scholarly journals High-pressure metamorphism in the Aegean, eastern Mediterranean: Underplating and exhumation from the Late Cretaceous until the Miocene to Recent above the retreating Hellenic subduction zone

Tectonics ◽  
2003 ◽  
Vol 22 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Uwe Ring ◽  
Paul W. Layer
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Late Cretaceous ◽  
Eastern Mediterranean ◽  
Hellenic Subduction Zone ◽  
High Pressure Metamorphism

Geochemical and Nd isotopic constraints for the origin of eclogite protoliths, northern Cordillera: implications for the Paleozoic tectonic evolution of the Yukon-Tanana terrane

1999 ◽  
Vol 36 (10) ◽  
pp. 1697-1709 ◽  
Author(s):  
Robert A Creaser ◽  
Jo-Anne S Goodwin-Bell ◽  
Philippe Erdmer
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Convergent Margins ◽  
Metasedimentary Rocks ◽  
High Pressure Metamorphism ◽  
Distal Edge ◽  
History Of ◽  
Convergent Plate Margin ◽  
Ocean Ridge ◽  
Subduction Zone Magmatism

On the basis of trace-element data, basaltic protoliths for Paleozoic eclogites from the Yukon-Tanana terrane (YTT) have diverse origins. Eclogites from Stewart Lake and the Simpson Range have characteristics of basaltic protoliths generated by subduction-zone magmatism, are hosted by serpentinitic-gabbroic rocks, and record Mississippian high-pressure metamorphism and cooling. In contrast, eclogites from Faro, Ross River, and Last Peak show either within-plate geochemistry or mid-ocean ridge protolith geochemistry with a small subduction component, are hosted by continental metasedimentary rocks of the Nisutlin assemblage, and record Permian high-pressure metamorphism and cooling. We interpret these results to derive from the following tectonic events in the Paleozoic history of the YTT: (1) activity at a Devonian-Mississippian convergent plate margin at the distal edge of North America, with near-contemporaneous subduction-zone magmatism and high-pressure metamorphism; (2) Mississippian rifting of that margin to form the outboard YTT, the Slide Mountain marginal basin, and the Faro, Ross River, and Last Peak eclogite protoliths; and (3) west-dipping subduction of the Slide Mountain Ocean under the outboard YTT in Permian time, to produce the Faro, Ross River, and Last Peak eclogites and Permian arc magmatism throughout the YTT. The basaltic protoliths of the Paleozoic YTT eclogites bear close similarity to those produced in rifted convergent margins, such as the Miocene Japanese arc - back-arc system.

scholarly journals Accretion-controlled forearc deformation pulses recorded by high-pressure paleo-accretionary wedges: the example of the Hellenic subduction zone

2021 ◽  
Author(s):  
Armel Menant ◽  
Onno Oncken ◽  
Johannes Glodny ◽  
Samuel Angiboust ◽  
Laurent Jolivet ◽  
...  
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Numerical Models ◽  
Carbonaceous Material ◽  
Plate Interface ◽  
Stress Regime ◽  
Hellenic Subduction Zone ◽  
Driving Mechanisms ◽  
Wide Range

<p>Subduction margins are the loci of a wide range of deformation processes occurring at different timescales along the plate interface and in the overriding forearc crust. Whereas long-term deformation is usually considered as stable over Myr-long periods, this vision is challenged by an increasing number of observations suggesting a long-term pulsing evolution of active margins. To appraise this emerging view of a highly dynamic subduction system and identify the driving mechanisms, detailed studies on high pressure-low temperature (HP-LT) exhumed accretionary complexes are crucial as they open a window on the deformation history affecting the whole forearc region.</p><p>In this study, we combine structural and petrological observations, Raman spectroscopy on carbonaceous material, Rb/Sr multi-mineral geochronology and thermo-mechanical numerical models to unravel with an unprecedented resolution the tectono-metamorphic evolution of the Late-Cenozoic HP-LT nappe stack cropping out in western Crete (Hellenic subduction zone). A consistent decrease of peak temperatures and deformation ages toward the base of the nappe pile allows us to identify a minimum of three basal accretion episodes between ca. 24 Ma and ca. 15 Ma. On the basis of structural evidences and pressure-temperature-time-strain predictions from numerical modeling, we argue that each of these mass-flux events triggered a pulse in the strain rate, sometimes associated with a switch of the stress regime (i.e., compressional/extensional). Such accretion-controlled transient deformation episodes last at most ca. 1-2 Myr and may explain the poly-phased structural records of exhumed rocks without involving changes in far-field stress conditions. This long-term background tectonic signal controlled by deep accretionary processes plays a part in active deformations monitored at subduction margins, though it may remain blind to most of geodetic methods because of superimposed shorter-timescale transients, such as seismic-cycle-related events.</p>

scholarly journals A new approach to the opening of the eastern Mediterranean Sea and the origin of the Hellenic subduction zone. Part 2: The Hellenic subduction zone

2019 ◽  
Vol 56 (11) ◽  
pp. 1144-1162 ◽  
Author(s):  
Xavier Le Pichon ◽  
A.M. Celâl Şengör ◽  
Caner İmren
Keyword(s):  
Mediterranean Sea ◽  
Subduction Zone ◽  
Eastern Mediterranean ◽  
Accretionary Wedge ◽  
Geophysical Research ◽  
Independent Evidence ◽  
Eastern Mediterranean Sea ◽  
Northern Margin ◽  
Hellenic Subduction Zone ◽  
The North

