Chairman: Acad. SABBA STEFANESCU
DEVELOPMENT OF BOREHOLE LOGGING FOR THE SOLID MINERAL SUBSTANCES IN ROMANIA
S. GH. IORDACHE
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents a succinct history of borehole logging research methodology
development for the solid mineral substances in Romania.
Key words: borehole logging history in Romania, solid mineral substances.
CONTRIBUTIONS TO BOREHOLE LOGGING INVESTIGATION
OF POLYMETALLIC SULPHIDE MINERALIZATIONS
IN ALTIN-TEPE MINE EXTENSION
S. GH. IORDACHE
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the borehole logging methodology and results, obtained
by investigation of polymetallic sulphides from Altin-Tepe mine extension.
Key words: borehole logging, methodology and results, polymetallic sulphides
RADIOMETRIC INVESTIGATIONS IN PRECAMBRIAN FORMATIONS
FROM AL HOMURA ZONE, THE ARAB REPUBLIC OF YEMEN
N. HEREDEA
Enterprise of Geological and Geophysical Surveys, Bucharest
The radiometric complex investigations established the radiometric characteristics
of the main petrographic types of rocks, pointing out on a whole a region with
thorium feature, where anomalies generated by the quartz-feldspar pegmatities,
granites, quartz veins and Schibam migmatized biotitic gneiss were identified.
Key words: A.R. Yemen, Al Homura, radiometric investigations, thorium region,
pegmatities, granites, gneiss.
GEOELECTRICAL CONTRIBUTIONS OF THE IDENTIFICATION OF A
PORPHYRY COPPER MINERALIZATION IN THE "DEALUL UNGURULUI –
MUNCEASCA" ZONE, METALIFERI MOUNTAINS
M. MUNTEANU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper synthetically presents the geoelectrical image obtained on the
important Neogene volcanic structure in the Dealul Ungurului. For the elaboration
of the interpretative model, the geoelectrical information have been correlated
with other geophysical, geological and mining data as well.
Key words: Dealul Ungurului, Metaliferi Mountains, Neogene volcanic porphyry,
copper, geoelectrical image, interpretation model.
GEOELECTRICAL CONTRIBUTION TO PROSPECTING THE GOLD-SILVER
MINERALIZATION IN VALIUG-BOGATUL AREA, SEMENIC MOUNTAINS
C. ANGHELA, M. SIMIONESCU, V. SERAFIMOVICI
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the results obtained through induced polarization, resistivity
and self potential investigations both in identifying the gold-silver mineralization
and elucidating the geological structure.
Key words: Valiug, Semenic Mountains, induced polarization, resistivity, self
potential, gold-silver mineralization, geological structure.
BOREHOLE LOGGING COMPLEX INVESTIGATION OF COAL IN FLORESTI – MAGURENI
AREA
C. DOBRE
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the borehole logging methodology applied for coal investigation
in Floresti – Magureni area.
The paper also presents quantitative and qualitative data determined from the
recorded log.
Key words: Floresti – Magureni area, borehole logging, quantitative and
qualitative data, coal.
Hg SPECTROMETRICAL RESEARCHES IN THE METALIFERI MOUNTAINS
D. IOANE
Institute of Geology and Geophysics, Bucharest
The paper presents the results of the Hg spectrometrical researches, carried out between 1979 and 1983, by using field and laboratory measurements. Methdological aspects and the efficiency of the Hg spectrometry in hydrothermal halos studies of the Metaliferi Mountains are commented.
GEOPHYSICAL AND ARCHAEOLOGICAL RESEARCHES IN THE SOMOVA DEPOSIT AREA (NORTH
DOBROGEA)
D. IOANE1, FL. TOPOLOVEANU2, Z. IOANE1, VL. FILIPCIUC3,
I. SEGHEDI1, GH. MATEESCU1, D. ONCESCU3, AL. SZAKACS1
1Institute of Geology and Geophysics, Bucharest
2"Delta Dunarii" Museum, Tulcea
3Enterprise of Geological and Geophysical Surveys, Bucharest
On the occasion of geophysical field works carried out in 1984 an unknown Geo-Dacian
settlement was discovered (probably 4th century – 3th century B.C.).
The site seems to be related with the neighboring sulphides ores in the Somova
area. This paper presents the preliminary results of some geophysical (magnetometry
and electrometry), dowsing and archaeological researches.
