Tracking the birth and growth of Cimmeria: Geochronology and origins of intrusive rocks from NW Iran
Graphical abstract
Introduction
The geochronological evolution, paleo-positions and mechanisms involved in the growth and reworking of the Phanerozoic supercontinents and adjoining continental blocks have been a matter of debate for many years. The Middle East consists of a complex mosaic of several continental blocks that were located between the Gondwana and Eurasia supercontinents to the S-SW and N-NE, respectively (Ruban et al., 2007). These continental blocks make up the core of the present-day crust of Caucasus (Armenia, Azerbaijan, Georgia and southwest Russia), Turkey, Iran, Afghanistan and the Tibetan plateau. They are weakly to strongly deformed and stacked within a wide tectonic belt between the Eurasian, Arabian and Indian plates. They record several pulses of magmatism and both tectonic extension and shortening during the whole Phanerozoic. However, their basement rocks and sedimentary cover suggest that all of these terranes shared an analogous tectono-magmatic heritage during some time in the Late Neoproterozoic. The Middle East terranes were affected by the processes that were responsible for the opening of Paleotethys and Neotethys oceans and henceforth the evolution of the Hun (or Hunic) and Cimmerian terranes (e.g. Cocks and Torsvik, 2002; Stampfli, 1996; von Raumer, 1998; von Raumer et al., 2003; von Raumer et al., 2015; von Raumer et al., 2002) (Fig. 1). Two major Paleozoic rifting episodes have been suggested to have occurred along the margins of Gondwana within the present-day Middle East (Ruban et al., 2007; Stampfli et al., 1991; Stampfli, 2000). The first occurred during the Ordovician and led to the opening of Paleotethys and detachment of the Hun terranes from Gondwana and their migration toward Eurasia. The second episode occurred in Permian to Triassic time and caused the rifting and drifting of several Cimmerian terranes away from Gondwana.
The Cimmerian Orogeny, which is believed to have begun 250 Ma ago and continued for ~80 Myr (until ~170 Ma; Permian to Early Jurassic), reflected the detachment of Cimmeria from northern Gondwana, the opening of Neotethys, the closure of Paleotethys and the docking of Cimmeria to southern Eurasia (Golonka, 2004). The main continental blocks that were involved during this orogeny include the Tauride-Anatolia (Turkey), Persia (Iran), Lhasa-Qiangtang (Tibet) and Sibumasu (SE Asia) terranes (Fig. 1). The rifting-off of Cimmeria progressed from east to west and the continental blocks moved northward and sutured to Eurasia (Stampfli and Borel, 2002).
The Cimmerian blocks of Anatolia and Persia are suggested to be parts of a single contiguous orogenic plateau, consisting of a series of allochthonous Gondwanan continental terranes with 600–500 Ma-aged magmatic and meta-igneous basement rocks (Moghadam et al., 2017b; Moghadam et al., 2015a), although (Tauride-) Anatolia seems to have behaved differently, as a distinct continental block detached from Gondwana during the Early Triassic and accreted to Laurasia in the Late Cretaceous (Topuz et al., 2020; Topuz et al., 2013). This different time of detachment from Gondwana and accretion to Laurasia for Tauride-Anatolia suggest that Tauride-Anatolia might not be a part of the Cimmerian blocks (Topuz et al., 2013).
Geochronological and geochemical data from Anatolia and Persia indicate that Ediacaran-early Cambrian (Cadomian) crustal extension and an accompanying magmatic “flare-up” started at ~570 Ma and ended at ~525 Ma, lasting for more than 45 Myr (Moghadam et al., 2017c; Shafaii Moghadam et al., 2020). Cadomian rocks can be found in northwestern, northeastern and central Iran (Fig. 2A). Subsequent recurring Phanerozoic extension and thickening of the crust with significant addition of juvenile magmas led to further growth of Anatolia-Persian continental crust.
