GEODYNAMICS

Aim of the work is tectonophysical identify the totality of the deformation structures of the collisional evolutionary stage, which determine the tectonic style of the Transition Zone between Dnieper-Donets Basin and the Donbas Foldbelt. Methods. For the research, we used the author's technique for reconstructing the fields of tectonic deformations and tectonophysical analysis of geostructures. The analytical base of the research was made up of new materials of geological mapping of the territory of the transition zone between the Basin and the Foldbelt. Results. Inversion deformations of the Dnieper-Donets Paleorift were controlled by lattices of tectonites of regionally stable submeridional directions of movements. An analysis of structural patterns of tectonites indicates over the riftogenic faults of the basement in the sedimentary cover of the transition zone, echeloned stages of plumage are formed, composed of thrusts with a significant component of horizontal displacement. The tectonic style of the Transition Zone is determined by the pushing on the low dislocation autochthonous of the Basin of the repeatedly deformed, crumpled into the folds of sedimentary geomas from the Foldbelt. The allochthon structural and tectonic framework consists of thrusts, coulisse-jointed structural ensembles of thrusts, folded covers of transverse extrusion of geomas from axial to side zones, and folded covers of longitudinal thrust towards the depression. All together its form the Western Donets Cover-folded Region, the main structural element of which is the Segment of the Tectonic Wedging of geomass. The north-eastern flank of the Segment is formed by linear anticlinal zones - Torsky-Drobishivska, North-Donets, Matrossko-Toshkovska, south-western - Petrovsko-Novotroitska. The structural apex of the Segment is a tectonic junction at the ends of dynamically conjugated thrusts in the area of the joint of the salt-dome shafts of the axial part of the Basin. Scientific novelty. The tectonic inversion is responsible for the formation of three folded structural floors - the Herzinian, Laramian and Attic. According to the dynamically coupled lattice, a cover-folding system of tectonic thrusting was formed in them, which was first diagnosed as a Segment of Tectonic Wedging of geomas by the Donbas Foldbelt. On the basis of this, within the Transtition Zone, a Western-Donetsk cover-folded Region was separated, covering two tectonic areas in intensity and style of deformation of the sedimentary cover - Kalmius-Toretsky area of scaly covering in the southwestern part, which is limited to the South Donbass Melange Zone in the south, and the Lugansk-Kamyshuvakhsky area of the coulisse-jointed uplift-folding on the northeastern part, which from the north is limited by the low-folded Mesozoic-Cenozoic cover. They are separated by the Central Zone of Strike-slip control along the axial folded zone of large stage-jointed uplift-folds, which include Great-Kamyshuvakhska, Novotroitska, Druzhkovsko-Konstantinovska and Main anticlines. Practical significance. Based on the actual geo-mapping data, it is proved the riftogenic structure in the southeast of the Dnieper-Donets Paleorift is destroyed by folding at the stages of platform activation. Allocation of territory of the Western Donetsk Сover-folded Region allow to correct the scheme of tectonic zoning of the Dnieper-Donets Basin, which is the basis for modeling the geodynamics of the Transition Zone formation.

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Tectonic inversion of the Dnieper-Donets basin. Part 1. Collizion tectonics of the Western-Donets graben

Geology Geography Ecology ◽

10.26565/2410-7360-2020-52-01 ◽

2020 ◽

Keyword(s):

