scholarly journals Subduction initiation and back-arc opening north of Neo-Tethys: Evidence from the Late Cretaceous Torbat-e-Heydarieh ophiolite of NE Iran

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1083-1105 ◽  
Author(s):  
Hadi Shafaii Moghadam ◽  
R.J. Stern ◽  
W.L. Griffin ◽  
M.Z. Khedr ◽  
M. Kirchenbaur ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Subduction Zones ◽  
Mantle Peridotite ◽  
Igneous Rocks ◽  
Subduction Initiation ◽  
The North ◽  
Depleted Mantle ◽  
Back Arc ◽  
Cretaceous Subduction ◽  
Ne Iran

Abstract How new subduction zones form is an ongoing scientific question with key implications for our understanding of how this process influences the behavior of the overriding plate. Here we focus on the effects of a Late Cretaceous subduction-initiation (SI) event in Iran and show how SI caused enough extension to open a back-arc basin in NE Iran. The Late Cretaceous Torbat-e-Heydarieh ophiolite (THO) is well exposed as part of the Sabzevar-Torbat-e-Heydarieh ophiolite belt. It is dominated by mantle peridotite, with a thin crustal sequence. The THO mantle sequence consists of harzburgite, clinopyroxene-harzburgite, plagioclase lherzolite, impregnated lherzolite, and dunite. Spinel in THO mantle peridotites show variable Cr# (10–63), similar to both abyssal and fore-arc peridotites. The igneous rocks (gabbros and dikes intruding mantle peridotite, pillowed and massive lavas, amphibole gabbros, plagiogranites and associated diorites, and diabase dikes) display rare earth element patterns similar to MORB, arc tholeiite and back-arc basin basalt. Zircons from six samples, including plagiogranites and dikes within mantle peridotite, yield U-Pb ages of ca. 99–92 Ma, indicating that the THO formed during the Late Cretaceous and was magmatically active for ∼7 m.y. THO igneous rocks have variable εNd(t) of +5.7 to +8.2 and εHf(t) ranging from +14.9 to +21.5; zircons have εHf(t) of +8.1 to +18.5. These isotopic compositions indicate that the THO rocks were derived from an isotopically depleted mantle source similar to that of the Indian Ocean, which was slightly affected by the recycling of subducted sediments. We conclude that the THO and other Sabzevar-Torbat-e-Heydarieh ophiolites formed in a back-arc basin well to the north of the Late Cretaceous fore-arc, now represented by the Zagros ophiolites, testifying that a broad region of Iran was affected by upper-plate extension accompanying Late Cretaceous subduction initiation.

scholarly journals The Middle-Late Cretaceous Zagros ophiolites, Iran: Linking of a 3000 km swath of subduction initiation fore-arc lithosphere from Troodos, Cyprus to Oman

2021 ◽  
Author(s):  
H.S. Moghadam ◽  
Q.L. Li ◽  
W.L. Griffin ◽  
M. Chiaradia ◽  
K. Hoernle ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Incompatible Element ◽  
Geochronological Data ◽  
Crustal Rocks ◽  
Subduction Initiation ◽  
Depleted Mantle ◽  
History Of ◽  
Ophiolitic Belt ◽  
Magmatic History ◽  
Back Arc

