IP Anomalies Research Articles

The Audiological Profile and Rehabilitation of Patients with Incomplete Partition Type II and Large Vestibular Aqueducts.

Incomplete partition type II (IP-II) malformation is often accompanied by a large vestibular aqueduct (LVA). In IP anomalies, the patient's auditory rehabilitation requirements are decided according to the presence of inner ear structures and the degree of hearing loss (HL). There has been limited research on auditory rehabilitation (AR) requirement selection in patients diagnosed with IP-II and LVA. This study investigated the typical characteristics of HL and AR choices in patients diagnosed with IP-II and LVA. Patients with IP-II and LVA (n=55; 25 women and 30 men) were identified, and audiological evaluations were performed. The patient's demographic characteristics, the type and degree of HL, the AR method, age at diagnosis, and educational status were retrospectively compared. The distribution of our 55 patients according to cochlear implants, hearing aids (HA), and bimodal applications was 29.1% (n=16), 43.6% (n=24), and 27.3% (n=15), respectively. Statistical analyses using chi-square tests found no significant differences in the incidence of dizziness/imbalance, tinnitus, HL progression, or the degree and onset of HL among the patients. The data revealed different audiological characteristics among patients with IP-II and LVA, as well as different AR solutions. The most widely used AR modality was found to be HA. Prediction of sudden versus progressive HL development among patients is challenging, and the characteristics of IP-II vary. Therefore, they should be interpreted with caution.

Integration of Electrical Resistivity and Induced Polarization Technique for Oil Spill Investigation in Kegbara-Dere, Gokana LGA, Rivers State

Oil spill is a very complex phenomenon which requires detailed investigation using integrated techniques to identify the major contaminant anomalies in the study area, hence the need to investigate the spill contaminant is very key to obtaining data that would aid in the provision of requisite information for remediation. The study area was modelled using 2-D resistivity and induced polarization tomography for delineation of plumes resulting from the oil spills and those caused by mineralized bodies. 2-D data acquisition techniques were used to obtain apparent resistivity and IP data. Interpretation of electrical resistivity and IP tomograms shows that the hydrocarbon plumes signatures are masked by signatures from polarized bodies within the subsurface. The identification and isolation of the resistivity anomalies from the IP anomalies are of major concern in this research. Resistivity and induced polarization tomograms are used to accurately delineate the plume boundaries and also identify of regions masked by the presence of clays and other mineralized bodies within the subsurface.

Integration of induced polarization, resistivity, and magnetic data of IOA occurrences in Ararenda, western of the Santa Quiteria magmatic arc, Ceará Brazil

The Neoproterozoic Santa-Quitéria Magmatic Arc (SQMA) hosts significant IOA occurrences that were recently documented in their geological, petrographic, geochemical, and geochronological aspects. To advance the understanding of the geologic framework and metallogenetic potential beneath the SQMA, we used an integrated geophysical approach. In this context, this study is the first geophysical evaluation of these occurrences and provides valuable insights into the ore mineralization of this under-researched region. Seven profiles (E-W direction) were acquired using magnetic, resistivity, and induced polarization methods. The results allowed us to integrate the geological map information with the geophysical anomalies at the subsurface. According to the resistivity and IP inversions there are resistive and chargeable bodies at depths ranging from the surface to up to 180 m, and it is possible to associate the IP anomalies in shallow depths to deep magnetic 3D anomalies modeled. Most 3D magnetic anomalies are located on or very close to the IOA occurrences identified on the surface. The positive anomalies on the IP-chargeability map are related with the sites of alterations, shears, and contact zones. In addition, based on geological mapping, there is a correlation between high chargeability values and high magnetic values with iron formations (iron ore). In contrast, the correlation between high chargeability and low magnetic values indicates metal sulfides (including copper). The results presented here is a start point to further exploration work for this mineral system and we can suggest the future development of more dense geophysical data to better characterize it. An exploratory drilling holes campaign should be used in a second stage as a basis for the 3D geological model of this area. These two approaches will be crucial to improve the mineral knowledge of the SQMA.