Transition Zone ◽

Sedimentary Cover ◽

Donets Basin ◽

Tectonic Deformation ◽

Sedimentary Sequence ◽

Heterogeneous Distribution ◽

Three Generations ◽

The North ◽

Thrust Front ◽

Folded Structure

Formulation of the problem. New results of tectonophysical studies of the structural-kinematic evolution of the Earth's crust of Dnieper-Donets paleorift at the collision stage are presented in the paper. The subject of research is a complex of deformation structures that complicate the sedimentary cover in the transitional zone with Donets folded structure. Review of previous publications and studies. According to new mapping data, tectonic deformations of the sedimentary cover were controlled by systems of faults of the north, northwest, and southeast vergence. The lattices of the Hercynian, Lamaric, and Attic tectonites determine the specific “cross-thrust” structure of pushing. Due to the heterogeneous distribution of deformations of different ages, the stratigraphic volume of the sedimentary sequence varies in area from the Pliocene-Anthropogenic to the Mesozoic-Cenozoic. Overthrusts and linear folding of three generations permeate the sedimentary sequence of the transition zone from east to west for hundreds of kilometers within the eastern part of Izyumsky paleorift segment. Methods. Using the original method of tectonic deformation fields’ reconstruction and tectonophysics analysis of structures, collision deformations of the platform sedimentary cover of the southeastern part of Dnieper-Donets depression are studied. The materials of geological mapping of the transition zone and instrumental definitions of the vergence of the Hercynian, Laramian, and Attic faults constituted the analytical base of tectonophysical studies. Results. In the transition zone, West-Donets segment of the tectonic wedging, which completely destroys the riftogenic structure in the southeast of the basin was identified. It was formed as a result of a thrust on the syneclise autochthon repeatedly deformed, crumpled into the folds of geomass from the western slopes of Donets folded structure. It consists of structural ensembles of linear thrust folds, tectonic covers of transverse, pushing of sedimentary geomas from axial to onboard zones, and folded covers of longitudinal thrust. The thrust covers and folds of allochthon end in the depression with scaly compression fans formed at the ends of the main thrusts. In the thrust front of West Donets segment, a geodynamic discharge strip was diagnosed, where structural zones of displacement of geomass were formed. On the north-eastern flank of the thrust front they are represented by large linear anticlinal zones of the so-called “open Paleozoic structures”, such as Torsko-Drobishevsk, North-Donets, Matrossko-Toshkovsk zones, and on the southwestern - Petrovsky-Novotroitsk zone of reverse-folds. The structural peak of the West-Donets segment is the tectonic node of thrusts and strike-slips of three generations, localized in the joint area of the central and southern structural branches of the axial salt-dome folding. Scientific novelty and practical significance. The current regional tectonic scheme has been revised on the conceptual foundations of dynamic geotectonics. It is shown that the riftogenic structure of the transition zone at the collision stage of evolution was completely destroyed by deformations of three generations. Lattice of tectonites, thrust cover and uplift folding zones of the Hercynian, Laramian, and Attic generations together form West-Donets cover-fold region within it. The main tectonic element of the region is the segment of the tectonic wedging of the same name. By the nature of the structure in its northern part, Lugansk-Kamyshevakhsky district is distinguished by a link echelon of linear folding, and in the south by Kalmius-Toretsky region of tectonic thrust cover. West Donets segment is an important component of the structural-tectonic frame of the sedimentary cover, which determines the modern transverse tectonic segmentation of the paleorift.

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Сollision deformations of the Dnieper-Donets Depression. Article 1. Tectonics of the articulation zone with the Donets folding structure

Geology and Geochemistry of Combustible Minerals ◽

10.15407/ggcm2019.03.076 ◽

2019 ◽

Vol 3 (180) ◽

pp. 76-89

Author(s):

Оleksiy Bartashchuk

Keyword(s):