Key words: magnetometry, electrometry, dowsing, archaeology, North Dobrogea
NEW GEOPHYSICAL DATA IN THE HONDOL AREA– METALIFERI MOUNTAINS
D. IOANE, J. ANDREI, GABRIELA GRABARI
Enterprise of Design and Research for the Oil Industry Equipment, Ploiesti
The geological and metallogenetical features of the Hondol area are well
known, due to an old mining activity, being suitable for the testing of modern
geophysical techniques. The correlation of the underground and field geophysical
data pointed out an interesting zone for Pb – Zn sulphides, in a large
hydrothermal halo.
Key words: magnetometry, gamma ray spectrometry, Hg spectrometry, energy dispersive,
X-ray fluorescence, hydrothermal halo.
ABOUT SOME NEW THEORETICAL AND PRACTICAL FEATURES IN THE INDUCTION LOGGING
DEVELOPMENT
AL. BABSKOW
Institute of Geology and Geophysics, Bucharest
Some new mathematical models, which express quantitatively the skin-effect
influence, both on the directivity characteristics and on the geothermal factor,
are discussed.
Further, some new achievements in the fields of researching and designing the
induction log apparatus are presented. The chosen solutions allows, correcting
the skin-effect, as a result of the propagation phenomenon, as well as converting
the conductivity signal into resistivity signal, by reciprocation.
Key words: mathematical models, skin-effect influence, induction log apparatus,
conductivity/resistivity signal reciprocation.
BOREHOLE LOGGING INSTRUMENTS FOR COMPLEX MEASUREMENTS IN MINERALS AND COAL
BOREHOLES
I. VISAN
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the outfit of borehole logging with electronic instruments
for complex measurements in boreholes of minerals and coal: surface instruments,
bottom ones, and interpretation on computer. Personal contributions are also
presented for improving working parameters of various geophysical devices.
Key words: borehole logging instruments, working parameters, minerals and coal
boreholes
GEOPHYSICAL IMAGES – SEDIMENTOLOGICALLY INTERPRETED –
REGARDING THE LAKES OF THE DANUBE DELTA AND THE RAZELM – SINOE SYSTEM
SORIN RADAN, MARIA RADAN, SILVIU RADAN
Institute of Geology and Geophysics, Bucharest
In this paper some magnetic and susceptibility maps and profiles regarding
the main lakes of the Danube Delta, Razelm-Sinoe system and its satellite lakes
are presented. The geophysical images obtained as a result of the application
of different methodological variants (susceptibilimetry on bottom sediment
samples, cores and profiles; magnetometry with the sensor "towed on bottom" and "under
water's surface"; kappa-magnetometry) are interpreted sedimentologically.
Key words: magnetic susceptibility map, magnetic profile, bottom sediment,
Danube Delta, Razelm-Sinoe lacustrine system
THE INVERSE PROBLEM SOLVING POSSIBILITIES IN RADIOMETRY
R. CONSTANTINESCU, GH. GRECEA
Enterprise of Rare Metals, Bucharest
The paper presents filtering, clustering and recognition statistical methods,
applied in identifying source types having generated the measured gamma-ray
fields.
Key words: filtering, clustering, recognition gamma-ray fields.
THE URANIUM ANALYSIS BY GAMMA-RAY SPECTROMETRY EMITTED BY THE FISSION FRAGMENTS
A. LUNG, O CARUTASU, R. CONSTANTINESCU, V. CRINGAN
Enterprise of Rare Metals, Bucharest
The paper reports the uranium analysis possibilities in geological samples,
by gamma-ray spectrometry emitted by the U238 and U235 fission fragments,
as obtained by reactor irradiation.
Key words: gamma-ray spectrometry fission fragments.
ISOTOPIC AND GEOCHRONOLOGICAL STUDIES CONCERNING THE
GRANITIZATION PROCESS FROM THE EASTERN CARPATHIANS
AND THE ASSOCIATED MINERALIZATION
G. POP1, I. CRISTEA1, M. ENE1, G. POPESCU2, M. SOROIU2
1Enterprise of Rare Metals, Bucharest
2Institute for Physics and Nuclear Engineering, Bucharest–Magurele
The study of Sr, Rb, Pb isotopes and the radiometric datings carried out
on minerals, whole rocks and claysih minerals, provide specifications concerning
the time sequence of the petrogenetic processes and metallogenetic stages defining
the evolution of the crystalline nucleus of the Eastern Carpathians.
The extrapolation of these data allows paragenesis evaluation for prospecting
and exploration purposes.
