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  • 1
    Electronic Resource
    Electronic Resource
    Activation of the Kost-Sagitullin rearrangement in a series of 2-benzylpyrimidine derivatives (2000)
    Springer
    Chemistry of heterocyclic compounds 36 (2000), S. 613-614 
    Details
    ISSN: 1573-8353
    Keywords: 2-benzylpyrimidine ; methylamine ; pyrimidinium salts ; pyridine ; enamine rearrangement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290857
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of fused systems containing an angular nitrogen atom from substituted 2-benzyl-4-hydrazinopyridimines (2000)
    Springer
    Chemistry of heterocyclic compounds 36 (2000), S. 185-189 
    Details
    ISSN: 1573-8353
    Keywords: hydrazides ; hydrazone ; Dimroth rearrangement ; pyrimidine ; pyrimido[6,1-c][1,2,4]triazine ; 1,2,4-triazolo[2,3-c]pyrimidine ; 1,2,4-triazolo[4,3-c]pyrimidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The condensation of substituted 2-benzyl-4-hydrazinopyrimidines with phenylpyruvic acid gave the corresponding hydrazones, which cyclize upon the action of POCl, to give derivatives of pyrimido[6,1-c][1,2,4]-triazine. The substituted 2-benzylpyrimidinylhydrazides of some carboxylic acids react with POCl, to give 1,2,4-triazolo[4,3-c]pyrimidines. The reaction of 7-benzyl-5-methyl-l-phenyl-1,2,4-triazolo[2,3-c]pyrimidine with sodium ethylate leads to rearrangement and formation of 7-benzyl-5-methyl-2-phenyl-1,2,4-triazolo[2,3-c]pyrimidine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283550
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  • 3
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    New and revised radiolarian biochronology for the sedimentary cover of ophiolites in the Lesser Caucasus (Armenia) (2010)
    In:  Geological Society Special Publication 340: 383-391.
    Details
    Publication Date: 2010-09-14
    Description: In order to improve our understanding of the palaeogeographic and geodynamic evolution of the Tethyan realms preserved in the Lesser Caucasus we here review the existing data for the sedimentary cover of ophiolites preserved in Armenia. Particular attention is given to those dated sedimentary rocks that are in direct genetic contact with ophiolitic lavas, as they provide constraints for submarine oceanic activity. The oldest available ages come from the Sevan-Akera suture zone that point to a Late Triassic oceanization. Data from both the Sevan and Vedi ophiolites provide evidence for Middle Jurassic (Bajocian) submarine activity, that continued until at least the Late Jurassic (Mid/Late Oxfordian to Late Kimmeridgian/Early Tithonian), as dated recently in Stepanavan and in this study for the Vedi ophiolite.
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  • 4
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    Radiolarian evidence for the age of chert blocks from the Upper Cretaceous ophiolitic melange unit of the Erakh area, Armenia (2015)
    Geological Society (of London)
    Details
    Publication Date: 2015-12-16
    Description: Two new and relatively well-preserved radiolarian faunas were extracted from blocks included in the Cretaceous ophiolitic mélange unit that crops out in the Erakh area south of Yerevan, Armenia. One of these radiolarian assemblages was extracted from cherts that are in stratigraphic contact with variolitic lavas. This radiolarian assemblage suggests a late Aalenian to middle Bajocian age (Unitary Association Zones 2–3) based on the co-occurrence of the species Parasaturnalis diplocyclis (Yao) and Transhsuum hisuikyoense (Isozaki & Matsuda). A second radiolarian assemblage was obtained from a block, several metres thick, of alternating pelagic limestones and cherts. It was characterized by the co-occurrence of the species Hemicryptocapsa capita Tan and Dicerosaturnalis dicranacanthos (Squinabol). The presence of these two species within the same assemblage correlates with Unitary Association Zone 17 and these samples are therefore assigned to the late Valanginian. These results suggest that submarine volcanic activity took place during the late Aalenian–middle Bajocian interval and that mixed carbonate and siliceous ooze accumulated during the late Valanginian. Previous biochronological data on Radiolaria from the Erakh mélange and the Vedi ophiolite are reviewed and their implications for the geodynamic and palaeoenvironmental evolution of the Tethyan ocean in Armenia are discussed.