Time-domain solution of Cole-Cole model with induced polarization method

The spectral parameters of the Cole-Cole model can be used to distinguish the IP anomalies of different geological bodies. However, the frequency domain IP requires a lot of observation data and its efficiency in field work is low. In view of this reality which is very common to use the data of the time-domain IP. It is necessary to study the law of the time-domain solution of Cole-Cole model with induced polarization method. First of all, this paper transforms the complex resistivity in the frequency domain into the time-varying resistivity in the time domain through the inverse Laplace transform, then by changing different Cole-Cole parameters in the time domain so that we can observe the changing law of time-varying resistivity time-spectrum characteristics caused by different parameters.

Application of the singularity mapping technique to identify local anomalies by polarization data (a case study: Hamyj Copper Deposit, Iran)

Separating anomalies plays a critical role on mineral exploration. In this paper, IP anomalies have been determined by concentration-area (C-A) and singularity methods. Then a comparison has been made between the methods. The singularity map (as well as fractal method) is usually applied in the geochemical exploration process; however, it has not been widely used in the geoelectrical methods so far. In this research, it has been successfully applied to utilize this method to process IP data (recognize anomaly induced polarization data in Hamyj copper deposit). Hamyj deposit is located about 80 km west of Birjand city, South Khorasan province, Iran. In this area, resistivity and induced polarization data have been surveyed by dipole-dipole array. Finally, according to the mentioned method, 67 % of the anomalies (singularity index) are confirmed by the concentration-area method which showed significant adaption with each other. Also, a suitable area is determined by a singularity map for drilling.

EVALUATION OF COPPER DEPOSITS PROSPECT IN WAI WAJO AREA OF SIKKA REGENCY, EAST NUSA TENGGARA PROVINCE

Lowo Deba prospect in Sikka Regency, East Nusa Tenggara Province shows significant evidences for copper deposit. The prospect is discovered by joint cooperation activity between Directorate of Mineral Resources Inventory (DMRI) and Korea Resources Corporation (KORES) in the systematic exploration program. The evaluation based on the quantitative analysis of rock and mineral characteristics as well as geologic mapping, petrography, mineragraphy, fluid inclusion, spectra analysis (PIMA), geochemical and geophysical data. The geology of the prospect area consists of Miocene volcanics of Kiro Formation and Tanahau Formation, intrusion of granodiorite and Quaternary volcanics. The volcanic rock shows the characteristic of tholeiitic magma. The predominant system of lineaments in the prospect area tends to be NE-SW trend. This fault structure appears to have closely relationship with the mineralization in Lowo Deba prospect. The mineralization and alteration outcrops appear to be structural controlled to form epithermal deposit type. Most of the mineralizations are hosted by phyllic – argillic altered andesitic to dacitic tuff which is intruded by granodiorite. Rock samples indicate the mineralization type is quartz vein containing chalcopyrite, galena, sphalerite, covellite and pyrite. The best grade revealed from these altered rocks of 6,980 ppm Cu and 50 ppb Au, and from quartz vein of 4,868 ppm Cu and 57 ppb Au. Mineralization stages evolved from initial higher temperatures (> 320° C) to later lower temperatures (near 170° C). Soil geochemical analysis identify two zones of combined anomaly i.e. Au-Cu-Mo and AgPb-Zn. Those anomalies are concentrated in the phyllic and argillic altered andesitic tuff. These soil anomaly coincide with IP anomalies which are found in electrode separation index of n=5 and n=7 in line WA7 with chargeability value up to 405.7 Msec and resistivity value of 37.7 Ohm-m. In general high chargeability and low resistivity anomalies are developed in the direction of southwest to northeast and still open to the northeast. The high chargeability value allows to predict the occurrence of copper deposits potential. Some bore holes are proposed for the next survey to confirm the presence of new copper deposits in the prospect area.