New trace-element, radiogenic Sr-Nd-Pb isotopic and geochronological data from Middle-Late Cretaceous Zagros ophiolites of Iran give new insights into the tectono-magmatic history of these supra-subduction zone (SSZ)-type ophiolites. The distribution of Middle-Late Cretaceous SSZ-type ophiolites in Iran comprises two parallel belts: (1) the outer Zagros ophiolitic belt and (2) the inner Zagros ophiolitic belt. These Middle-Late Cretaceous ophiolites were generated by seafloor spreading in what became the fore-arc and back-arc during the subduction initiation event and now define a ∼3000-km-long belt from Cyprus to Turkey, Syria, Iran, the UAE, and Oman. The Zagros ophiolites contain complete (if disrupted) mantle and crustal sequences. Mantle sequences from both outer-belt and inner-belt ophiolites are dominated by dunites, harzburgites, and lherzolites with minor chromitite lenses. Peridotites are also intruded by gabbros and a variety of mafic to minor felsic (plagiogranite and dacite) dikes. Crustal rocks comprise ultramafic-mafic cumulates as well as isotropic gabbros, sheeted dike complexes, pillowed and massive lavas, and felsic rocks. Our new zircon U-Pb ages indicate that the outer-belt and inner-belt ophiolites formed near coevally during the Middle-Late Cretaceous; 100−96 Ma for the outer belt and 105−94 Ma for the inner belt. Both incompatible-element ratios and isotopic data confirm that depleted mantle and variable contributions of subduction components were involved in the genesis of outer-belt and inner-belt rocks. Our data for the outer belt and inner belt along with those from better-studied ophiolites in Cyprus, Turkey, the UAE, and Oman lead to the conclusion that a broad, ∼3000-km-long swath of fore-arc lithosphere was created during Middle-Late Cretaceous time.

Late Cretaceous subduction-related magmatism on the southern edge of Sabzevar basin, NE Iran

2019 ◽  
Vol 176 (3) ◽  
pp. 530-552 ◽  
Author(s):  
Zakie Kazemi ◽  
Habibollah Ghasemi ◽  
Romain Tilhac ◽  
William Griffin ◽  
Hadi Shafaii Moghadam ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Cretaceous Subduction ◽  
Ne Iran

scholarly journals Structure of oceanic crust in back-arc basins modulated by mantle source heterogeneity

Geology ◽  
2020 ◽  
Author(s):  
Ingo Grevemeyer ◽  
Shuichi Kodaira ◽  
Gou Fujie ◽  
Narumi Takahashi
Keyword(s):  
Oceanic Crust ◽  
Mantle Source ◽  
Seismic Data ◽  
Lower Crust ◽  
Subduction Zones ◽  
P Wave ◽  
Spreading Ridge ◽  
Volcanic Arc ◽  
Depleted Mantle ◽  
Back Arc

Subduction zones may develop submarine spreading centers that occur on the overriding plate behind the volcanic arc. In these back-arc settings, the subducting slab controls the pattern of mantle advection and may entrain hydrous melts from the volcanic arc or slab into the melting region of the spreading ridge. We recorded seismic data across the Western Mariana Ridge (WMR, northwestern Pacific Ocean), a remnant island arc with back-arc basins on either side. Its margins and both basins show distinctly different crustal structure. Crust to the west of the WMR, in the Parece Vela Basin, is 4–5 km thick, and the lower crust indicates seismic P-wave velocities of 6.5–6.8 km/s. To the east of the WMR, in the Mariana Trough Basin, the crust is ~7 km thick, and the lower crust supports seismic velocities of 7.2–7.4 km/s. This structural diversity is corroborated by seismic data from other back-arc basins, arguing that a chemically diverse and heterogeneous mantle, which may differ from a normal mid-ocean-ridge–type mantle source, controls the amount of melting in back-arc basins. Mantle heterogeneity might not be solely controlled by entrainment of hydrous melt, but also by cold or depleted mantle invading the back-arc while a subduction zone reconfigures. Crust formed in back-arc basins may therefore differ in thickness and velocity structure from normal oceanic crust.

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.

4D stress signals in the upper plate record subduction nucleation and lateral propagation

2021 ◽  
Author(s):  
Brandon Shuck ◽  
Sean Gulick ◽  
Harm Van Avendonk ◽  
Michael Gurnis ◽  
Rupert Sutherland ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Time Lag ◽  
Plate Boundary ◽  
Subduction Initiation ◽  
The North ◽  
Stress Signal ◽  
Show Evidence ◽  
Stress Signals ◽  
Geologic Record ◽  
Geodynamic Models

