Mesozoic–Cenozoic mafic magmatism in Sanandaj–Sirjan Zone, Zagros Orogen (Western Iran): Geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros

Deevsalar, Reza; Shinjo, Ryuichi; Ghaderi, Majid; Murata, Mamoru; Hoskin, Paul W. O.; Oshiro, Shoma; Wang, Kuo‐Lung; Lee, Hao Yang; Neill, Iain

doi:10.1016/j.lithos.2017.05.009

Cited by 48 publications

(27 citation statements)

References 115 publications

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“…The Nodoushan alkaline gabbroic rocks are enriched in incompatible elements typical of plume‐related magmas, that is, LREE, Ti, and Nb, resulting in LREE‐enriched patterns of rare‐earth elements and Nb positive anomalies in the multi‐element diagrams (Figure ), which are similar to those of continental hot spots. HFSE, LILE, and LREE enrichments of the samples are in agreement with the involvement of a mantle plume in their genesis (Saha et al, ; Simonov, Mikolaichuk, Safonova, Kotlyarov, & Kovyazin, ), and OIB‐like trace element characteristics such as enriched HFSE, LILE, and LREE reflect a within‐plate character and asthenospheric source (Deevsalar et al, ). Their high Nb/La and La/Yb ratios are also consistent with those of OIB‐like asthenospheric mantle (approximately >1) rather than lithospheric mantle melts (approximately <0.5; Bradshaw & Smith, ; Smith, Sánchez, Walker, & Wang, ; Figure c).…”

Section: Discussionsupporting

confidence: 70%

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

et al. 2018

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The Zagros Orogen formed during the Cenozoic collision of Arabia with Eurasia and resulted in the closure of the Neo‐Tethys Ocean. Collision was preceded by a complicated tectonic history involving Pan‐African orogenesis, Late Palaeozoic rifting and the formation of Neo‐Tethys, and subsequent Mesozoic convergence on the northern margin of the ocean contemporaneous with ophiolite obduction on its southern margin. The Sanandaj–Sirjan Zone (SaSZ) is a metamorphic belt within the Zagros Orogen of Gondwanan provenance. U–Pb zircon geochronology has revealed the presence of Pan‐African igneous and metamorphic basement complexes, in addition to minor late Palaeozoic plutons and abundant Jurassic plutonic rocks. This study presents a LA‐ICP‐MS U–Pb apatite age of 440.7 ± 3.7 Ma from a gabbroic body on the central north‐eastern margin of the SaSZ (Nodoushan region). Based on petrography and geochemistry, en route fractional crystallization of ascending magma was an important process in the evolution of the intrusive rocks. Geochemical characteristics imply that the south‐west Nodoushan alkaline gabbroic magma was originated from the asthenospheric mantle source, whereas the high ratios of (La/Yb)N and (Dy/Yb)N are related to the low degree of partial melting from the garnet‐bearing mantle source. Enrichment pattern of Nb, Ta, and Ti and depletion of Rb, Th, and Y are similar to the OIB pattern and intraplate alkaline magmatic rocks. High εNd(t) values (+1.29 to +1.50), low initial Sr isotopic ratios (0.703679–0.704098), and trace element ratios (e.g., Nb/La, Ce/Pb, Ba/Nb, and Th/Nb) indicate that crustal contamination was insignificant in its petrogenesis. The petrogenesis of the Nodoushan alkaline gabbroic rocks could be related to the presence of extensional phase, upwelling and decompressional melting of asthenospheric mantle in the rift basin which was associated with the opening of the Paleo‐Tethys Ocean in Late Ordovician to Silurian times.

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Section: Discussionsupporting

confidence: 70%

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

et al. 2018

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“…C‐SaSZ Jurassic intrusions include more than 20 big (>8 km across) plutons and many smaller ones (Figure b). Most granites have been dated by zircon U–Pb methods as listed in Table DR1 (Ahadnejad, Valizadeh, Deevsalar, & Rezaei‐Kahkhaei, ; Azizi, Asahara, Mehrabi, & Chung, ; Azizi, Hadi, Asahara, & Mohammad, ; Azizi, Najari, et al, ; Bayati, Esmaeily, Maghdour‐Mashhour, Li, & Stern, ; Chiu et al, ; Deevsalar et al, ; Esna‐Ashari et al, ; Fazlnia et al, , ; Hunziker et al, ; Khalaji et al, ; Mahmoudi, Corfu, Masoudi, Mehrabi, & Mohajjel, ; Mousivand et al, ; Shahbazi et al, ; Shakerardakani et al, ; Yajam et al, ; Zhang et al, ). The oldest is the 177 Ma Kolah Ghazi intrusion (Bayati et al, ) and the youngest are 144 Ma granites near Sanandaj (Azizi et al, ; Yajam et al, ; Zhang et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…We compiled all chemical data for C‐SaSZ intrusions published in international journals over the past few years (Azizi & Asahara, ; Azizi et al, ; Azizi, Najari, et al, ; Deevsalar et al, ; Esna‐Ashari et al, ; Khalaji et al, ; Maanijou et al, ; Mahmoudi et al, ; Shahbazi et al, ); these data are summarized in Table DR2. We do not use Ta because several of these studies pulverized in tungsten carbide.…”

