scholarly journals The structures of the Alai and Kichi-Karakol depressions and the latest deformations in their mountainous surroundings (Southern Tien Shan)

LITOSFERA ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 771-790
Author(s):  
E. S. Przhiyalgovskii ◽  
E. V. Lavrushina
Keyword(s):  
Sedimentary Cover ◽  
Active Faults ◽  
Morphological Structure ◽  
Geological Mapping ◽  
Tien Shan ◽  
Crustal Rock ◽  
Paleozoic Basement ◽  
Basement Faults ◽  
Entire Complex ◽  
Sediment Cover

Research subject. A series of research studies was conducted in the Alai Range area, at the junction of the folded Tien Shan and Pamir provinces with the purpose of investigating the morphological structure of alpine deformations in the Paleozoic basement and Mesozoic–Cenozoic sediment cover.Materials and Methods. Structural and geological observations were carried out in the Alai and Kichi-Karakol inter-mountain depressions and their mountainous surroundings. These investigations included an analysis of the morphology and orientation of the deformation structures of the sedimentary cover and structural inconsistencies based on detailed geological mapping; measurements of the orientations of tectonic slickenlines and slickensides in the zones of active faults; processing the entire complex of data in terms of kinematic strain indicators using proven methods and calculation programs in order to determine the main parameters of the stress-strain state of the upper crustal rock complexes.Results. The age intervals and kinematic conditions of the main phases of structural transformation of the Southern Tien Shan at the Alpine stage of tectogenesis were determined based new structural and geological data, as well as materials published in previous works. It was demonstrated that, in the territory of Alai, the most significant deformations and activation of the Paleozoic basement faults occurred at the Neogene-Quarter boundary. Conclusions. At the present stage, the area under study constitutes a relatively stable block, which does not experience significant deformations associated with the encroachment of the upper crustal rock complexes of the Northern Pamir from the south.

scholarly journals IDENTIFYING FAULT ACTIVITY IN THE CENTRAL EVOIKOS GULF (GREECE)

2018 ◽  
Vol 40 (1) ◽  
pp. 439 ◽  
Author(s):  
Th. Rondoyanni ◽  
D. Galanakis ◽  
Ch. Georgiou ◽  
I. Baskoutas
Keyword(s):  
Late Quaternary ◽  
Active Faults ◽  
Point Of View ◽  
Geological Mapping ◽  
Normal Faults ◽  
Geophysical Research ◽  
Alluvial Deposits ◽  
Moderate Seismicity ◽  
Limestone Bedrock ◽  
Topographic Relief

Geological mapping on a 1:5.000 scale and a tectonic analysis in the wider Chalkida region of the Island of Evia and the adjacent Drossia area of Central Greece, have allowed the identification of a number of active and potentially active normal faults. These faults have been formed or reactivated during the Late Quaternary, since they affect Pleistocene brackish and terrestrial deposits. Some of the faults affect the contact of the limestone bedrock with the Quaternary formations, presenting characteristic polished surfaces. The faults, in places covered by the alluvial deposits of the Chalkida plain, are also detected by geophysical research. Among the identified faults, the most important are considered the Aghios Minas- Chalkida, the Avlida and the Lefkadi active faults. The first one extends from Drossia to the Chalkida area, crossing the sea straights, and has an ENE-WSW direction and a south dip. The other two, are parallel antithetic faults oriented WNW-ESE, and bound the South Evoikos Gulf on the Greek mainland and the Evia Island respectively. The mapping and evaluation of active faults in this region of moderate seismicity, with low topographic relief and consequent absence of morphotectonic features, is especially important from a seismic hazard point of view.

scholarly journals Remote predictive geological mapping as a tool for the reconstruction of the complex geodynamic evolution of Melanesia

