Paleogeographic position of the central Dodecanese Islands, southeastern Greece: The push-pull of Pelagonia

2021 ◽  
Author(s):  
B. Grasemann ◽  
D.A. Schneider ◽  
K. Soukis ◽  
V. Roche ◽  
B. Hubmann
Keyword(s):  
Normal Fault ◽  
White Mica ◽  
The North ◽  
Tectonic History ◽  
Fold And Thrust Belt ◽  
Tectonic Position ◽  
History Of ◽  
Single Grain ◽  
Back Arc ◽  
Bottom To Top

The paleogeographic position of the central Dodecanese Islands at the transition between the Aegean and Anatolian plates plays a considerable role in understanding the link between both geologically unique domains. In this study, we investigate the tectonic history of the central Dodecanese Islands and the general correlation with the Aegean and western Anatolian and focus on the poorly studied islands of Kalymnos and Telendos. Three different major tectonic units were mapped on both islands from bottom to top: (1) The Kefala Unit consists of late Paleozoic, fossil-rich limestones, which have been deformed into a SE-vergent fold-and-thrust belt sealed by an up to 200-m-thick wildflysch-type olistostrome with marble and ultramafic blocks on a scale of tens of meters. (2) The Marina Basement Unit consists of a Variscan amphibolite facies basement with garnet mica schists, quartzites, and amphibolites. (3) Verrucano-type formation violet shales and Mesozoic unmetamorphosed limestones form the Marina Cover Unit. Correlation of these units with other units in the Aegean suggests that Kalymnos is paleogeographically located at the southern margin of the Pelagonian domain, and therefore it was in a structurally upper tectonic position during the Paleogene Alpine orogeny. New white mica 40Ar/39Ar ages confirm the Carboniferous deformation of the Marina Basement Unit followed by a weak Triassic thermal event. Single-grain white mica 40Ar/39Ar ages from pressure solution cleavage of the newly defined Telendos Thrust suggest that the Marina Basement Unit was thrusted toward the north on top of the Kefala Unit in the Paleocene. Located at a tectonically upper position, the units exposed in the central Dodecanese escaped subduction and the syn-orogenic, high-pressure metamorphism. However, these units were affected by post-orogenic extension, and the contact between the Marina Basement Unit and the non-metamorphic Marina Cover Unit has been reactivated by the cataclastic top-to-SSW, low-angle Kalymnos Detachment. Zircon (U-Th)/He ages from the Kefala and Marina Basement Units are ca. 30 Ma, which indicates that exhumation and cooling below the Kalymnos Detachment started in the Oligocene. Conjugate brittle high-angle normal fault systems, which resulted in the formation of four major WNW-ESE−trending graben systems on Kalymnos, localized mainly in the Marina Cover Unit and probably rooted in the mechanically linked Kalymnos Detachment. Since Oligo-Miocene deformation in the northern Dodecanese records top-to-NNE extension and the Kalymnos Detachment accommodated top-to-SSW extension, we suggest that back-arc extension in the whole Aegean realm and transition to the Anatolian plate is bivergent.

Are Wilson Cycles preserved in Archean cratons? A comparison of the North China and Slave cratons

2014 ◽  
Vol 51 (3) ◽  
pp. 297-311 ◽  
Author(s):  
Timothy M. Kusky ◽  
Xiaoyong Li ◽  
Zhensheng Wang ◽  
Jianmin Fu ◽  
Luo Ze ◽  
...  
Keyword(s):  
North China Craton ◽  
Plate Tectonics ◽  
North China ◽  
Passive Margin ◽  
The North ◽  
Tectonic History ◽  
History Of ◽  
Pacific Slab ◽  
Arc Setting ◽  
Back Arc