Transition Zone ◽

Sedimentary Cover ◽

The Body ◽

Donets Basin ◽

Tectonic Deformation ◽

Sedimentary Sequence ◽

The South ◽

The West ◽

South Eastern ◽

Three Generations

The article is the first part of a trilogy devoted to the study of post-rift deformations of the riftogenic structure of the Dnieper-Donets paleorift. The mechanisms of collision warping of the horizons of the sedimentary cover of the southeastern part of the Dnieper-Donets depression are considered. According to the previous mapping data, the tectonic deformations of the sedimentary cover were controlled by systems of faults of the north, north-west, and south-east vergence. The lattices of tectonites of the Hercynian, Lamaric, and Attic generations determine the specific “cross-thrust” structure of pushing. Overthrusts and linear folding of three generations permeate the sedimentary sequence of the transition zone from east to west for hundreds of kilometers within the eastern part of Izyumsky paleorift segment. The analytical base of the research was the materials of geological mapping of the zone of the junction of the depression with the Donets fold structure. Using field definitions of the tectonite vergency of the Hercynian, Laramide and Attic phases of tectogenesis, the original method of reconstruction of tectonic deformation fields and tectonophysics analysis of structures, collision deformations of the sedimentary cover of the south-eastern part of the Dnieper-Donets paleorift are studied. The tectonophysical analysis of tectonites of different ages indicates that together they control the cover-thrust and folded deformations of the riftogenic structure. Overthrusts and linear reverse-folding of three generations form the West-Donetsk integumentary-folding region, within which a segment of the same name tectonic thrust is distinguished. By pushing the system of repeatedly deformed, crushed into folds of geomass sedimentary rocks on weakly deployed syneclise deposits, the riftogenic structure of the south-eastern part of the basin is completely destroyed. The structural-tectonic framework of the allochthone, pushed from the side of the Donets structure, is composed of dynamically conjugated lattices of Hercynian, Laramide, and Attic tectonites. They control the echelon backstage of linear reverse-folds, tectonic plate-covers of transverse extrusion of sedimentary geomass from axial to airborne zones and folded covers of longitudinal thrust from the south-east. The riftogenic structure of the transition zone between the Dnieper-Donets basin and the Donets folded structure was completely destroyed by deformations of three generations of platform activation. The dynamically coupled tectonite lattice, the overlays, and the folded zones of the Hercynian, Laramide, and Attic generations jointly form the West-Donets fold-fold region within its boundaries. The main tectonic element of the area is the eponymous subregional tectonic thrust segment. The central structural zone is Veliko-Kamyshevakhskaya, Novotroitskaya, Druzhkovsko-Konstantinovskaya and Main anticlines. The central zone divides the body of the segment into two tectonic regions according to the tectonic style and intensity of deformation of the sedimentary sequence. The northern part is occupied by the Luhansk-Kamyshevakhsky region of the rocky-layered linear folding of the thrust, and the southern part is the Kalmius-Toretsky region of scaly tectonic covers.

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Geodynamics of the France Southeast Basin

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.181.6.477 ◽

2010 ◽

Vol 181 (6) ◽

pp. 477-501 ◽

Cited By ~ 20

Author(s):

Xavier Le Pichon ◽

Claude Rangin ◽

Youri Hamon ◽

Nicolas Loget ◽

Jin Ying Lin ◽

...

Keyword(s):

Seismic Activity ◽

Sedimentary Cover ◽

Central Basin ◽

The South ◽

Western Basin ◽

Active Deformation ◽

The North ◽

The Alps ◽

Sediment Cover ◽

Surrounding Areas

AbstractWe investigate the geodynamics of the Southeast Basin with the help of maps of the basement and of major sedimentary horizons based on available seismic reflection profiles and drill holes. We also present a study of the seismicity along the Middle Durance fault. The present seismic activity of the SE Basin cannot be attributed to the Africa/Eurasia shortening since spatial geodesy demonstrates that there is no significant motion of Corsica-Sardinia with respect to Eurasia and since gravitational collapse of the Alps has characterized the last few millions years. Our study demonstrates that the basement of this 140 by 200 km Triassic basin has been essentially undeformed since its formation, most probably because of the hardening of the cooling lithosphere after its 50% thinning during the Triassic distension. The regional geodynamics are thus dominated by the interaction of this rigid unit with the surrounding zones of active deformation. The 12 km thick Mesozoic sediment cover includes at its base an up to 4 km thick mostly evaporitic Triassic layer that is hot and consequently highly fluid. The sedimentary cover is thus decoupled from the basement. As a result, the sedimentary cover does not have enough strength to produce reliefs exceeding about 500 to 750 m. That the deformation and seismicity affecting the basin are the results of cover tectonics is confirmed by the fact that seismic activity in the basin only affects the sedimentary cover. Based on our mapping of the structure of the basin, we propose a simple mechanism accounting for the Neogene deformation of the sedimentary cover. The formation of the higher Alps has first resulted to the north in the shortening of the Diois-Baronnies sedimentary cover that elevated the top of Jurassic horizons by about 4 km with respect to surrounding areas to the south and west. There was thus passage from a brittle-ductile basement decollement within the higher Alps to an evaporitic decollement within the Diois-Baronnies. This shortening and consequent elevation finally induced the southward motion of the basin cover south of the Lure mountain during and after the Middle Miocene. This southward motion was absorbed by the formation of the Luberon and Trévaresse mountains to the south. To the east of the Durance fault, there is no large sediment cover. The seismicity there, is related to the absorption of the Alps collapse within the basement itself. To the west of the Salon-Cavaillon fault, on the other hand, gravity induces a NNE motion of the sedimentary cover with extension to the south and shortening to the north near Mont Ventoux. When considering the seismicity of this area, it is thus important to distinguish between the western Basin panel, west of the Salon-Cavaillon fault affected by very slow NNE gliding of the sedimentary cover, with extension to the south and shortening to the north; the central Basin panel west of the Durance fault with S gliding of the sedimentary cover and increasing shortening to the south; and finally the basement panel east of the Durance fault with intrabasement absorption of the Alps collapse through strike-slip and thrust faults.

