scholarly journals SIMPLE FORMS OF ZIRCON CRYSTALS FROM CRYSTALLINE ROCKS OF THE UKRAINIAN SHIELD AND THEIR MORPHOLOGICAL TYPES

2020 ◽  
pp. 20-27
Author(s):  
I. Kvasnytsya ◽  
V. Kvasnytsya
Keyword(s):  
Simple Form ◽  
Morphological Type ◽  
Crystalline Rocks ◽  
Ukrainian Shield ◽  
Alkaline Magmatism ◽  
Alkaline Rocks ◽  
Azov Region ◽  
Almost All ◽  
Zircon Type ◽  
Geochemical Specialization

The main basics in geometric crystallography of zircon, developed by many researchers in the 18th - 20th centuries, are briefly described. The data of goniometric study of zircon from crystalline rocks of the Ukrainian Shield (USh) are summarized. They cover zircon predominantly from granites and alkaline rocks of most the USh megablocks. The set of habit simple forms on zircon crystals is small: {111}, {110}, {100}, {221}, {331} and {311}. These forms define two contrasting habits of zircon crystals - prismatic and dipyramidal. Among the prismatic crystals several main morphological types of crystals are distinguished: {110} + {111} – zircon type, {100} + {111} – hyacinth type, {110} +100} + {111}, {110} +{100} + {111} + {311} and {110} + {100} + {311} – intermediate hyacinth-zircon types. Among the dipyramidal crystals two morphological types are contrasting — faceted by {111} dipyramid and {111} + {331} + {221} dipyramid combinations. The simple form {111} is developed on almost all zircon crystals from crystalline rocks of the USh, unless it is completely displaced on the heads of the crystals by the ditetragonal dipyramid {311}. For zircon crystals from syenites, mariupolites, albitites and some pegmatites the {111} is habit form. The simple form prism {110} is also developed on almost all zircon crystals from crystalline rocks of the USh, with the exception of many {111} dipyramidal crystals from syenites of the Zhovtnevy massif and hyacinth type of zircon crystals. It determines the most common morphological type of zircon crystals of prismatic habit – zircon type. The simple form prism {100} is less common on zircon crystals from crystalline rocks of the USh than the form {110}. It determines the hyacinth morphological type of zircon crystals of a prismatic habit. It is characteristic of zircon from granites of the Azov and Middle Dnipro regions. The simple form {311} is well developed on zircon crystals of hyacinth-zircon type from granites. It is almost absent on dipyramidal zircon crystals from alkaline rocks. The simple forms {221} and {331} are well developed only on dipyramidal crystals from syenites, mariupolites, albitites and some pegmatites of the Azov region. They are especially characteristic of zircon crystals of the Azov deposit. The simple form pinacoid {001} is rare and poorly developed; it was found only on zircon crystals of a prismatic habit from carbonatites of the Chernigiv massif and on dipyramidal crystals from syenites of the same massif. Another two dipyramids {101} and {211} can be attributed to reliable simple forms on zircon crystals from crystalline rocks of the USh. However, they are rare and found only on zircon crystals from acid rocks. Other goniometrically studied simple forms are poorly developed and incomplete, their reliability is questionable and therefore not accepted by us for consideration. The data presented on simple forms, habits and the main morphological types of zircon crystals from crystalline rocks of the USh almost completely confirm the main points on the morphological and structural bases of the crystallomorphology of zircon. First of all, this concerns two contrasting habit types of zircon crystals: dipyramidal crystals grow mainly in alkaline rocks and various morphological types of prismatic crystals grow in acidic rocks. In general, the set, the degree of importance and the distribution of simple forms on zircon crystals from crystalline rocks of the USh correspond to the morphological and structural series of crystals of this mineral. At the same time, the diversity of the morphological types of prismatic zircon crystals from granites still does not have a proper explanation. For the time being, it can be stated that each petrological type of granite can be characterized by a specific morphological type or types of prismatic zircon crystals. The dipyramidal zircon from most manifestations of alkaline rocks of the USh is younger than prismatic zircon from acidic rocks of the USh. Zircons from syenites of the Yastrubetsky and Zhovtnevy massifs and the Azov deposit have a Paleoproterozoic age of ∼1770 Ma. It characterizes the only stage of Paleoproterozoic alkaline magmatism, powerfully manifested in the USh and rich in rare-earth geochemical specialization. Dipyramidal zircons in these rocks are prevalent and even dominate (in mariupolites of the Zhovtnevy massif and syenites of the Azov deposit). Zircons from syenites and carbonatites of the Chernigiv massif, among which there are more rare dipyramidal crystals, are much more ancient - about 2000 Ma. Zircons from acidic rocks of the USh formed mainly in the period of 2.2–1.8 billion years. The dipyramidal zircon on the USh is a Precambrian formation, which reflects the Paleoproterozoic stage of the USh history, which is relatively narrow in time. Such zircon occurs in the Neogene and Quaternary terrigenous sediments of the southwestern part of the USh, which may indicate the presence in this area of still unknown Paleoproterozoic sources of alkaline magmatism. Dipyramidal zircon crystals may also belong to different albitized rocks and pegmatites of acidic and alkaline rocks.