Geophysical surveying over VMS deposits in oman

Airborne and ground geophysical information was acquired to help locate prospective ground and to directly detect Cyprus-type Volcanogenic Massive Sulphides in the Northern Oman Ophiolite terrane. Airborne magnetic low zones were identified as areas of interest for ground geophysical surveying since footwall alteration, including magnetite destruction, is associated with the generation of these copper-rich VMS deposits. The Hatta and Shinas gossans and surrounding prospective volcanic rocks were surveyed with Time Domain Gradient Array Induced Polarisation, 100 m single moving loop SiroTEM and ground magnetic data. The 2 Mt Shinas deposit hidden beneath 20 m of resistive gravel cover, exhibits a weak Ch5 TEM anomaly related to copper-rich pyritic massive sulphide and an associated discrete IP anomaly coincident with the underlying stringer mineralisation. These are down-faulted from the outcropping auriferous debris flow breccia gossan. At a lower stratigraphic position in the nearby Hatta area, SiroTEM and Gradient Array IP anomalies have outlined four smaller massive sulphide breccia deposits that host economic copper grades. These deposits are associated with a major hydrothermal upflow zone in the footwall basalts that is characterised by magnetite depletion and weak chargeability. A combined approach of airborne geophysics, Landsat, geochemistry and geological mapping identified prospective areas for the utilisation of ground geophysics, which provided valuable guidance to site discovery drillholes.

The Moonta-Wallaroo mining district, South Australia: A geophysical perspective

Located on the Yorke Peninsula in South Australia, the Moonta-Wallaroo area is an important area of historical copper mining. Hydrothermal copper-gold-silver sulphide mineralisation occurs in Palaeoproterozoic and Mesoproterozoic metamorphic and igneous rocks, but there is no outcrop of these basement rocks due to subdued relief and extensive sedimentary cover. The lack of outcrop, plus the complexity of the local geology, means that basement geological maps of the area are largely speculative. An interpretation of semi-regional aeromagnetic data from the area suggests the basement comprises meta-igneous rocks overlain to the east by an increasing thickness of sedimentary and/or meta-sedimentary cover. Anomalies interpreted to be of stratigraphic origin are quite well developed in areas of meta-sedimentary rocks, and regional strike is interpreted as trending northeast-southwest. Linear anomalies to the north and west of the Wallaroo Mines are interpreted as resulting from magnetite deposited in faults during a regional iron-rich metasomatic event. Based on this interpretation, a major east-west/northeast-southwest trending deformation zone is recognised, interpreted as a locus of reverse and dextral faulting. The entire study area is cross-cut by late brittle faults that trend mainly northwest-southeast. This interpretation/structural scenario is consistent with mine-scale structural studies in both the Moonta and Wallaroo Mines, although, the resolution of the aeromagnetic data is insufficient to map deposit-scale structures. Ground-based geophysical exploration in the Moonta-Wallaroo area is hindered by the generally electrically conductive environment and the presence of cultural features, such as wire fences. However, surface and downhole time-domain EM surveys have successfully located massive-sulphide mineralisation comprising the Poona and Wheal Hughes deposits. The Poona deposit has also been shown to give rise to an IP response, and there is evidence that the lodes elsewhere in the Moonta area are also associated with IP anomalies.

Geophysical exploration of the Puhipuhi epithermal area, Northland, New Zealand

The Puhipuhi epithermal area, which occurs in a region of graywacke basement partially covered by basalt and lake-bed deposits, is characterized by both large-scale and small-scale geophysical anomalies. Known occurrences of locally intense alteration or silicification are typically associated with strong gravity, resistivity or IP anomalies. Gravity data define a complex negative residual anomaly (up to −50 gu) which has been used to identify and delineate a large area (about 20 km2) of low-density, presumably clay-altered, graywacke basement rocks. This zone, modeled as extending to a few kilometers depth, encompasses, but is more extensive than, the known areas of alteration and has a close spatial association with the basalt cover rocks. Short-wavelength gravity minima and maxima, which indicate that the most intense alteration of the basement rocks occurs below the basalt, correlate, in part, with the inferred location of hydrothermal upflow zones. The control on the location of these zones and their relationship to the location of the basalts is not well known; however, if the basalts acted as a cap rock to the geothermal system, then these areas merit further exploration. High (≥100 ohm-m) and low (≤10 ohm-m) resistivity and high (≥30 mS) IP anomalies occur in association with known silicification, clay alteration and sulfide mineralisation, respectively. In addition, magnetic data help constrain the relative timing of hydrothermal alteration and basaltic volcanism and indicate that mineralisation was broadly synchronous with volcanism.

