Margin of Western-Eastern Carpathians Transition Zone in the Light of MT and Gravity Data

2005 ◽  
Author(s):  
M. Stefaniuk ◽  
M. Wojdyla ◽  
A. Maksym ◽  
P. Targosz
Keyword(s):  
Transition Zone ◽  
Gravity Data ◽  
Eastern Carpathians

Crustal structure in the transition zone from the Precambrian to Palaeozoic platform in the southern Baltic Sea – inferences from newly acquired potential field and seismic data

2020 ◽  
Author(s):  
Małgorzata Ponikowska ◽  
Stanislaw Mazur ◽  
Michał Malinowski ◽  
Christian Hübscher ◽  
Ingo Heyde ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Transition Zone ◽  
Crustal Structure ◽  
Seismic Data ◽  
Potential Field ◽  
Gravity Data ◽  
Southern Baltic Sea ◽  
Gravity And Magnetic ◽  
Southern Baltic ◽  
Sea Area

<p>The southern Baltic Sea area is in the transition zone between the Fennoscandian Shield as part of the East European Craton (EEC) and the West European Platform. This area is characterised by a mosaic of various geological blocks separated by several fault zones formed throughout the Phanerozoic. The most prominent tectonic feature is the NW–SE trending Sorgenfrei-Tornquist Zone, crossing the southern Baltic Sea area between Scania in Sweden and Pomerania in Poland. Recently, this area was covered with the new multi-channel seismic data (MCS), acquired during the “BalTec” cruise of the German R/V Maria S. Merian. In addition to MCS data, hydroacoustic and gravity data were collected along the same profiles.</p><p>The new data, acquired during the “BalTec” cruise in 2016, include 3500 km of MCS data and 7000 km of gravity data. This is the first such a regional survey in the southern Baltic Sea, which provides a gapless image of sedimentary layer with a high resolution from seafloor to the base of Permian salt (North German-Polish Basin) or Palaeozoic strata (EEC). In addition, a 230-km long refraction/wide-angle reflection (WARR) profile was acquired across the transition zone to image its deeper structure. This profile is nearly parallel to the western Polish coast in half a distance to Bornholm.</p><p>The main topic of our study is the structure of Phanerozoic sedimentary cover in the southern Baltic Sea and its relationship to the geological evolution of the area situated at the junction of two major tectonic units of NW Europe. In the methodological part of our research, we are going to develop the process of integration of potential field modelling into seismic interpretation workflow. Another important point is testing the capability of marine versus satellite gravity data to reflect the geometry of shallow tectonic structures.</p><p>The first step in analysis of potential field data was integration of marine gravity with a regional gravity dataset. The result was a coherent gravity grid, which was used for further advanced processing, involving calculation of transformations and derivatives. We also included a regional magnetic grid in the advanced processing. Calculated derivatives and filters of gravity and magnetic data were applied for qualitative interpretation, i.e., compilation of a structural map based on the location and nature of gravity and magnetic anomalies. In addition, a preliminary 2D forward model was produced for the WARR profile to provide an image of the broad crustal structure. The next 2D models will be built upon seismic reflection profiles acquired during the “BalTec” cruise. The results will be eventually used to calibrate the three-dimensional model for the top of crystalline basement derived from gravity inversion.</p><p>This study was funded by the Polish National Science Centre grant no UMO-2017/25/B/ST10/01348.</p>

scholarly journals 3D Mafic Topography of the Transition Zone between the North-Western Boundary of the Congo Craton and the Kribi-Campo Sedimentary Basin from Gravity Inversion

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Sévérin Nguiya ◽  
Willy Lemotio ◽  
Philippe Njandjock Nouck ◽  
Marcelin M. Pemi ◽  
Alain-Pierre K. Tokam ◽  
...  
Keyword(s):  
Transition Zone ◽  
Sedimentary Basin ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Gravity Inversion ◽  
Western Boundary ◽  
Northern Margin ◽  
Velocity Models ◽  
The North ◽  
North Western

