Seismicity, Deformation, and Metamorphism in the Western Hellenic Subduction Zone: New Constraints From Tomography

Halpaap, Felix; Rondenay, S.; Ottemöller, Lars

doi:10.1002/2017jb015154

Cited by 56 publications

(111 citation statements)

References 90 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observations from the western Hellenic subduction zone (Halpaap et al, ) suggest complex patterns of fluid migration into the mantle wedge and overriding lithosphere that are also consistent with our model results. The western Hellenic subduction zone (Figure a) is characterized by slow continental subduction in the north and faster oceanic subduction in the south (Pearce et al, ).…”

Section: Discussionsupporting

confidence: 91%

“…Our model results further show that the length scale and timescale of fluid migration depends on bulk viscosity and permeability. The two pathways shown in the forward models compare well with, and may explain, observations in natural subduction systems such as the west Hellenic subduction (Halpaap et al, ) and in southeast Japan (Saita et al, ).…”

Section: Discussionsupporting

confidence: 78%

“…As the melts have a much larger shear viscosity (~10 5 ) than water, the compaction length of melt migration is much smaller, explaining why the fluid pathways of the melts may be less prone to being diverted by the high‐pressure zone. The amplitude of the V s anomalies shown in Figure varies along strike (see Halpaap et al, ), reflecting varying water content between the northern and southern subducting slab and the potential effects of 3‐D dynamics (see, e.g., Davies et al, ). Similar observations are made in the Andean subduction zone (Schurr et al, ).…”

Section: Discussionmentioning

confidence: 97%

See 2 more Smart Citations

Water Migration in the Subduction Mantle Wedge: A Two‐Phase Flow Approach

2019

Self Cite

View full text Add to dashboard Cite

Subduction zones are the main entry points of water into Earth's mantle and play an important role in the global water cycle. The progressive release of water by metamorphic dehydration induces important physical‐chemical processes, including subduction zone earthquakes. Yet, how water migrates in subduction zones is not well understood. We investigate this problem by explicitly modeling two‐phase flow processes, in which fluids migrate through a compacting and decompacting solid matrix. Our results show that water migration is strongly affected by subduction dynamics, which exhibits three characteristic stages in our models: (1) an early stage of subduction initiation; (2) an intermediate stage of gravity‐driven steepening of the slab; and (3) a late stage of quasi steady state subduction. Two main water pathways are found in the models: trenchward and arcward. They form in the first two stages and become steady in the third stage. Depending on the depth of water release from the subducting slab, water migration focuses in different pathways: a shallow release depth (e.g., 40 km) leads the water mainly through the trenchward pathway, a deep release depth (e.g., 120 km) promotes an arcward pathway and a long horizontal migration distance (~300 km) from the trench, and an intermediate release depth (e.g., 80 km) leads water to both pathways. We compare our models with seismic studies from southeast Japan (Saita et al., 2015, https://doi.org/10.1002/2015GL063084) and the west Hellenic subduction zone (Halpaap et al., 2018, https://doi.org/10.1002/2017JB015154) and provide geodynamical explanations for these seismic observations in natural subduction environments.

show abstract

Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

Water Migration in the Subduction Mantle Wedge: A Two‐Phase Flow Approach

2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…This indicates that our tomographic model has no resolution to clarify whether the subducting Hellenic slab has a tear or not across the KTF. Recent local tomography, however, suggests that a slab tear does not exist at least in the shallow mantle beneath the KTF (Halpaap et al, ).…”

Section: Discussionmentioning

confidence: 99%

Mantle Dynamics of the Eastern Mediterranean and Middle East: Constraints From P‐Wave Anisotropic Tomography