Exploring the Solomon Islands with airborne geophysics

The Island of Guadalcanal occurs as an ‘s’ shape with each end twisted along the en echelon chain of the Solomon Islands primary fractured arc. The regional geology of Guadalcanal consists broadly of Mesozoic gabbroic and ultrabasic basement with Tertiary intrusives and sedimentary cover, and Quaternary volcanics.Helicopter borne magnetic and radiometric surveying was completed to delineate known gold-copper porphyry and epithermal style mineralisation events as well as locating structurally favourable sites for the emplacement and control of mineralisation.Porphyry prospects in the mountainous southern weather coast are coincident with magnetic features that correlate with IP anomalies. An intense amplitude magnetic anomaly on the southern side of Mount Turipukumahi is interpreted as an intrusive in the contact between gabbro and Kavo greywacke beds where magnetite rich skarn is likely to exist.A post volcanic event at the Sutakiki prospect is apparent as an outer halo of magnetite and potassium destruction 2km in diameter. The event is also coincident with a circular topographic depression with magnetic ring dykes occurring within. The topographic depression and ring dykes suggest it is a remnant of a collapsed strato-volcano, which is the possible control for present gold mineralisation.Controlling mechanisms for widespread mineralisation near the Gold Ridge deposit appears related to a 10 km-diameter partially collapsed strato-volcano that is evident from both the digital terrain model and Radarsat images. An inner 5km-diameter halo of potassium anomalies is directly coincident with anomalous surface gold and copper sampling results.Other volcano occurrences evident from the Radarsat and magnetic data indicate the presence of a magmatic arc. Hot springs are located along the proposed arc, which appears to be a control of most of the mineralisation that exists on the island.

Dual-frequency and multi-parameter IP instrument and its application research

Variable IP method mainly measures the Percent Frequency Effect (PFE), and phase IP method mainly measures phase. They both aim at finding IP anomaly. However, only using PFE anomaly or single phase anomaly can’t distinguish IP body’s property. The authors put forward a new method—dual-frequency and multi-parameter IP method, which can not only find anomaly of PFE and phase, but also provide the property information of IP anomaly resource. The authors also have invented the dual-frequency and multi-parameter IP instrument. A lot of experiments and field work have been done. The results show that the instrument is valuable in distinguishing IP anomalies.

Geological setting, history of discovery and exploration economics of Precambrian gold occurrences in Finland

