutation Entropy, Correlation Coefficient and Wavelet Threshold Denoising

Despite the increased attention that has been given to the unmanned aerial vehicle (UAV)-based magnetic survey systems in the past decade, the processing of UAV magnetic data is still a tough task. In this paper, we propose a novel noise reduction method of UAV magnetic data based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), permutation entropy (PE), correlation coefficient and wavelet threshold denoising. The original signal is first decomposed into several intrinsic mode functions (IMFs) by CEEMDAN, and the PE of each IMF is calculated. Second, IMFs are divided into four categories according to the quartiles of PE, namely, noise IMFs, noise-dominant IMFs, signal-dominant IMFs, and signal IMFs. Then the noise IMFs are removed, and correlation coefficients are used to identify the real signal-dominant IMFs. Finally, the wavelet threshold denoising is applied to the real signal-dominant IMFs, the denoised signal can be obtained by combining the signal IMFs and the denoised IMFs. Both synthetic and field experiments are conducted to verify the effectiveness of the proposed method. The results show that the proposed method can eliminate the interference to a great extent, which lays a foundation for the further interpretation of UAV magnetic data.

Magnetic and spectrometric studies of Al-Gor area, Southwestern Sinai, Egypt

Al-Gor area is a part of Southwestern Sinai of Egypt. It is considered as one of the most promising areas for mineralization in Egypt, being rich in many mineral deposits of: manganese, iron, copper, zinc, lead, cobalt, nickel, silver, gibbsite, and uranium. Besides, some industrial ore minerals such as kaolin and glass sand,… etc. are also found in this area. The area was studied by Gama-ray spectrometry to trace the radioactive anomalies, their concentrations and their relationship to the existing rocks, and by magnetic survey to study the relationship of radioactive anomalies and their trends with the trends of geological structures. The gamma-ray spectrometric maps show different levels over the surveyed area, which reflect contrasting radioelement contents for the exposed various rock types. The highest radiospectrometric levels are located in the northwest southeast direction and some scattered parts all over the study area. They are mainly associated with Um-Bogma Formation, bearing gibbsite. The study area possesses radiospectrometric ranging between 0.6 and 110.9 Ur as a total-count, 0.1 to 1.8 % for K, 0.1 to 99 ppm for eU and 0.1 to 23 ppm for eTh. The qualitative analyses of magnetic data show the existences of a number of different magnetic anomalies, with different amplitudes and frequencies as well as trends. From the application of spectral analyses of magnetic data, the regional and residual depths of magnetic anomalies can be computed. The first depth represents the regional (deep-seated) anomalies, at about 75 m and the residual (shallow-seated) anomalies, at about 20 m. The trends of the structures as derived from the spectrometric and ratio maps correspond to those inferred from the residual-component magnetic map, which reflects the effect of structures on the concentration of radioactive elements and, consequently mineralization.