Tectonic implications of the metamorphic field gradient in the Austrian Drosendorf and Gföhl units, Moldanubian Zone

2020 ◽  
Author(s):  
Dominik Sorger ◽  
Christoph A. Hauzenberger ◽  
Manfred Linner ◽  
Fritz Finger ◽  
Harald Fritz
Keyword(s):  
Variscan Orogeny ◽  
Duplex Structure ◽  
The South ◽  
Mafic Rocks ◽  
Moldanubian Zone ◽  
Second Stage ◽  
The North ◽  
Tectonic Position ◽  
Lower Crustal ◽  
Comprehensive Study

<p>The Moldanubian Zone in Austria is traditionally subdivided into several tectonostratigraphic subunits, which were juxtaposed to their nowadays position during the Variscan orogeny. The Gföhl unit at the highest tectonic position exposes the Moldanubian granulites at the top, underlain by the granitic Gföhl orthogneiss. At its base lies the Raabs unit, a sequence of mafic rocks (amphibolites and sepentinites) accompanied by metasediments. The Drosendorf unit represents a sedimentary sequence mainly consisting of paragneisses, amphibolites and marbles. At the lowest position the Ostrong unit is dominated by low-P paragneisses with local appearances of eclogites.<br>A comprehensive study along four W–E profiles from the Danube valley (P1) in the south, to the Thaya valley (P4) in the north, revealed a disparate distribution of metamorphic conditions within the Drosendorf and the Gföhl units (Raabs unit and Gföhl orthogneiss). Along P1 several lithologies of the investigated units show similar P–T conditions of 0.8–1.2 GPa and 750–800 °C, followed by a decompression stage to 0.6–0.8 GPa and ~750 °C. Towards the north the temperature within the Drosendorf unit is continuously decreasing to 650–700 °C, at pressure conditions of 0.4–0.8 GPa. P–T conditions for Raabs unit and Gföhl orthogneiss are decreasing as well but are increasing again at P4. At the western end of P4 they reach similar conditions as in P1 (0.6–1.0 GPa and 725–800), but a decrease towards the east can be observed. A slight W–E decreasing trend is also observable in P2 and P3. Th–U–Pb microprobe dating of several metasedimentary and orthogneiss samples resulted in a Carboniferous age (~340 Ma) for metamorphism. At one locality in the south an older monazite generation indicates an incipient collisional metamorphism in the Devonian (~370 Ma).<br>The observed N–S gradient indicates that the southern parts represent formerly deeper buried lower crustal parts, whereas towards the north middle crustal levels are exposed, which were exhumed in a first stage. In a second stage of exhumation in the northernmost area, the oblique thrusting of lower crustal segment including the Gföhl unit onto the already exhumed lower-middle crustal parts caused the formation of a duplex structure, which is responsible for the present appearance of the area around the Drosendorf window.</p>

Sur les rhyolites et les granites prevarisques en Normandie et en Vendee

1943 ◽  
Vol S5-XIII (4-6) ◽  
pp. 139-151
Author(s):  
Gilbert Mathieu
Keyword(s):  
Variscan Orogeny ◽  
The South ◽  
The North ◽  
Rigid Mass ◽  
Armorican Massif

Abstract An account of the pre-Carboniferous rhyolites and granites of Normandy and Vendee, France. Precambrian granite masses and Precambrian and Cambrian conglomerates containing ancient granite and rhyolite pebbles occur in both regions, and indicate that the Carboniferous granites of the Armorican massif were emplaced during the Variscan orogeny in a zone of subsidence between the rigid mass of Normandy to the north and Vendee to the south.

scholarly journals Distribution of bovine fasciolosis and associated factors in south Espírito Santo, Brazil: an update

2014 ◽  
Vol 23 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Isabella Vilhena Freire Martins ◽  
Barbara Rauta de Avelar ◽  
Cintia das Chagas Bernardo ◽  
Alann Casotti de Leão ◽  
Maria Julia Salim
Keyword(s):  
Geographical Distribution ◽  
Fasciola Hepatica ◽  
Control Measures ◽  
The South ◽  
Final Model ◽  
Fecal Samples ◽  
Espírito Santo ◽  
Second Stage ◽  
The North ◽  
Espirito Santo

The geographical distribution and factors associated with bovine fasciolosis in the south of Espírito Santo were updated and the prevalences of this disease and of snails of the genus Lymnaea in the municipality of Jerônimo Monteiro were calculated. In the first stage, fecal samples were collected from 10% of the herds of 115 farms in 23 municipalities and interviews were conducted with owners. Generalized linear mixed models were used. In the second stage, in Jerônimo Monteiro municipality, feces and mollusks were collected from all farms registered in the milk cooperatives in the region. The mollusks were identified and examined for infection by Fasciola hepatica. Fasciolosis was diagnosed in 18 (78%) of the 23 municipalities. Of the 1157 fecal samples examined, 19.01% were positive for eggs of F. hepatica. The final model shows statistical evidence of associations between positive farms and previous cases of fasciolosis and concomitant grazing of cattle with other definitive hosts. In the evaluated farms from the studied municipality the prevalence of fasciolosis and Lymnaea was of 66.7% and 23.8%, respectively. Mollusks were found in flooded areas and the animals' drinking water troughs. The wide geographical distribution of bovine fasciolosis in the south of Espírito Santo requires control measures to prevent its expansion towards the north of this state and other places characterized as F. hepatica free-infection.