Key words: isotopes, geochronology; granitization, metallogenesis; petrogenesis,
Eastern Carpathians, prospecting and exploration workings, paragenesis
ISOTOPIC AND GEOCHRONOLOGICAL STUDIES ON THE BANATITIC
MAGMATISM, METAMORPHISM AND ASSOCIATED MINERALIZATIONS
FROM THE BIHOR MOUNTAINS
GH. POP1, L. WEISZ1, GH. POPESCU2
1Enterprise of Rare Metals, Bucharest
2Institute for Physics and Nuclear Engineering, Bucharest – Magurele
The paper presents a new dating of absolute age of the magmatic and metamorphic
rocks from the Bihor Mountains, carried out through the Rb – Sr isotopic
method. It specifies the origin from the upper mantle as well as the Campanian
age of the granitic batholith. For dating the polymetalliferous mineralization
the isotopic analysis of lead from the galenas was made.
Key words: absolute age, Rb – Sr isotopic method, Pb isotopic analysis,
upper mantle, Campanian.
PHYSICAL-MINERALOGICAL STUDY OF RADIOACTIVE ELEMENTS DISTRIBUTION IN ROCKS
BY FISSION TRACK
CRISTINA BALANESCU1, EUFROSINA WEISZ2
1Enterprise of Rare Metals, Bucharest
2Institute for Physics and Nuclear Engineering, Bucharest – Magurele
We describe a physical-mineralogical method by which uranium distribution,
abundance and occurrence in natural rocks of constitutive minerals are studied.
A sandwich – mica as detector, thin section of rock as sample are used;
mica as support is irradiated for 12 minutes in a neutron flux of 5 x 1011
n/cm2/s, at the nuclear reactor. A micromap of fission tracks by visualising
and counting every microscopical field is made, then the host minerals are
identified.
Key words: micromapping, fission track, U-distribution in rock minerals.
THE Rn HALOES SURVEY BY TRACK-ETCH METHOD
O. CARUTASU
Enterprise of Rare Metals, Bucharest
The paper points out the track-etch method when exploring U. It consists
of establishing the Ra distribution on the surface we had in view. The survey
is carried out on a network, by using solid state alpha detectors. This method
also refers to the exploration of deep hidden bodies.
Key words: Ra, U, exploration by track-etch.
IMPLICATIONS OF RADIOACTIVE DISEQUILIBRIUM IN FIELD GAMMA-RAY SPECTROMETRY
D. PAICU
The paper is presented in extenso in this issue, page 37
PARTICULARITIES OF THE GAMMA-RAY SPECTRES "IN SITU"
M. SASARMAN, V. GEORGESCU
Enterprise of Rare Metals, Bucharest
The multitude of aspects concerning the shape and size in which we find radioactive
sources in different geological conditions, as well as different medium conditions,
gives to the ?-ray specters which are emitted by those sources a lot of particularities.
The knowledge of these particularities is of primary necessity in solving a
lot of important problems in applied ?-spectrometry such as: the solution of "inverse
problem" and others.
The present work attempts to classify the above-presented particularities and
the involved factors, as well as to analyze the interaction processes which
determine those particularities.
Key words: gamma-ray, energetical specters, radioactive source, geological
conditions, interaction, applied gamma spectrometry
THE GAMMA-RAY FIELDS MODELLING
R. CONSTANTINESCU
Enterprise of Rare Metals, Bucharest
The paper presents the results obtained in gamma-ray fields modelling, by statistical "Monte Carlo" type methods pointing out at the same time the possibilities of shortening the computing time when using these methods.
THE DETERMINATION OF THE QUANTITATIVE ATIOS BETWEEN
U, Ka AND Th, IN THE GEOLOGICAL SAMPLES, BY PURE Ge DETECTOR
GAMMA-RAY SPECTROMETRY
A. LUNG, O. CARUTASU, I. PORDEA
Enterprise of Rare Metals, Bucharest
The paper presents the manner of simultaneous analysis of U, Ka and Th by natural
gamma-ray spectrometry, with pure Ge detector and multichannel analyzer.
The above mentioned method solves the difficult situations when certain geological
samples, collected from hypergenesis areas, have a strong radioactive disequilibrium.
Key words: detector, pure Ge, uranium, radium, thorium analysis.
MODELING THE DEEP GEOLOGICAL STRUCTURE OF THE GILAU MASSIF
FROM THE AEROMAGNETIC AND GRAVIMETRIC DATA
F. SCURTU1, V. STOENESCU1, D. ROMANESCU1, T. CRISTESCU2, M. ABAIU2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest
A structural model of the studied region, iteratively improved by successive
approximations, was obtained by computer processing of the aeromagnetic and
Bouguer maps. The initial maps and those obtained by mathematical modeling
are in coincidence within the limits of the accuracy of the former ones.
