Alkaline magmas in zones of continental convergence: The Tezhsar volcano-intrusive ring complex, Armenia

Sokół, Krzysztof; Halama, Ralf; Meliksetian, Khachatur; Savov, Ivan P.; Navasardyan, Gevorg; Sudo, Masafumi

doi:10.1016/j.lithos.2018.08.028

Cited by 25 publications

(10 citation statements)

References 90 publications

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“…In the Turkish part of the belt, a series of continental blocks collided through the Cretaceous and Cenozoic, and this was associated with two significant periods of post-collisional, ultrapotassic magmatism, one of Eocene to Early Miocene age, and the second in the Middle Miocene (Prelević et al, 2012;Dilek and Altunkaynak, 2007). Further east, Eocene to Oligocene alkaline magmatism was also common (Sokół et al, 2018). The most significant REE deposit formed at this time was the Oligocene alkaline-carbonatite Kizilcaören Deposit in Turkey (Öztürk et al, 2019;Nikiforov et al, 2014).…”

Section: Cenozoicmentioning

confidence: 93%

Carbonatites and Alkaline Igneous Rocks in Post-Collisional Settings: Storehouses of Rare Earth Elements

et al. 2021

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The rare earth elements (REE) are critical raw materials for much of modern technology, particularly renewable energy infrastructure and electric vehicles that are vital for the energy transition. Many of the world’s largest REE deposits occur in alkaline rocks and carbonatites, which are found in intracontinental, rift-related settings, and also in syn- to post-collisional settings. Post-collisional settings host significant REE deposits, such as those of the Mianning-Dechang belt in China. This paper reviews REE mineralisation in syn- to post-collisional alkaline-carbonatite complexes worldwide, in order to demonstrate some of the key physical and chemical features of these deposits. We use three examples, in Scotland, Namibia, and Turkey, to illustrate the structure of these systems. We review published geochemical data and use these to build up a broad model for the REE mineral system in post-collisional alkaline-carbonatite complexes. It is evident that immiscibility of carbonate-rich magmas and fluids plays an important part in generating mineralisation in these settings, with REE, Ba and F partitioning into the carbonate-rich phase. The most significant REE mineralisation in post-collisional alkaline-carbonatite complexes occurs in shallow-level, carbothermal or carbonatite intrusions, but deeper carbonatite bodies and associated alteration zones may also have REE enrichment.

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Section: Cenozoicmentioning

confidence: 93%

Carbonatites and Alkaline Igneous Rocks in Post-Collisional Settings: Storehouses of Rare Earth Elements

et al. 2021

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“…In the Late Cretaceous-Paleogene, the majority of surface part of the present-day Geghama highland was located below sealevel, which follows from the frequent presence of Cenomanian-Turonian limestone, marl, sandstone and conglomerate lying unconformably on the crystalline basement and upward grading to the Paleogene shallow-water sediments. Eocene-Early Miocene magmatic rocks related to the development of active continental margin are usually represented by andesitic and basaltic lava flows, tuffs and tuff breccias, as well as granitoid bodies of normal and elevated alkalinity (Sokol et al, 2018). The cessation of subduction beneath the region at the beginning of Neogene caused the attenuation of volcanic activity (Lebedev et al, 2013b) and subsequent emergence of the Armenian block above sealevel.…”

Section: Brief Geological Description Of the Geghama Highlandmentioning

confidence: 99%

The Pliocene Post-Collisional Volcanism of Central Armenia: Isotope-Geochronology and Geochemical Evolution of Magmatic Melts

