Tectonic history of a segment of the Pelagonian zone, northeastern Greece

1981 ◽  
Vol 18 (7) ◽  
pp. 1111-1126 ◽  
Author(s):  
Damian Nance
Keyword(s):  
Large Scale ◽  
Root Zone ◽  
Regional Metamorphism ◽  
Late Eocene ◽  
Metamorphic Rocks ◽  
Tectonic History ◽  
History Of ◽  
Ophiolitic Rocks ◽  
Platform Carbonates ◽  
Pelagonian Zone

Continental metamorphic rocks and ophiolitic bodies within the Pelagonian zone of the Hellenides in the Livadi area, northeastern Greece, show repeated periods of deformation that accompany thermal events of Early Cretaceous and possibly Late Eocene age. Structures associated with the earlier deformation indicate thrusting towards the northeast accompanying regional metamorphism of upper greenschist to lower amphibolite facies. Later structures and a retrogression to lower greenschist facies associated with emplacement of the Livadi ophiolitic rocks into their present position are likewise attributed to northeast-directed thrusting and probably accompanied the allochthonous movement of the Pelagonian basement over the Mesozoic platform carbonates of Mt. Olympos.Emplacement vectors of northeast polarity are inconsistent with tectonic models of the Hellenides involving large-scale southwestward obduction of Mesozoic ophiolites from a single ocean located northeast of the Pelagonian zone. Tectonic models involving the converging emplacement of Mesozoic ophiolites from two oceans lying northeast and southwest of the Pelagonian zone are more compatible with the observed structures, the latter ocean providing a potential root zone for the deformed ophiolitic rocks at Livadi.The orientation of minor structures associated with thrusting that postdates the emplacement of the Livadi ophiolitic rocks is consistent with movement from north to south.

XIX.—Metamorphic History of the Schichallion Complex (Perthshire)

1958 ◽  
Vol 63 (2) ◽  
pp. 413-431 ◽  
Author(s):  
N. Rast
Keyword(s):  
Regional Metamorphism ◽  
Igneous Rocks ◽  
Metamorphic Rocks ◽  
Present Contribution ◽  
Scottish Highlands ◽  
Metamorphic History ◽  
Fine Grain ◽  
Tectonic History ◽  
History Of ◽  
Garnet Zone

SynopsisThe Schichallion complex is situated in the Central Highlands of Scotland between the villages Struan and Kinloch Rannoch. The area is of considerable geological interest and has been investigated stratigraphically and structurally by E. M. Anderson and Bailey and McCallien. As a consequence of their researches a complete stratigraphical succession has been established. Thus, the metamorphic rocks of the area are classified into the Moinian and Dalradian systems, which are separated by a plane of tectonic discontinuity known as the Boundary Slide. The Moinian rocks are quartz-felspathic granulites, whereas the Dalradian system includes pelitic schists, quartzites, limestones as well as a variety of meta-igneous rocks.In his previous research the present author has established the tectonic history of the complex. In particular three episodes of folding (F1to F3) and a much later episode of faulting (F4) were recognized. Of these the F3episode is of least significance. Consequently, events after the F2movements can be in many cases regarded as post-folding.The present contribution is concerned essentially with the mapping of the metamorphic zones (garnet and staurolite-kyanite) and with a detailed study of the mineralogical evolution of regionally metamorphosed rocks within these zones.In the field it is possible to prove that the staurolite-kyanite zone is essentially post-folding, since the kyanitepegmatites are found to cut across the minor F2-folds. In this respect textural studies confirm the field observations. The study of the internal inclusions in garnets indicates that the garnet zone has a much longer history, since pre-F2garnets are found in the southern part of the complex and throughout the central part of the area syn-tectonic F2garnets are apparent. The pre-F2garnets contain a very fine-grain F1fabric. Hence the garnets in relation to the F1movements are post-tectonic. Thus, the regional metamorphism can be subdivided into three phases: the F1metamorphism, the F2metamorphism and the post-F2metamorphism. The latter, on structural evidence appears to be at least in part contemporaneous with the F3movements.The meta-igneous rocks of the area are grouped into the hornblende-schists and granular epidiorites. The hornblende-schists appear to have suffered deformation and recrystallization during F1and F2episodes of movement. On the other hand the granular epidiorites are later than the F1and the F2movements. Although in the southern parts of the district the epidiorites have been slightly deformed, elsewhere they preserve the original ophitic texture and cut across the F1and F2folds. The deformation in the south is attributed to the effects of the F3folding. The epidiorites have been evidently emplaced as dolerites after the F2movements and before the F3metamorphism.The localized retrogressive metamorphism is associated with the F4movements, which are responsible for the Loch Tay Fault. The Fault is later than the minor intrusives associated with the Younger Granites of the Scottish Highlands and is suggested to be of a Lower or Middle O.R.S. age.On the basis of the chemical composition of the plagioclase felspars it is proposed to include all the staurolite and kyanite bearing rocks into the epidote-amphibolite facies. In this respect temperature and the hydrostatic pressure are assumed to have been the main factors, since similar minerals came into existence during static and dynamic stages of metamorphism alike.