New Findings of Rare Minerals in Alkaline Rocks of Ukrainian Shield

2020 ◽  
Vol 42 (4) ◽  
pp. 3-22
Author(s):  
V.V. SHARYGIN ◽  
S.G. KRYVDIK ◽  
O.V. DUBYNA
Keyword(s):  
Rare Earth ◽  
Chemical Composition ◽  
Ukrainian Shield ◽  
Silicate Mineral ◽  
Alkaline Rocks ◽  
First Finding ◽  
Azov Region ◽  
New Findings ◽  
Oxide Minerals

Over recent years, new rare minerals have been discovered in the alkaline rocks of the Ukrainian Shield. Agpaitic varieties of alkaline magmatic and metasomatic rocks turned out to be especially abundant in rare minerals. Numerous findings are related to alkaline metasomatites which are considered to be fenites and apofenite albitites of the Dmytrivka quarry. It is well known primarily by the presence of various accessory (Nb, REE, and Zr) minerals, as well as silicate and oxide minerals that are rare for Ukraine. The most common albite microcline fenites of this quarry are characterized by rare-earth mineralization, whereas the concentration of REE decreases in apofenite albitites and Zr and Nb increase. New rare minerals were also found in the essentially albite rock with astrophyllite, alkaline pyroxene and amphibole of the Malatersa massif and agpaitic phonolites of the Oktyabrsky massif. In the rocks of the mentioned massifs and occurrences of alkaline rocks the most interesting are the findings of the perraultite — jinshajiangite series. They were found in three points of the Azov area and include 1) perraultite and jinshajiangite in the alkaline metasomatites of the Dmytrivka quarry; 2) only perraultite in agpaitic phonolites of the Oktyabrsky massif (Kam’yana gully); 3) jinshajiangite in a veined albite rock among the gabbro of the Malatersa massif. Baotite and minerals of the hejtmanite — bafertisite series were also found in the metasomatites of the Dmytrivka quarry. The latter belong to intermediate varieties in terms of MnO (10-17 wt.%) and FeO (10-17 wt.%) which distinguishes them from Fe-rich bafertisite from other regions. A silicate mineral with high content of Na, Zr, Mn and elevated Ti and Nb is rarely observed as small inclusions in the kupletskite grains from alkaline metasomatite of the Dmytrivka quarry. According to the chemical composition it was previously diagnosed as janhaugite. Tainiolite was found in some occurrences of alkaline metasomatites in the Azov region. In addition small aggregates of the REE-enriched epidote were found in fenites of the Kaplany village, which is probably the first finding in Ukraine. Two new Zr minerals have been found in the aegirine syenites of the Korsun-Novomyrhorod pluton: elpidite and mineral with a high content of Y2O3 (13-14 wt.%) (Y-hagatalite ?).