The study covers 39 gold occurrences in Finland where gold is the only or most important ore metal. They occur as clusters in three geologically different environments: in eastern Finland 2.9–2.7 Ga Archaean greenstone belts, early Proterozoic (2.5–1.9 Ga) greenstone belts in northern Finland, and the 2.0–1.75 Ga Svecokarelian complex. The occurrences in greenstone belts are characterized by mafic-ultramafic host rocks, greenschist-grade metamorphism, extensive alteration, and association with regional shear zones; they are thus analogous to mesothermal gold deposits in other shields. Svecokarelian gold mineralization usually occurs in the contact zones of tonalitic intrusions and are typified by amphibolite grade metamorphism, a vein-type mode of occurrence, small-scale alteration, lack of carbonatization, and the presence of arsenopyrite and chalcopyrite. Exploration for gold in the Svecokarelian areas has almost invariably resulted from the finding of mineralized boulders and exposures (70% of the occurrences were outcropping), whereas in the greenstone belts, it has mainly been based on indications provided by regional geochemical till surveys. Local till geochemistry has contributed more than any other method, since about 20% of occurrences were discovered with this method alone and over 50% in conjunction with other indications. Two occurrences were discovered by drilling geophysical anomalies, and Slingram or IP anomalies contributed to discovery in 20% of cases, magnetic anomalies in 12% and VLF anomalies in 5%. Fifteen percent of the occurrences were discovered on the basis of mineralized outcrops and 5% on the basis of boulders. One occurrence was found directly due to geological analogy. The total budget for gold exploration in Finland was about C$ 38 million in 1984–1988, during which time most of the occurrences were found. About 29% of the budget was allocated to local till geochemistry (100 000 samples analysed), 31% for drilling (103 km drilled), 31% for mapping, trenching and overall expenses and 9% for ground geophysics (650 km 2 surveyed). The present study suggests that the gold potential is fairly high in Finland and that large areas remain underprospected. Considering the starting point of gold exploration and the results obtained so far, the abundant use of geochemical methods has been fully justified. In the future, however, successful exploration will require a higher priority for drilling.

Modelling of resistivity and IP anomalies of a thin conductor with an integral equation

A method is presented for calculating the resistivity and IP anomalies of a thin conductor. The conductor is represented by a two-dimensional conductive surface, and consequently the electric charge on its boundaries can be described as a two-dimensional surface charge. The potential on the surface is solved from an integrodifferential equation. For moderate conductivity values of the surface, the same equation can also be used in calculating the potential outside the conductor. For high conductivity, however, the charge density on the conductor is first solved with the aid of Coulomb's law, where the potential acts as primary term. The potential outside the conductor is then calculated from the known charge density by again applying the Coulomb's law. This procedure is valid over the whole conductivity range from zero to practically infinite values. For a perfect conductor, the potential can also be calculated directly by applying the equipotential condition of the conductor. As an application, the potential and charge distributions of the model are considered as a function of the longitudinal conductance of the conductor.

Calculation of resistivity and IP anomalies of a plate model with an integral equation

In order to achieve more flexibility for state feedback control design, a new design method based on Lipschitz switching surfaces is proposed for a class of n-th order linear systems subject to on-off control input in this paper. The Lipschitz switching surface is piecewise smooth and developed by the combination of several available smooth subsurfaces due to the partitioned domains of interest. Due to the discontinuity of the on-off input, Filippov's differential inclusion is adopted to describe the dynamics of trajectories of the closed-loop system. The globally asymptotic stability of the on-off control system with Lipschitz switching surfaces is illustrated by means of nonsmooth analysis and LaSalle's invariant principle for nonsmooth systems.

Lithologically Discordant Resistivity and IP Anomalies Associated With Hydrocarbons in the Rocky Mountain Foothills of Alberta Canada

The foothills of the Rocky Mountains in Alberta Canada contain several producing gas fields which are located in traps formed by the intense thrust faulting which characterizes this zone. The gas is found in Mississipian (Lower Carboniferous) rocks and the depth of the reservoirs lies in the range 3 to 6 km, with the depth being greater as the front of the Rocky Mountains is approached. The outcropping rocks of the area are Cretaceous sandstones and shales of marine and continental origin.

The modified pseudo-depth section as a tool in resistivity and IP prospecting — A case history

Following the depths of investigation of different electrode arrays, given byRoy andApparao (1971) andRoy (1972), a modified pseudo-depth section was suggested for any array byApparao andSarma (1981) as a tool in resistivity and IP prospecting. The tool was used for the interpretation of IP and resistivity anomalies obtained in a virgin area—Jonnagiri village, Pattikonda Taluq, Kurnool district (A.P.) India. Two of the four bore holes recommended encountered sulphide mineralization, while the other two met with white altered ashy material at the position of the maximum anomaly contour in the depth sections. The drilling results prove the utility of the modified pseudosections in the interpretation of the field data.