First Polish Greenland Expedition 1937: on the 80th anniversary of the event

Polar Record ◽  
2017 ◽  
Vol 53 (4) ◽  
pp. 358-363
Author(s):  
Krzysztof Migała ◽  
Tymoteusz Sawiński ◽  
Jacek Piasecki
Keyword(s):  
Great Influence ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The South ◽  
80Th Anniversary ◽  
The North ◽  
Post War ◽  
Eastern Edge ◽  
Comprehensive Study

ABSTRACTThis paper describes the first Polish expedition to Greenland in 1937. The fieldwork was carried out in western Greenland at the eastern edge of Arfersiorfik Fjord between Disko Bay in the north and Nordre Strömfjord in the south. The main goal was to undertake a comprehensive study of a fragment of the Greenland ice sheet edge and its foreland focusing on a cartographic survey. The first ever map of this region entitled The Polish expedition to give new names. In the post-war history, expedition members exerted great influence on the development of Polish polar research.

scholarly journals The crustal structure of the Northeast Greenland continental shelf across the extension of the West Jan Mayen Fracture Zone

2020 ◽  
Author(s):  
Thomas Funck ◽  
Andreas Skifter Madsen ◽  
Christian Berndt ◽  
Anke Dannowski ◽  
Dieter Franke ◽  
...  
Keyword(s):  
Continental Margin ◽  
Crustal Structure ◽  
Fracture Zone ◽  
Seismic Refraction ◽  
Moho Depth ◽  
Gravity Modeling ◽  
The South ◽  
The West ◽  
The North ◽  
Lower Crustal

<p>Between August and October 2017, the German research vessel Maria S. Merian acquired geophysical data along the Northeast Greenland continental margin during its cruise MSM-67. This included seismic reflection and wide-angle/refraction data as well as potential field data. In comparison to the conjugate mid-Norwegian margins, the Northeast Greenland continental margin is less well studied. Hence, one of the key objectives of the expedition was to improve the understanding of the opening of the Northeast Atlantic Ocean and the evolution of the conjugate margin pair. One particular goal of the experiment was the mapping of the lateral extent of magmatism associated with the opening and how this relates to margin segmentation.</p><p>Seismic refraction line BGR17-2R2 runs on the shelf and parallel to the coast of NE Greenland. It crosses the landward extension of the West Jan Mayen Fracture Zone that separates the seafloor spreading along the Mohn’s Ridge in the north from the Kolbeinsey Ridge in the south. A total of 29 ocean bottom seismometers (OBS) equipped with a hydrophone and three-component geophones were deployed along the 235-km-long line. The seismic source was a G-gun array with a total volume of 4840 cubic inches (79.3 L) fired every 60 s. In the central and northern part of the line, two older seismic refraction profiles are crossed (lines AWI2003-500 and 400, respectively), which run perpendicular to the margin and can be used for lateral correlation of the crustal structure.</p><p>For the initial analysis, a velocity model was developed by forward and inverse modeling of travel times using the program RAYINVR. Later, a travel time tomography was carried out employing the code Tomo2D and performing a Monte Carlo analysis with 100 inversions from which an average model was calculated. The models show a 1-to 3-km-thick sedimentary column with velocities ranging from 1.6 to 4.0 km/s. In the central and northern part, a 1-km-thick layer with velocities around 4.6 km/s is underlying the sediments and is interpreted to consist of volcanic material. Below and extending along the entire length of the line, velocities of 5.6 km/s are observed in a layer that is ~2 km thick. The crystalline basement has a depth around 5 km with higher velocities in the north (6.5 km/s) than in the south (6.3 km/s). High lower crustal velocities (>7.2 km/s) are observed along the entire line and either indicate magmatic underplating or lower crustal sill intrusions. The Moho depth is seismically constrained along the central part of the line where it is 30 km. Gravity modeling suggest a depth of 35 and 27 km at the southern and northern limit of the profile, respectively. Within the zone of the landward extension of the West Jan Mayen Fracture Zone, a decrease in mid-crustal velocities by 0.2 km/s is observed. Slightly to the north of the fracture zone, a 50-km-wide zone with increased mid-and lower crustal velocities may indicate an igneous center in an area where the upper volcanic layer is shallowest.</p>

scholarly journals STRONG SEISMIC EVENTS on the SOUTH-WESTERN FLANK of the BAIKAL RIFT in 2014: November 1, 2014, Кp=13.6, Mw=4.6, I0=7–8 URIK EARTHQUAKE and December 5, 2014, Кp=13.9, Mw=4.9, I0=7–8 HOVSGOL EARTHQUAKE