A review and comparison of the tectonic history of the North China and Slave cratons reveal that the two cratons have many similarities and some significant differences. The similarities rest in the conclusion that both cratons have a history of a Wilson Cycle, having experienced rifting of an old continent in the late Archean, development of a rift to passive margin sequence, collision of this passive margin with arcs within 100–200 Ma of the formation of the passive margin, reversal of subduction polarity, then eventual climactic collision with another arc terrane, microcontinental fragment, or continent. This cycle demonstrates the operation of Paleozoic-style plate tectonics in the late Archean. The main differences lie in the later tectonic evolution. The Slave’s post-cratonization history is dominated by subduction dipping away from the interior of the craton, and later incorporation into the interior of a larger continent, whereas the North China Craton has had a long history of subduction beneath the craton, including presently being located above the flat-lying Pacific slab resting in the mantle transition zone, placing it in a broad back-arc setting, with multiple mantle hydration events and collisions along its borders. The hydration enhances melting in the overlying mantle, and leads to melts migrating upwards to thermochemically erode the lithospheric root. This major difference may explain why the relatively small Slave craton preserves its thick Archean lithospheric root, whereas the eastern North China Craton has lost it.

scholarly journals Cenozoic tectonic history of the North America-Caribbean plate boundary zone in western Cuba

1997 ◽  
Vol 102 (B5) ◽  
pp. 10055-10082 ◽  
Author(s):  
Mark B. Gordon ◽  
Paul Mann ◽  
Dámaso Cáceres ◽  
Raúl Flores
Keyword(s):  
North America ◽  
Plate Boundary ◽  
Boundary Zone ◽  
Caribbean Plate ◽  
The North ◽  
Tectonic History ◽  
History Of ◽  
Plate Boundary Zone

The Barreme Basin and the Gevaudan diapir - an example of the interplay between compressional tectonics and salt diapirism

2020 ◽  
Author(s):  
Rod Graham ◽  
Adam Csicsek
Keyword(s):  
Foreland Basin ◽  
Finite Geometry ◽  
Driving Mechanism ◽  
Salt Diapirism ◽  
Sedimentary Evolution ◽  
Tectonic History ◽  
Thrust Belts ◽  
Fold And Thrust Belt ◽  
History Of

<p><strong>The Barreme Basin and the Gevaudan diapir - an example of the interplay between compressional tectonics and salt diapirism </strong></p><p><strong> </strong></p><p><strong>Adam Csicsek and Rod Graham</strong></p><p>Imperial College London</p><p><strong> </strong></p><p>Our understanding of the role of salt diapirism in determining the finite geometry of fold and thrust belts has grown apace in the last few years, but the interplay between the two remains a significant problem for structural interpretation. The Gevaudan diapir in the fold and thrust belt of the sub-Alpine chain of Haute Provence is well known and has been documented by numerous eminent alpine structural geologists. Graciansky, Dardot, Mascle, Gidon and Lickorish and Ford have all described and illustrated the geometry and evolution of the structure, and Lickorish and Ford’s interpretation is figured as an example of  diapirism  in a compressional setting by Jackson and Hudec in their text on salt tectonics. We review these various interpretations and present another.</p><p>The differences between the various interpretations say much about the complex interplay of salt diapirism and thin-skinned thrusting and have profound implications for the way we interpret the tectonic and sedimentary evolution of the Barreme basin which lies adjacent to the diapir</p><p>The Barreme basin is a thrust-top fragment of the Provencal foreland basin and has been described in detail from both sedimentological (e.g. Evans and Elliott, 1999) and structural (e.g. Antoni and Meckel, 1997) points of view. Here we make the case that it is also a salt related minibasin - a secondary minibasin developed on a now welded allochthonous Middle Cretaceous salt canopy.  We believe that within the basin it is possible to interpret successive depocentres which may record progressive salt withdrawal. We argue that though thrust loading must be the fundamental driving mechanism responsible for salt movement late in the tectonic history of the region, thrusting has not done much more than modify existing salt related geometry.    </p>

On the nature of the crust in the vicinity of the southeast Newfoundland Ridge

1978 ◽  
Vol 15 (9) ◽  
pp. 1462-1471 ◽  
Author(s):  
K. D. Sullivan ◽  
C. E. Keen
Keyword(s):  
Focal Point ◽  
Magnetic Data ◽  
Seismic Structure ◽  
Grand Banks ◽  
The North ◽  
Tectonic History ◽  
History Of ◽  
Continental Origin ◽  
Magnetic Lineations ◽  
Gravity And Magnetic Data

This paper presents new seismic reflection, refraction, gravity, and magnetic data bearing on the nature of the crust in the vicinity of the Newfoundland Ridge and the J-anomaly Ridge, immediately south of the Grand Banks. This area experienced a complicated plate tectonic history being the focal point for interactions of the North American, African, and Iberian plates. New data have recently been published for this region and conflicting interpretations have been offered in relation to the oceanic or continental origin of the crust there. The data presented here show that the seismic structure and the most reasonable models for the magnetic anomalies are more consistent with an oceanic origin. The trends and offsets in the magnetic lineations and possible differences in subsidence, north and south of the Newfoundland Ridge, are discussed in relation to possible modes of formation of this feature. It is proposed that similar subsidence histories since mid-Cretaceous time on the Grand Banks and J-anomaly Ridge are related to a similarity in the thermal history of the lithosphere beneath these areas, as the ridge crest migrated eastwards, and do not require the same type of crust to underlie both areas.

