Conductive anomalies related to the Mérida Andes derived from the 3D inversion of a magnetotelluric profile

2020 ◽  
Author(s):  
José Cruces ◽  
Oliver Ritter ◽  
Ute Weckmann ◽  
Kristina Tietze ◽  
Michael Schmitz
Keyword(s):  
Prominent Feature ◽  
3D Inversion ◽  
Geological Structures ◽  
The North ◽  
Major Fault ◽  
Tectonic Escape ◽  
Dimensionality Analysis ◽  
The Caribbean ◽  
Entire Dataset ◽  
North Western

<div><span>Abstract</span> <div>The geodynamic settings of north-western Venezuela are conditioned by the expulsion of the North Andean Block (NAB), and the deformational structures related to the Caribbean – South America plate interactions. The most prominent feature is the 100 km wide Mérida Andes (MA) that reach from the Colombian border to the Caribbean coast over more than 500 km. We present the analysis of a magnetotelluric (MT) profile acquired at 72 broadband sites along a 240 km long profile with station spacing between 3 and 5 km across the central part of the MA, including the sedimentary Maracaibo (MB) and Barinas-Apure (BAB) basins. Phase Tensors (PT) are consistent with 1D/2D dimensionality above the MB and the BAB, however, stations above the MA show a clear 3D dimensionality, with the induction vectors indicating the presence of off-profile structures. Following the dimensionality analysis, 3D inversions of the entire dataset were performed, employing the finite differences code ModEM. The results are in agreement with prominent geological structures, and are particularly effective in modelling the depth extensions of major fault systems. A conductive structure east from the profile at mid crustal levels seems to correlate with the tectonic escape of the Trujillo block, which is part of the NAB.</div> </div>

Etude tectonique de la region sud de la Nerthe

1966 ◽  
Vol S7-VIII (5) ◽  
pp. 712-726 ◽  
Author(s):  
Claude Froget ◽  
Gerard Guieu ◽  
Max Robert Roux
Keyword(s):  
Complex Network ◽  
Upper Cretaceous ◽  
Mediterranean Coast ◽  
Prominent Feature ◽  
The South ◽  
The North ◽  
Major Fault ◽  
Tectonic Study ◽  
And Behavior ◽  
Sketch Map

Abstract Stratigraphic and tectonic study of the southern Nerthe [Mediterranean coast of France] is based on a sketch map at 1:5,000. The most prominent feature of the region is the presence of the middle and upper Cretaceous, which most commonly forms depressions (B) arranged in synclines or eroded and buried anticlines: to the north under the inverted edge of an anticline (A); to the south, under the front of an overthrust (C). The structure and behavior of units (A), (B), and (C) are defined. Units (A) and (C) had a tendency to be displaced in opposite directions, after sinking of the medial unit (B), becoming somewhat mutually overlapped (the Grand-Vallat). The major fault placing these units in contact is transformed toward the Graffian [highlands] into a complex network of fractures gradually connecting with the Triassic axis of the Rove. Relations with adjacent tectonic units are considered (Etoile overthrust, Marseilles basin). A chronology of the different movements is proposed, from the upper Cretaceous to the Miocene, based on a general examination of the folded zone north of Marseilles.

scholarly journals Comment on “Emplazamiento del magmatismo Paleoceno-Eoceno bajo un régimen transtensional y su evolución a un equilibrio dinámico en el borde occidental de Colombia” by Grajales et al., Rev. Mex. Cienc. Geol. (2020), 37(3), 250-268

2021 ◽  
Vol 38 (2) ◽  
pp. 141-147
Author(s):  
Ángel A. Barbosa-Espitia ◽  
George D. Kamenov ◽  
David A. Foster ◽  
Sergio A. Restrepo-Moreno ◽  
Andrés Pardo-Trujillo ◽  
...  
Keyword(s):  
Alternative Interpretation ◽  
Geochemical Data ◽  
Northern Andes ◽  
The North ◽  
Western Cordillera ◽  
Plausible Model ◽  
The Caribbean ◽  
Subduction System ◽  
Central Cordillera ◽  
North Western

