scholarly journals Geological and structural setting of the Vinodol Valley (NW Adriatic, Croatia): insights into its tectonic evolution based on structural investigations

2019 ◽  
Vol 72 (3) ◽  
pp. 179-193 ◽  
Author(s):  
Damir Palenik ◽  
Dubravko Matičec ◽  
Ladislav Fuček ◽  
Bojan Matoš ◽  
Marijan Herak ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Structural Investigations ◽  
Structural Setting

scholarly journals Thrusting and debris entrainment in a surging glacier: Bakaninbreen, Svalbard

1996 ◽  
Vol 22 ◽  
pp. 241-248 ◽  
Author(s):  
Michael J. Hambrey ◽  
Julian A. Dowdeswell ◽  
Tavi Murray ◽  
Philip R. Porter
Keyword(s):  
Tectonic Evolution ◽  
Sedimentary Facies ◽  
Shear Zones ◽  
Hot Water ◽  
Important Process ◽  
High Angle ◽  
Glacier Surface ◽  
Structural Investigations ◽  
Fine Grained ◽  
Drill Stem

Bakaninbreen, a 17 km long glacier terminating in fjord waters in central Spitsbergen (77°45′ N, 17°20′E), began to surge between the springs of 1985 and 1986. By summer 1994 the surge front had reached a position 3 km from the terminus and had almost ceased propagation. Structural investigations were undertaken to characterise the tectonic evolution of this thermally complex surge-type glacier, and the role played by thrusting and its effect on debris entrainment. Much of the glacier surface, particularly within and below the surge front, displayed transverse high-angle thrusts, defined by discrete fractures bounded by coarse clear ice. Some fractures were associated with a film of mud, whereas in others a discrete laver of diamicton, with interstitial ice several decimetres thick, was evident. Within the surge front, and genetically related to the thrusts, was a number of shear zones several metres wide. These were defined by fine-grained ice that was the product of the grinding up of crystals during shear (mylonitization). Three main sedimentary facies are associated with the thrusts: mud, gravelly mud and clast-rich muddy diamicton. The diamicton has the character of basal glacial debris: grain-size distribution ranging from clay to cobble size, clasts with a predominance in the sub-angular and sub-rounded classes, and striated and faceted clasts. Hot-water drilling through the glacier revealed several englacial layers above the surge front, and debris brought up on the drill stem suggests a basal origin. At least some of these englacial layers are probably the sub-surface continuations of the thrusts. The observed facies indicate that the glacier is moving over a soft, deformable bed and that thrusting is an important process in transferring debris to the surface, especially when the surge front is propagating down-glacier.

Structural setting and tectonic evolution of offshore North Sinai, Egypt

2010 ◽  
Vol 341 (1) ◽  
pp. 65-84 ◽  
Author(s):  
M. Yousef ◽  
A. R. Moustafa ◽  
M. Shann
Keyword(s):  
Tectonic Evolution ◽  
Structural Setting ◽  
North Sinai

scholarly journals Late-stage tectonic evolution of the Al-Hajar Mountains, Oman: new constraints from Palaeogene sedimentary units and low-temperature thermochronometry

2019 ◽  
Vol 157 (7) ◽  
pp. 1031-1044 ◽  
Author(s):  
A Corradetti ◽  
V Spina ◽  
S Tavani ◽  
JC Ringenbach ◽  
M Sabbatino ◽  
...  
Keyword(s):  
Low Temperature ◽  
Tectonic Evolution ◽  
Sedimentary Rocks ◽  
Structural Data ◽  
Late Eocene ◽  
Seismic Interpretation ◽  
Structural Investigations ◽  
Mountain Belt ◽  
Tethys Ocean ◽  
Mountain Chain

AbstractMountain building in the Al-Hajar Mountains (NE Oman) occurred during two major shortening stages, related to the convergence between Africa–Arabia and Eurasia, separated by nearly 30 Ma of tectonic quiescence. Most of the shortening was accommodated during the Late Cretaceous, when northward subduction of the Neo-Tethys Ocean was followed by the ophiolites obduction on top of the former Mesozoic margin. This shortening event lasted until the latest Santonian – early Campanian. Maastrichtian to Eocene carbonates unconformably overlie the eroded nappes and seal the Cretaceous foredeep. These neo-autochthonous post-nappe sedimentary rocks were deformed, along with the underlying Cretaceous tectonic pile, during the second shortening event, itself including two main exhumation stages. In this study we combine remotely sensed structural data, seismic interpretation, field-based structural investigations and apatite (U–Th)/He (AHe) cooling ages to obtain new insights into the Cenozoic deformation stage. Seismic interpretation indicates the occurrence of a late Eocene flexural basin, later deformed by an Oligocene thrusting event, during which the post-nappe succession and the underlying Cretaceous nappes of the internal foredeep were uplifted. This stage was followed by folding of the post-nappe succession during the Miocene. AHe data from detrital siliciclastic deposits in the frontal area of the mountain chain provide cooling ages spanning from 17.3 to 42 Ma, consistent with available data for the structural culminations of Oman. Our work points out how renewal of flexural subsidence in the foredeep and uplift of the mountain belt were coeval processes, followed by layer-parallel shortening preceding final fold amplification.

