Geochemistry and geochronology of the Neoproterozoic Pan-African Transcaucasian Massif (Republic of Georgia) and implications for island arc evolution of the late Precambrian Arabian–Nubian Shield

Zakariadze, G. S.; Dilek, Yıldırım; Adamia, Shota; Oberhänsli, Roland; Karpenko, S. F.; Bazylev, B. A.; Solov'eva, N. V.

doi:10.1016/j.gr.2006.05.012

Cited by 65 publications

(34 citation statements)

References 44 publications

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“…More detailed analysis of regional deformations shows that about 60 % of this rate is taken by the Lesser Caucasian suture, and the rest is accommodated in crustal shortening in the Southern Caucasus (Allen et al, 2004;Forte et al, 2010). Pre-Cenozoic evolution of this area was connected with the closing of the Tethys Ocean between Eurasian and Gondwana continental parts (e.g., Khain 1975;Adamia, 1975;Adamia et al, 2008;Zakariadze et al, 2007). Convergence of the ocean with continents during the Late ProterozoicEarly Cenozoic pre-collisional stage resulted at accretion of island arcs, intra-arc rifts and back-arc basins etc.…”

Section: Geodynamics and Volcanism Of Caucasus And Surrounding Areasmentioning

confidence: 99%

Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography

et al. 2012

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Abstract. In the paper, we discuss the problem of continental collision and related volcanism in the Caucasus and surrounding areas based on the analysis of the upper mantle seismic structure in a recently derived model by Koulakov (2011). This model, which includes P and Svelocity anomalies down to 1000 km depth, was obtained from tomographic inversion of worldwide travel time data from the catalogue of the International Seismological Center. It can be seen that the Caucasus region is squeezed between two continental plates, Arabian to the south and European to the north, which are displayed in the tomographic model as high-velocity bodies down to about 200-250 km depth. On the contrary, a very bright low-velocity anomaly beneath the collision area implies that the lithosphere in this zone is very thin, which is also supported by strong horizontal deformations and crustal thickening indicating weak properties of the lithosphere. In the contact between stable continental and collision zones, we observe a rather complex alternation of seismic anomalies having the shapes of sinking drops. We propose that the convergence process causes crustal thickening and transformation of the lower crust material into the dense eclogite. When achieving a critical mass, the dense eclogitic drops trigger detachment of the mantle lithosphere and its delamination. The observed high-velocity bodies in the upper mantle may indicate the parts of the descending mantle lithosphere which were detached from the edges of the continental lithosphere plates. Very thin, or even absent, mantle parts of the lithosphere leads to the presence of hot asthenosphere just below the crust. The crustal shortening and eclogitisation of the lower crustal layer leads to the dominantly felsic composition of the crust which is favourable for the upward heat transport from the mantle. This, and also the factors of frictional heating and the radioactivity of felsic rocks, may be the origin of volcanic centres in the Caucasus and surrounding collisional areas.

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Section: Geodynamics and Volcanism Of Caucasus And Surrounding Areasmentioning

confidence: 99%

Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography

et al. 2012

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“…There is no direct evidence of Neoproterozoic juvenile crust farther north, although it is generally assumed that such crust extends to the northern limit of the Arabian Plate in southern Turkey. Neoproterozoic crust of Gondwanan origin crops out as structural enclaves, or peri-Gondwana domains, in the Eurasian Plate -in the Alpine Belt of southern Europe, the Balkans, Turkey, Georgia, and interior Iran (e.g., [91]). The exact details of the history of these domains is not fully known and many questions and problems remain (see reviews [92,93]).…”

Section: Margins Of the Ansmentioning

confidence: 99%

An Expanding Arabian-Nubian Shield Geochronologic and Isotopic Dataset: Defining Limits and Confirming the Tectonic Setting of a Neoproterozoic Accretionary Orogen