Grajales et al. (2020) reviewed geochronological and geochemical data from Paleogene volcanic and plutonic rocks outcropping in the Panama-Choco Block (north western Cordillera) and southern Western Cordillera, as well as the Central Cordillera of Colombia. These data were used to support a model of continuous Paleogene arc magmatism along the Colombian continental margin, and to propose a paleogeographic model for the arc. The authors did not discuss previously published paleomagnetic, geochemical, geochronological, thermochronological and provenance constraints from Cretaceous to Miocene rocks of western and northern Colombia, Panama, and Ecuador that support a more plausible model of a double subduction system controlled by the convergence of the Caribbean and Farallon plates beneath the north Andean block during Paleogene. In this comment, we discuss shortcomings in the data and model proposed by Grajales et al. (2020) and present an alternative interpretation for contemporaneous arc-like magmatism during the Paleogene in the Northern Andes. We conclude that the double subduction system is the more plausible explanation for the contemporaneous arc-like magmatism during the Paleogene, currently exposed in the northern and southern portions of the Northern Andes.

U-Pb on Zircon and Monazite Geochronology of Granites of the Zhytomyr and Sheremetiv Complexes, the North-Western Region of the Ukrainian Shield

2018 ◽  
Vol 40 (2) ◽  
pp. 63-85 ◽  
Author(s):  
L. Shumlyanskyy ◽  
L. Stepanyuk ◽  
S. Claesson ◽  
K. Rudenko ◽  
A. Bekker
Keyword(s):  
Ukrainian Shield ◽  
Western Region ◽  
The North ◽  
North Western

Assessment of the Reactions of Algal Communities to Influence of Climatic Factors in the North-Western Black Sea Ecosystem

2018 ◽  
Vol 20 (2) ◽  
pp. 121-134 ◽  
Author(s):  
G. G. Minicheva ◽  
V. N. Bolshakov ◽  
E. S. Kalashnik ◽  
A. B. Zotov ◽  
A. V. Marinets
Keyword(s):  
Black Sea ◽  
Climatic Factors ◽  
Algal Communities ◽  
The North ◽  
North Western

Training of Village Teachers in Vilna Educational District in the 1860s and 1870s

2020 ◽  
Vol 58 ◽  
pp. 181-192
Author(s):  
Anna A. Komzolova
Keyword(s):  
Educational Reform ◽  
Rural Teachers ◽  
Cultural Brokers ◽  
The North ◽  
Central Russia ◽  
Russian Intelligentsia ◽  
Trained Teachers ◽  
The Village ◽  
North Western

One of the results of the educational reform of the 1860s was the formation of the regular personnel of village teachers. In Vilna educational district the goal was not to invite teachers from central Russia, but to train them on the spot by establishing special seminaries. Trained teachers were supposed to perform the role of «cultural brokers» – the intermediaries between local peasants and the outside world, between the culture of Russian intelligentsia and the culture of the Belarusian people. The article examines how officials and teachers of Vilna educational district saw the role of rural teachers as «cultural brokers» in the context of the linguistic and cultural diversity of the North-Western Provinces. According to them, the graduates of the pedagogical seminaries had to remain within the peasant estate and to keep in touch with their folk «roots». The special «mission» of the village teachers was in promoting the ideas of «Russian elements» and historical proximity to Russia among Belarusian peasants.

The population of Red Deer (Cervus elaphus L., 1758) in Tulcea county (Romania)

2010 ◽  
Vol 53 (1) ◽  
pp. 351-356
Author(s):  
Sorin Geacu
Keyword(s):  
Cervus Elaphus ◽  
Red Deer ◽  
Forest Land ◽  
The West ◽  
Spreading Area ◽  
Deer Population ◽  
The North ◽  
Natural Expansion ◽  
North Western

The population of Red Deer (Cervus elaphus L., 1758) in Tulcea county (Romania) The presence of the Red Deer in the North-western parts of Tulcea County is an example of the natural expansion of a species spreading area. In North Dobrogea, this mammal first occurred only forty years ago. The first specimens were spotted on Cocoşul Hill (on the territory of Niculiţel area) in 1970. Peak numbers (68 individuals) were registered in the spring of 1987. The deer population (67 specimens in 2007) of this county extended along 10 km from West to East and 20 km from North to South over a total of 23,000 ha (55% of which was forest land) in the East of the Măcin Mountains and in the West of the Niculiţel Plateau.

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