The structure of the transition zone between the north-western boundary of the Congo Craton and the Kribi-Campo sedimentary basin is still a matter of scientific debate. In this study, the existing gravity data are interpreted in order to better understand the geodynamics of the area. Qualitatively, results show that the major gravity highs are associated with long-wavelength shallow sources of the coastal sedimentary basin, while large negative anomalies trending E-W correlate to low dense intrusive bodies found along the northern limit of the Congo Craton. For the delineation of the causative sources, the gravity anomalies have been inverted based on the Parker-Oldenburg iterative process. As inputs, we used a reference depth of 20 km obtained by spectral analysis and successively, the density contrasts 0.19 g/cm3 and 0.24 g/cm3, deduced from available 1D shear wave velocity models. The results reveal an irregular topography of the mafic interface characterized by a sequence of horst and graben structures with mafic depths varying between 15.6 km and 23.4 km. The shallower depths (15.6-17 km) are associated with the uprising of the mafic interface towards the upper crust. This intrusion may have been initiated during the extension of the Archean Ntem crust resulting in a thinning of the continental crust beneath the coastal sedimentary basin. The subsidence of the mafic interface beneath the craton is materialized by 2 similar graben structures located beneath both Matomb and Ebolowa at a maximum depth of 23.4 km. The intermediate depths (18-22 km) are correlated to the suture zone along the Pouma-Bipindi area. The location of some landslides across the area matches within the northern margin of the Congo Craton and suggests that this margin may also impact on their occurrence. This work provides new insights into the geodynamics, regional tectonics, and basin geometry.

scholarly journals Crustal Structure of the Nile Delta: Interpretation of Seismic-Constrained Satellite-Based Gravity Data

2021 ◽  
Vol 13 (10) ◽  
pp. 1934
Author(s):  
Soha Hassan ◽  
Mohamed Sultan ◽  
Mohamed Sobh ◽  
Mohamed S. Elhebiry ◽  
Khaled Zahran ◽  
...  
Keyword(s):  
Continental Crust ◽  
Transition Zone ◽  
Nile Delta ◽  
Gravity Data ◽  
Tectonic Setting ◽  
Volcanic Eruptions ◽  
Passive Margin ◽  
The North ◽  
Hinge Zone ◽  
Levant Margin

Interpretations of the tectonic setting of the Nile Delta of Egypt and its offshore extension are challenged by the thick sedimentary cover that conceals the underlying structures and by the paucity of deep seismic data and boreholes. A crustal thickness model, constrained by available seismic and geological data, was constructed for the Nile Delta by inversion of satellite gravity data (GOCO06s), and a two-dimensional (2D) forward density model was generated along the Delta’s entire length. Modelling results reveal the following: (1) the Nile Delta is formed of two distinctive crustal units: the Southern Delta Block (SDB) and the Northern Delta Basin (NDB) separated by a hinge zone, a feature widely reported from passive margin settings; (2) the SDB is characterized by an east–west-trending low-gravity (~−40 mGal) anomaly indicative of continental crust characteristics (depth to Moho (DTM): 36–38 km); (3) the NDB and its offshore extension are characterized by high gravity anomalies (hinge zone: ~10 mGal; Delta shore line: >40 mGal; south Herodotus Basin: ~140 mGal) that are here attributed to crustal thinning and stretching and decrease in DTM, which is ~35 km at the hinge zone, 30–32 km at the shoreline, and 22–20 km south of the Herodotus Basin; and (4) an apparent continuation of the east-northeast–west-southwest transitional crust of the Nile Delta towards the north-northeast–south-southwest-trending Levant margin in the east. These observations together with the reported extensional tectonics along the hinge zone, NDB and its offshore, the low to moderate seismic activity, and the absence of volcanic eruptions in the Nile Delta are all consistent with the NDB being a non-volcanic passive margin transition zone between the North African continental crust (SDB) and the Mediterranean oceanic crust (Herodotus Basin), with the NDB representing a westward extension of the Levant margin extensional transition zone.

A COMPARATIVE ANALYSIS OF HISTORICAL FLOOD EVENTS (POST-1990) IN THE TREBEŞ-NEGEL REPRESENTATIVE BASIN FOR EASTERN CARPATHIANS AND SUBCARPATHIANS TRANSITION ZONE

2021 ◽  
Vol 16 (1) ◽  
pp. 31-46
Author(s):  
Larisa Elena PAVELUC ◽  
◽  
Alin MIHU-PINTILIE ◽  
Elena HUŢANU ◽  
Adrian GROZAVU
Keyword(s):  
Comparative Analysis ◽  
Transition Zone ◽  
Small Scale ◽  
Flood Events ◽  
European Network ◽  
Entire Region ◽  
Eastern Carpathians ◽  
Hydrological Hazards ◽  
Mitigation Effort ◽  
Heavy Rains