From arc evolution to arc-continent collision: Late Cretaceous–middle Eocene geology of the Eastern Pontides, northeastern Turkey

2019 ◽  
Vol 131 (11-12) ◽  
pp. 1889-1906 ◽  
Author(s):  
Özgür Kandemir ◽  
Kenan Akbayram ◽  
Mehmet Çobankaya ◽  
Fatih Kanar ◽  
Şükrü Pehlivan ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Middle Eocene ◽  
Structural Data ◽  
Massive Sulfide ◽  
Arc Volcanism ◽  
Eastern Pontides ◽  
The North ◽  
Fold And Thrust Belt ◽  
Volcaniclastic Rocks ◽  
Back Arc

Abstract The Eastern Pontide Arc, a major fossil submarine arc of the world, was formed by northward subduction of the northern Neo-Tethys lithosphere under the Eurasian margin. The arc’s volcano-sedimentary sequence and its cover contain abundant fossils. Our new systematical paleontological and structural data suggest the Late Cretaceous arc volcanism was initiated at early-middle Turonian and continued uninterruptedly until the end of the early Maastrichtian, in the northern part of the Eastern Pontides. We measured ∼5500-m-thick arc deposits, suggesting a deposition rate of ∼220 m Ma–1 in ∼25 m.y. We have also defined four different chemical volcanic episodes: (1) an early-middle Turonian–Santonian mafic-intermediate episode, (2) a Santonian acidic episode; when the main volcanic centers were formed as huge acidic domes-calderas comprising the volcanogenic massive sulfide ores, (3) a late Santonian–late Campanian mafic-intermediate episode, and (4) a late Campanian–early Maastrichtian acidic episode. The volcaniclastic rocks were deposited in a deepwater extensional basin until the late Campanian. Between late Campanian and early Maastrichtian, intra-arc extension resulted in opening of back-arc in the north, while the southern part of the arc remained active and uplifted. The back-arc basin was most probably connected to the Eastern Black Sea Basin. In the back-arc basin, early Maastrichtian volcano-sedimentary arc sequence was transitionally overlain by pelagic sediments until late Danian suggesting continuous deep-marine conditions. However, the subsidence of the uplifted-arc-region did not occur until late Maastrichtian. We have documented a Selandian–early Thanetian (57–60 Ma) regional hiatus defining the closure age of the İzmir-Ankara-Erzincan Ocean along the Eastern Pontides. Between late Thanetian and late Lutetian synorogenic turbidites and postcollisional volcanics were deposited. The Eastern Pontide fold-and-thrust belt started to form at early Eocene (ca. 55 Ma) and thrusting continued in the post-Lutetian times.

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.

Geochronologic and thermobarometric constraints on the metamorphic history of the Fairbanks Mining District, western Yukon-Tanana terrane, Alaska

2002 ◽  
Vol 39 (7) ◽  
pp. 1107-1126 ◽  
Author(s):  
Thomas A Douglas ◽  
Paul W Layer ◽  
Rainer J Newberry ◽  
Mary J Keskinen
Keyword(s):  
Thrust Fault ◽  
White Mica ◽  
Mining District ◽  
East Central ◽  
Diamond Drill ◽  
Metamorphic History ◽  
Structural History ◽  
History Of ◽  
Radiogenic Argon ◽  
Single Grain