scholarly journals Alkaline rocks of the Ukrainian Shield: Some mineralogical, petrological and geochemical features

Mineralogia ◽  
2013 ◽  
Vol 44 (3-4) ◽  
pp. 115-124 ◽  
Author(s):  
Aleksandr N. Ponomarenko ◽  
Stepan G. Kryvdik ◽  
Aleksandr V. Grinchenko
Keyword(s):  
Wide Distribution ◽  
Ukrainian Shield ◽  
Alkaline Magmatism ◽  
Alkaline Rocks ◽  
Precambrian Rocks ◽  
Western Province ◽  
Rock Types ◽  
Alkaline Feldspar ◽  
Granite Complex ◽  
Proterozoic Age

AbstractThe Ukrainian Shield (USh) is a typical province of Proterozoic alkaline magmatism where about 50 massifs and occurrences of alkaline rocks and carbonatites have been found. In spite of the wide distribution of Devonian basaltic- and alkaline magmatic rocks in the Dnieper-Donetsk depression adjacent to the USh, and in a marginal zone of the USh adjacent to folded Donbass, only alkaline rocks of Proterozoic age (1.8-2.1 Ga) that have been identified in the central interior of the USh. Some discrete bodies of 2.8 Ga subalkaline rocks also occur in Bogdanivka massif (Azov area). Occurrences of both Proterozoic (prevailing) and Phanerozoic (Devonian) alkaline rocks and kimberlites are only found in the eastern part of the USh (Azov area). Kimberlites in the central part of the Ukrainian Shield (Kirovograd region) are also of Proterozoic age (ca 1.8 Ga). It is this predominance of Precambrian rocks that makes the USh so different from other alkaline provinces where Phanerozoic alkaline rocks and kimberlites commonly prevail over Precambrian rocks. The lack of Phanerozoic alkaline magmatism on USh is poorly understood. Two main complexes of alkaline rocks - alkaline-ultrabasic (carbonatitic) and gabbro- syenitic - are distinguished in the USh. There are also rare occurrences of rock types such as alkaline- and alkaline-feldspar granites that may represent one separate alkaline-granite complex. Alkaline rocks present in the Eastern (Azov) province and in the Western province display essentially different geochemical character. Those of the Eastern province show characteristics typical of alkaline-ultrabasic rocks (e.g. high contents of incompatible rare elementssuch as Nb, REE, Zr, Y, Sr, whereas those in the Western province are characterized by low contents of Nb and Zr, and REE in some cases. This fact is interpreted as reflecting different geodynamic conditions of their origin. The Eastern rocks were formed in rift settings, the Western rocks in crustal compressional settings (collision, subduction). Various mineral deposits of phosphorus (apatite), niobium, REE, yttrium and zirconium, including unusually rich ores of REE, Y and Zr (Azov and Yastrybetsky) are associated with the alkaline rocks and carbonatites of the USh.

scholarly journals Geochemistry of Nb and Та in magmatic rocks of the Ukrainian Shield

2020 ◽  
Vol 41 ◽  
pp. 12-31
Author(s):  
S.G. Kryvdik ◽  
◽  
O.V Dubyna ◽  
◽  
Keyword(s):  
Igneous Rocks ◽  
Ukrainian Shield ◽  
Geochemical Data ◽  
Alkaline Rocks ◽  
Magmatic Rocks ◽  
Azov Sea ◽  
Continental Rifts ◽  
Alkaline Feldspar ◽  
High Concentrations ◽  
Almost All

