10 research outputs found

    The South Armenian Block: Gondwanan origin and Tethyan evolution in space and time

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    The geodynamic evolution of the South Armenian Block (SAB) within the Tethyan realm during the Palaeozoic to present-day is poorly constrained. Much of the SAB is covered by Cenozoic sediments so that the relationships between the SAB and the neighbouring terranes of Central Iran, the Pontides and Taurides are unclear. Here we present new geochronological, palaeomagnetic, and geochemical constraints to shed light on the Gondwanan and Cimmerian provenance of the SAB, timing of its rifting, and geodynamic evolution since the Permian. We report new 40Ar/39Ar and zircon U-Pb ages and compositional data on magmatic sills and dykes in the Late Devonian sedimentary cover, as well as metamorphic rocks that constitute part of the SAB basement. Zircon age distributions, ranging from ∼3.6 Ga to 100 Ma, firmly establish a Gondwanan origin for the SAB. Trondhjemite intrusions into the basement at ∼263 Ma are consistent with a SW-dipping active continental margin. Mafic intraplate intrusions at ∼246 Ma (OIB) and ∼234 Ma (P-MORB) in the sedimentary cover likely represent the incipient stages of breakup of the NE Gondwanan margin and opening of the Neotethys. Andesitic dykes at ∼117 Ma testify to the melting of subduction-modified lithosphere. In contrast to current interpretations, we show that the SAB should be considered separate from the Taurides, and that the Armenian ophiolite complexes formed chiefly in the Eurasian forearc. Based on the new constraints, we provide a geodynamic reconstruction of the SAB since the Permian, in which it started rifting from Gondwana alongside the Pontides, likely reached the Iranian margin in Early Jurassic times, and was subject to episodes of intraplate (∼189 Ma) and NE-dipping subduction-related (∼117 Ma) magmatism

    The Epidemiologic Vocabulary of the West and the Former Soviet Union: Different Sides of the Same Science

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    OBJECTIVE: The purpose of this project was to develop an English-Russian Epidemiology Dictionary, which is needed for improved international collaboration in public health surveillance. INTRODUCTION: As part of the US Department of Defense strategy to counter biological threats, the Defense Threat Reduction Agency’s Cooperative Biological Engagement Program is enhancing the capabilities of countries in the former Soviet Union (FSU) to detect, diagnose, and report endemic and epidemic, man-made or natural cases of especially dangerous pathogens. During these engagements, it was noted that Western-trained and Soviet-trained epidemiologists have difficulty, beyond that of simple translation, in exchanging ideas. The Soviet public health system and epidemiology developed independently of that of other nations. Whereas epidemiology in the West is thought of in terms of disease determinants in populations and relies on statistics to make inferences, classical Soviet epidemiology is founded on a more ecological view with the main focus on infectious diseases’ spread theory. Consequently many fundamental Soviet terms and concepts lack simple correlates in English and other languages outside the Soviet sphere; the same is true when attempting to translate from English to Russian and other languages of the FSU. Systematic review of the differences in FSU and Western epidemiologic concepts and terminology is therefore needed for strengthening understanding and collaboration in disease surveillance, pandemic preparedness, response to biological terrorism, etc. METHODS: Following an extensive search of the Russian and English literature by a working group of Western and FSU epidemiologists, we created a matrix containing English and Russian definitions of key epidemiologic terms found in FSU and Western epidemiology manuals and dictionaries, such as A Dictionary of Epidemiology (1), Epidemiology Manual (2) and many other sources. Particular emphasis was placed on terms relating to infectious disease surveillance, analysis of surveillance data, and outbreak investigation. In order to compare the definitions of each term and to elucidate differences in usage and existing gaps, all definitions were translated into English and Russian so that the definitions could be compared side by side and discussed by the working group. RESULTS: Six hundred and thirty one terms from 27 English and 51 Russian sources were chosen for inclusion based on their importance in applied epidemiology in either the West or the FSU. Review of the definitions showed that many terms within biosurveillance and infectious disease public health practice are used differently, and some concepts are lacking altogether in the Russian or English literature. Significant gaps in FSU epidemiology are in the areas of biostatistics and epidemiologic study designs. There are distinctive differences in FSU and Western epidemiology in the conceptualization and classification of disease transmission, surveillance practices, and control measures. CONCLUSIONS: Epidemiologic concepts and definitions significantly differed in the FSU and Western literature. To improve biosurveillance and international collaboration, recognition of these differences must occur. Detailed analysis of epidemiology terminology differences will be discussed in the presentation and paper. Major limitations of the work were scarcity of prior research on the subject and lack of bilingual epidemiologists with the good understanding of FSU and Western approaches. A bilingual reference in the form of a dictionary will greatly improve mutual comprehension and collaboration in the areas of biosurveillance and public health practice

    The Epidemiologic Vocabulary of the West and the Former Soviet Union: Different Sides of the Same Science

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    The purpose of this projectwas to develop an English-Russian Epidemiology Dictionary, which is needed for improved international collaboration in public health surveillance. Epidemiologic concepts and definitions significantly differed in the former Soviet Union (FSU) and Western literature. To improve biosurveillance and international collaboration, recognition of these differences must occur. Detailed analysis of epidemiology terminology differences will be discussed in the presentation and paper. Major limitations of the work were scarcity of prior research on the subject and lack of bilingual epidemiologists with the good understanding of FSU and Western approaches. A bilingual reference in the form of a dictionary will greatly improve mutual comprehension and collaboration in the areas of biosurveillance and public health practice