This study presents new petrologic and thermochronologic information from the Fairbanks district of east central Alaska that indicate a complex metamorphic and structural history for the western Yukon–Tanana terrane. Garnet–biotite and garnet–pyroxene thermometry and jadeite barometry yield prograde temperatures and pressures for the Chatanika eclogite (523°C, 14–15 kbar (1 kbar = 100 MPa)). Cooling from peak eclogitization is estimated from 40Ar/39Ar single grain geochronology at ~210–180 Ma. Secondary white mica ages of 140–115 Ma along the fault contact between eclogite and underlying lower amphibolite-facies rocks constrain the age of the event that placed the Chatanika eclogite over the Fairbanks schist. Based on observations from field mapping and diamond drill samples, we interpret this structural contact as a thrust fault. Garnet–biotite mineral pairs are reset by as much as 200°C within this fault zone. Biotite and white mica ages of ~100–110 Ma, combined with Jurassic amphibole ages in Fairbanks schist samples, indicate the Fairbanks schist and Chatanika eclogite cooled through biotite and white mica argon closure temperatures in the early Cretaceous. Intrusion of mid-Cretaceous, calc-alkalic, gold-related granitic plutons in the Fairbanks district are evidenced by loss of radiogenic argon in many of the 40Ar/39Ar age fractions. Eocene basalt is visible in six widely separated localities within the eastern part of the Fairbanks district. However, the pervasiveness of a 50 Ma resetting event in samples as far as 30 km from present day basalt localities indicates the Eocene flows were either deposited throughout the Fairbanks area or are associated with large plutons at depth.

Structural Features of the Alston Block

1933 ◽  
Vol 70 (6) ◽  
pp. 241-254 ◽  
Author(s):  
K. C. Dunham
Keyword(s):  
Structural Features ◽  
Geological Survey ◽  
North West ◽  
Northern Area ◽  
The North ◽  
Tectonic History ◽  
Fault Block ◽  
History Of ◽  
The Cross ◽  
North And South

The Northumbrian Fault-block, forming the central part of the Pennine Chain, is a region of gently tilted Carboniferous sediments, bounded on the north, west, and south by major faultlines. It is divided naturally into two structurally complementary areas, symmetrically disposed to the north and south of the syncline of Stainmore. The present paper is concerned exclusively with the northern area, named by F. M. Trotter and S. E. Hollingworth the “Alston Block” (1928) and by H. G. A. Hickling the “Cross Fell Block” (1930). The first-named authors, who have recently completed a revision of the Geological Survey sheet covering the north-west corner of the block, have discussed in detail the structure of that district and have described the broad outlines of the tectonic history of the block (1928, 1932).

Nd isotopic evidence for crustal recycling in the ca. 2.0 Ga subsurface of western Canada

1991 ◽  
Vol 28 (8) ◽  
pp. 1140-1147 ◽  
Author(s):  
R. J. Thériault ◽  
G. M. Ross
Keyword(s):  
Isotopic Data ◽  
Tectonic Zone ◽  
Isotopic Signatures ◽  
Crustal Recycling ◽  
The North ◽  
Tectonic History ◽  
Depleted Mantle ◽  
History Of ◽  
Mantle Component ◽  
Northern Alberta

Sm–Nd isotopic data are presented for 23 drill-core samples from five aeromagnetically and geochronologically (U–Pb zircon) distinct domains of the Precambrian basement of northern Alberta. The domains in question are the Taltson (1.96–1.94 Ga), Buffalo Head (2.32–1.99 Ga), Chinchaga (2.19–2.09 Ga), Ksituan (1.99–1.90 Ga), and Nova (2.81 Ga). These domains are truncated to the north and south by the Great Slave Lake shear zone and the Snowbird tectonic zone, respectively.Initial εNd values are −5.0 to −9.7 for the Taltson, +0.2 to −6.3 for the Buffalo Head, +0.6 to −1.8 for the Chinchaga, −1.8 to −2.1 for the Ksituan and +5.6 for the Nova. Crustal residence model ages fall in the 2.5–2.8 Ga range. The Nd isotopic signatures may be viewed in terms of mixing a minimum of 10% Archean continental crust with a depleted-mantle component. Speculations on the tectonic history of the basement domains in question involve the assembly of Archean crustal nuclei to form the Buffalo Head – Chinchaga composite domain. Arc magmatism resulting from plate subduction to the east and west of the Buffalo Head – Chinchaga composite domain would have generated the Taltson and Ksituan domains. The Nd isotopic data suggest that the basement of northern Alberta consists of crust of late Archean crustal residence age which has been extensively remobilized in the Early Proterozoic.

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