et al. 2021

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The paper presents the results of isotope-geochronological and petrological-geochemical study of young volcanic rocks in the Geghama highland (Central Armenia), which were formed at the Pliocene-Early Quaternary stage of the Late Cenozoic post-collisional magmatism of the Lesser Caucasus. The boundaries of the area of volcanic activity manifested during this stage were established. The total duration (3.5-1.9 Ma) of the Pliocene-Early Quaternary stage, the time range of its main phases, and the scale and nature of eruptions were determined. Petrological and geochemical data indicate that the studied young volcanic rocks from Central Armenia belong to the mildly alkaline series and are represented by a continuous association of (trachy-)basalt-mugearite-latite-trachyte-rhyolite. The geochemical evolution of parental basaltic melts was mainly controlled by the fractional crystallization with Cpx as the main cumulus phase. Crustal assimilation and mixing of magmas were of limited importance: their possible contribution was recorded only in the most silicic rocks. The deep source responsible for magma generation under the studied part of the Lesser Caucasus at the Pliocene-Pleistocene boundary was represented by the asthenospheric mantle that was enriched during previous long-term (tens of millions of years) subduction of the Neotethys slab. Melting occurred in the Grt-peridotite stability zone; the composition of derived melts was geochemically similar to E-MORB basalts. An important feature of the regional mantle source was the notable admixture of subduction component. The generalization of the obtained petrological-geochemical and isotope-geochemical data on the young igneous rocks formed at different stages of Late Cenozoic magmatism at the Geghama highland allowed us to trace the evolution of the main parameters (mineral, chemical, and isotopic composition, depth of location, degree of melting) of mantle reservoirs responsible for magma generation beneath Central Armenia at the post-collisional stage (from the Late Miocene to the Holocene).

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“…This model accounts for the coexistence of early Eocene high-K and shoshonitic magmatism with adakite-like tendencies. After the end of the roll-back, slab-pull provoked slab break-off (Sperner et al, 2001) of the north dipping Northern Neotethyan oceanic lithosphere from the SAB (Sokol et al, 2018).…”

Section: 1029/2020tc006336mentioning

confidence: 99%

Jurassic to Cenozoic Magmatic and Geodynamic Evolution of the Eastern Pontides and Caucasus Belts, and Their Relationship With the Eastern Black Sea Basin Opening

et al. 2020

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The magmatic arcs of the Eastern Pontides and Lesser Caucasus lie in continuation from one another. A comparison of the subduction-related magmatic rocks outcropping throughout this segment of the Northern Tethyan belt exhibits chronological disparities, questioning the common subduction history of the Eastern Pontides and the Lesser Caucasus regions. New data and observations including geochronological and geochemical data, relative to subduction-to collision-related magmatic rocks, argue a novel paleogeographic reconstruction illustrating Mesozoic and Cenozoic evolution of this region. Jurassic to Early Cretaceous arc magmatism runs mainly from the Sochi-Ritsa/Bechasyn regions (Greater Caucasus) toward the southeast to the Alaverdi region and further into the Lesser Caucasus. Late Cretaceous and Cenozoic arc magmatism is evidenced throughout the Eastern Pontides extending through the Bolnisi region to the Lesser Caucasus arc. East to west, Jurassic to Early Cretaceous and Late Cretaceous to Cenozoic portions of arc split to the north and south of the Eastern Black Sea, respectively. Throughout Cretaceous subduction, this segment of the magmatic arc of the Southern Eurasian margin was torn in two due to the oblique opening of the Eastern Black Sea as a back-arc to intra-arc basin, from west to east. This reconstitution implies that the Jurassic-Early Cretaceous subduction-related magmatic rocks of the Greater Caucasus are remnant portions of the Eastern Pontides and Lesser Caucasus arcs. This infers the emplacement of subduction-to collision-related magmatic rocks throughout the Mesozoic and Cenozoic along the entire Southern Eurasian margin is solely due to a single long-lasting north dipping subduction.

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Alkaline magmas in zones of continental convergence: The Tezhsar volcano-intrusive ring complex, Armenia

Cited by 25 publications

References 90 publications

Carbonatites and Alkaline Igneous Rocks in Post-Collisional Settings: Storehouses of Rare Earth Elements

Carbonatites and Alkaline Igneous Rocks in Post-Collisional Settings: Storehouses of Rare Earth Elements

The Pliocene Post-Collisional Volcanism of Central Armenia: Isotope-Geochronology and Geochemical Evolution of Magmatic Melts

Jurassic to Cenozoic Magmatic and Geodynamic Evolution of the Eastern Pontides and Caucasus Belts, and Their Relationship With the Eastern Black Sea Basin Opening

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