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Oligocene-Miocene extension led to mantle exhumation in the central Ligurian Basin, Western Alpine Domain

10.5194/se-2019-187 ◽

2019 ◽

Cited By ~ 1

Author(s):

Anke Dannowski ◽

Heidrun Kopp ◽

Ingo Grevemeyer ◽

Dietrich Lange ◽

Martin Thowart ◽

...

Keyword(s):

Gravity Data ◽

Sedimentary Cover ◽

Seafloor Spreading ◽

Wide Angle ◽

The South ◽

Seismic Line ◽

Acoustic Basement ◽

North West ◽

The North ◽

Ligurian Basin

Abstract. The Ligurian Basin is located in the Mediterranean Sea to the north-west of Corsica at the transition from the western Alpine orogen to the Apennine system and was generated by the south-eastward trench retreat of the Apennines-Calabrian subduction zone. Late Oligocene to Miocene rifting caused continental extension and subsidence, leading to the opening of the basin. Yet, it still remains enigmatic if rifting caused continental break-up and seafloor spreading. To reveal its lithospheric architecture, we acquired a state of the art seismic refraction and wide-angle reflection profile in the Ligurian Basin. The seismic line was recorded in the framework of SPP2017 4D-MB, the German component of the European AlpArray initiative, and trends in a NE-SW direction at the centre of the Ligurian Basin, roughly parallel to the French coastline. The seismic data recorded on the newly developed GEOLOG recorder, designed at GEOMAR, are dominated by sedimentary refractions and show mantle Pn arrivals at offsets of up to 70 km and a very prominent wide-angle Moho reflection. The main features share several characteristics (i.e. offset range, continuity) generally associated with continental settings rather than documenting oceanic crust emplaced by seafloor spreading. Seismic tomography results are augmented by gravity data and yield a 7.5–8 km thick sedimentary cover which is directly underlain by serpentinised mantle material at the south-western end of the profile. The acoustic basement at the north-eastern termination is interpreted to be continental crust, thickening towards the NE. Our study reveals that the oceanic domain does not extend as far north as previously assumed and that extension led to extreme continental thinning and exhumation of sub-continental mantle which eventually became serpentinised.