    Pleistocene - Holocene volcanism at the Karkar geothermal prospect, Armenia

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    Pleistocene to Holocene volcanic centres north of the Bitlis-Zagros suture in Turkey, Iran, Armenia and Georgia represent both volcanic hazards and potential or actual geothermal energy resources. Such challenges and opportunities cannot be fully quantified without understanding these volcanoes’ petrogenesis, geochronology and magmatic, tectonic or other eruption triggers. We discuss the age and igneous geology of the Karkar monogenetic volcanic field in Syunik, SE Armenia. The ~30 km2 field is beside the location of Armenia’s only geothermal energy test drilling site. Eruptions of fissure-fed trachybasaltic andesite to trachyandesite occurred on a trans-tensional pull-apart segment of the Pambak-Sevan-Syunik Fault and have previously been interpreted to be of Holocene age. We conducted high-resolution duplicate 40Ar/39Ar dating of 7 groundmass separates, providing composite plateau or inverse isochron ages ranging from 6 ± 3 ka to 332 ± 9 ka (2). Each lava flow displays petrographic and geochemical patterns consistent with melting of subduction-modified lithospheric mantle and crystal fractionation involving ol, sp, opx and cpx, amp and plg. Some crystal-scale zoning was observed, implying recharge prior to eruption, and a preliminary estimate of cpx crystallisation pressures indicates storage in the mid- to upper crust, which may be of relevance for geothermal developments. These data indicate that volcanic activity in Syunik and elsewhere in Armenia overlapped with human occupation and that the presence of a substantive heat source for geothermal energy and a lava inundation hazard for local infrastructure should be further considered. Additional geophysical monitoring of the Pambak-Sevan-Syunik Fault is merited, along with detailed determination of the depths of magma storage both here and also at Porak volcano 40 km north of Karkar

    Pleistocene - Holocene volcanism at the Karkar geothermal prospect, Armenia

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    Quaternary volcanic centres north of the Bitlis-Zagros suture in Turkey, Iran and the Caucasus represent both volcanic hazards and potential or actual geothermal energy resources. Such challenges and opportunities cannot be fully quantified without understanding these volcanoes' petrogenesis, geochronology and magmatic, tectonic or other eruption triggers. In this preliminary study, we discuss the age and geology of the Karkar monogenetic volcanic field in Syunik, SE Armenia. The ∼70 km2 field is close to Armenia's only geothermal energy test drilling site. Fissure-fed trachybasaltic andesite to trachyandesite lavas erupted on a trans-tensional segment of the Syunik branch of the Pambak-Sevan-Syunik Fault, where previous studies suggested a Holocene age for the youngest eruptions. Here, high-resolution duplicate 40Ar/39Ar dating of 7 groundmass separates provided inverse isochron ages ranging from 7.4 ± 3.6 ka and 7.9 ± 2.9 ka to 353 ± 20 ka (2σ). Each lava flow displays petrographic and whole rock geochemical patterns consistent with melting of subduction-modified lithospheric mantle and extensive evolution within the crust involving fractional crystallisation and mixing of magma batches. Data confirm that volcanic activity related to the Syunik Fault overlapped with Palaeolithic to Bronze Age human occupation and remains a minor lava inundation hazard. Further geochemical work will allow constraint of the depth and timescales of magma storage. Both Karkar and the area around Porak volcano, which lies 35 km N of Karkar on the Syunik Fault, might be considered for future geothermal energy developments

    The South Armenian Block: Gondwanan origin and Tethyan evolution in space and time

    Get PDF
    The geodynamic evolution of the South Armenian Block (SAB) within the Tethyan realm during the Palaeozoic to present-day is poorly constrained. Much of the SAB is covered by Cenozoic sediments so that the relationships between the SAB and the neighbouring terranes of Central Iran, the Pontides and Taurides are unclear. Here we present new geochronological, palaeomagnetic, and geochemical constraints to shed light on the Gondwanan and Cimmerian provenance of the SAB, timing of its rifting, and geodynamic evolution since the Permian. We report new 40Ar/39Ar and zircon U-Pb ages and compositional data on magmatic sills and dykes in the Late Devonian sedimentary cover, as well as metamorphic rocks that constitute part of the SAB basement. Zircon age distributions, ranging from ∼3.6 Ga to 100 Ma, firmly establish a Gondwanan origin for the SAB. Trondhjemite intrusions into the basement at ∼263 Ma are consistent with a SW-dipping active continental margin. Mafic intraplate intrusions at ∼246 Ma (OIB) and ∼234 Ma (P-MORB) in the sedimentary cover likely represent the incipient stages of breakup of the NE Gondwanan margin and opening of the Neotethys. Andesitic dykes at ∼117 Ma testify to the melting of subduction-modified lithosphere. In contrast to current interpretations, we show that the SAB should be considered separate from the Taurides, and that the Armenian ophiolite complexes formed chiefly in the Eurasian forearc. Based on the new constraints, we provide a geodynamic reconstruction of the SAB since the Permian, in which it started rifting from Gondwana alongside the Pontides, likely reached the Iranian margin in Early Jurassic times, and was subject to episodes of intraplate (∼189 Ma) and NE-dipping subduction-related (∼117 Ma) magmatism
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