Temporal, geochemical and geodynamic evolution of the Late Cretaceous subduction zone volcanism in the eastern Sakarya Zone, NE Turkey: Implications for mantle-crust interaction in an arc setting

AbstractThe Kızıldağ (Hatay) ophiolite in Turkey represents remnants of the southern Neotethyan ocean and is characterized by a complete ocean lithospheric section. It formed in a fore-arc setting above a N-dipping intraoceanic subduction zone, and represents the undeformed, more northerly part of the same thrust sheet that also forms the Baer–Bassit ophiolite to the south. The ophiolite was emplaced southwards from the southerly Neotethyan ocean in Maastrichtian time. U–Pb and Sm–Nd dates are used to constrain the crystallization age and duration of magmatic activity of the Kızıldağ ophiolite. U–Pb dating yielded ages of 91.7 ± 1.9 Ma for a plagiogranite and 91.6 ± 3.8 Ma for a cumulate gabbro. The cumulate gabbro also yielded a Sm–Nd isochron age of 95.3 ± 6.9 Ma. The measured ages suggest that the oceanic crust of the Kızıldağ ophiolite formed in a maximum time period of 6 Ma, and that the plagiogranite may have formed later than the gabbroic section. The U–Pb zircon ages from the Kızıldağ ophiolite and the cooling age of a metamorphic sole beneath the Baer–Bassit ophiolite are indistinguishable within the analytical uncertainties. This indicates the presence of young and hot oceanic lithosphere at the time of intraoceanic subduction/thrusting in the southern Neotethys. The U–Pb zircon ages from the Kızıldağ, the Troodos and the Semail ophiolites overlap within analytical uncertainties, suggesting that these ophiolites are contemporaneous and genetically and tectonically related within the same Late Cretaceous southern Neotethyan ocean.

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Mesozoic Tectonic Setting of SE Sundaland After Magmatism and Suture Evidences in JS-1 Ridge Area

10.29118/ipa21-g-14 ◽

2021 ◽

Keyword(s):

Early Cretaceous ◽

Late Cretaceous ◽

Tectonic Setting ◽

Plate Boundary ◽

Early Jurassic ◽

The South ◽

Magmatic Arc ◽

Plate Convergence ◽

Ridge Area ◽

Cretaceous Subduction

Mesozoic plate convergence in SE Sundaland has been a source of debate for decades. A determination of plate convergence boundaries and timing have been explained in many publications, but not all boundaries were associated with magmatism. Through integration of both plate configurations and magmatic deposits, the basement can be accurately characterized over time and areal extents. This paper will discuss Cretaceous subductions and magmatic arc trends in SE Sundaland area with additional evidence found in JS-1 Ridge. At least three subduction trends are captured during the Mesozoic in the study area: 1) Early Jurassic – Early Cretaceous trend of Meratus, 2) Early Cretaceous trend of Bantimala and 3) Late Cretaceous trend in the southernmost study area. The Early Jurassic – Early Cretaceous subduction occurred along the South and East boundary of Sundaland (SW Borneo terrane) and passes through the Meratus area. The Early Cretaceous subduction occurred along South and East boundary of Sundaland (SW Borneo and Paternoster terranes) and pass through the Bantimala area. The Late Cretaceous subduction occurred along South and East boundary of Sundaland (SW Borneo, Paternoster and SE Java – South Sulawesi terranes), but is slightly shifted to the South approaching the Oligocene – Recent subduction zone. Magmatic arc trends can also be generally grouped into three periods, with each period corresponds to the subduction processes at the time. The first magmatic arc (Early Jurassic – Early Cretaceous) is present in core of SW Borneo terrane and partly produces the Schwaner Magmatism. The second Cretaceous magmatic arc (Early Cretaceous) trend is present in the SW Borneo terrane but is slightly shifted southeastward It is responsible for magmatism in North Java offshore, northern JS-1 Ridge and Meratus areas. The third magmatic arc trend is formed by Late Cretaceous volcanic rocks in Luk Ulo, the southern JS-1 Ridge and the eastern Makassar Strait areas. These all occur during the same time within the Cretaceous magmatic arc. Though a mélange rock sample has not been found in JS-1 Ridge area, there is evidence of an accretionary prism in the area as evidenced by the geometry observed on a new 3D seismic dataset. Based on the structural trend of Meratus (NNE-SSW) coupled with the regional plate boundary understanding, this suggests that both Meratus & JS-1 Ridge are part of the same suture zone between SW Borneo and Paternoster terranes. The gradual age transition observed in the JS-1 Ridge area suggests a southward shift of the magmatic arc during Early Cretaceous to Late Cretaceous times.