2020 ◽  
Author(s):  
Philipp Brandl ◽  
Anna Kraetschell ◽  
Justin Emberley ◽  
Mark Hannington ◽  
Margaret Stewart ◽  
...  
Keyword(s):  
Large Scale ◽  
Solomon Islands ◽  
Sedimentary Cover ◽  
Complete Information ◽  
Geological Mapping ◽  
Geophysical Data ◽  
Geodynamic Evolution ◽  
Predictive Mapping ◽  
Lithostratigraphic Units ◽  
Geological Map

<p>The offshore regions of Eastern Papua New Guinea and the Solomon Islands include several active and remnant arc and backarc systems that formed in response to complex plate tectonic adjustments following subduction initiation in the Eocene. Although there has been extensive exploration for offshore petroleum resources, and more than 54 research cruises have investigated or transited the region since 1993, a comprehensive regional geological map, including the deep marine areas, has not been available at a scale that permits quantitative analysis of the basin history. We present the first map that depicts interpreted assemblage- and formation-level lithostratigraphic units correlated across the marine basins and adjacent land masses. The mapped assemblages and large-scale formations are based on a compilation of land-based geological maps, marine geophysical data (hydroacoustics, magnetics, and gravity) integrated with the results of geological sampling, ocean drilling, seismic surveys, and seabed observations.</p><p>More than 400,000 km<sup>2 </sup>of the map area covered by ship-based multibeam and other geophysical data were inspected to derive the offshore geological units. In areas with limited data, the units were extrapolated from well-documented formations in adjacent regions with more complete information, including on land. This approach follows closely the techniques used for remote predictive mapping in other regions of the Earth where geological information is sparse. Geological boundaries were constrained by ship-based multibeam data reprocessed at 35-m to 50-m resolution and integrated with the Global Multi-Resolution Topography (GMRT) gridded at 100 m. Lithotectonic assemblages were assigned on the basis of plate structure, crustal type and thickness, age, composition, and sedimentary cover and further refined by bathymetric and geophysical data from the literature and cruise reports. The final compilation is generalized and presented here at 1:1 М. Our new approach integrates conventional mapping on land with remote predictive mapping of the ocean floor.</p><p>The newly compiled geological map illustrates the diversity of assemblages in the region and its complex geodynamic evolution. The resolution of our map allows to perform quantitative analyses of area-age relationships and thus crustal growth. Further geoscientific analyses may allow to estimate the regional mineral potential and to delineate permissive areas as future exploration targets.</p>

Geodynamics of the France Southeast Basin

2010 ◽  
Vol 181 (6) ◽  
pp. 477-501 ◽  
Author(s):  
Xavier Le Pichon ◽  
Claude Rangin ◽  
Youri Hamon ◽  
Nicolas Loget ◽  
Jin Ying Lin ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Sedimentary Cover ◽  
Central Basin ◽  
The South ◽  
Western Basin ◽  
Active Deformation ◽  
The North ◽  
The Alps ◽  
Sediment Cover ◽  
Surrounding Areas