2020 ◽  
pp. 350-363
Author(s):  
V. Melnikova ◽  
N. Gileva ◽  
A. Seredkina ◽  
Ya. Radziminovich
Keyword(s):  
Normal Fault ◽  
Baikal Rift Zone ◽  
Strike Slip ◽  
Historical Seismicity ◽  
Seismic Events ◽  
The South ◽  
Moment Tensors ◽  
The North ◽  
Western Flank ◽  
Tectonic Position

We consider two earthquakes occurred at the south-western flank of the Baikal rift zone (BRZ): Urik, November 1, 2014 (Mwreg=4.6) and Hovsgol, December 5, 2014 (Mwreg=4.9). First of them is localized within the area of the Main Sayan fault, the second one is located at the north of the Hovsgol Lake. Seismic moment tensors (focal mechanisms, scalar seismic moments, moment magnitudes and hypocentral depths) of the study seismic events were calculated based on surface wave amplitude spectra. Earthquake hypocenters were found to be situated in the middle crust (h=14–21 km). Both events occurred under the strike-slip stress-strain field. The strike-slip was combined with a normal fault component in the source of the Urik earthquake and with a thrust fault component in the source of the Hovsgol earthquake. In both cases, shaking intensity in the nearest settlements (=42–124 km) was less than 4–5. Analysis of historical seismicity, seismological data on the Urik and Hovsgol earthquakes and the tectonic position of their sources demonstrates that the considered events are typical for the south-western flank of the BRZ and confirms the existence of the transition zone from rift structures at the central parts of the BRZ to regional compression structures in Northern Mongolia.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

US and Russian policies and strategies in the Middle East: Iraq and Syria as a model

2019 ◽  
pp. 220
Author(s):  
Esraa Aladdin Noori ◽  
Nasser Zain AlAbidine Ahmed
Keyword(s):  
Middle East ◽  
East Asia ◽  
Balance Of Power ◽  
Western World ◽  
International Conflicts ◽  
The South ◽  
The West ◽  
The North ◽  
East Region ◽  
Middle East Region

The Russian-American relations have undergone many stages of conflict and competition over cooperation that have left their mark on the international balance of power in the Middle East. The Iraqi and Syrian crises are a detailed development in the Middle East region. The Middle East region has allowed some regional and international conflicts to intensify, with the expansion of the geopolitical circle, which, if applied strategically to the Middle East region, covers the area between Afghanistan and East Asia, From the north to the Maghreb to the west and to the Sudan and the Greater Sahara to the south, its strategic importance will seem clear. It is the main lifeline of the Western world.

Depositional Environment Drive as Overpressure Generation: Study Case in “Gap” Field, North West Java Basin

2020 ◽  
Author(s):  
A., C. Prasetyo
Keyword(s):  
Clay Mineral ◽  
Depositional Environment ◽  
Mineral Content ◽  
Hydrocarbon Generation ◽  
Well Test ◽  
Burial History ◽  
The South ◽  
North West ◽  
The North ◽  
Geological Processes

Overpressure existence represents a geological hazard; therefore, an accurate pore pressure prediction is critical for well planning and drilling procedures, etc. Overpressure is a geological phenomenon usually generated by two mechanisms, loading (disequilibrium compaction) and unloading mechanisms (diagenesis and hydrocarbon generation) and they are all geological processes. This research was conducted based on analytical and descriptive methods integrated with well data including wireline log, laboratory test and well test data. This research was conducted based on quantitative estimate of pore pressures using the Eaton Method. The stages are determining shale intervals with GR logs, calculating vertical stress/overburden stress values, determining normal compaction trends, making cross plots of sonic logs against density logs, calculating geothermal gradients, analyzing hydrocarbon maturity, and calculating sedimentation rates with burial history. The research conducted an analysis method on the distribution of clay mineral composition to determine depositional environment and its relationship to overpressure. The wells include GAP-01, GAP-02, GAP-03, and GAP-04 which has an overpressure zone range at depth 8501-10988 ft. The pressure value within the 4 wells has a range between 4358-7451 Psi. Overpressure mechanism in the GAP field is caused by non-loading mechanism (clay mineral diagenesis and hydrocarbon maturation). Overpressure distribution is controlled by its stratigraphy. Therefore, it is possible overpressure is spread quite broadly, especially in the low morphology of the “GAP” Field. This relates to the delta depositional environment with thick shale. Based on clay minerals distribution, the northern part (GAP 02 & 03) has more clay mineral content compared to the south and this can be interpreted increasingly towards sea (low energy regime) and facies turned into pro-delta. Overpressure might be found shallower in the north than the south due to higher clay mineral content present to the north.

Observed seasonal regimes of North-South Atlantic Ocean interbasin exchange

2019 ◽  
Author(s):  
Hamed D. Ibrahim
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Volume Flux ◽  
The South ◽  
The North ◽  
Basin Scale ◽  
Interbasin Exchange ◽  
North And South

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

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