Section: Resultsmentioning

confidence: 99%

“…Initial 87 Sr/ 86 Sr and 143 Nd/ 144 Nd for C‐SaSZ intrusions (Table DR2; Azizi & Asahara, ; Azizi et al, ; Azizi, Najari, et al, ; Deevsalar et al, ; Esna‐Ashari et al, ; Khalaji et al, ; Shahbazi et al, ) range widely. Mafic rocks mostly show positive ε Nd (t) and low 87 Sr/ 86 Sr (i) and plot in the depleted mantle field (Figure a).…”

Section: Resultsmentioning

confidence: 99%

“…Most studies of Jurassic SaSZ igneous rocks consider that these formed at a convergent plate margin (Berberian & Berberian, ; Deevsalar et al, ; Esna‐Ashari, Tiepolo, Valizadeh, Hassanzadeh, & Sepahi, ; Khalaji, Esmaeily, Valizadeh, & Rahimpour‐Bonab, ; Maanijou, Aliani, Miri, & Lentz, ; Sepahi, Salami, Lentz, McFarlane, & Maanijou, ; Shahbazi et al, ). Recent works have increasingly questioned this interpretation (Azizi, Lucci, Stern, Hasannejad, & Asahara, ; Hunziker, Burg, Bouilhol, & Quadt, ; Zhang, Chen, Yang, Hou, & Aghazadeh, ).…”

Section: Introductionmentioning

confidence: 99%

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Jurassic igneous rocks of the central Sanandaj–Sirjan zone (Iran) mark a propagating continental rift, not a magmatic arc

Azizi

Stern

2019

Terra Nova

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Jurassic igneous bodies of the Sanandaj-Sirjan zone (SaSZ) in SW Iran are generally considered as a magmatic arc but critical evaluation of modern geochronology, geochemistry and radiogenic isotopes challenges this conclusion. There is no evidence for sustained igneous activity along the ~1,200 km long SaSZ, as expected for a convergent plate margin; instead activity was brief at most sites and propagated NW at ~20 mm/a. Jurassic igneous rocks define a bimodal suite of gabbro-diorite and granite. Chemical and isotopic compositions of mafic rocks indicate subcontinental lithospheric mantle sources that mostly lacked subduction-related modifications. The arc-like features of S-type granites reflect massive involvement of Cadomian crust and younger sediments to generate felsic melts in response to mafic intrusions. We conclude that Jurassic SaSZ igneous activity occurred in a continental rift, not an arc. SaSZ igneous rocks do not indicate that subduction along the SW margin of Eurasia began in Jurassic time. NW SE 130 J s J s Legend Jurassic metavolcanic Jurassic hornfels Jurassic granitoids Jurassic unmetamorphosed rocks S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Azizi H, Stern RJ. Jurassic igneous rocks of the central Sanandaj-Sirjan zone (Iran) mark a propagating continental rift, not a magmatic arc. Terra Nova.

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Zircon U–Pb and titanite U–Th–Pb ages of the Ghorveh mixed granitoid pluton: Implications for the Late Jurassic supra‐subduction extension of the Sanandaj–Sirjan Zone, Iran

et al. 2022

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The Ghorveh batholith, located in the central part of the Sanandaj–Sirjan Zone (SSZ), Iran, preserves several sequences of Mesozoic plutonic and volcanic rocks. This study presents systematic analyses of the calc‐alkaline granites and monzodiorites from the southern part of the Ghorveh pluton. The granites are metaluminous to slightly peraluminous with A/CNK ratios of 0.97–1.02, indicating an A‐type granitic affinity. High Rb, Th, and K and low Sr, P, and Ti concentrations indicate an involvement of crustal materials. Whole‐rock negative εNd(t) values and relatively high TDM1 model ages support a continental crustal source. Thus, the granites are of fractionated A‐type in composition produced by partial melting of crustal materials. The monzodiorites have incompatible trace element patterns with enrichment in light rare earth elements (LREEs) and large‐ion lithophile elements (LILEs) relative to heavy rare earth elements and high‐field strength elements. This combined with the high Mg# values and the positive εNd and εHf(t) values, indicate a mantle‐derived origin. Dating results show that the granites and monzodiorites have uniform crystallization ages of ~150 Ma. Previous results and our new data suggest that the Jurassic subduction of Neo‐Tethyan Oceanic crust under the Eurasian continent was followed by slab rollback that induced back‐arc extension. Heat transfer from arc magmas increased the degree of decompressional melting in the thinned lithosphere. Melting of the presumably homogeneous crust was concurrent with emplacement of the intermediate composition magmas. Consequently, we propose that the Ghorveh area of the central SSZ developed in a supra‐subduction extensional phase during the Late Jurassic.

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Mesozoic–Cenozoic mafic magmatism in Sanandaj–Sirjan Zone, Zagros Orogen (Western Iran): Geochemical and isotopic inferences from Middle Jurassic and Late Eocene gabbros

Cited by 48 publications

References 115 publications

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

Jurassic igneous rocks of the central Sanandaj–Sirjan zone (Iran) mark a propagating continental rift, not a magmatic arc

Zircon U–Pb and titanite U–Th–Pb ages of the Ghorveh mixed granitoid pluton: Implications for the Late Jurassic supra‐subduction extension of the Sanandaj–Sirjan Zone, Iran

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