AbstractWe investigate the geodynamics of the Southeast Basin with the help of maps of the basement and of major sedimentary horizons based on available seismic reflection profiles and drill holes. We also present a study of the seismicity along the Middle Durance fault. The present seismic activity of the SE Basin cannot be attributed to the Africa/Eurasia shortening since spatial geodesy demonstrates that there is no significant motion of Corsica-Sardinia with respect to Eurasia and since gravitational collapse of the Alps has characterized the last few millions years. Our study demonstrates that the basement of this 140 by 200 km Triassic basin has been essentially undeformed since its formation, most probably because of the hardening of the cooling lithosphere after its 50% thinning during the Triassic distension. The regional geodynamics are thus dominated by the interaction of this rigid unit with the surrounding zones of active deformation. The 12 km thick Mesozoic sediment cover includes at its base an up to 4 km thick mostly evaporitic Triassic layer that is hot and consequently highly fluid. The sedimentary cover is thus decoupled from the basement. As a result, the sedimentary cover does not have enough strength to produce reliefs exceeding about 500 to 750 m. That the deformation and seismicity affecting the basin are the results of cover tectonics is confirmed by the fact that seismic activity in the basin only affects the sedimentary cover. Based on our mapping of the structure of the basin, we propose a simple mechanism accounting for the Neogene deformation of the sedimentary cover. The formation of the higher Alps has first resulted to the north in the shortening of the Diois-Baronnies sedimentary cover that elevated the top of Jurassic horizons by about 4 km with respect to surrounding areas to the south and west. There was thus passage from a brittle-ductile basement decollement within the higher Alps to an evaporitic decollement within the Diois-Baronnies. This shortening and consequent elevation finally induced the southward motion of the basin cover south of the Lure mountain during and after the Middle Miocene. This southward motion was absorbed by the formation of the Luberon and Trévaresse mountains to the south. To the east of the Durance fault, there is no large sediment cover. The seismicity there, is related to the absorption of the Alps collapse within the basement itself. To the west of the Salon-Cavaillon fault, on the other hand, gravity induces a NNE motion of the sedimentary cover with extension to the south and shortening to the north near Mont Ventoux. When considering the seismicity of this area, it is thus important to distinguish between the western Basin panel, west of the Salon-Cavaillon fault affected by very slow NNE gliding of the sedimentary cover, with extension to the south and shortening to the north; the central Basin panel west of the Durance fault with S gliding of the sedimentary cover and increasing shortening to the south; and finally the basement panel east of the Durance fault with intrabasement absorption of the Alps collapse through strike-slip and thrust faults.

scholarly journals Tectonic stress regime in the 2003–2004 and 2012–2015 earthquake swarms in the Ubaye Valley, French Alps

2018 ◽  
Vol 175 (6) ◽  
pp. 1997-2008 ◽  
Author(s):  
Lucia Fojtíková ◽  
Václav Vavryčuk
Keyword(s):  
Seismic Activity ◽  
Joint Inversion ◽  
Earthquake Swarm ◽  
Active Faults ◽  
Tectonic Stress ◽  
Geological Mapping ◽  
Earthquake Swarms ◽  
Stress Regime ◽  
French Alps ◽  
Principal Axes

Abstract We study two earthquake swarms that occurred in the Ubaye Valley, French Alps within the past decade: the 2003–2004 earthquake swarm with the strongest shock of magnitude ML = 2.7, and the 2012–2015 earthquake swarm with the strongest shock of magnitude ML = 4.8. The 2003–2004 seismic activity clustered along a 9-km-long rupture zone at depth between 3 and 8 km. The 2012–2015 activity occurred a few kilometres to the northwest from the previous one. We applied the iterative joint inversion for stress and fault orientations developed by Vavryčuk (2014) to focal mechanisms of 74 events of the 2003–2004 swarm and of 13 strongest events of the 2012–2015 swarm. The retrieved stress regime is consistent for both seismic activities. The σ 3 principal axis is nearly horizontal with azimuth of ~ 103°. The σ 1 and σ 2 principal axes are inclined and their stress magnitudes are similar. The active faults are optimally oriented for shear faulting with respect to tectonic stress and differ from major fault systems known from geological mapping in the region. The estimated low value of friction coefficient at the faults 0.2–0.3 supports an idea of seismic activity triggered or strongly affected by presence of fluids.

Under the ice and over the sky – aspects of building the International Quaternary Map of Europe and potentially useful parallels to planetary geological map projects

2020 ◽  
Author(s):  
Kristine Asch ◽  
Andrea Naß ◽  
Stephan van Gasselt
Keyword(s):  
Land Surface ◽  
Active Faults ◽  
Geological Mapping ◽  
Geographical Information ◽  
Current Status ◽  
Small Scale ◽  
Scientific Quality ◽  
European Continent ◽  
Geological Map ◽  
Set Up