Structural and metamorphic evolution of the Ambin massif (western Alps): toward a new alternative exhumation model for the Briançonnais domain

2007 ◽  
Vol 178 (6) ◽  
pp. 437-458 ◽  
Author(s):  
Jerome Ganne ◽  
Jean-Michel Bertrand ◽  
Serge Fudral ◽  
Didier Marquer ◽  
Olivier Vidal
Keyword(s):  
Tectonic Evolution ◽  
Large Scale ◽  
Regional Scale ◽  
Shear Bands ◽  
Shear Zones ◽  
Western Alps ◽  
Ductile Deformation ◽  
Movement Direction ◽  
Lower Grade ◽  
Structural Investigations

Abstract The basement domes of the central part of western Alps may result either from a multistage tectonic evolution with a dominant horizontal shortening component, an extensional behaviour, or both. The Ambin massif belongs to the “Briançonnais” domain and is located within the HP metamorphic zone. It was chosen for a reappraisal of the tectonic evolution of the Internal Alps in its western segment. Structural investigations have shown that Alpine HP rocks were exhumed in three successive stages. The D1 stage was roughly coeval with the observed peak metamorphic conditions and corresponds to a non-coaxial regime with dominant horizontal shortening and north movement direction. Petrological observations and P-T estimates show that the exhumation process was initiated during D1, the corresponding mechanism being still poorly understood. The D2 stage took place under low-blueschist facies conditions and culminated under greenschist facies conditions. It developed a retrogressive foliation and pervasive shear-zones at all scales that locally define major tectonic contacts. D2 shear zones show a top-to-east movement direction and correspond actually to large-scale detachment faults responsible for the juxtaposition of less metamorphic units above the Ambin basement and thus to a large part of the exhumation of HP rocks toward the surface. D2 shear zones were subsequently deformed by D3 open folds, large antiforms (e.g. the Ambin dome) and associated brittle-ductile D3 shear-bands. The D1 to D3 P-T conditions and P-T path of the blueschists occurring in the deepest part of the Ambin dome, was estimated by using the multi-equilibrium thermobarometric method of the Tweeq and Thermocalc softwares. Peak pressure conditions, estimated at about 14–16 Kb, 500oC, are followed by a nearly-isothermal decompression that occurred concurrently with the major D1–D2 change in the ductile deformation regime. Eastwards, the Schistes Lustrés units exhibit a similar geometry on top of the Gran Paradiso dome but exhibit opposite D2 movement direction. Lower-grade units are lying above higher-grade units, the shear zones occurring in between being similar to Ambin’s D2 detachments. Thus at regional scale, the D2 detachments seem to form together with the Ambin shear-zones, a network of conjugate detachments. Such a pattern suggests that the exhumation history is mostly controlled by a D2+D3 crustal-scale vertical shortening resulting in the thinning of the previous tectonic pile formed during D1. The slab-break off hypothesis may explain such an extensional behaviour within the western Pennine domain. It is suggested that the thermo-mechanical rebound of the residual European slab initiated between 35 and 32 Ma the fast exhumation of the previously thickened orogenic wedge (stack of D1 HP slices). It was immediately followed by a collapse of the wedge that may correspond to the E-W Oligocene extensional event responsible for the opening of rifts in the West European platform.

scholarly journals Thrusting and debris entrainment in a surging glacier: Bakaninbreen, Svalbard

1996 ◽  
Vol 22 ◽  
pp. 241-248 ◽  
Author(s):  
Michael J. Hambrey ◽  
Julian A. Dowdeswell ◽  
Tavi Murray ◽  
Philip R. Porter
Keyword(s):  
Tectonic Evolution ◽  
Sedimentary Facies ◽  
Shear Zones ◽  
Hot Water ◽  
Important Process ◽  
High Angle ◽  
Glacier Surface ◽  
Structural Investigations ◽  
Fine Grained ◽  
Drill Stem

Bakaninbreen, a 17 km long glacier terminating in fjord waters in central Spitsbergen (77°45′ N, 17°20′E), began to surge between the springs of 1985 and 1986. By summer 1994 the surge front had reached a position 3 km from the terminus and had almost ceased propagation. Structural investigations were undertaken to characterise the tectonic evolution of this thermally complex surge-type glacier, and the role played by thrusting and its effect on debris entrainment. Much of the glacier surface, particularly within and below the surge front, displayed transverse high-angle thrusts, defined by discrete fractures bounded by coarse clear ice. Some fractures were associated with a film of mud, whereas in others a discrete laver of diamicton, with interstitial ice several decimetres thick, was evident. Within the surge front, and genetically related to the thrusts, was a number of shear zones several metres wide. These were defined by fine-grained ice that was the product of the grinding up of crystals during shear (mylonitization). Three main sedimentary facies are associated with the thrusts: mud, gravelly mud and clast-rich muddy diamicton. The diamicton has the character of basal glacial debris: grain-size distribution ranging from clay to cobble size, clasts with a predominance in the sub-angular and sub-rounded classes, and striated and faceted clasts. Hot-water drilling through the glacier revealed several englacial layers above the surge front, and debris brought up on the drill stem suggests a basal origin. At least some of these englacial layers are probably the sub-surface continuations of the thrusts. The observed facies indicate that the glacier is moving over a soft, deformable bed and that thrusting is an important process in transferring debris to the surface, especially when the surge front is propagating down-glacier.

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