An 3D gravimetric and magnetic modeling methodology for regions with rugged
relief and complicated geology was elaborated. Finally, the deep geological
structure image, including crystalline schists, the Muntele Mare granite and
banatitic intrusions, some of them presenting perhaps economic interest, is
presented.
Key words: modeling, aeromagnetic data, gravimetric data, petrophysical data,
Apuseni Mountains, Gilau Massif.
NEW CONSIDERATIONS REGARDING GEOLOGICAL SIGNIFICANCE
OF GEOPHYSICAL REGIONAL DATA IN THE ZONE
OF ALKALINE MASSIF FROM DITRAU
T. STRUGARU, N. HEREDEA, D. HANNICH, V. ZORILESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents some new considerations concerning the deep structure
of the Ditrau massif on the basis of aeromagnetometric, aerospectrometric,
gravimetric and petrophysical data. Accepting a magnetic origin, geophysical
data indicate the striking root tendency of the massif up to 10 km depth and
a possible manifestation of a similar magmatic activity to NE.
Key words: Ditrau alkaline massif, regional geophysics, deep structure, striking
root tendency, magmatic origin.
THREE-DIMENSIONAL MODELING PROCEDURE FOR THE POLARIZATION METHOD
I. STOICA, M. IANAS
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents a procedure of three-dimensional modeling on computer
for the induced polarization method, which may be applied in the case of geological
surroundings without contrasts of resistivity or with small contrasts.
The resolution capacity is also studied for various arrangement of electrodes
depending on the geometry of the polarizable bodies.
Key words: induced polarization, three-dimensional modeling, resolution, electrode
arrangements, bodies geometry.
SEISMIC INVESTIGATION OF WEATHERING ZONE OF SALT IN SOVATA AREA
P. CRISTEA, V. MANJ, MIHAELA GEORGESCU
Institute of Geology and Geophysics, Bucharest
Using both the detailed shallow refraction method as applied to the media
exhibiting a vertical velocity gradient and a suitable processing methodology,
it has been possible to investigate the weathering zone of the salt massif
in the Sovata area.
Some seismic tomographic images are presented at different levels taking into
account the seismic velocity distributions.
Key words: seismic prospecting, continuous refracted waves, salt.
RESULTS OF GAMMA AEROSPECTROMETRIC AND GROUND RADIOMETRIC SURVEYS OF THE
TALAGIU ZONE
FL. RADULESCU1, I. NARCOSANU2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest
Using the results of aerospectrometric ground radiometric and laboratory
gamma spectrometric surveys, the paper presents the possibility offered by
aerospectrometry in separating the various types of alteration, especially
in zones of potassic hydrothermalism.
Key words: aerospectrometric rresults, ground radiometry, Talagiu zone.
PROCESSING AND GEOLOGICAL INTERPRETATION OF
AEROSPECTROMETRIC DATA FROM THE EASTERN ZONE
OF THE FAGARAS MASSIF
FL. RADULESCU1, L. NEDELCU1, N. HEREDEA2
1Institute of Geology and Geophysics, Bucharest
2Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the results obtained by statistical processing of aerospectrometric
data from the eastern zone of the Fagaras Massif. The data are interpreted
both on a regional scale (correlation of data with the main geological formation)
and on a local scale, with a view to clearing up the geological significance
of anomalous zones.
Key words: statistical processing, gamma aerospectrometry, geological interpretation,
Fagaras zone.
CONSIDERATIONS ON THEORETICAL AND APPLIED FIELD GAMMA SPECTROMETRY
FL. RADULESCU, D. IOANE
Institute of Geology and Geophysics
The paper deals with the main theoretical aspects concerning field gamma
spectrometry. The following problems are approached: efficiency of NaI (Tl)
detectors; size of the surface of collecting the radiation; investigation depth;
theoretical calculation of sensitivity; tridimensional models. From the point
of view of applied research, the paper presents the way in which data are processed
for obtaining direct and derived maps.
Key words: field gamma spectrometry, efficiency and sensitivity of NaI(Tl).
COMBINED CRUSTAL ASSIMILATION AND FRACTIONAL
CRYSTALLIZATION MODEL (DONALD J. DE'PAOLO). APPLIED TO Rb and Sr
CONCENTRATIONS AND TO ISOTOPIC RATIO 87Sr/86Sr OBTAINED
ON SAMPLES FROM CALIMANI MTS
GABRIELA GRABARI1, I. SEGHEDI1, GH. POPESCU2, SERGIU PELTZ1
1Institute of Geology and Geophysics
2Institute for Nuclear Physics and Engineering, Bucharest – Magurele
Equations describing trace elements and isotopic ratios evolution in a magma
chamber simultaneously affected by fractional crystallization and wallrock
assimilation are presented (equations published by D.J. De'Paolo). These equations
are applied to Rb and Sr concentrations and to the ratio 87Sr/86Sr obtained
on samples from the Calimani Mts., establishing parameters in agreement with
the obtained data.