<p>The project of the International Quaternary Map of Europe project (IQUAME 2500) is a major international initiative coordinated by BGR under the auspices of the CGMW (Commission of the Geological Map of the Word, Sub-Commission Europe) and with support of INQUA (International Union for Quaternary Research). It started in 2011 at the INQUA congress in Bern and aims to show the distribution of Quaternary features at the land surface and general marine deposits across the entire European continent. The map is planned as web-based geographical information system (GIS) and is going to include the Quaternary on- and off-shore information on e.g. glaciogenic elements, geomorphologic features, age and lithology of Quaternary units, last extent of ice sheets (Weichselian, Saalian, if possible Elsterian), faults, active faults off-shore Quaternary information (in cooperation with the European Union EMODnet Geology project) and more.</p><p>Partner institutions from more than 30 countries including geological survey organisations from Russia in the East, Portugal in the West, Norway in the North and Cyprus in the South are participating; a scientific board of Quaternary researchers ensures the high scientific quality of resulting map. For a multinational and cross-boundary project like this, international collaboration is the key to success. This project requires that data originally set up in a plethora of regional and national classifications need to be adapted, integrated and harmonized in respect to semantics, structure and geometry. To achieve this aim common rules needed to used such as those defined by the European INSPIRE Directive or be set up and applied by all participants:  structured vocabularies (incl. definitions of terms) to describe the above contents, cartographic guidelines to suite the scale and last but not least generally applicable tools to aid the partners to submit their data to the project.</p><p>Ultimately, the aim is to create an pan-European, internationally harmonized, comprehensive, spatial geological database where relevant properties of the Quaternary layers can be retrieved, combined, selected and cross-referenced across political boundaries and also to provide a summary of the current status of European Quaternary geological research.</p><p>Looking at planetary mapping, e.g. of Mars and Moon, there are several similarities. The surfaces of terrestrial planets are shaped by geologic processes that are similar to those operating on Earth, therefore endogenic and exogenic landforms (such as lava flows, glacial deposits, and impact craters) are regularly mapped by the scientific community.  Beside specific scientific mapping projects conducted by individual researchers and groups different organisations and institutes are producing planetary maps, such as NASA, ESA, ROSCOSMOS and MIIGAiK (Russia), USGS (USA), CAS/NOAC/SGCAS/RADI (China), DLR (Germany), or the British Ordnance Survey. This presentation aims to introduce the small-scale Quaternary mapping of one part of planet Earth, i.e. Europe, to present its collaborative aspects, to highlight the parallels to planetary mapping and to suggest potentially useful aspects for planetary geological mapping projects.</p>

scholarly journals Sanaga Fault: Evidence of Neotectonics and Landscape Evolution in Edéa Region (Cameroon, Centre-Africa)

2018 ◽  
Vol 10 (3) ◽  
pp. 57 ◽  
Author(s):  
Augustin P. Moussango Ibohn ◽  
François Mvondo Owono ◽  
Bernard Njom ◽  
Simon P. Mbog Bassong ◽  
Jean-Paul Sep Nlomngan ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Active Faults ◽  
Drainage System ◽  
Passive Margin ◽  
Normal Faults ◽  
Pan African ◽  
Richter Scale ◽  
Main Driver ◽  
Proterozoic Basement ◽  
Set Up

Morphometric parameters extracted fromDEM (90 m) combined with field and literature data of Edéa region, a portion of Cameroonian passive margin located between 3°43’ - 4°00 ’N and 10°00’ - 10°15’E, were used to constraint the present day landscape and forces that have acted and is currently acting on its evolving topography. The obtained results show that the Sanaga Fault is one of the main driver forces responsible for this evolution. Set up during the Pan-African orogeny, this fault which affects a good part of the Proterozoic basement and Tertiary sedimentary cover has developed two systems of secondary active faults different by their nature and characteristics, quite visible in the Edéa region: the Ekitté System, shearing normal faults with a N-S to NNE-SSW strike and the Sanaga-Batignol System shearing directional faults with a NW-SE strike. Most of these faults constitute the river beds and play iteratively, deeply affecting both the drainage system and the landscape. Morphometric indices used reveal that the landscape has been rejuvenated and experiences uplifts and tiltings to present-day due to these reactivations. Structural and petrographical analyses confirm the current role played by the Sanaga Fault and its systems in the segmentation of the region into block tectonics and the occurrence of pseudotachylites and tectonic breccia. Block tectonics, pseudotachylites, tectonic breccias are accompanied with the recent earth tremors with magnitudes comprised between 2.6 and 4.0 on the Richter scale highlighting the neotectonics in this region.