scholarly journals Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

Tectonics ◽  
2008 ◽  
Vol 27 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Julien Collot ◽  
Louis Geli ◽  
Yves Lafoy ◽  
Roland Vially ◽  
Dominique Cluzel ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
New Caledonia ◽  
Late Eocene ◽  
Southwest Pacific ◽  
Tectonic History ◽  
History Of

scholarly journals Mesostructures and deformational history of the Central Crystallines: an example from Garhwal Himalaya, India

1998 ◽  
Vol 17 ◽  
Author(s):  
V. K. Singh ◽  
S. P. Singh ◽  
P. S. Saklani ◽  
C. S. Dubey
Keyword(s):  
Large Scale ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Geochronological Data ◽  
Deformational History ◽  
Crenulation Cleavage ◽  
Ductile Shearing ◽  
History Of ◽  
Transcurrent Faults ◽  
East West

Structural analysis reveals that the Central Crystallines in the Garhwal region were subjected to four phases of deformations (D1 to D4). The D1 deformational phase is highly obliterated and usually found as F1 intrafolial (rootless) tight isoclinal folds in migmatites and gneisses. The D2 deformational phase produced strong pervasive S2 schistosity and asymmetric and open fold (F2) plunging 20-30° towards ENE-WSW. The L2 lineation plunge 5-10° towards east-west is well developed in medium grade metamorphic rocks. The D1 deformations were responsible for F3 folds reflected in large scale anticlinal and synclinal, overturned and recumbent folds, which have 10-40° plunges towards NW. The late D3 deformational stresses were responsible for shearing along the middle limbs of F1 folds and they ultimately initiated thrusting. The NNE­ SSW plunging mineral or stretching lineation (L3), S3 crenulation cleavage and S-C fabrics were developed during the dominant ductile shearing related to the late D3 deformation. The D4 phase characterised by brittle-ductile deformation (minor kinks, puckers, transverse/transcurrent faults, and S-C' fabrics) and extensive cataclasis along thrust- and fault-zones reflects the last episode of deformation. The structural and geochronological data indicate that D1 and D2 deformation episodes may be related to the Precambrian time while D3 and D4 are exclusively of the Tertiary age.

scholarly journals Late Cretaceous to Paleogene post-obduction extension and subsequent Neogene compression in the Oman Mountains

GeoArabia ◽  
2006 ◽  
Vol 11 (4) ◽  
pp. 17-40 ◽  
Author(s):  
Marc Fournier ◽  
Claude Lepvrier ◽  
Philippe Razin ◽  
Laurent Jolivet
Keyword(s):  
Late Cretaceous ◽  
Large Scale ◽  
Early Miocene ◽  
Normal Faults ◽  
Zagros Mountains ◽  
Lower Eocene ◽  
Oman Mountains ◽  
Tectonic History ◽  
History Of ◽  
Arabian Platform

