Geology, geochemistry and petrogenesis of post-collisional adakitic intrusions and related dikes in the Khoynarood area, NW Iran

Nia, Hossein Mahmoudi; Baghban, Saeid; Simmonds, Vartan

doi:10.1016/j.chemer.2017.02.001

Cited by 10 publications

(7 citation statements)

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“…Strong enrichments in large‐ion lithophile elements (LILE) are obvious, such as Rb, Ba, Th, and U and depletion in compatible HFSE, such as Nb, Ta, and Ti. According to Mahmoudi Nia, Baghban, and Simmonds (2017), high Sr content and the negative anomalies of Ti, Ta, and Nb shows a lack of plagioclase fractionation and occurrence of Fe and Ti oxides throughout partial melting and crystal fractionation. Richards, Spell, Rameh, Razique, and Fletcher (2012) thought that depleted MREE‐HREE strongly propose REE fractionation controlled by hornblende leading to low Y and Yb (HREE) concentrations decreasing with increasing SiO 2 .…”

Section: Whole‐rock Geochemical Resultsmentioning

confidence: 99%

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Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

et al. 2020

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Cenozoic adakitic rocks of the northern part of the Central Iran Structural Zone (CISZ) are among the notable geological features of the terrains in northeast Iran, so a comprehensive comparison of several of these adakitic sequences is presented. This lithogeochemical analysis is constrained to examining adakitic magmatism of the three magmatic belts within the CISZ, which from southeast to northeast and from oldest to youngest are as follows: (a) south of Shahrood‐Damghan, (b) north‐northwest of Sabzevar‐Neyshabour, and (c) south of Qouchan and west of Esfarayen. Radiogenic isotope analysis using Rb–Sr and Sm–Nd methods show that the adakitic rocks associated with Qouchan‐Esfarayen magmatism have 0.512581 to 0.51288 initial 143Nd/144Nd and 0.703903 to 0.705627 initial 87Sr/86Sr, with εNd −0.86 to 4.98. Adakitic rocks in south to southeast Shahrood have 0.512775 to 0.512893 initial 143Nd/144Nd and 0.703746 to 0.705314 initial 87Sr/88Sr, with εNd 3.69 to 6.0, and adakites emplaced into the Sabzevar ophiolite have 0.512846 to 0.512911 initial 143Nd/144Nd and 0.70379 to 0.705019 initial 87Sr/86Sr contents with εNd of 5.26 to 6.54. Isotopic initial ratios of Nd and Sr support an origin involving partial melting of the subducting oceanic lithosphere of the northern branch of Neo‐Tethys and the associated suprasubduction mantle wedge in producing these adakitic rocks.

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Section: Whole‐rock Geochemical Resultsmentioning

confidence: 99%

“…Kay (1978) thought that adakitic rocks were related to convergent plate margin arcs through melting of oceanic crust. Mahmoudi Nia et al (2017) pointed out that in NW Iran, there are some adakitic rocks that are related to subduction of Neo‐Tethyan oceanic lithosphere.…”

Section: Discussionmentioning

confidence: 99%

Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

et al. 2020

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“…Adakites form from partial melting of young oceanic crust in subduction zones (Defant and Drummond, 1990). They form from young and hot oceanic crust, retaining its F I G U R E 7 Plots of andesite host rocks of Sarcheshmeh PCD (Table 3) on Winchester and Floyd (1977) diagram Frost and Frost (2008) primary temperature, and are more readily melted (Defant and Drummond, 1990;Mahmoudi Nia et al, 2017). There are four types of adakites: (1) high silica adakites (HSA), (2) low silica adakites (LSA), (3) continental or potassic adakites, and (4) Archean adakites (Percival et al, 2003).…”

Section: The Origin Of Adakitic Volcanismmentioning

confidence: 99%

Petrology and geochemistry of adakitic intrusions and dykes at Sarcheshmeh porphyry Cu‐Mo ± Au deposit, Iran: Insights into their source

et al. 2022

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The Sarcheshmeh porphyry copper deposit (PCD) is located in the southeast part of the arc‐related Urumieh‐Dokhtar volcano‐plutonic belt. This PCD was formed by intrusion of a Middle Miocene granodiorite to tonalite stock into the volcano‐sedimentary rocks that are mainly andesite exhibiting Early Tertiary thrusting and faulting. On the basis of geochemistry of intrusive rocks, they are calc‐alkalic and alkali‐calcic suites that are consistent with oxidized I‐type magmas. The Fe2O3/FeO ratio in the Sarcheshmeh PCD is 1 to 3, consistent with a high oxygen fugacity. The igneous rocks of Sarcheshmeh PCD belong to a mature arc, but related to a post‐collision arc setting. Considerable evidence supports adakitic affinities of the Sarcheshmeh rocks, including geochemical values of Sr > 300 ppm (ave., 594 ppm), high ratios of Sr/Y > 20 (ave., 75), La/Yb > 20 (ave., 30), and enrichment of LREE and LILE relative to HREE and HFSE. The adakites of Sarcheshmeh belong to high‐silica adakites (HSA) that can be formed by melting of subducting seawater‐altered oceanic plate, which interact with the mantle wedge then followed by slab break‐off with local transtension in the middle part of the Dehaj‐Sarduieh belt. In rocks of the region, the ratios of Th/Ce > 0.12 and Nb/Zr > 0.05 suggest that the subducting crust has a role in forming different groups of these rocks. Geotectonic discrimination diagrams are used to distinguish between normal arc and slab failure magmatic systems, including Nb versus Y, La/Sm versus Sm/Yb, La/Yb versus Gd/Yb, and Rb versus Nb + Y diagrams. The plutonic rocks of the Sarcheshmeh PCD have characteristics consistent with adakites derived via slab failure, which are obviously metallogenically favorable magmatic systems. Adakitic melts generated rapidly during sinking of a broken slab (into higher temperature mantle), buoyantly migrate through the subcontinental lithospheric mantle (SCLM), which is related to structural evolution of that SCLM with local extension or transpression.