We discuss the structure of the present Hellenic subduction zone. We show that the present Hellenic subduction zone was formed at about 15 Ma when it started to consume the Mediterranean lithosphere and to form the large accretionary wedge that covers a large part of the eastern Mediterranean. We establish that there is independent evidence that the very large Hellenic Trough that it created was formed simultaneously. Shortly before, an 8–10 km thick backstop that extends 200 km southward, where it presently abuts the African margin, was put into place. We reconstruct the northern margin of the eastern Mediterranean Sea prior to the Hellenic subduction in a new and independent way. The faults recently identified by Sachpazi et al. (2016a . Geophysical Research Letters, 43: 651–658) and Sachpazi et al. (2016b . Geophysical Research Letters, 43: 9619–9626) within the Hellenic seismic slab are a key element of our reconstruction. This is because the slab, which is part of the Nubia plate, is rigid and the faults within it coincide with the lines of slip congruent with the relative motion of the Aegean block over it. These faults demonstrate that about 400 to 500 kilometers of eastern Mediterranean lithosphere have been subducted with essentially the same southwestward direction of motion during the last 15 Myr. Our reconstruction shows that before the onset of the Hellenic subduction, the northern margin of the eastern Mediterranean Sea coincided with a major Jurassic transform fault that limited the eastern Mediterranean to the north during its formation in the Jurassic and Early Cretaceous as proposed in part 1. We discuss the implications of this reconstruction on the Neogene evolution of the Anatolia–Aegea block and its geodynamics.

Supra-subduction zone ophiolites of Central Anatolia: geochemical evidence from the Sarikaraman Ophiolite, Aksaray, Turkey

1996 ◽  
Vol 60 (402) ◽  
pp. 697-710 ◽  
Author(s):  
M. K. Yaliniz ◽  
P. A. Floyd ◽  
M. C. Göncüoğlu
Keyword(s):  
Subduction Zone ◽  
Late Cretaceous ◽  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Central Anatolia ◽  
Chemical Characteristics ◽  
Crystalline Complex ◽  
Geochemical Evidence ◽  
The North

AbstractThe Central Anatolian Crystalline Complex (CACC), situated between the northern and southern oceanic strands of Neotethys, contain a number of little-studied ophiolitic bodies of late Cretaceous age that have a bearing on the Mesozoic development of this region. The pillow lavas and sheeted dykes of the Sarikaraman Ophiolite were originally a comagmatic differentiated series of vesicular, aphyric and olivine-poor, plagioclase—clinopyroxene phyric tholeiites, but now exhibit greenschist facies assemblages. A set of late dolerite dykes cross-cutting the whole volcanic sequence are more chemically evolved and were probably derived from a different source. Relative to N-MORB the lavas and dykes are enriched in some LIL elements (K, Rb, Cs, U, Th and Sr) and depleted in HFS elements (Nb, Ta, Hf, Zr, Ti and Y) and lightREE. In terms of immobile elements the ophiolitic basalts have the broad chemical characteristics of island are tholeiites that were formed in a supra-subduction zone setting, whereas the late dykes are more akin to N-MORB. In this respect the Sarikaraman Ophiolite is similar to other ophiolites found in the eastern Mediterranean region and emphasizes the preservation of this particular environment in the CACC. If all the Central Anatolian Ophiolites (of which the Sarikaraman Ophiolite is one example) were derived via southward thrusting from the Vardar-Izmir-Ankara-Erzincan Ocean branch to the north, age relationships suggest that this segment of ocean crust was relatively short-lived before obduction onto the CACC.

scholarly journals Up the down escalator: the exhumation of (ultra)-high pressure terranes during on-going subduction

2012 ◽  
Vol 4 (1) ◽  
pp. 745-781 ◽  
Author(s):  
C. J. Warren
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Continental Crust ◽  
Subduction Zones ◽  
Crustal Material ◽  
Time And Space ◽  
Ultra High Pressure ◽  
Tectonic Environment ◽  
Tectonic Style ◽  
Weak Material

Abstract. The exhumation of high and ultra-high pressure rocks is ubiquitous in Phanerozoic orogens created during continental collisions, and is common in many ocean-ocean and ocean-continent subduction zone environments. Three different tectonic environments have previously been reported, which exhume deeply buried material by different mechanisms and at different rates. However it is becoming increasingly clear that no single mechanism dominates in any particular tectonic environment, and the mechanism may change in time and space within the same subduction zone. In order for buoyant continental crust to subduct, it must remain attached to a stronger and denser substrate, but in order to exhume, it must detach (and therefore at least locally weaken) and be initially buoyant. Denser oceanic crust subducts more readily than more buoyant continental crust but exhumation must be assisted by entrainment within more buoyant and weak material such as serpentinite or driven by the exhumation of structurally lower continental crustal material. Weakening mechanisms responsible for the detachment of crust at depth include strain, hydration, melting, grain size reduction and the development of foliation. These may act locally or may act on the bulk of the subducted material. Metamorphic reactions, metastability and the composition of the subducted crust all affect buoyancy and overall strength. Subduction zones change in style both in time and space, and exhumation mechanisms change to reflect the tectonic style and overall force regime within the subduction zone. Exhumation events may be transient and occur only once in a particular subduction zone or orogen, or may be more continuous or occur multiple times.

The occurrence and timing of high-pressure metamorphism on Margarita Island, Venezuela: a constraint on Caribbean-South America interaction

2009 ◽  
Vol 328 (1) ◽  
pp. 705-741 ◽  
Author(s):  
Walter V. Maresch ◽  
Rolf Kluge ◽  
Albrecht Baumann ◽  
James L. Pindell ◽  
Gabriela Krückhans-Lueder ◽  
...  
Keyword(s):  
High Pressure ◽  
South America ◽  
High Pressure Metamorphism
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