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Geophysical modeling of Devonian plutons in the southern Gulf of St. Lawrence: implications for Appalachian terrane boundaries in Maritime Canada

Canadian Journal of Earth Sciences ◽

10.1139/e07-038 ◽

2007 ◽

Vol 44 (11) ◽

pp. 1551-1565 ◽

Cited By ~ 1

Author(s):

Lori A Cook ◽

Sonya A Dehler ◽

Sandra M Barr

Keyword(s):

Magnetic Anomaly ◽

Prince Edward Island ◽

Sedimentary Cover ◽

Complex Structure ◽

Physical Property ◽

Gravity Anomalies ◽

The South ◽

Cape Breton Island ◽

The North ◽

Cape Breton

A prominent positive magnetic anomaly spans the 100 km distance between Prince Edward Island and Cape Breton Island in the southern Gulf of St. Lawrence. The anomaly occurs in an area of complex structure where Appalachian terrane boundaries are poorly resolved because of thick late Paleozoic sedimentary cover. Analysis of the magnetic anomaly led to the interpretation that it is produced by four separate, approximately circular, source bodies aligned along the northwesterly trend of the anomaly. Seismic data, physical property measurements, and magnetic and gravity anomalies were used to further investigate the anomaly sources through forward modeling techniques. The four source bodies have densities and magnetic susceptibilities compatible with dioritic to granitic compositions. Modeling also suggests that basement to the north of the plutons has higher density and susceptibility than basement to the south, and hence the source bodies are interpreted as plutons emplaced along the boundary between Ganderian composite terranes to the north and the Ganderian Brookville – Bras d’Or terrane to the south. This interpretation suggests that the Ganderia–Avalonia boundary is located farther south, and shows the need for re-evaluation of the location and role of the Canso fault in offsetting terranes between Cape Breton Island and southern New Brunswick.

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GEODYNAMICS

GEODYNAMICS ◽

10.23939/jgd2021.02.053 ◽

2021 ◽

Vol 2(31)2021 (2(31)) ◽

pp. 53-65

Author(s):

Оleksii Bartaschuk ◽

◽

Vasyl Suyarko ◽

Keyword(s):

Oil And Gas ◽

System Organization ◽

Sedimentary Cover ◽

Kinematic Model ◽

Strike Slip ◽

Donets Basin ◽

Western Slope ◽

The South ◽

Tectonic Plates ◽

Tectonic Inversion

The article studies the system organization of inversion tectonic deformations of the Dnieper-Donetsk Basin which covered the territory of the Western Donetsk Graben. The research uses the kinematic and structural-paragenetic analysis of inversion structural transformation of the folded floors of the sedimentary cover of the Graben. The original model of tectonic inversion of the Dnieper-Donets Basin was completed from the previous models. The tectonic inversion of the Dnieper-Donets Paleorift rift-like structures began at the late Hercynian stage in the geodynamic environment of the territory of the Eastern European Platform general collision. Tectonophysical analysis shows that the inversion folding was formed by the mechanism of sedimentary horizons longitudinal bending in the environment of the interference of the intraplate submeridional collision compression and the regional strike-slip stress field. At the Mesozoic-Cenozoic stage, tectonic inversion continued in the field of right-hand strike-slip deformations with a variable compressive component. This caused the formation of folded covers of tectonic plates and scales in the uplift-thrust mode. They, Hercynian neo-autochthonous formations and further the weakly located syneclise autochthon of the South-east of the Basin. The pressure of the "tectonic stamp" geoblock of the Donetsk Foldbelt contributed to the formationof the Segment body of geomass Tectonic Wedging. It was diagnosed with a structural orocline of transverse extension of the sliding type. Large linear throw-folded zones were formed within geodynamic bands of injection and displacement of geomass along the front of the orocline. The tectonic compression fan, characteristic of geodynamic compression zones, was formed in the foreland of the orocline, on the ends of the main thrusts. They served as “tectonic rails”of the allochthon invasion within the rift-like structure. There are the transverse zones of tectonic sutures formed on the roots of the folding covers of the Hercynian neo-autochthon thrusting, which are located in the hinterland of the orocline in the Foldbelt Western slope. The study completed an original kinematic model of tectonic inversion of the transition zone between the Dnieper-Donets Basin and Donets Foldbelt. According to the model, the pressure of the “tectonic stamp” geoblock initiated the invasion of the Segment of Tectonic Wedging which consists of the intensively dislocated allochthonous geomass. The Segment destroyed the rift-like structure and formed the Western Donetsk Cover-Folded Region in the South-eastern part of the Basin. The system organization model of inversion complications of the rift-like structure in the territory of the Western Donetsk Graben will allow to improve the regional geological schemes of tectonic oil and gas zoning.