ABSTRACT After the obduction of the Semail ophiolitic nappe onto the Arabian Platform in the Late Cretaceous, north Oman underwent several phases of extension before being affected by compression in the framework of the Arabia-Eurasia convergence. A tectonic survey, based on structural analysis of fault-slip data in the post-nappe units of the Oman Mountains, allowed us to identify major events of the Late Cretaceous and Cenozoic tectonic history of northern Oman. An early ENE-WSW extensional phase is indicated by synsedimentary normal faults in the Upper Cretaceous to lower Eocene formations. This extensional phase, which immediately followed ductile extension and exhumation of high-pressure rocks in the Saih Hatat region of the Oman Mountains, is associated with large-scale normal faulting in the northeast Oman margin and the development of the Abat Basin. A second extensional phase, recorded in lower Oligocene formations and only documented by minor structures, is characterized by NNE (N20°E) and NW (N150°E) oriented extensions. It is interpreted as the far-field effect of the Oligocene-Miocene rifting in the Gulf of Aden. A late E-W to NE-SW directed compressional phase started in the late Oligocene or early Miocene, shortly after the collision in the Zagros Mountains. It is attested by folding, and strike-slip and reverse faulting in the Cenozoic series. The direction of compression changed from ENE-WSW in the Early Miocene to almost N-S in the Pliocene.

Three-dimensional visualization of top-down superimposed thrust sheets in the SW Grenville Province, Ontario

2019 ◽  
Vol 157 (2) ◽  
pp. 149-159
Author(s):  
Jacob W.D. Strong ◽  
Alan P. Dickin
Keyword(s):  
Large Scale ◽  
3D Visualization ◽  
3D Structure ◽  
Three Dimensional ◽  
Grenville Province ◽  
Tectonic History ◽  
Thrust Sheets ◽  
History Of ◽  
Seismic Sections ◽  
Back Arc

AbstractTo properly understand the tectonic history of the Grenville Province it is necessary to have a reliable, scientifically based understanding of the present-day three-dimensional (3D) structure of the orogen. Based on detailed Nd isotope mapping of surface boundaries and Lithoprobe seismic sections, this study provides the first detailed visualization of the 3D structure of the Grenville gneiss belt in Ontario using the SketchUp software package. The 3D visualization supports a model in which thrust geometry was imposed from the top downwards, controlled by the NW boundary of the Central Metasedimentary Belt that originated as a failed back-arc rift zone. The Central Metasedimentary Belt boundary controlled the trajectory of the Allochthon Boundary Thrust, its underlying tectonic duplex and, ultimately, the Grenville Front. This process of superimposed thrusting explains the large-scale change in the trajectory of the Grenville Front north of Georgian Bay that has been called the ‘Big Bend’. To assist in visualizing the 3D model, a fly-through animation is provided in the supplementary material.

Les bassins sedimentaires du nord de la Corse; essai de synthese stratigraphique et apercu tectonique

1964 ◽  
Vol S7-VI (3) ◽  
pp. 322-333
Author(s):  
Roland Delcey ◽  
Jean Claude Limasset ◽  
Pierre Routhier
Keyword(s):  
Metamorphic Rocks ◽  
Pillow Lavas ◽  
Tectonic History ◽  
Basement Rocks ◽  
Structural Nature ◽  
History Of

Abstract The Saint Florent, Balagne, and Francardo basins of northern Corsica, surrounded by Paleozoic granitic and metamorphic rocks, are occupied by Permian to Triassic arkosic clastics and rhyolite overlain by dolomitic limestones, Jurassic limestones and spilite pillow lavas, Cretaceous flysch and overlying Globotrunca marly and sandy limestones, Eocene arkosic clastics, Nummulite limestone, and flysch. Although the paleogeographic history of the three basins differs in details, it was essentially the same in major features. The tectonic history, however, differed considerably depending on the structural nature of the underlying basement rocks of the basins. Presence of nappes of distant origin is suspected from relationships of the Cretaceous flysch and the Paleozoic schists east of Francardo.

scholarly journals Did true frogs ‘dispersify’?