NW Iran is a particularly good region to examine the processes that created and modified the Cimmerian crust. This region exposes an abundance of Neoproterozoic-Phanerozoic sedimentary-magmatic rocks and suture-related rocks such as the Khoy ophiolite, reflecting multiple episodes of subduction from Ediacaran to Cenozoic time (Moghadam et al., 2017b). Several phases of magmatism as well as extension and shortening are recorded, importantly during the Late Paleozoic (Devonian-Carboniferous to Permian) and Jurassic-Cretaceous (Azizi et al., 2018; Azizi et al., 2016; Moghadam et al., 2015c). This is an excellent place for tracing Cimmerian magmatic evolution, as the granitoids range in age from Ediacaran through Devonian-Carboniferous and Permian to Jurassic. NW Iran is separated from Eurasia by the Jurassic Sevan-Akera suture of the Lesser Caucasus (Fig. 2A).
There are several important unresolved issues pertaining to the Cimmerian evolution of NW Iran; e.g., what are the precise ages of the granitoid plutonic rocks in NW Iran and their relations to the evolution of Cimmerian blocks? What can these tell us about the detachment of Cimmeria from Gondwanaland, its northward migration, and its collision with Eurasia during the Triassic time?
This study combines multiple approaches including U-Pb and O-Hf isotopes in zircon and whole-rock trace-element and isotopic geochemistry to identify and characterize the major magmatic events in NW Iran. We use these new results and compile published data on Cadomian, Devonian and Carboniferous rocks, to reconstruct the tectonic evolution of Cimmeria, especially the processes responsible for Cimmerian crustal genesis, break-up and accretion to southern Eurasia. The Neoproterozoic-Phanerozoic magmatic episodes in NW Iran have along-strike equivalents in Anatolia, which reflect orogen-scale geodynamic processes. Therefore, the magmatic history of Iran can be used to reconstruct the tectonic evolution of the Iranian-Anatolian orogeny from Neoproterozoic to present.
Section snippets
Geological setting and sample descriptions
NW Iran is a complex collage of Paleozoic-Mesozoic magmatic terranes, Ediacaran consolidated basement and fragments of oceanic crust that accumulated between Anatolia in the west, the Caucasus accreted terranes in the north and the central Iranian block to the east (Fig. 2A). In the north, the NW Iran terrane is separated from paleo-Eurasia (Scythian platform) by the Sevan-Akera suture zone, hosting the Amasia ophiolite (Lesser Caucasus, NW Armenia). This ophiolite includes gabbroic rocks with
Ediacaran-Early Cambrian magmatism
We have analyzed eight samples of suspected Cadomian metagabbros and granitic-gabbroic gneisses from near Salmas and Ghushchi (Fig. 2A). The conventional concordia diagrams for these Cadomian samples are shown in Fig. 4.
Zircons from granitic gneisses (samples SL14-1, SL14-18 and SL14-50) range in size from 50 to 150 μm and are mostly colourless, transparent and subhedral-euhedral prismatic to stubby crystals. Their CL images exhibit oscillatory and patchy zoning, indicating a magmatic origin.
Discussion
A dataset of Lu-Hf isotope values is used in this study to simulate the tectono-magmatic evolution of the intrusive pulses from NW Iran and to compare these results with the Late Neoproterozoic- Cenozoic magmatic events from the Persian Block.
Three major tectono-magmatic episodes, including crustal growth and reworking of the Persian Block, have been identified along NW Iran. These record the crustal evolution of Cimmeria, including: 1) Late Neoproterozoic growth and consolidation of the
Conclusions
New and compiled whole-rock geochemical, isotopic, and geochronological data from magmatic rocks help to identify and characterize the major magmatic events that have occurred in NW Iran over ~460 Myr, from late Neoproterozoic (~600 Ma) to Early Cretaceous (~140 Ma). These magmatic events are presented below from oldest to youngest with estimates of their principal age ranges and geochemical as well as zircon εHf values.
- 1-
The Ediacaran-Early Cambrian magmatism (600–500 Ma, with a peak in
CRediT authorship contribution statement
Hadi Shafaii Moghadam: Conceptualization, Formal analysis, Investigation, Writing - original draft. Qiu-li Li: Project administration, Data curation, Funding acquisition, Writing - review & editing. William L. Griffin: Data curation, Funding acquisition, Writing - review & editing. Orhan Karsli: Investigation, Writing - review & editing. Jose F. Santos: Data curation, Formal analysis, Writing - review & editing. C.J. Ottley: Data curation, Formal analysis, Writing - review & editing. Ghasem
Declaration of competing interest
The authors declare that they have no pecuniary or other personal interest, direct or indirect, in any matter that raises or may raise a conflict of interest.