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The Late Cenozoic geodynamic evolution of the central segment of the Andean subduction zone

Geotectonics ◽

10.1134/s0016852109040050 ◽

2009 ◽

Vol 43 (4) ◽

pp. 305-323 ◽

Cited By ~ 3

Author(s):

T. V. Romanyuk

Keyword(s):

Subduction Zone ◽

Late Cenozoic ◽

Geodynamic Evolution ◽

Central Segment ◽

Andean Subduction

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Subduction-related magmatic imprint of most Philippine ophiolites: implications on the early geodynamic evolution of the Philippine archipelago

BSGF - Earth Sciences Bulletin ◽

10.2113/175.5.443 ◽

2004 ◽

Vol 175 (5) ◽

pp. 443-460 ◽

Cited By ~ 53

Author(s):

Rodolfo A. Tamayo* ◽

René C. Maury* ◽

Graciano P. Yumul ◽

Mireille Polvé ◽

Joseph Cotten ◽

...

Keyword(s):

Partial Melting ◽

Subduction Zone ◽

Volcanic Rocks ◽

The Philippines ◽

Island Arc ◽

Island Arcs ◽

Geodynamic Evolution ◽

Wide Range ◽

Opening And Closing ◽

Back Arc

Abstract The basement complexes of the Philippine archipelago include at least 20 ophiolites and ophiolitic complexes. These complexes are characterised by volcanic sequences displaying geochemical compositions similar to those observed in MORB, transitional MORB-island arc tholeiites and arc volcanic rocks originating from modern Pacific-type oceans, back-arc basins and island arcs. Ocean island basalt-like rocks are rarely encountered in the volcanic sequences. The gabbros from the ophiolites contain clinopyroxenes and plagioclases showing a wide range of XMg and An values, respectively. Some of these gabbros exhibit mineral chemistries suggesting their derivation from basaltic liquids formed from mantle sources that underwent either high degrees of partial melting or several partial melting episodes. Moreover, some of the gabbros display a crystallization sequence where orthopyroxene and clinopyroxene appeared before plagioclase. The major element compositions of coexisting orthopyroxenes and olivines from the mantle peridotites are consistent with low to high degrees of partial melting. Accessory spinels in these peridotites display a wide range of XCr values as well with some of them above the empirical upper limit of 0.6 often observed in most modern mid-oceanic ridge (MOR) mantle rocks. Co-existing olivines and spinels from the peridotites also exhibit compositions suggesting that they lastly equilibrated under oxidizing mantle conditions. The juxtaposition of volcanic rocks showing affinities with modern MOR and island arc environments suggests that most of the volcanic sequences in Philippine ophiolites formed in subduction-related geodynamic settings. Similarly, their associated gabbros and peridotites display mineralogical characteristics and mineral chemistries consistent with their derivation from modern supra-subduction zone-like environments. Alternatively, these rocks could have, in part, evolved in a supra-subduction zone even though they originated from a MOR-like setting. A simplified scenario regarding the early geodynamic evolution of the Philippines is proposed on the basis of the geochemical signatures of the ophiolites, their ages of formation and the ages and origins of the oceanic basins actually bounding the archipelago, including basins presumed to be now totally consumed. This scenario envisages the early development of the archipelago to be largely dominated by the opening and closing of oceanic basins. Fragments of these basins provided the substratum on top of which the Cretaceous to Recent volcanic arcs of the Philippines were emplaced.

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The Late Cretaceous Asteroussia event as recorded in the Cyclades: a potential key to Western Tethys tectonic evolution

10.5194/egusphere-egu21-3890 ◽

2021 ◽

Author(s):

Sonia Yeung ◽

Marnie Forster ◽

Emmanuel Skourtsos ◽

Gordon Lister

Keyword(s):