The European Network of Experimental and Representative Basins (ENERB) is the results of several experimental projects concerning the hydrological forecasting and flood mitigation effort which have been implemented within states member of European Union. In Romania, the hydrometric activity for ENERB it is currently composed of 14 representative basins (RB) of which the Trebeş-Negel (184 km2) was selected as RB for Eastern Carpathian and Subcarpathian transition zone. Located in one of the most affected territories by hydrological hazards, the Trebeş-Negel RB reacted as a small-scale flood sensor for the entire region. Using the well-documented discharge and pluviometric database collected at five gauge stations within the study area, we develop the first comparative analysis of historical flood events that occurred in the Trebeş-Negel RB post-1990. Five exceptional floods were selected: flood events from July 2 to July 8, 1991; flood events from June 16 to June 22, 1992; flood events from July 11 to July 14, 2005; flood events from July 26 to July 31, 2010; and flood events from June 28 to July 1, 2018. All flood events envisaged were caused by heavy rains, when significant amounts of precipitations were recorded which sometimes exceeded 100 mm/day.

STRUCTURE OF THE BEAUFORT SEA CONTINENTAL MARGIN

Geophysics ◽  
1970 ◽  
Vol 35 (5) ◽  
pp. 849-861 ◽  
Author(s):  
R. J. Wold ◽  
T. L. Woodzick ◽  
N. A. Ostenso
Keyword(s):  
Transition Zone ◽  
Continental Margin ◽  
Gravity Data ◽  
Beaufort Sea ◽  
Continental Margins ◽  
Banks Island ◽  
Basement Rocks ◽  
Area North ◽  
Free Air Anomaly ◽  
Gravity Map

An airlifted gravity survey was conducted in 1968 in the Beaufort Sea between Barter Island and Banks Island, south into the Mackenzie River Delta area and northward to about 74° latitude. The 1968 gravity data were combined with data from previous airlifted surveys and ice island T‐3. The major feature of the free‐air anomaly gravity map of this area is a more or less continuous 100 mgal high paralleling the coast from Barrow, Alaska, to the edge of the survey area north of Banks Island. The gravity high is explained by a thinning of the crust and a ridge in the basement rocks at about the 200 m isobath. This linear anomaly is broken by saddles off the Colville, Mackenzie, and Bernard Rivers, which are interpreted to reflect sedimentary fans built by the discharge of these rivers. Two‐dimensional crustal models constructed from gravity profiles indicate a narrow transition zone from ocean to continental crustal thickness, 55 km to 100 km shoreward of the 2000 m isobath. In a review of continental margin structure, Worzel (1968) found the transition zone to be centered under the 2000 m isobath. The departure from “normal” in the Beaufort Sea area may be explained by a greater accumulation of sediments seaward of the “structural” continental margins. This accumulation implies a faster rate of sedimentation and/or a greater age for the Beaufort Sea continental margins than for those analyzed by Worzel.

Advances in marine geophysical research of continental margins

1968 ◽  
Vol 5 (4) ◽  
pp. 963-983 ◽  
Author(s):  
J. Lamar Worzel
Keyword(s):  
Transition Zone ◽  
Gravity Data ◽  
Sedimentary Cover ◽  
Seismic Refraction ◽  
Continental Margins ◽  
Geophysical Research ◽  
Continental Shelves ◽  
America South ◽  
Seismic Refraction Data ◽  
Refraction Data

Geophysical data available for the continental margins of North America, South America, Africa, and Europe are examined and summarized. Seismic reflection profiling provide much detail of the uppermost sedimentary cover; seismic refraction data delineate the broad outlines of the upper crustal layers; and gravity data restrict the choices of the deeper crustal structure and that of the upper mantle.Conclusions about the variability of the sedimentation at the various continental shelves, slopes, and rises are given. The transition zone between continental and oceanic structure is restricted to a narrow zone varying between 50 km and 300 km in width for various coasts. This transition zone is localized in the region of the 2000 m isobath for all the coasts studied. The continental margins are generally in isostatic equilibrium as a whole, although departing from this equilibrium somewhat, expecially in the transition zone.

Sign in / Sign up

Export Citation Format

Share Document