Acknowledgments
This study was funded by the “National Key Research and Development Program of China (2016YFE0203000)” and by “Chinese Academy of Sciences, President's International Fellowship Initiative (PIFI, 2019VCB0013)”. Financial support was also received from the Alexander von Humboldt Foundation in the form of a senior research grant and GEOMAR Helmholtz Centre while preparing these results for publication. Zircon U-Pb and Lu-Hf isotopic data from Macquarie University were obtained using
References (140)
- et al.
Zircon U–Pb ages and geochemistry of Devonian A-type granites in the Iraqi Zagros Suture Zone (Damamna area): new evidence for magmatic activity related to the Hercynian orogeny
Lithos
(2016) - et al.
Geochemistry, petrogenesis, and tectonic setting of the Almogholagh batholith in the Sanandaj-Sirjan zone, western Iran
J. Afr. Earth Sci.
(2017) - et al.
Sveconorwegian crustal underplating in southwestern Fennoscandia: LAM-ICPMS U-Pb and Lu-Hf isotope evidence from granites and gneisses in Telemark, southern Norway
Lithos
(2007) - et al.
The last stages of the Avalonian-Cadomian arc in NW Iberian Massif: isotopic and igneous record for a long-lived peri-Gondwanan magmatic arc
Tectonophysics
(2016) - et al.
Geochronological and geochemical constraints on the petrogenesis of high-K granite from the Suffi abad area, Sanandaj-Sirjan Zone, NW Iran
Chem. Erde Geochem.
(2011) - et al.
Strongly peraluminous leucogranite (Ebrahim-Attar granite) as evidence for extensional tectonic regime in the Cretaceous, Sanandaj Sirjan zone, northwest Iran
Chem. Erde Geochem.
(2016) - et al.
A-type granitoid in Hasansalaran complex, northwestern Iran: evidence for extensional tectonic regime in northern Gondwana in the Late Paleozoic
J. Geodyn.
(2017) - et al.
The Late Jurassic Panjeh submarine volcano in the northern Sanandaj-Sirjan Zone, northwest Iran: mantle plume or active margin?
Lithos
(2018) - et al.
Avalonian and Cadomian terranes in North Dobrogea, Romania
Precambrian Res.
(2010) - et al.
Geochemistry and petrogenesis of Kolah-Ghazi granitoids of Iran: insights into the Jurassic Sanandaj-Sirjan magmatic arc
Chem. Erde Geochem.
(2017)
Zircon dating, Sr and Nd isotopes, and element geochemistry of the Khalifan pluton, NW Iran: evidence for Variscan magmatism in a supposedly Cimmerian superterrane
J. Asian Earth Sci.
The Cadomian active margin (North Armorican Massif, France): a segment of the North Atlantic Panafrican belt
Tectonophysics
A hafnium isotope and trace element perspective on melting of the depleted mantle
Earth Planet. Sci. Lett.
Structures and timing of Permian rifting in the central Oman Mountains (Saih Hatat)
Tectonophysics
Zircon Hf isotopic constraints on magmatic and tectonic evolution in Iran: implications for crustal growth in the Tethyan orogenic belt
J. Asian Earth Sci.
Young bimodal volcanism at Medicine Lake volcanic center, northern California
Geochim. Cosmochim. Acta
Mesozoic-Cenozoic mafic magmatism in Sanandaj-Sirjan Zone, Zagros Orogen (Western Iran): geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros
Lithos
Trace-element and isotopic effects of combined wallrock assimilation and fractional crystallization
Earth Planet. Sci. Lett.
Geochemistry and zircon U-Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran
J. Asian Earth Sci.
The Sanandaj-Sirjan Zone in the Neo-Tethyan suture, western Iran: zircon U-Pb evidence of late Palaeozoic rifting of northern Gondwana and mid-Jurassic orogenesis
Gondwana Res.
The augen gneisses of the Peloritani Mountains (NE Sicily): granitoid magma production during rapid evolution of the northern Gondwana margin at the end of the Precambrian
Gondwana Res.
Chemical composition of the continental crust as revealed by studies in East China
Geochim. Cosmochim. Acta
Processes of crust formation in the early Earth imaged through Hf isotopes from the East Pilbara Terrane
Precambrian Res.