It was made an attempt to generalize geochemical data of Nb and Ta concentration in the most common igneous rocks of the Ukrainian Shield (USh). In the majority of widely distributed rocks of the USh (normal and subalkaline granitoids) the Nb and Ta concentration are similar to upper crust but lower the accepted Clark value for acidic rocks. In the more differentiated rapakivi granites concentrations of these elements reach or exceed the Clark’s concentrations (up to 35 ppm). Only highly differentiated alkaline rocks and alkaline feldspar granites (Perga, Kamiani mogyly, Ruska Poliana massifs) have high Nb concentrations (up to 800, 120 and 370 ppm, respectively). Medium rocks of the normal range are the least geochemically studied and typically are characterized low Nb and Ta concentrations. Almost all gabbroids as well as their metamorphosed analogues in the greenstone structures, are characterized by very low Nb (and Ta) concentration (two or more orders of magnitude) compared with Clark’s values for basic rocks (20 ppm Nb and 0.48 ppm Ta) according to A.P. Vinogradov. Against this background, increased of Nb and Ta concentration is observed in the main rocks of anorthosite-rapakivi-granite plutons. Howover even in these rocks concentration of these elements rarely reach or does not achieve the values which are typical for subalkaline and alkaline basalts of continental rifts. The regional heterogeneity in Nb and Ta distribution is observed in alkaline rocks of different composition: in the Azov Sea region these rocks are characterized by high concentrations, while in the western part of the USh the content of these elements is extremely low. The increased concentration of these elements is also revealed in kimberlites from the Azov Sea region and the Kyrovohrad megablock of the USh. The authors give some considerations and assumptions about the dependence on geochemical features of the Precambrian igneous rocks of the USh from the geodynamic conditions of their formation.

scholarly journals Galaxies hosting an active galactic nucleus: a view from the CALIFA survey

2020 ◽  
Vol 492 (3) ◽  
pp. 3073-3090 ◽  
Author(s):  
Eduardo A D Lacerda ◽  
Sebastián F Sánchez ◽  
R Cid Fernandes ◽  
Carlos López-Cobá ◽  
Carlos Espinosa-Ponce ◽  
...  
Keyword(s):  
Star Formation ◽  
Morphological Type ◽  
Molecular Gas ◽  
Main Role ◽  
Type I ◽  
Massive Galaxies ◽  
Star Forming ◽  
Integral Field Spectroscopy ◽  
Almost All ◽  
Formation Efficiency

ABSTRACT We study the presence of optically-selected active galactic nuclei (AGNs) within a sample of 867 galaxies extracted from the extended Calar-Alto Legacy Integral Field spectroscopy Area (eCALIFA) spanning all morphological classes. We identify 10 Type-I and 24 Type-II AGNs, amounting to ∼4 per cent of our sample, similar to the fraction reported by previous explorations in the same redshift range. We compare the integrated properties of the ionized and molecular gas, and stellar population of AGN hosts and their non-active counterparts, combining them with morphological information. The AGN hosts are found in transitory parts (i.e. green-valley) in almost all analysed properties which present bimodal distributions (i.e. a region where reside star-forming galaxies and another with quiescent/retired ones). Regarding morphology, we find AGN hosts among the most massive galaxies, with enhanced central stellar-mass surface density in comparison to the average population at each morphological type. Moreover, their distribution peaks at the Sab-Sb classes and none are found among very late-type galaxies (>Scd). Finally, we inspect how the AGN could act in their hosts regarding the quenching of star-formation. The main role of the AGN in the quenching process appears to be the removal (or heating) of molecular gas, rather than an additional suppression of the already observed decrease of the star-formation efficiency from late-to-early type galaxies.