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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  • 5
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    Geochemistry of the Eocene magmatic rocks from the Lesser Caucasus area (Armenia): evidence of a subduction geodynamic environment (2016)
    Geological Society (of London)
    Details
    Publication Date: 2016-02-05
    Description: This paper is focused on petrological and geochemical data obtained on a series of Middle and Upper Eocene magmatic rocks from the Lesser Caucasus of Armenia in order to elucidate magma sources and geodynamic processes. Middle–Upper Eocene magmatism is present in two main zones: the Amasia–Sevan–Hakari suture zone (ASHSZ) and the so-called South Armenian Microplate (SAM). Volcanic rocks from both places range from basalt to rhyolite and mostly display a calc-alkaline character. Trace element patterns from the SAM and ASHSZ samples show mobile-elements enrichment (Rb, Ba, Th) together with strong negative high field strength elements (Nb, Ta, Hf, Zr) anomalies. The (La/Sm) N ratio yields very close values for both areas. Conversely, the (La/Yb) N ratio is, on average, significantly higher for SAM than for ASHSZ, suggesting the presence of residual garnet at the source of the SAM volcanic rocks. Nevertheless, trace elements suggest partial melting from phlogopite- and amphibole-bearing spinel lherzolitic mantle sources. Neodymium and strontium isotopes yield Nd (40Ma) and 87 Sr/ 86 Sr (40Ma) ratios ranging, respectively, from –0.3 to +6.6 and from 0.70314 to 0.70531 for SAM samples, and from +3.4 to +6.8 and from 0.70393 to 0.70433 for ASHSZ samples. Initial Pb/Pb isotopic ratios yield close values for both areas but with slightly higher and more homogeneous 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios for SAM samples. Such features concur with a more pronounced slab-component contribution in the frontal part of the volcanic belt, that is, in the SAM domain. No significant crustal contamination has been detected in the studied Eocene magmatic rocks from both the ASHSZ and SAM. Considering geodynamic and geochemical constraints, we propose that this magmatism is connected with a north-dipping Southern Neotethys subduction, in an extensional (back-arc) environment of orogenic belts. The Arabia–Eurasia collision and the closure of the Neotethys Ocean may have occurred after this magmatic event.
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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  • 6
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    Progressive orocline formation in the Eastern Pontides-Lesser Caucasus (2015)
    Geological Society (of London)
    Details
    Publication Date: 2015-10-29
    Description: The Eastern Pontides–Lesser Caucasus fold–thrust belt displays a peculiar northwards arc-shaped geometry that was defined as an orocline in earlier studies. The Lesser Caucasus was affected by two main tectonic events that could have caused orocline formation: (1) Paleocene–Eocene collision of the South Armenian Block with Eurasia; and (2) Oligocene–Miocene Arabia–Eurasia collision. We tested the hypothesis that the Lesser Caucasus is an orocline and aimed to time the formation of this orocline. To determine the vertical axis rotations, 37 sites were sampled for palaeomagnetism in rocks of Upper Cretaceous–Miocene age in Georgia and Armenia. In addition, we compiled a review of c. 100 available datasets. A strike test was applied to the remaining datasets, which were divided into four chronological sub-sets, leading us to conclude that the Eastern Pontides–Lesser Caucasus fold–thrust belt forms a progressive orocline. We concluded that: (1) some pre-existing curvature must have been present before the Late Cretaceous; (2) the orocline acquired part of its curvature after the Paleocene and before the Middle Eocene as a result of South Armenian Block–Eurasia collision; and (3) about 50% of the curvature formed after the Eocene and probably before the Late Miocene, probably as a result of Arabia–Eurasia collision. Supplementary material: Results from rock magnetic experiments, reversal and fold tests and equal area projections of the characteristic remanent magnetizations for each site, as well as biostratigraphic ages and a table with palaeomagnetic results from the literature review (with assigned numbers referred to in the text) are available at http://www.geolsoc.org.uk/SUP18852 .
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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  • 7
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    Radiolarian biostratigraphic constraints for latest Jurassic-earliest Cretaceous submarine volcanic activity in the Tethyan oceanic realm of the Sevan ophiolite (Armenia) (2012)
    Societe Geologique de France (SGF)
    Details
    Publication Date: 2012-09-01
    Description: Biostratigraphic constraints for the sedimentary cover of the ophiolites preserved in Armenia are of key importance for the palaeogeographic and geodynamic reconstruction of the greater area between Eurasia and the South-Armenian block, which is a micro-continent of Gondwanian origin. We present here radiolarian data obtained from radiolarites that are intercalated in a sequence of mafic volcanic rocks on the northern flank of the Dali valley (east of Lake Sevan), which is considered to be part of the Sevan ophiolite. Mafic sills and dykes with well-preserved igneous textures are probably part of the same sequence. The pseudomorphosis of primary phases indicates that the igneous rocks are strongly affected by alteration in the greenschist facies condition. The plagiogranites that are present in this locality appear to be intrusive into the mafic sequence. The radiolarian assemblages extracted from radiolarian cherts intercalated in the mafic volcanic rocks are dated as latest Tithonian-Late Valanginian; they contain metric rounded blocks of oolitic limestones with crinoid fragments, suggesting that these shallow water limestones slid during the Jurassic/Cretaceous transition into a rugged oceanic floor in which radiolarian ooze accumulated.