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Middle Paleozoic-Mesozoic boundary of the North Asian craton and the Okhotsk terrane: new geochemical and geochronological data and their geodynamic interpretation

Stephan Mueller Special Publication Series ◽

10.5194/smsps-4-71-2009 ◽

2009 ◽

Vol 4 ◽

pp. 71-84 ◽

Cited By ~ 12

Author(s):

A. V. Prokopiev ◽

J. Toro ◽

J. K. Hourigan ◽

A. G. Bakharev ◽

E. L. Miller

Keyword(s):

Continental Margin ◽

Sedimentary Cover ◽

Late Devonian ◽

Low Grade ◽

The South ◽

Metamorphic Belt ◽

North Asian Craton ◽

The North ◽

North Asia ◽

Middle Paleozoic

Abstract. The Okhotsk terrane, located east of the South Verkhoyansk sector of the Verkhoyansk fold-and-thrust belt, has Archean crystalline basement and Riphean to Early Paleozoic sedimentary cover similar to that of the adjacent the North Asian craton. However, 2.6 Ga biotite orthogneisses of the Upper Maya uplift of the Okhotsk terrane yielded Early Devonian 40Ar/39Ar cooling ages, evidence of a Mid-Paleozoic metamorphic event not previously known. These gneisses are also intruded by 375±2 Ma (Late Devonian) calc-alkaline granodiorite plutons that we interpret as part of a continental margin volcanic arc. Therefore, Late Devonian rifting, which affected the entire eastern margin of North Asia separating the Okhotsk terrane from the North Asian craton, was probably a back-arc event. Our limited 40Ar/39Ar data from the South Verkhoyansk metamorphic belt suggests that low grade metamorphism and deformation started in the Late Jurassic due to accretion of the Okhotsk terrane to the North Asia margin along the Bilyakchan fault. Shortening and ductile strain continued in the core of the South Verkhoyansk metamorphic belt until about 120 Ma due to paleo-Pacific subduction along the Uda-Murgal continental margin arc.

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An investigation of the igneous rocks on Hareøen and western Nûgssuaq, West Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v35.7251 ◽

1971 ◽

Vol 35 ◽

pp. 11-13

Author(s):

N Hald

Keyword(s):

East Coast ◽

Geological Mapping ◽

Igneous Rocks ◽

South Coast ◽

The South ◽

West Greenland ◽

North West ◽

North East ◽

The North ◽

Basaltic Lavas

Hareøen is an island north-west of Disko in western Greenland. It has the form of a plateau, whose highest point - 512 metres - is found near the south coast. Like the neighbouring parts of Nugssuaq and Disko, Hareøen consists chiefly of Tertiary basaltic lavas. The island first attracted attention on account of the presence of interbasaltic, coal-bearing sediments on the north-east coast. These were already examined by Giesecke in 1811 (Giesecke, 1910) and later among others by Steenstrup (1874) and B.E. Koch (1959). A petrographie investigation of the basalts was first undertaken by Holmes (1919), who described loose fragments rich in K2O. Lavas from the south coast, colleeted and analysed by Pedersen (1970), also have a high content of potash. V. Miinther in the years 1948-49 untertook geological mapping of the island, on which the present investigation is supported (Miinther, in press).

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Antenatal hepatitis B screening in Nigeria: A comparative analysis with syphilis and HIV

International Journal of STD & AIDS ◽

10.1177/09564624211035922 ◽

2021 ◽

pp. 095646242110359

Author(s):

Babayemi O Olakunde ◽

Daniel A Adeyinka ◽

Chinwendu D Ndukwe ◽

Tolulope T Oladele ◽

Hidayat B Yahaya ◽

...