scholarly journals The seismogenic fault system of the 2017 <i>M<sub>w</sub></i> 7.3 Iran-Iraq earthquake: constraints from surface and subsurface data, cross-section balancing and restoration

2018 ◽  
Author(s):  
Stefano Tavani ◽  
Mariano Parente ◽  
Francesco Puzone ◽  
Amerigo Corradetti ◽  
Gholamreza Gharabeigli ◽  
...  
Keyword(s):  
Cross Section ◽  
Sedimentary Cover ◽  
Active Faults ◽  
Fault System ◽  
Limited Information ◽  
Seismogenic Fault ◽  
Plate Convergence ◽  
Mountain Front ◽  
Seismogenic Structures ◽  
Seismic Reflection Profiles

Abstract. The 2017 Mw Iran-Iraq earthquake occurred in a region where the pattern of major plate convergence is well constrained, but limited information is available on the seismogenic structures. Geological observations, interpretation of seismic reflection profiles, and well data are used in this paper to build a regional balanced cross-section that provides a comprehensive picture of the geometry and dimensional parameters of active faults in the hypocentral area. Our results indicate: (i) coexistence of thin- and thick-skinned thrusting, (ii) reactivation of inherited structures, and (iii) occurrence of weak units promoting heterogeneous deformation within the Paleo-Cenozoic sedimentary cover and partial decoupling from the underlying basement. According to our study, the main shock of the November 2017 seismic sequence is located within the basement, along the low-angle Mountain Front Fault. Aftershocks unzipped the up-dip portion of the same fault. This merges with a detachment level located at the base of the Paleozoic succession, to form a crustal-scale fault-bend anticline. Size and geometry of the Mountain Front Fault are consistent with a down-dip rupture width of 30 km, which is required for an Mw 7.3 earthquake.

scholarly journals From ductile to brittle, late- to post-orogenic evolution of the Betic Cordillera: Structural insights from the northeastern Internal zones

2013 ◽  
Vol 184 (4-5) ◽  
pp. 405-425 ◽  
Author(s):  
Romain Augier ◽  
Laurent Jolivet ◽  
Damien Do couto ◽  
François Negro
Keyword(s):  
Shear Zone ◽  
Sedimentary Cover ◽  
Active Faults ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Betic Cordillera ◽  
Small Scale ◽  
Extensional Tectonics ◽  
Stress Regime ◽  
Meso Scale

