Early Paleozoic mafic magmatic events on the eastern margin of the Siberian Craton

Khudoley, A. K.; Prokopiev, A. V.; Chamberlain, Kevin R.; Ernst, Richard E.; Jowitt, Simon M.; Malyshev, Sergey V.; Zaitsev, A. I.; Kropachev, A. P.; Королева, О. В.

doi:10.1016/j.lithos.2012.08.008

Cited by 37 publications

(40 citation statements)

References 31 publications

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“…High Tb/Yb ratios (2.06-2.20) of the alkaline mafic dykes reflect a deep melting level in the stability field of the garnetperidotite mantle likely at a depth of more than 90 km, whereas the subalkaline mafic dyke has a lower Tb/Yb ratio (1.15) indicative for melting of shallower spinel-peridotite mantle at a depth of less than 90 km (Wang et al 2002;Khudoley et al 2013). In comparison, Tb/Yb and La/Sm ratios of the source region of Dare-Hedavand metagabbros range from 1.30 to 2.08 and 1.40 to 2.65, suggesting they were produced through various degrees of partial melting and/or point to a stronger enrichment of their mantle source.…”

Section: Magma Generationmentioning

confidence: 99%

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Shakerardakani¹,

Neubauer²,

Bernroider³

et al. 2017

Geologica Carpathica

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Abstract:In this paper, we present detailed field observations, chronological, geochemical and Sr-Nd isotopic data and discuss the petrogenetic aspects of two types of mafic dykes, of alkaline to subalkaline nature. The alkaline mafic dykes exhibit a cumulate to foliated texture and strike NW-SE, parallel to the main trend of the region. The 40 Ar/ 39 Ar amphibole age of 321.32 ± 0.55 Ma from an alkaline mafic dyke is interpreted as an indication of Carboniferous cooling through ca. 550 °C after intrusion of the dyke into the granitic Galeh-Doz orthogneiss and Amphibolite-Metagabbro units, the latter with Early Carboniferous amphibolite facies grade metamorphism and containing the Dare-Hedavand metagabbro with a similar Carboniferous age. The alkaline and subalkaline mafic dykes can be geochemically categorized into those with light REE-enriched patterns [(La/Yb) N = 8.32-9.28] and others with a rather flat REE pattern [(La/Yb) N = 1.16] and with a negative Nb anomaly. Together, the mafic dykes show oceanic island basalt to MORB geochemical signature, respectively. This is consistent, as well, with the (Tb/Yb) PM ratios. The alkaline mafic dykes were formed within an enriched mantle source at depths of ˃ 90 km, generating a suite of alkaline basalts. In comparison, the subalkaline mafic dykes were formed within more depleted mantle source at depths of ˂ 90 km. The subalkaline mafic dyke is characterized by 87 Sr/ 86 Sr ratio of 0.706 and positive ɛ Nd (t) value of + 0.77, whereas 87 Sr/ 86 Sr ratio of 0.708 and ɛ Nd (t) value of + 1.65 of the alkaline mafic dyke, consistent with the derivation from an enriched mantle source. There is no evidence that the mafic dykes were affected by significant crustal contamination during emplacement. Because of the similar age, the generation of magmas of alkaline mafic dykes and of the Dare-Hedavand metagabbro are assumed to reflect the same process of lithospheric or asthenospheric melting. Carboniferous back-arc rifting is the likely geodynamic setting of mafic dyke generation and emplacement. In contrast, the subalkaline mafic sill is likely related to the emplacement of the Jurassic Darijune gabbro.

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Section: Magma Generationmentioning

confidence: 99%

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Shakerardakani¹,

Neubauer²,

Bernroider³

et al. 2017

Geologica Carpathica

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“…10a). The cumulate mafic samples plot above the Tb/Yb discrimination line indicative of melting of garnet peridotite mantle at depth [90 km, whereas isotropic mafic samples derive from shallower spinel-peridotite mantle melting at a depth \90 km (Herzberg 1995;Wang et al 2002;Khudoley et al 2013). Except for samples P-124, P-125 (fine-grained metagabbroic greenschists) and P-105 (talc-bearing greenschist) that show moderately low (La/Sm) PM ratios, all the other samples have higher (La/Sm) PM ratios.…”

Section: Magma Sourcementioning

confidence: 99%

“…Except for samples P-124, P-125 (fine-grained metagabbroic greenschists) and P-105 (talc-bearing greenschist) that show moderately low (La/Sm) PM ratios, all the other samples have higher (La/Sm) PM ratios. Khudoley et al (2013) suggest that this difference can be caused by three processes, namely crustal contamination or increased partial melting, both of which can increase La/Sm ratios in a melt, or melting of a depleted source, which would lower La/Sm ratios. In the (Th/Yb) PM vs. (Nb/Yb) PM diagram (Fig.…”