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“…Cenozoic continental-collision-zone adakitic rocks occur mainly in the Tethyan tectonic domain across Eurasia in, for example, the Carpathian-Pannonian (e.g., Seghedi et al, 2004), Greece (e.g., Marchev et al, 2013), Turkey-Iran (e.g., Dokuz et al, 2013;Jahangiri, 2007;Moghadam et al, 2016;Nia et al, 2017;Omrani et al, 2008;Pang et al, 2016;Topuz et al, 2011), and Himalaya-Tibet (e.g., Chung et al, 2003Chung et al, , 2005Chung et al, , 2009Hou et al, 2004Hou et al, , 2012Wang et al, 2005Wang et al, , 2008bGao et al, 2007;Zeng et al, 2011;Jiang et al, 2014;Ma et al, 2014;Zhang et al, 2014;Long et al, 2015;Liu et al, 2017;Ou et al, 2017) regions. They comprise mainly granites-(granodiorite porphyries)-dacites-rhyolites with ages of 56-2.5 Ma and SiO 2 contents (57.0-77.0 wt.%) similar to those of Cenozoic arc adakitic rocks, but with higher total-alkali (3.5-13.0 wt.%), Figure 4b), consistent with multiple crustal components in their sources, such as thickened ancient lower crust and subducted continental crust.…”

Section: Cenozoic Adakitic Rocks In Continental Collision Zonesmentioning

confidence: 99%

Adakitic rocks at convergent plate boundaries: Compositions and petrogenesis

Wang

Hao

Zhang

et al. 2020

Sci. China Earth Sci.

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Adakitic rocks are intermediate-acid magmatic rocks characterized by enrichment in light rare-earth elements, depletion in heavy rare-earth elements, positive to negligible Eu and Sr anomalies, and high La/Yb and Sr/Y ratios. Cenozoic adakitic rocks generated by partial melting of subducted oceanic crust (slab) under eclogite-facies conditions (i.e., the original definition of "adakite") occur mainly in Pacific Rim volcanic arcs (intra-oceanic, continental, and continental-margin island arcs), whereas those generated by partial melting of thickened lower crust occur mainly in Tethyan Tibetan collisional orogens. In volcanic arcs, adakitic melts derived from the melting of subducted oceanic crust metasomatize the mantle wedge to form a unique rock suite comprising adakite-adakite-type high-Mg andesite-Piip-type high-Mg andesite-Nb-rich basalt-boninite. This suite differs from the basalt-andesite-dacite-rhyolite suite formed from mantle wedge metasomatized by fluids derived from subducted oceanic crust. Previously published data indicate that partial melting of mafic rocks can generate adakitic magmas under pressure, temperature, and hydrous conditions of 1.2-3.0 GPa, 800-1000°C, and 1.5-6.0 wt.% H 2 O, respectively, leaving residual minerals of garnet and rutile with little or no plagioclase. Cenozoic Au and Cu deposits occur proximally to adakitic rocks, with host rocks of some deposits actually being adakitic rocks. Adakitic rocks thus have important implications for both deep-Earth dynamics and Cu-Au mineralization/exploration. Although studies of Cenozoic adakitic rocks have made many important advances, there remain weaknesses in some important areas such as their tectonic settings, petrogenesis, magma sources, melt-mantle interactions of pre-Cenozoic adakitic rocks, and their relationship with the onset of plate tectonics and crustal growth. Future research directions are likely to involve (1) the generation of adakitic magmas by experimental simulations of partial melting of different types of rock (including intermediate-acid rocks) and magma fractional crystallization at different temperatures and pressures, (2) the relationship between magma reservoir evolution and the formation of adakitic rocks, (3) the tectonic setting and petrogenesis of pre-Cenozoic adakitic rocks and related geodynamic processes, (4) interactions between slab melts and the mantle wedge, (5) the formation of Archean adakitic tonalite-trondhjemite-granodiorite and its link to the onset of plate tectonics and crustal growth, and (6) the relationship between the formation of adakitic rocks and metal mineralization in different tectonic settings.

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Geology, geochemistry and petrogenesis of post-collisional adakitic intrusions and related dikes in the Khoynarood area, NW Iran

Cited by 10 publications

References 82 publications

Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

Petrology and geochemistry of adakitic intrusions and dykes at Sarcheshmeh porphyry Cu‐Mo ± Au deposit, Iran: Insights into their source

Adakitic rocks at convergent plate boundaries: Compositions and petrogenesis

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