Eocene post-collisional magmatism in Himalaya orogenic belt: evidence from petrography, zircon U-Pb age and Sr-Nd-Hf isotope of the Mayum alkaline complex, southern Lhasa subterrane

2020 ◽  
Author(s):  
Xiaoshuang Chen ◽  
Haijin Xu
Keyword(s):  
Oceanic Lithosphere ◽  
Hf Isotope ◽  
Alkaline Magmatism ◽  
Early Eocene ◽  
Alkaline Complex ◽  
Southern Tibet ◽  
Quartz Syenite ◽  
Alkaline Rocks ◽  
Slab Breakoff ◽  
T Values

<p>Alkaline magmatism is commonly generated in extensional settings, playing an important role in constraining the timing of slab breakoff. Eocene post-collisional magmatism is widely distributed along the Gangdese belt of southern Tibet. However, few Eocene post-collisional alkaline magmatism has been identified. Here, we present a comprehensive study of whole-rock geochemistry, zircon U-Pb ages and Sr-Nd-Hf isotopes of the Mayum alkaline complex from the Southern Lhasa Subterrane, providing an insight into the timing of breakoff of the Neo-Tethyan slab. The alkaline complex is composed of amphibolite syenite, quartz syenite and alkaline granite. The mafic microgranular enclaves are ubiquitous in the syenites. Zircon U-Pb analyses indicates that the alkaline rocks were generated in Early Eocene (ca. 53-50 Ma). These ages suggest that the alkaline rocks emplaced shortly (10-15Ma) after the continental collision between the Indian and Eurasian plates. The alkaline rocks have high SiO<sub>2 </sub>(64.32-77.36 wt.%), Na<sub>2</sub>O + K<sub>2</sub>O (6.63-9.03 wt.%) contents, low MgO (0.14-2.52 wt.%) contents. These rocks show obvious arc-like geochemical features in trace elements, i.e., enrichment in LILEs (e.g., Rb, K), LREEs, Th and U, and depletion in HFSEs (e.g., Nb, Ta, Ti), HREEs with strongly to moderately negative Eu anomalies (δEu=0.28–0.72). These features together with high FeO<sup>T</sup>/MgO, Ga/Al, Ce/Nb and Y/Nb values, and low Ba, Sr contents, suggesting that the Mayum alkaline rocks belong to an A2-type granitoids. Besides, the alkaline rocks have homogeneous initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios (0.7052-0.7059) and negative ε<sub>Nd</sub>(t) values (-2.1 to -0.9) for whole-rock, and positive zircon ε<sub>Hf</sub>(t) values (+0.73 to +11.16). Nd-Hf isotope decoupling suggests that the alkaline was likely produced by mixing of mantle- and crust-derived magmas under a post-collisional extensional setting. Combined with previous published results, we propose that the slab breakoff of the subducting Neo-Tethyan oceanic lithosphere at least prior to Early Eocene (ca. 53Ma). The Eocene Mayum alkaline complex might be related to asthenosphere upwelling trigged by the slab breakoff.</p>

On the participation of natural salts in alkaline magmatism. Article 3. Genetic aspects of the model of salt-alkaline interactions

LITOSFERA ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 172-197
Author(s):  
G. A. Belenitskaya
Keyword(s):  
Genetic Model ◽  
Black Shales ◽  
Volatile Components ◽  
Alkaline Magmatism ◽  
Upward Movement ◽  
Alkaline Salt ◽  
Alkaline Rocks ◽  
Positive Assessment ◽  
Probable Role ◽  
Spatio Temporal