Section: Magma Sourcementioning

confidence: 99%

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Tectonic significance of Triassic mafic rocks in the June Complex, Sanandaj–Sirjan zone, Iran

et al. 2017

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This study concentrates on the petrological and geochemical investigation of mafic rocks embedded within the voluminous Triassic June Complex of the central Sanandaj-Sirjan zone (Iran), which are crucial to reconstruct the geodynamics of the Neotethyan passive margin. The Triassic mafic rocks are alkaline to sub-alkaline basalts, containing 43.36-49.09 wt% SiO 2 , 5.19-20.61 wt% MgO and 0.66-4.59 wt% total alkalis. Based on MgO concentrations, the mafic rocks fall into two groups: cumulates (Mg# = 51.61-58.94) and isotropic basaltic liquids (Mg# = 24.54-42.66). In all samples, the chondrite-normalized REE patterns show enrichment of light REEs with variable (La/Yb) N ratios ranging from 2.48 to 9.00, which confirm their amalgamated OIB-like and E-MORB-like signatures. Enrichment in large-ion lithophile elements and depletion in high field strength elements (HFSE) relative to the primitive mantle further support this interpretation. No samples point to crustal contamination, all having undergone fractionation of olivine ? clinopyroxene ? plagioclase. Nevertheless, elemental data suggest that the substantial variations in (La/Sm) PM and Zr/Nb ratios can be explained by variable degrees of partial melting rather than fractional crystallization from a common parental magma. The high (Nb/Yb) PM ratio in the alkaline mafic rocks points to the mixing of magmas from enriched and depleted mantle sources. Abundant OIB alkaline basalts and rare E-MORB appear to be linked to the drifting stage on the northern passive margin of the Neotethys Ocean.

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“…The chemical specificity of the Lower Cambrian basites and their mantle sources, the bimodal rhyolite-basalt magmatism, and the Vendian-Cambrian sedimentation history provide sufficient arguments to consider the Early Paleozoic rifting and the associated magmatic activation as consequences of the plume-lithosphere interaction in the northeastern Siberian Craton. The paleoreconstructions [Sears, 2012;Khudoley et al, 2013] suggest that the main rifting events occurred due to the lithosphere breakup through the junction zone of the Siberian and North American cratons which existed in the Early Cambrian. It is also assumed that the breakup was accompanied by the formation of a large igneous province which relics are present in the basin complex of the Canadian Cordillera in North America, as well as in the Olenek and Kharaulakh uplifts.…”

mentioning

confidence: 99%

The Early Paleozoic Basite Magmatism in the Northeastern Siberian Craton

Kiselev¹,

Кочнев²,

Ярмолюк³

et al. 2016

Geodin. tektonofiz.

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Abstract:The Early Cambrian tectonomagmatic activation is manifested in the northeastern passive margin of the Siberian Craton within the area of the Olenek uplift, as well as in the Kharaulakh segment of the Verkhoyansk foldthrust belt that was thrusted onto the craton in the Mesozoic. In the Olenek uplift, igneous rocks occur as basite diatremes, small basalt covers, dolerite dykes and sills intruded into the overlying Upper Vendian carbonate sediments. Stratiform bodies of explosive breccias are present in basal sandstones at the bottom of the Lower Cambrian sediment section. According to the zircon-based U-Pb datings [Bowring et al., 1993], the age of explosive basite breccias samples from the Olenek uplift (543.9±0.24 Ma) correlates with the age of potash-rhyolites (534.6±0.5 Ma) from the basal Lower Cambrian conglomerates in the Kharaulakh uplift section. The geodynamic evolution of the northeastern margin of the Siberian craton at the end of the Vendian and the beginning of the Cambrian periods is reflected not only in the magmatism, but also in the thicknesses and facial characteristics of the correlating sediments of the regional passive sea basins [Pelechaty et al., 1996]. The northern and eastern margins of the craton were subject to progressive uplifting at the end of the Vendian, which resulted in dewatering and paleokarsting. Uplifting was associated with the formation of siliceous clastic shelf sediments in the southern margin of the basin and the explosive and intrusive basite magmatic activations in the Olenek uplift and rhyolite bimodal-basite magmatic activation in the Kharaulakh uplift. The observed Vendian-Cambrian stratigraphic relations and manifestations of the basite magmatism suggest that at the northeastern margin of the craton, the lithosphere was subject to stretching. The assumed rift volcanicsedimentary associations are thin and represent the southern, the most remote part of the shoulder of the rift developed (in present-day coordinates) along the northern margin of the Siberian Craton. The chemical specificity of the Lower Cambrian basites and their mantle sources, the bimodal rhyolite-basalt magmatism, and the Vendian-Cambrian sedimentation history provide sufficient arguments to consider the Early Paleozoic rifting and the associated magmatic activation as consequences of the plume-lithosphere interaction in the northeastern Siberian Craton. The paleoreconstructions [Sears, 2012;Khudoley et al., 2013] suggest that the main rifting events occurred due to the lithosphere breakup through the junction zone of the Siberian and North American cratons which existed in the Early Cambrian. It is also assumed that the breakup was accompanied by the formation of a large igneous province which relics are present in the basin complex of the Canadian Cordillera in North America, as well as in the Olenek and Kharaulakh uplifts. The Early Paleozoic rifting and magmatism may reflect the final phase of the disintegration of the Rodinia supercontinent fragments. Аннотация: Раннекембрийская текто...

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Early Paleozoic mafic magmatic events on the eastern margin of the Siberian Craton

Cited by 37 publications

References 31 publications

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

Tectonic significance of Triassic mafic rocks in the June Complex, Sanandaj–Sirjan zone, Iran

The Early Paleozoic Basite Magmatism in the Northeastern Siberian Craton

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