Wei

Zhao

Wei

et al. 2019

Geochem Geophys Geosyst

View full text Add to dashboard Cite

High‐resolution images of P‐wave anisotropic tomography beneath the Eastern Mediterranean and Middle East are determined by inverting a large number of high‐quality P‐wave arrival times. Our results clearly show along‐strike variations of subducting slabs in the Hellenic subduction zone. At least three high‐velocity anomalies are imaged beneath and behind the north Hellenides, which are associated with the subducting Hellenic slab at different stages, while in regions further south, a single slab is revealed that has subducted down to a depth of ~1,100 km. The slab feature is not prominent in the Cyprus subduction zone, but a fine‐scale high‐velocity structure is revealed beneath the central Anatolia, which may reflect the detached Cyprus slab. Trench‐parallel fast‐velocity directions occur in the forearc mantle wedge of the Hellenic subduction zone, which may reflect mantle flow induced by slab curvature. In the backarc north Aegean and westernmost Anatolia, dominant NNE‐SSW to N‐S fast‐velocity directions exist in the shallow mantle, which accord well with the extensional direction of present deformation at the surface, suggesting a vertically coherent deformation in the lithosphere. Our results reveal a large‐scale mantle flow beneath western Arabia, which is possibly related to the Zagros and Caucasus orogens and westward motion of the Anatolia lithosphere. The Arabian lithospheric plate is thinner beneath the Zagros than that under the Mesopotamian Foredeep, suggesting that a large portion of the crust was scrapped off from the subducted Arabian lithosphere during the Zagros orogen.

show abstract

“…This is usually attributed to the transformation of crustal rocks into eclogites, essentially removing the velocity contrast to the surrounding mantle (Hacker et al, 2003;Hetényi et al, 2007;Rondenay et al, 2008). However, the crustal signal does not disappear abruptly, but a transitional zone, characterized by progressive blurring of the signal, is typically observed (e.g., Halpaap et al, 2018;Schneider et al, 2013). This is presumably caused by partial eclogitization of the downgoing crust, a process seemingly active at depth beneath the Himalaya-Tibet collision system today, where the signal of the Indian lower crust decreases progressively while its density increases (Hetényi et al, 2007;Nabelek et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Modification of the Seismic Properties of Subducting Continental Crust by Eclogitization and Deformation Processes

et al. 2019

View full text Add to dashboard Cite

Subduction zone processes and the resulting geometries at depth are widely studied by large‐scale geophysical imaging techniques. The subsequent interpretations are dependent on information from surface exposures of fossil subduction and collision zones, which help to discern probable lithologies and their structural relationships at depth. For this purpose, we collected samples from Holsnøy in the Bergen Arcs of western Norway, which constitutes a well‐preserved slice of continental crust, deeply buried and partially eclogitized during Caledonian collision. We derived seismic properties of both the lower crustal granulite‐facies protolith and the eclogite‐facies shear zones by performing laboratory measurements on cube‐shaped samples. P and S wave velocities were measured in three perpendicular directions, along the principal fabric directions of the rock. Resulting velocities agree with seismic velocities calculated using thermodynamic modeling and confirm that eclogitization causes a significant increase of the seismic velocity. Further, eclogitization results in decreased VP/VS ratios and, when associated with deformation, an increase of the seismic anisotropy due to the crystallographic preferred orientation of omphacite that were obtained from neutron diffraction measurements. The structural framework of this exposed complex combined with the characteristic variations of seismic properties from the lower crustal protolith to the high‐pressure assemblage provides the possibility to detect comparable structures at depth in currently active settings using seismological methods such as the receiver function method.

show abstract

Seismicity, Deformation, and Metamorphism in the Western Hellenic Subduction Zone: New Constraints From Tomography

Cited by 56 publications

References 90 publications

Water Migration in the Subduction Mantle Wedge: A Two‐Phase Flow Approach

Water Migration in the Subduction Mantle Wedge: A Two‐Phase Flow Approach

Mantle Dynamics of the Eastern Mediterranean and Middle East: Constraints From P‐Wave Anisotropic Tomography

Modification of the Seismic Properties of Subducting Continental Crust by Eclogitization and Deformation Processes

Contact Info

Product

Resources

About