Johnson¹

2014

TOGEOJ

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Geologic investigations of the Arabian-Nubian Shield (ANS) are supported by a valuable, expanding dataset of geochronologic ages and isotopic analyses. U-Pb zircon SIMS, TIMS, and evaporation data provide robust temporal control on depositional, volcanic, and intrusive events. Nd, Sr, O and, increasingly, Hf isotopic studies provide insights into magma sources and constraints on crustal recycling. Apart from well-established exceptions where Paleoproterozoic and Archean rocks intercalated in the ANS underwent Neoproterozoic reworking, the data elegantly confirm the Neoproterozoic age and juvenile character of the bulk of the ANS. The geochronologic and isotopic data reveal that some ANS sedimentary, volcanic, and igneous rocks contain pre-Neoproterozoic material as xenocrysts and possible glaciogenic clasts, but give no evidence that the ANS is otherwise underlain by any extensive tracts of older crust. Together with structural mapping, the expanding dataset confirms ANS boundaries where long-inferred in the west and suggests the placement of hitherto uncertain boundaries elsewhere. The suggested boundaries imply that the ANS is of a somewhat smaller size than considered in published discussions, which in turn impacts assessment of Neoproterozoic crustal growth rate. The Arabian-Nubian Shield (ANS) is an accretionary orogen at the northern end (present-day coordinates) of the East African Orogen. It is one of the largest expanses of mantle-derived, juvenile Neoproterozoic crust on Earth, underlying an area of ~2.7 x 10 6 km 2 . Its western boundary is a contact with pre-Neoproterozoic crust belonging to the Saharan Metacraton and Congo-Tanzania Craton. Farther south, the ANS is in contact with the Congo-Tanzania Craton and Mozambique Belt. A southeastern ANS margin is recognized as a contact with pre-Neoproterozoic gneiss belonging to a crustal block referred to as Azania. An eastern ANS margin, long a topic of debate, is suspected beneath Phanerozoic cover in central Arabia, and a northwestern margin with late Mesoproterozoic crust is suspected in Sinai.

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“…This fault, of NE-SW trend and with its sinistral movements, displaced NW Iran lithologies (Didon and Gemain 1976 The Allahyarlu-Kaleybar-Northern Iran Suture Zone, determined by Late Carboniferous to Triassic metamorphic and ophiolitic exposures, was the western continuation of a branch of the Paleotethys Basin in Iran (Alavi 1991b;Ruttner 1993;Alavi 1996;Ghazi et al 2001;Seyed-Emami 2003;Zanchi et al 2006;Ghavidel-Syooki 2008;Zanchetta et al 2009;Omrani and Moazzen 2010;Sheikholeslami and Kouhpeyma 2012;Shafaii Moghadam et al in press). It is likely that the Allahyarlu ophiolite complex was displaced to higher latitudes by the dextral Talysh Fault (Eftekharnejad 1975;Didon and Gemain 1976;Kazmin and Tikhonova 2006;Zakariadze et al 2007; Sudi Ajirlu and Jahangiri 2010a).…”

Section: Geologic Backgroundmentioning

confidence: 99%

“…Concerning the western continuation of the Allahyarlu-Kaleybar Suture Zone, some researchers believe that it may be the Sevan-Akera Suture Zone (Eftekharnejad 1975;Babakhani and Nazer 1991;Zakariadze et al 2007) but because of dextral Talysh and sinistral Araks Fault activities, the Allahyarlu Suture Zone moved to higher latitudes (Didon and Gemain 1976;Sudi Ajirlu and Jahangiri 2010a). Since the Sevan-Akera Suture Zone is situated at higher latitudes than the Allahyarlu Suture Zone, the probability of its being the western continuation of the Allahyarlu Suture Zone is questionable.…”

Section: Geologic Backgroundmentioning

confidence: 99%

“…The main evidence to consider this zone as a block is the existence of mafic and ultramafic rocks and ophiolite mélanges along the Tabriz and Allahyarlu-Hovai Faults (Berberian et al 1981; Babakhani and Nazer 1991; Sudi Ajirlu and Jahangiri 2010a). (2) Folding along the Talysh and Allahyarlu-Hovai Faults indicates that northward and northeastward movements and compression are occurring along these faults (Didon and Gemain 1976;Lescuyer and Riou 1976;Zonenshain and Le Pichon 1986;Alavi 1996;Allen et al 2003Allen et al , 2005Masson et al 2006;Zakariadze et al 2007;Galoyan et al 2009 Based on slider movements of the Azerbaijan Block (Didon and Gemain 1976;Lescuyer and Riou 1976;Zonenshain and Le Pichon 1986;Masson et al 2006) and considering that the Ahar Block is part of the Azerbaijan Block Golonka 2004;Masson et al 2006), the Allahyarlu ophiolite marking the suture can be considered as the western continuation of the northern Iran ophiolitic and metamorphic belt.…”

Section: The Ahar Blockmentioning

confidence: 99%

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Role of the Allahyarlu ophiolite in the tectonic evolution of NW Iran and adjacent areas (Late Carboniferous — Recent)

Ajirlu¹,

Moazzen²

2014

Central European Geology

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Geochemistry and geochronology of the Neoproterozoic Pan-African Transcaucasian Massif (Republic of Georgia) and implications for island arc evolution of the late Precambrian Arabian–Nubian Shield

Cited by 65 publications

References 44 publications

Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography

Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography

An Expanding Arabian-Nubian Shield Geochronologic and Isotopic Dataset: Defining Limits and Confirming the Tectonic Setting of a Neoproterozoic Accretionary Orogen

Role of the Allahyarlu ophiolite in the tectonic evolution of NW Iran and adjacent areas (Late Carboniferous — Recent)

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