Research subject. An analysis of regional and global geological material characterizing the spatio-temporal relationships between alkaline magmatic and saline complexes allowed the author to propose and justify a new geological-genetic model of alkaline magmatism. This model considers saline complexes, located along the paths of the upward movement of deep magmas, as additional sources of alkaline and volatile components.Materials and methods. Three articles are devoted to the discussion and justification of this model. Two articles were devoted to geological aspects of the problem. The prerequisites and signs of the participation of ancient saline complexes in alkaline magmatism were characterized. It was shown that the presence of saline rocks in the deep zones of the earth's crust along the paths of the upward movement of deep magma flows is a geologically natural and common phenomenon. Natural alkaline-salt associations (spatio-temporal combinations of alkaline and salt objects) were indicated; their tectonic types were distinguished. A global overview of their different-age analogues (neo- and paleogeodynamic) was given.Results and discussion. The collected data made it possible to evaluate older (than magmas) salt-bearing complexes (deeply buried in the substrate) as a possible important and active participant in the ontogenesis of alkaline complexes, to give a positive assessment of the geological aspects of the “magma halocontamination” model and salt-magmatic interactions; to formulate the main geological-genetic provisions of this model.Conclusion. This article focuses on the discussion of the genetic aspects of the proposed model with an assessment of the probable role and significance of various halophilic components in the formation of alkaline magmas and their features. For this purpose, the similarity features in the spatial and quantitative distribution of halophilic and foydaphilic components in salt and alkaline rocks are considered; the probable role of various halophilic components in the formation of alkaline specialization of magmas, in the emergence of a rich set of unusual features of alkaline rocks (material, structural, morphological, etc.) is discussed. The probability of participation of the complex of paragenic (non-salt) members of the halophilic community (dolomites, anhydrites, black shales and associated ore components) in the interaction with hot magma is estimated. A comparative analysis of some basic provisions of the model under consideration with other geological-genetic models of alkaline petrogenesis is performed. The advantages of this model and its predictive capabilities are evaluated. A number of ideas have been proposed by the author for the first time, thus requiring further elucidation.

Dipyramidal Zircon Crystals From Alkaline Rocks of the Azov Region

2016 ◽  
Vol 38 (3) ◽  
pp. 9-23 ◽  
Author(s):  
V. Kvasnytsya ◽  
O. Vyshnevskyi ◽  
I. Kvasnytsya ◽  
I. Gurnenko
Keyword(s):  
Alkaline Rocks ◽  
Azov Region

Mineralogical–geochemical constraints on intrusives in central Anatolia, Turkey: tectono-magmatic evolution and characteristics of mantle source

2005 ◽  
Vol 142 (2) ◽  
pp. 187-207 ◽  
Author(s):  
N. İLBEYLİ
Keyword(s):  
Mantle Source ◽  
Central Anatolia ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Alkaline Rocks ◽  
Rock Types ◽  
Slab Breakoff ◽  
Wide Range ◽  
Cretaceous Magmatism ◽  
Geochemical Constraints

Collision-related rocks intrude metamorphic rocks overthrust by ophiolitic units to make up the Central Anatolian Crystalline Complex. A wide variety of rock types were produced by the latest Cretaceous magmatism in the complex. These rocks can be divided into three distinct units: (1) calc-alkaline (Ağaçören, Behrekdağ, Cefalıkdağ, Çelebi, Ekecikdağ, Halaçlı, Karamadazı, Kösefakılı, Terlemez, Üçkapılı, Yozgat); (2) sub-alkaline (Baranadağ); and (3) alkaline (Atdere, Davulalan, Eğrialan, Hamit, İdişdağı, Karaçayır). The calc-alkaline rocks are metaluminous/peraluminous I- to S-type plutons ranging from monzodiorite to granite. The sub-alkaline rocks are metaluminous I-type plutons ranging from monzonite to granite. The alkaline rocks are metaluminous to peralkaline plutons, predominantly A-type, ranging from foid-bearing monzosyenite to granite. These plutons crystallized under varying pressures (5.3–2.6 kbar) and a wide range of temperatures (858–698 °C) from highly oxidized magmas (log fO2 −17 to −12). All intrusive rocks display enrichment in LILE and LREE compare to HFSE and have high 87Sr/86Sr and low 143Nd/144Nd ratios. These characteristics indicate that these rocks are derived from a mantle source containing large subduction components, and have experienced assimilation coupled with fractional crystallization (AFC) during uprise through crust. The coexistence of calc-alkaline and alkaline magmatism in the complex may be ascribed to mantle source heterogeneity before collision. Either thermal perturbation of the metasomatized lithosphere by delamination of the thermal boundary layer or removal of a subducted plate (slab breakoff) are the likely mechanisms for the initiation of the collision-related magmatism in the complex.

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