Key words: wallrock assimilation, fractional crystallization, rubidium, strontium,
87Sr/86Sr.
GRAVITY EQUIVALENT SOURCES
M. IVAN
University of Bucharest, Faculty of Geology and Geography, Geology and Geophysics
Chair,
Bucharest
The fundamental ambiguity of the gravity field is amplified by the finite
number of data points. Consequently, erroneous results can be obtained when
the data acquired on irregular topographic surfaces are processed with equivalent-source
techniques.
A synthetic but realistic model illustrates the assertion.
Key words: gravity field, fundamental ambiguity, equivalent-source techniques,
irregular topographic surface.
INITIATION OF BOARD OFFSHORE GRAVIMETRIC SURVEYS ON THE ROMANIAN BLACK
SEA CONTINENTAL SHELF
C. S. SAVA
Institute of Geology and Geophysics, Bucharest
Following the endowment of the Institute of Geology and Geophysics with gravimetric
equipment of GMN – K type, board offshore gravimetric surveys were initiated
in 1983 on the Romanian Black Sea continental shelf.
The paper presents problems related to the preparation of the equipment under
laboratory conditions, its fitting aboard and the measurements carried out
in a network of marine profiles as well as the first results of the processing
of data obtained so far.
Key words: offshore gravimetric survey, continental shelf.
NUMERICAL MODEL FOR HEAT TRANSFER IN GEOTHERMAL FLOWING WELLS
P. CRACIUN
Institute of Geology and Geophysics, Bucharest
In order to analyze the heat transfer from the water column in geothermal
wells to the rocks, a bidimensional numerical model is presented.
The equation of energy conservation is written in finite difference and the
computer solution of the program performed yields the axial temperature distribution.
The influence of the fluid rate variation, geothermal gradient and the well
radius temperature profiles in flowing wells is tested.
Key words: numerical simulation, heat transfer, hydrodynamics, geothermal waters,
computer program.
PETROPHYSICAL DATA CONCERNING THE ROCKS FROM THE FAGARAS CENTRAL MASSIF
D. ROMANESCU, V. STOENESCU, ANCA GEORGESCU, ELENA SZABO
Institute of Geology and Geophysics, Bucharest
The rocks belonging to the crystalline formations between Arefu and Citisoara
are characterized from the magnetic and density point of view. Somewhat greater
density values in the Fagaras series are to be noticed. The amphybolites – classified
in 4 types – as well as some rocks containing magnetite, have been separated
by means of magnetic properties.
Key words: magnetic properties, density, metamorphic rocks, Fagaras Massif.
POSSIBILITIES OF USING THE THREE-DIMENSIONAL MODELS IN ELECTRICAL PROSPECTING
P. GEORGESCU1, I. GAVRILA2, G. ION2
1University of Bucharest, Faculty of Geology and Geophysics, Geology and Geophysics Chair, Bucharest
2Enterprise of geological and Geophysical Surveys, Bucharest
The ways of using the three-dimensional models both in field data interpretation
and in prospecting work planning are analyzed.
An original method for three dimensional models computation is briefly described.
Key words: electrical prospecting, resistivity, electrical configuration, apparent
resistivity anomaly, three-dimensional models
THE THERMAL CONDUCTIVITY OF SOME ROCKS FROM THE PANNONIAN DEPRESSION
A. NEGUT, M. PAUCA
The University of Bucharest, Faculty of Geology and Geography, Geology and
Geophysics Dept., Bucharest
The results of thermal conductivity determination, by the divided-bar method,
of 105-rocks samples from wells located on some structures from the Pannonian
Depression, are presented in the paper. Most of the analyzed rocks are obtained
from Tomnatec, Jimbolia and Sinnicolaul Mare structures; the measured thermal
conductivity varies in the range from 1.20 to 3.96 mcal/cm°C.s (0.5 – 1.66
W/m.°C) and belong to two main lithological types, siltstones and silty
sandstones.
The observed thermal conductivity variations versus lithology and depth and
implications of their knowledge for Pannonian Depression, a zone particular
geothermal interest, are discussed.
Key words: thermal conductivity.