The relations between Gondwana and the adjacent peripheral Cadomian domain—constrains on the origin, history, and paleogeography of the peripheral domain
Gondwana Research
Mesozoic radiolarians from the Kermanshah formation (Iran)
Compt. Rendus Palevol
Plate tectonic evolution of the southern margin of Eurasia in the Mesozoic and Cenozoic
Tectonophysics
The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites
Geochim. Cosmochim. Acta
Zircon chemistry and magma mixing, SE China: in-situ analysis of Hf isotopes, Tonglu and Pingtan igneous complexes
Lithos
A new petrogenetic model for meta-granitic rocks in the central and southern Menderes Massif - W Turkey: implications for Cadomian crustal evolution within the Pan-African mega-cycle
Precambrian Res.
Neoproterozoic continental arc volcanism at the northern edge of the Arabian Plate, SE Turkey
Precambrian Res.
New structural and petrological data on the Amasia ophiolites (NW Sevan-Akera suture zone, Lesser Caucasus): insights for a large-scale obduction in Armenia and NE Turkey
Tectonophysics
Zircon U-Pb-Hf isotopes, bulk-rock geochemistry and Sr-Nd-Pb isotopes from late Neoproterozoic basement in the Mahneshan area, NW Iran: implications for Ediacaran active continental margin along the northern Gondwana and constraints on the late Oligocene crustal anatexis
Gondwana Res.
Detrital zircon provenance of Neoproterozoic to Cenozoic deposits in Iran: implications for chronostratigraphy and collisional tectonics
Tectonophysics
The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U-Pb zircon geochronology
Chem. Geol.
Deciphering the shoshonitic monzonites with I-type characteristic, the Sisdaği pluton, NE Turkey: magmatic response to continental lithospheric thinning
J. Asian Earth Sci.
Latest Cretaceous “A(2)-type” granites in the Sakarya Zone, NE Turkey: partial melting of mafic lower crust in response to roll-back of Neo-Tethyan oceanic lithosphere
Lithos
Petrology and geochemistry of the granitoid complex of Boroujerd, Sanandaj-Sirjan Zone, Western Iran
J. Asian Earth Sci.
Two plates - many subduction zones: the Variscan orogeny reconsidered
Gondwana Res.
The Tethyan plume: geochemical diversity of Middle Permian basalts from the Oman rifted margin
Lithos
Petrogenesis and tectonic significance of the similar to 850 Ma Gangbian alkaline complex in South China: evidence from in situ zircon U-Pb dating, Hf-O isotopes and whole-rock geochemistry
Lithos
The Cadomian Orogeny and the opening of the Rheic Ocean: the diacrony of geotectonic processes constrained by LA-ICP-MS U-Pb zircon dating (Ossa-Morena and Saxo-Thuringian Zones, Iberian and Bohemian Massifs)
Tectonophysics
The Cadomian Orogen: Neoproterozoic to Early Cambrian crustal growth and orogenic zoning along the periphery of the West African Craton-Constraints from U-Pb zircon ages and Hf isotopes (Schwarzburg Antiform, Germany)
Precambrian Res.
U-Pb dating and emplacement history of granitoid plutons in the northern Sanandaj-Sirjan Zone, Iran
J. Asian Earth Sci.
Crustal growth along a non-collisional cratonic margin: a Lu-Hf isotopic survey of the Eastern Cordilleran granitoids of Peru
Earth Planet. Sci. Lett.
Ophiolites of Iran: keys to understanding the tectonic evolution of SW Asia: (II) Mesozoic ophiolites
J. Asian Earth Sci.
Devonian to Permian evolution of the Paleo-Tethys Ocean: new evidence from U–Pb zircon dating and Sr–Nd–Pb isotopes of the Darrehanjir–Mashhad “ophiolites”, NE Iran
Gondwana Res.
Petrogenesis and tectonic implications of Late Carboniferous A-type granites and gabbronorites in NW Iran: geochronological and geochemical constraints
Lithos
Neoproterozoic magmatic flare-up along the N. margin of Gondwana: the Taknar complex, NE Iran
Earth Planet. Sci. Lett.
Early Paleozoic tectonic reconstruction of Iran: tales from detrital zircon geochronology
Lithos
Evolution of the Rheic Ocean
Gondwana Res.
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