Wyniki wyszukiwania - BazTech

1

Contrasting tectonic styles of the western and eastern parts of the Western Carpathian Klippen Belt in Slovakia based on magnetotelluric sounding of deep tectonic structures

Bezák Vladimír, Vozár Ján, Majcin Dušan, Klanica Radek, Madarás Ján

Geological Quarterly

|

2021

|

Vol. 65, No. 2

art. no. 25

EN

To characterize the deep structure of the Klippen Belt, we made magnetotelluric measurements in profiles across the western and eastern segments in the territory of Slovakia, from which we created 3D models. The models revealed significant differences in tectonic structure between these segments. In the western segment, the Klippen Belt is located in the southern reversing wing of the original subduction flower structure (retroarc thrusting) with an overthrust to the south onto the Inner Western Carpathian units. This structure was later modified by significant transpressional movements. In the eastern segment, the Klippen Belt is primarily an organic part of the accretionary wedge of the Outer Western Carpathians and it is overthrusted onto the Flysch Belt. This was followed by modification of the structures, mostly in a transpressional regime, including local reversing overthrusts and the development of a steep fault boundary, mainly along the southern margin, against the Inner Carpathian Paleogene succession. These differences between the structure of the western and eastern Klippen Belt segments indicate the contrast between the interaction of the western and eastern parts of the Inner Western Carpathians with the European Platform. In the western part, oblique collision and sinistral transpression dominate. In the eastern part, by contrast, subduction and orthogonal collision dominated over later transpressional modifications.

2

Dhahal structure : an example of transpression associated with the Dead Sea transform in Wadi Araba, Jordan

Atallah M., Mustafa H., El-Akhal H., Al-Taj M.

Acta Geologica Polonica

|

2005

|

Vol. 55, no. 4

361-370

EN

The Dhahal Mountains located at the eastern margin of the northern Wadi Araba sinistral fault represent an example of a transpression associated with the Dead Sea transform, which is a sinistral wrench fault. This structure was formed as a result of right bending of the Humrat Fidan active sinistral fault, which is a parallel strand of the Dead Sea transform located east of the main Wadi Araba fault. The fault bend caused uplift and squeezing of the Cretaceous and Tertiary rocks of the transpression. Positive flower structures, folds, fault-bounded wedge-shaped pop-ups and reverse faults are the main structural elements that characterized the Dhahal transpression. Folds are found as sets or as single anticlines and synclines. The major trend of the fold axes is N50°; the principal stress axis (σ1) is perpendicular to this trend (N140°).This trend deviates 26° anticlockwise from that of the Dead Sea stress system (DSS) (as obtained from fault slip data north of the study area), which is responsible for the formation of the Dead Sea transform. Evidence of active uplift in the Dhahal structure is provided by the sharp topography relative to the surrounding areas, and the low mountain front sinuosity index of the western margin of the Dhahal mountains.

3

Non-planar strike-slip Gnieździska - Brzeziny fault (SW Mesozoic margin of the Holy Cross Mountains, central Poland)

Mastella L., Konon A.

Acta Geologica Polonica

|

2002

|

Vol. 52, nr 4

471-480

EN

Based on the analysis of detailed geological maps, air photos, radar images and tectonic mesostructures the geometry and mechanism of formation of the Gnieździska-Brzeziny fault have been determined. The fault represents a typical example of a dextral strike-slip fault occurring in the SW margin of the Holy Cross Mountains. The trace of the fault is curvilinear-sinusoidal, which produced restraining and releasing bends as well as restraining stepovers.

4

Palaeozoic orogeneses in the Sudetes: a geodynamic model

Cymerman Z.

Geological Quarterly

|

2000

|

Vol. 44, Nr 1

59-80

EN

The Palaeozoic geodynamic evolution of the Sudetes resulted from two successive orogenic events: (1) Ordovician-Silurian geotectonic processes (pre-Variscan stages), and (2) the Variscan orogeny. Early Palaeozoic rifting of Cadomian crustal segments and opening of the Ligerian (Galicia-Massif Central) and/or Saxothuringian Ocean occurred in Ordovician-Silurian times on the northern (peri-Gondwana) periphery of the Bohemian Massif. At the same time, the Góry Sowie terrane with a magmatic arc affinity quite probably developed on the SW margin of Baltica due to subduction of the Tornquist Ocean. Two major structural events characterised the Variscan evolution of the Sudetes: (1) regional-scale ductile thrusting of Late Devonian-Early Carboniferous age, and (2) Early Carboniferous-Early Permian regional extension. Ductile thrusting is characterised by: (I) a general NNE-directed, dextral transpressional stacking of ductile nappes due to oblique collision of the Moldanubian and Moravian microplates in the Eastern Sudetes, and (II) SW- to NW-directed, sinistral transpressional stacking of ductile nappes due to westward lateral extrusion of continental crust in the Central and Western Sudetes, itself a result of oblique indentation of the Central Sudetic oceanic lithosphere. The first Variscan deformation in the Sudetes might reflect a purely convergent setting that evolved into a transpressive setting during oblique convergence. Special attention is given to the geometry and kinematics of intraplate tectonic escape and a model of indentation processes in the Sudetes. The presented new geotectonic model for the Variscan evolution of the Sudetes is consistent with lateral escape of the Saxothuringian terrane as an important way of accommodating Variscan strain in the NE part of the Bohemian Massif. This model explains the lateral expulsion (escape) process as due to the indentation of the Central Sudetic terrane along with the Góry Sowie terrane and by the oblique subduction of the Ligerian/Saxothuringian Ocean(s) (now tectonically dismembered ophiolitic rocks of the Central Sudetic terrane).