    Print ISSN: 0037-9409
    Electronic ISSN: 0037-9409
    Topics: Geosciences
    Published by Societe Geologique de France (SGF)
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  • 8
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    Geological history of ophiolites in the Lesser Caucasus and correlation with the Izmir-Ankara-Erzincan suture zone: insights from radiolarian biochronology (2012)
    Societe Geologique de France (SGF)
    Details
    Publication Date: 2012-09-01
    Description: Three distinct radiolarian assemblages were obtained in this study; two of them were extracted from large blocks of radiolarites included in a mélange NW of Lake Sevan (Dzknaget). The latest Tithonian-Late Valanginian assemblage comes from a coherent sequence of 6–7 m-thick radiolarites with intercalations of lavas and rounded blocks of shallow-water limestones. The Late Barremian-Early Aptian assemblage found in the second block allows correlation with radiolarites dated recently in Karabagh. A third radiolarian assemblage comes from Vedi and establishes that radiolarian ooze was accumulated in the Tethyan realm of the Lesser Caucasus until at least the middle Albian. A synthesis of all available micropaleontological (radiolarian) and geochronological ages for the ophiolites present in Armenia and Karabagh points to the following scenario for their geological evolution: the initial phase of oceanic floor spreading was under way during the Late Triassic (Carnian) or even slightly before; the bulk of oceanic lithosphere preserved today in the Lesser Caucasus was formed during the Jurassic; evidence for subaerial volcanic activity is recorded in tuffite intercalations in the Middle-Upper Jurassic radiolarian cherts; an oceanic volcanic plateau was formed during the Late Barremian-Aptian (or possibly even before) while the obduction of ophiolites took place during the Coniacian-Santonian. The geological history of ophiolites in the Lesser Caucasus shares a number of similarities with the Izmir-Ankara-Erzincan suture zone (i.e. initiation of ocean spreading during the Carnian, obduction after the Cenomanian), but there are also some differences especially with respect to the timing of the oceanic plateau emplacement.
    Print ISSN: 0037-9409
    Electronic ISSN: 0037-9409
    Topics: Geosciences
    Published by Societe Geologique de France (SGF)
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  • 9
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    New data on the tectonic evolution of the Khoy region, NW Iran (2016)
    Geological Society (of London)
    Details
    Publication Date: 2016-04-09
    Description: The Khoy region (NW Iran) is important in the clarification of the structural framework of the alpine belt between the Taurides, the Lesser Caucasus and the NW Iran belt. The area is well-known for these ophiolitic units. We present here new stratigraphic and structural data that can be used to reconstruct the tectonic evolution of this region and then try to establish connections between these belts. According to new dates from nannoplankton assemblages, the obducted ophiolite of the Khoy complex was thrust over a sheared Campanian olistostrome and lenses of amphibolite are included within the contact. The obduction event is also marked by erosion of the ophiolitic unit and the deposition of conglomerates, shales, sandstones and siltstones. Poorly extended Paleocene detrital deposits cover the Campanian–Maastrichtian rocks. The Eocene formations characterize a basin filled with volcanogenic and sedimentary layers. The Middle and Upper Eocene series unconformably overlie the ophiolites and their cover of Campanian–Maastrichtian and Paleocene deposits. This corresponds to a syn-orogenic basin formed after the collision between Eurasia and the Taurides–Anatolides–South Armenian microplate. The Oligocene–Miocene Qom Formation with basal conglomerates unconformably covers all the earlier formations, including the Palaeozoic formations, indicating intense shortening before its deposition. Compressional deformation continued and is manifested by numerous folds, mainly west-dipping thrusts and reverse faults cutting the Qom Formation, and by recent NW–SE dextral strike-slip faults. This illustrates the continuous shortening and uplift (with intense erosion) resulting from the advanced stage of the collision between Arabia and Eurasia. The structural location of the tectonic units suggests that the Khoy Gondwana-related basement was part of the South Armenian Block and that the Khoy allochthonous ophiolites were obducted on it from the Amasia–Stepanavan–Sevan–Hakari suture zone.
    Print ISSN: 0305-8719
    Electronic ISSN: 2041-4927
    Topics: Geosciences
    Published by Geological Society (of London)
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  • 10
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    Assessment of pollution levels and human health risk of heavy metals in dust deposited on Yerevan’s tree leaves (Armenia) (2016)
    Springer
    Details
    Publication Date: 2016-09-06
    Print ISSN: 2096-0956
    Electronic ISSN: 2365-7499
    Topics: Chemistry and Pharmacology , Geosciences
    Published by Springer
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