<div> <p><strong>Subduction zones are fundamental to Earth’s plate tectonic history yet details of how they initiate remain enigmatic. Geodynamic models suggest that early stages of subduction depend on whether underthrusting is driven by horizontal or vertical forces. If horizontal forces dominate, the upper plate experiences compression and uplift followed by extension and subsidence, whereas vertically-forced subduction involves only extension. Geologic evidence from the Izu-Bonin-Mariana forearc supports a ~1 Myr rapid transition, whereas observations from Oman indicate a >8 Myr time lag between initial underthrusting and the onset of upper plate extension. We present seismic images of the incipient Puysegur subduction zone south of New Zealand. Our data show evidence for a stress signal (compression followed by extension) that spread from north to south as the trench initiated and propagated along the plate boundary. Both the magnitude and duration of the compressional phase diminish from ~8 Myrs long in the north to ~5 Myrs in the south. This timing indicates that the transition to self-sustaining subduction is more rapid when an adjacent downgoing slab contributes a driving force that aids subduction initiation. We therefore argue for a new framework in which horizontal forces dominate at sites of subduction nucleation and vertical forces gradually strengthen during later propagation as the developing plate boundary weakens and the slab-pull force intensifies. Our findings corroborate evidence for ancient horizontally-forced subduction initiation events and suggest that the geologic record may be biased, since vertically-forced scenarios of subduction propagation are more likely to be preserved than destructive subduction nucleation events. </strong></p> </div>

Effect of plate motion on plume-induced subduction initiation

2021 ◽  
Author(s):  
Marzieh Baes ◽  
Stephan Sobolev ◽  
Taras Gerya ◽  
Robert Stern ◽  
Sascha Brune
Keyword(s):  
Subduction Zone ◽  
Late Cretaceous ◽  
Subduction Zones ◽  
Plate Tectonics ◽  
Plate Motion ◽  
Cascadia Subduction Zone ◽  
Caribbean Plate ◽  
Subduction Initiation ◽  
Southern Margin ◽  
The Caribbean

<p>Subduction zones are key components of plate tectonics and plate tectonics could not begin until the first subduction zone formed. Plume-induced subduction initiation, which has been proposed as triggering the beginning of plate tectonics (Gerya et al., 2015), is one of the few scenarios that can break the lithosphere and recycle a stagnant lid without requiring any pre-existing weak zones. So far, two natural examples of plume-induced subduction initiation have been recognized. The first was found in southern and western margins of the Caribbean Plate (Whattam and Stern 2014). Initiation of the Cascadia subduction zone in Eocene times has been proposed to be the second example of plume-induced subduction initiation (Stern and Dumitru, 2019).</p><p>The focus of previous studies was to inspect plume-lithosphere interaction either for the case of stationary lithosphere (e.g., Gerya et al., 2015) or for moving lithosphere without considering the effect of lithospheric magmatic weakening above the plume head (e.g., Moore et al., 1998). In present study we investigate the response of moving oceanic lithosphere to the arrival of a rising mantle plume head including the effect of magmatic lithospheric weakening. We used 3D numerical thermo-mechanical modeling. Using I3ELVIS code, which is based on finite difference staggered grid and marker-in-cell with an efficient OpenMP multigrid solver (Gerya, 2010), we show that plate motion may affect the plume-induced subduction initiation only if a moderate size plume head (with a radius of 140 km in our experiments) impinges on a young but subductable lithosphere (with the age of 20 Myr). Outcomes indicate that lithospheric strength and plume buoyancy are key parameters in penetration of the plume and subduction initiation and that plate speed has a minor effect. We propose that eastward motion of the Farallon plate in Late Cretaceous time could play a key role in forming new subduction zones along the western and southern margin of the Caribbean plate.</p><p> </p><p>References:</p><p>Gerya, T., 2010, Introduction to Numerical Geodynamic Modelling.. Cambridge University Press.</p><p>Gerya, T.V., Stern, R.J., Baes, M., Sobolev, S.V. and Whattam, S.A., 2015. Plume-induced subduction initiation triggered Plate Tectonics on Earth. Nature, 527, 221–225.</p><p>Moore, W. B., Schubert, G. and Tackley, P., 1998, Three-dimensional simulations of plume-lithosphere interaction at the Hawaiian swell. Science, 279, 1008-1011.</p><p>Stern, R.J., and Dumitru, T.A., 2019, Eocene initiation of the Cascadia subduction zone: A second example of plume-induced subduction initiation? Geosphere, v. 15, 659-681.</p><p>Whattam, S.A. and Stern, R.J., 2014. Late Cretaceous plume-induced subduction initiation along the southern margin of the Caribbean and NW South America: The first documented example with implications for the onset of plate tectonics. Gondwana Research, 27, doi: 10.1016/j.gr.2014.07.011.</p>