2017 ◽  
Vol 13 (8) ◽  
pp. 20170299 ◽  
Author(s):  
Kin Onn Chan ◽  
Rafe M. Brown
Keyword(s):  
Range Expansion ◽  
Large Scale ◽  
Late Eocene ◽  
Fundamental Interest ◽  
Biogeographic History ◽  
Ideal System ◽  
History Of ◽  
Biogeographic Regions ◽  
Geographical Expansion ◽  
The Impact

The interplay between range expansion and concomitant diversification is of fundamental interest to evolutionary biologists, particularly when linked to intercontinental dispersal and/or large scale extinctions. The evolutionary history of true frogs has been characterized by circumglobal range expansion. As a lineage that survived the Eocene–Oligocene extinction event (EOEE), the group provides an ideal system to test the prediction that range expansion triggers increased net diversification. We constructed the most densely sampled, time-calibrated phylogeny to date in order to: (i) characterize tempo and patterns of diversification; (ii) assess the impact of the EOEE; and (iii) test the hypothesis that range expansion was followed by increased net diversification. We show that late Eocene colonization of novel biogeographic regions was not affected by the EOEE and surprisingly, global expansion was not followed by increased net diversification. On the contrary, the diversification rate declined or did not shift following geographical expansion. Thus, the diversification history of true frogs contradicts the prevailing expectation that amphibian net diversification accelerated towards the present or increased following range expansion. Rather, our results demonstrate that despite their dynamic biogeographic history, true frogs diversified at a relatively constantly rate, even as they colonized the major land masses of Earth.

Microscopic and megascopic fabrics in the Skiddaw Group, Black Combe inlier, English Lake District

1969 ◽  
Vol 106 (6) ◽  
pp. 587-594 ◽  
Author(s):  
Douglas G. Helm
Keyword(s):  
Clay Minerals ◽  
Regional Metamorphism ◽  
Axial Plane ◽  
Low Grade ◽  
Lake District ◽  
Tectonic History ◽  
Lower Ordovician ◽  
English Lake District ◽  
History Of

SUMMARYThe rocks of the Skiddaw Group of the Black Combe inlier were subjected to low grade regional metamorphism during the D1 movementphase of an intra-Lower Ordovician orogenic episode. Mimetic recrystallisation of clay minerals parallel to the bedding was ubiquitous. Later, axial-plane cleavages were superimposed on this fabric. The nature of the cleavages and possible mechanism of their formation is discussed.Silica has been mobilised on at least three occasions during the tectonic history of the inlier. In no case was this due to metasomatism but simply to metamorphic differentiation. The D1 veins are of either quartz, or quartz and chlorite whereas veins of later generations are of quartz alone.

scholarly journals Regional geology of early Precambrian high-grade metamorphic rocks in West Greenland. Part 1: Kângnaitsoq to Ameralik

1972 ◽  
Vol 46 ◽  
pp. 1-46
Author(s):  
B.F Windley
Keyword(s):  
Large Scale ◽  
Ultramafic Rocks ◽  
Metamorphic Rocks ◽  
High Grade ◽  
Regional Geology ◽  
Early Precambrian ◽  
West Greenland ◽  
Fold Structure ◽  
History Of

Within this region three types of area are distinguished: 1. Amphibolite-grade areas which did not reach a granulite grade. 2. Granulite-grade areas. 3. Amphibolite-grade areas, many of which have been retrogressed from the earlier granulite grade. The main rocks are hypersthene-biotite gneisses, biotite-hornblende gneisses, amphibolites with or without orthopyroxene, sillimanite mica schists, rare marbles, skarns and quartzites, layered calcic anorthosites, a great variety of meta-ultramafic rocks including rare zoned talc lenses, abundant pegmatites, several generations of dolerite dykes locally amphibolitised by deep-seated fauIts. The fold structure of the region is characterised by abundant large-scale interference patterns. The history of the region is interpreted on the basis of a deformed cover/basement relationship, all major units being now mutually conformable.

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