Subduction Zone ◽

Late Cretaceous ◽

Ore Deposits ◽

Western Tethys ◽

Pressure Medium ◽

Flat Slab Subduction ◽

Extreme Extension ◽

Metamorphic Core ◽

Tectonic Slice ◽

Ar Geochronology

<div> <p>The Cretaceous arc system formed during closure of West Tethys closure has long been a research focus for crustal geometry and associated ore deposits. Understanding the Africa-Europe motion across time is the key to its resolution. Evidence as to the time that Tethys subduction initiated is preserved in subduction accreted tectonic slices such as in the Gondwanan basement terranes&#160;on&#160;Ios, Cyclades, Greece.&#160;<sup>40</sup>Ar/<sup>39</sup>Ar geochronology in its granitoid basement and the structurally overlying garnet-mica schist&#160;tectonic slice identified a Late Cretaceous&#160;high pressure, medium&#160;temperature (HP&#8211;MP) metamorphic event. The timing and metamorphic conditions are comparable with geochronology and metamorphic conditions reported from other Cycladic islands. We suggest the northward extension of the Asteroussia crystalline terrane on Crete should therefore include the Ios basement tectonic slices, thus revising the regional geometry of the terrane stack. The northern part of the Hellenic terrane stack is overlain by individual Cycladic Eclogite-Blueschist terrane slices (e.g., on Ios) and the southern part is underplated by the tectonic units of the external&#160;Hellenides (Crete). To make such an architecture possible, we propose a 250-300 km southward jump of the subduction megathrust when the Ios basement terranes were accreted to the European terrane stack. Such a significant leap of the subduction megathrust supports a tectonic mode switch in which crust above the subduction zone was first subjected to shortening followed by a stretching event.&#160; Accretion of the Asteroussia slices to the terrane stack likely commenced at or about ~38 Ma. During accretion, the already stretched and exhumed terranes&#160;of the Cycladic Eclogite-Blueschist&#160;Unit&#160;begun&#160;to thrust over the newly accreted Ios basement. The subduction jump had likely been accomplished by ~35&#160;Ma, with rollback recommencing after a period of flat slab subduction followed by slab break off in the new subduction zone. This would allow explanation of the extreme extension that exhumed the&#160;Ios basement terrane, with the Asteroussia slices defining the core of the Ios metamorphic core complex, followed by the onset of&#160;Oligo-Miocene&#160;extension and accompanying magmatism in the Cyclades.</p> </div>

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The Ganj Complex reinterpreted as a Late Cretaceous volcanic arc: Implications for the geodynamic evolution of the North Makran domain (southeast Iran)

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2020.104306 ◽

2020 ◽

Vol 195 ◽

pp. 104306 ◽

Cited By ~ 1

Author(s):

Edoardo Barbero ◽

Morteza Delavari ◽

Asghar Dolati ◽

Emilio Saccani ◽

Michele Marroni ◽

...

Keyword(s):

Late Cretaceous ◽

Geodynamic Evolution ◽

Volcanic Arc ◽

The North

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Distinguishing the Mélange-Forming Processes in Subduction-Accretion Complexes: Constraints from the Anisotropy of Magnetic Susceptibility (AMS)

Geosciences ◽

10.3390/geosciences9090381 ◽

2019 ◽

Vol 9 (9) ◽

pp. 381 ◽

Cited By ~ 2

Author(s):

Claudio Robustelli Test ◽

Andrea Festa ◽

Elena Zanella ◽

Giulia Codegone ◽

Emanuele Scaramuzzo

Keyword(s):

Magnetic Susceptibility ◽

Late Cretaceous ◽

Anisotropy Of Magnetic Susceptibility ◽

Magnetic Fabric ◽

Early Eocene ◽

Accretionary Complex ◽

Geodynamic Evolution ◽

Structural Investigations ◽

Laboratory Investigations ◽

Magnetic Features

The strong morphological similitude of the block-in-matrix fabric of chaotic rock units (mélanges and broken formations) makes problematic the recognition of their primary forming-processes. We present results of the comparison between magnetic fabric and mesoscale structural investigations of non-metamorphic tectonic, sedimentary, and polygenetic mélanges in the exhumed Late Cretaceous to early Eocene Ligurian accretionary complex and overlying wedge-top basin succession in the Northern Apennines (northwest Italy). Our findings show that the magnetic fabric reveals diagnostic configurations of principal anisotropy of magnetic susceptibility (AMS) axes orientation that are well comparable with the mesoscale block-in-matrix fabric of mélanges formed by different processes. Broken formations and tectonic mélanges show prolate and neutral-to-oblate ellipsoids, respectively, with magnetic fabric elements being consistent with those of the mesoscale anisotropic “structurally ordered” block-in-matrix fabric. Sedimentary mélanges show an oblate ellipsoid with a clear sedimentary magnetic fabric related to downslope gravitational emplacement. Polygenetic mélanges show the occurrence of a cumulative depositional and tectonic magnetic fabric. The comparison of field and laboratory investigations validate the analysis of magnetic features as a diagnostic tool suitable to analytically distinguish the contribution of different mélange forming-processes and their mutual superposition, and to better understand the geodynamic evolution of subduction-accretion complexes.

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