Oceanic crust generation in an island arc tectonic setting, SE Anatolian orogenic belt (Turkey)

2004 ◽  
Vol 141 (5) ◽  
pp. 583-603 ◽  
Author(s):  
OSMAN PARLAK ◽  
VOLKER HÖCK ◽  
HÜSEYİN KOZLU ◽  
MICHEL DELALOYE
Keyword(s):  
Late Cretaceous ◽  
Subduction Zones ◽  
Wide Spectrum ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Orogenic Belt ◽  
Mature Stage ◽  
Magmatic Arc ◽  
The North ◽  
Suprasubduction Zone

A number of Late Cretaceous ophiolitic bodies are located between the metamorphic massifs of the southeast Anatolian orogenic system. One of them, the Göksun ophiolite (northern Kahramanmaraş), which crops out in a tectonic window bounded by the Malatya metamorphic units on both the north and south, is located in the EW-trending nappe zone of the southeast Anatolian orogenic belt between Göksun and Afşin (northern Kahramanmaraş). It consists of ultramafic–mafic cumulates, isotropic gabbro, a sheeted dyke complex, plagiogranite, volcanic rocks and associated volcanosedimentary units. The ophiolitic rocks and the tectonically overlying Malatya–Keban metamorphic units were intruded by syn-collisional granitoids (∼ 85 Ma). The volcanic units are characterized by a wide spectrum of rocks ranging in composition from basalt to rhyolite. The sheeted dykes consist of diabase and microdiorite, whereas the isotropic gabbros consist of gabbro, diorite and quartzdiorite. The magmatic rocks in the Göksun ophiolite are part of a co-magmatic differentiated series of subalkaline tholeiites. Selective enrichment of some LIL elements (Rb, Ba, K, Sr and Th) and depletion of the HFS elements (Nb, Ta, Ti, Zr) relative to N-MORB are the main features of the upper crustal rocks. The presence of negative anomalies for Ta, Nb, Ti, the ratios of selected trace elements (Nb/Th, Th/Yb, Ta/Yb) and normalized REE patterns all are indicative of a subduction-related environment. All the geochemical evidence both from the volcanic rocks and the deeper levels (sheeted dykes and isotropic gabbro) show that the Göksun ophiolite formed during the mature stage of a suprasubduction zone (SSZ) tectonic setting in the southern branch of the Neotethyan ocean between the Malatya–Keban platform to the north and the Arabian platform to the south during Late Cretaceous times. Geological, geochronological and petrological data on the Göksun ophiolite and the Baskil magmatic arc suggest that there were two subduction zones, the first one dipping beneath the Malatya–Keban platform, generating the Baskil magmatic arc and the second one further south within the ocean basin, generating the Göksun ophiolite in a suprasubduction zone environment.

scholarly journals Kinematics of Late Cretaceous subduction initiation in the Neo-Tethys Ocean reconstructed from ophiolites of Turkey, Cyprus, and Syria

2017 ◽  
Vol 122 (5) ◽  
pp. 3953-3976 ◽  
Author(s):  
Marco Maffione ◽  
Douwe J. J. van Hinsbergen ◽  
Giovanni I. N. O. de Gelder ◽  
Freek C. van der Goes ◽  
Antony Morris
Keyword(s):  
Late Cretaceous ◽  
Subduction Initiation ◽  
Tethys Ocean ◽  
Cretaceous Subduction
Sign in / Sign up

Export Citation Format

Share Document