Abstract Relations between Alpine detachment-bounded metamorphic domes, crustal-scale strike-slip fault zones and sedimentary basins in the Internal zones of the Betic cordillera are still matter of debate. Current tectonic interpretations of these basins vary from late-orogenic extensional structures to compressional ones associated with strike-slip motions along major still active faults. Structural investigations including new field mapping, meso-scale faults recognition, palaeostress analysis of brittle small-scale faults systems were performed in the sedimentary cover of the Almanzora corridor and the Huércal-Overa basins, located either in the hanging wall unit of the Filabres extensional shear zone or at the termination of the Alhama de Murcia sinistral fault zone. In parallel, a detailed study of the ductile and the ductile-brittle deformation was carried out in the footwall unit of the Filabres extensional shear zone, in the Nevado-Fílabride complex. Three main brittle events were recognised in the basin cover including two extensional events that occurred prior to a weak tectonic inversion of the basin during a third, still active event. The first one, D1b is characterized by the development a first stress regime consistent with ~NW-SE extensional tectonics. Besides, the consistency between the latest ductile and the brittle kinematics for the Filabres extensional shear zone and the activity of meso-scale fault systems that primarily control the main SW-NE depocentres allow concluding to a top-to-the-NW continuum of strain during the final exhumation of the Nevado-Filábride complex. The resulting overall half-graben architecture of the basins is then related to the combination of the formation of the metamorphic domes that added a local control superimposed on the regional deformation. Indeed, after a consistent top-to-the-west shearing prevailing during most of the Nevado-Filábride exhumation, final exhumation stages were in turn, characterised by important kinematics changes with a subordinate top-to-the-NW sense of shear (D1b). The onset of sedimentation in the basins occurred shortly after the crossing of the ductile-brittle transition in the underlying metamorphic domes at ca. 14 Ma into SW-NE fault-bounded troughs. Tectonic subsidence was then maintained during D2b while extensional kinematics changed to N-S or even locally to SSW-NNE. Extensional tectonics then lasted most of the Tortonian during the final tectonic denudation increments of the Sierra de los Filabres achieved at ca. 9-8 Ma. Intramontane basins are therefore genuinely extensional and clearly related to the latest exhumation stages of the Nevado-Filábride complex in the back-arc domain. Conversely, at ca. 8 Ma, basins started to record a ~N-S to NNW-SSE compressional stress regime (D3b) and ceased to be active depocentres while shortening within the Internal zones then recorded only the Iberia/Africa convergence. The weak inversion of the basins however resulted either in the reactivation of originally extensional faults such as the Alhama de Murcia fault or the basin individualisation and a progressive water exchange reduction with the Atlantic ocean and is thus proposed to be directly responsible for the Late Miocene salinity crises.

scholarly journals Disjunctive dislocations of the upper crust of Tien Shan

2019 ◽  
Vol 484 (3) ◽  
pp. 316-319
Author(s):  
V. S. Burtman
Keyword(s):  
Active Faults ◽  
Tien Shan ◽  
Late Paleozoic ◽  
Seismic Events ◽  
Upper Crust ◽  
No Formation ◽  
The Rose

This paper analyzes the rose diagrams of the directions of 439 faults of the Variscian province, 476 faults of the Caledonian province, and 603 presently active faults of Tien Shan. It is shown that more than half of the faults of the Caledonian province of Tien Shan are a result of Late Paleozoic orogenesis, which spanned its entire territory. Our data indicate that seismic events of Tien Shan have resulted in no formation of new disjunctive dislocation in many cases exhibiting displacements along Paleozoic faults.

scholarly journals FEATURES OF THE GEOLOGICAL STRUCTURE OF SEDIMENTARY COVER OF FROLOVSKAYA MEGADEPRESSION DERIVED FROM THE RESULTSOF GENERALIZATION OF GEOLOGICAL AND GEOPHYSICAL DATA

2018 ◽  
pp. 7-16
Author(s):  
S. R. Bembel ◽  
V. G. Kobzov ◽  
R. M. Bembel ◽  
F. Z. Khafizov
Keyword(s):  
Sedimentary Cover ◽  
Geophysical Methods ◽  
Geological Structure ◽  
Geophysical Data ◽  
Seismic Profiles ◽  
Gravity And Magnetic ◽  
Drilling Data ◽  
Entire Complex ◽  
Cretaceous Deposits

The article is devoted to the features of the geological structure of Jurassic-Cretaceous deposits of Frolovskaya megadepression. These features are derived from the results of the generalization of the materials of regional seismic profiles, maps of gravity and magnetic prospecting, drilling data. The main petroleum prospects are associated with Jurassic deposits and pre-Jurassic basement. We conclude that it is necessary to intensify further researches with carrying out the entire complex of geophysical methods, including magnetic and gravity prospecting with an increased density of observations.

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