Keyword(s):

Hepatitis B ◽

Pregnant Women ◽

Health Sector ◽

Central Zone ◽

Screening Rate ◽

The South ◽

National Guidelines ◽

North East ◽

The North ◽

Hbv Screening

Nigeria has adopted routine screening of pregnant women for hepatitis B virus (HBV) as part of the interventions to eliminate its vertical transmission. However, there is a dearth of evidence on the coverage of routine antenatal HBV screening as recommended in the national guidelines. This study examined the antenatal HBV screening rate and the positivity rate compared with syphilis and HIV. We conducted a descriptive analysis of the 2019 national HIV/AIDS health sector data. The study included approximately 2.8 million pregnant women who received antenatal care (ANC) in over 6000 health facilities providing prevention of mother-to-child transmission of HIV services in Nigeria. Of the ANC clients, 0.2 million (7.2%) were screened for HBV. At the zonal level, the South West had the highest HBV screening rate (19%), while the lowest rate was in the North East (2.5%). The percentage of pregnant women screened for HBV was lower than those screened for syphilis (16.3%) and HIV (90.3%). Among those screened for HBV, the positivity rate was 5%. The HBV positivity rate ranged from 8.5% in the North Central zone to 1.3% in the South East zone. The positivity rates for syphilis and HIV were 0.4% and 0.5%, respectively. Our results indicate a low antenatal HBV screening rate and a wide disparity compared with HIV and syphilis. This finding highlights the need to understand and address the barriers affecting routine antenatal HBV screening and to strengthen the integration of HBV services into the HIV program in Nigeria.

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Coroboration of magnetotelluric investigations with other geophysical anomalies for a case study located in North-West to central part of Romania

10.5194/egusphere-egu2020-10242 ◽

2020 ◽

Author(s):

Natalia-Silvia Asimopolos ◽

Laurentiu Asimopolos

Keyword(s):

Transition Zone ◽

Sedimentary Cover ◽

Careful Analysis ◽

Geological Structure ◽

North West ◽

The North ◽

The Many ◽

Geophysical Anomalies

The results of the magnetoteluric investigations carried out along the profiles are presented in the form of sections in which the variations of the different parameters, the 2-D modeling, as well as the inversions.The results of the geophysical researches (magnetotellurics, gravity, geomagnetics) obtained were aimed at obtaining a unitary image on the deep geological structure in the investigated area. A number of information was obtained regarding such as:<ul><li>Determination of the thickness of the package of formations belonging to the post-tectogenetic sedimentary cover of the Transylvanian Depression; sedimentary sedimentary cover, conductive, with a maximum thickness of approximately 4000 m in the Pannonian Depression;</li> <li>Contouring of the Tethysian Major Suture (near the town of Alba Iulia in the Transylvanian Basin), represented by the Transylvanian nappes system (ofiolitic complex and sedimentary formations), with resistivities of about 500 Ohm*m, which separates two blocks with continental crust of different thicknesses (22- 27 km for Internal Dacids and 32-36 km for Median Dacids);</li> <li>Highlighting the change of nappes systems belonging to the Transylvanians, with a wide development both to the north (C&#259;p&#226;lnas-Techereu nappes and the nappes of Gro&#351;i and Cri&#351;), as well as to the east (the ophiolite complex and sedimentary cover), over the Biharia nappes system, respectively Central-Eastern Carpathian nappes; extension of the Codru and Biharia - Arie&#351;eni nappes, the last with higher resistivities (200 Ohm*m);</li> <li>Highlighting the transcrustal fault that marks the contact between the Inner Dacides and the Median ones;</li> <li>Individualization at the level of the lower crust of a transition zone; significant decrease of resistivity, as a consequence of the presence of the fluids in the transition zone, from the pressure in the pores from lithostatic type to the hydrostatic type (occurs at depths of 22 - 30 km and at temperatures of 350&#186; - 400&#186; C).</li> </ul>The electromagnetic data reflect the anomalies of electrical conductivity in a sensitive way, but due to the many causes that can generate them, a careful analysis of the particularities existing for each case, especially the superficial ones, was necessary.The correlation of the all the information provided in sections (resistivity, phases, density, magnetic susceptibility), inversions, modeling, lead to the validation of the model.

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