Neotectonics and geodynamics of the Scythian Plate

Based on the results of structural-geomorphological analysis and tectonophysical modeling we identified an active geodynamic area in the basement of the Scythian Plate, which includes the Rostov salient, the northern part of the Stavropol uplift, Kuma-Tyulenev swell, and the eastern part of the Karpinskii swell and Astrakhan salient. This area is also characterized by maximal lineament densities, high heat flow, seismicity and the occurrence of hydrocarbon accumulations. It has been shown that the orientation of deformations within the Scythian Plate and Greater Caucasus orogen exhibits good correlation with those documented in the modern structural geometry of the Schythian Plate.     

Neotectonics of the Deryugin Basin area (Sea of Okhotsk)

The data of the bottom “summit” surface were used for compiling the schematic structural-neotectonic map and map of the main neotectonic structural elements. Their comparison with the schematic paleogeographic maps of the lithophysical complexes for four periods (K₂-$ _{1 - 2} $ _{1 - 2} , $ \rlap{--} P_3 $ \rlap{--} P_3 -N₁¹, N₁^1–2, and N₁³-N₂) reveals that the largest part of the considered area was characterized by either a continental or relatively shallow-sea environment, except for the western areas occupied at that time by the relatively deep trough with its axis located substantially westward of the neotectonic Deryugin Basin and the Staritskii Trough. In the Late Pliocene, the deep paleotrough ($ \rlap{--} P_3 $ \rlap{--} P_3 -N₂²) and Deryugin Basin were likely occupied by shelf settings with continuing sedimentation. The paleogeographic environments of the area for the period from the terminal Pliocene to the late Riss (Taz) Glaciation (Q₂⁶; MIS6) are unknown so far. The most complete Quaternary section recovered by Core LV 28-34-2 consists of six units; the odd (1, 3, and 5) and even (2, 4, and 6) among them correspond to the warm and cold marine isotopic stages, respectively. Judging from the benthic foraminiferal assemblages, the water depths during cold periods were shallower as compared with the warm stages, which is explained by the respective ascending and descending bottom movements and, partially, by the eustatic sea level fluctuations. In the Late Pleistocene-Holocene (∼17 ka), the bottom of the Deryugin Basin and the summit part of the Institut Okeanologii Rise subsided with average rates of 8 and 3 cm/year, respectively.     

Activity stages and tectonic division in the Kuznetsk Basin,Southern Siberia

The fault system reflected in the topography and structure of Cenozoic cover sediments in the Kuznetsk Basin is mostly recent. The positions of recent faults match those of Paleozoic and Mesozoic disjunctive dislocations only at the Kuznetsk Alatau and the Salair Range boundaries. These marginal features are associated with the greatest amplitudes of vertical movements in recent time: 80–100 m; less frequently, up to 250 m in the north and within 600 m in the south. The recent disjunctive dislocations are generally fractured zones from 300 to 2000 m in width, which were occupied by watercourses during the formation of the erosion valley system. Except for marginal recent tectonic bodies, vertical movements along the majority of recent faults do not exceed 5–10 m, reaching 30–70 m at the boundaries of recent tectonic regions and subregions. There is no reliable evidence of notable horizontal movements. For particular bodies, it is conjectured to be within 300–700 m by analogy with other regions of the Altai–Sayan folded area.The recent fault pattern can be interpreted as a result of crushing by submeridional compression with a slight right slip. The types of recent tectonic activity are different in different areas of the depression. The smallest uplift is recorded in the north of the basin, where the elevations of the Late Cretaceous peneplain are within 300 m, being within 230–250 m in the near-Salair subregion. This points to an insignificant downwarping in this area. Vertical movements along recent faults within the region are small, and the most intense movements are at its boundary. The central region is slightly elevated with reference to the northern one, and the elevation of its planation surface is within 300–380 m. It is characterized by differentiated movements along block boundaries with amplitudes reaching 60–70 m. The maximum activity occurred in the southern region. The elevations of its Late Cretaceous peneplain vary from 400 to 600 m. This region is characterized by notable vertical movements along block boundaries in the form of straight tectonic scarps and valleys. The northern and central regions constitute the present-day Kuznetsk intermontane depression, whereas the southern region belongs to the periphery of the mountainous framing of the Kuznetsk Depression.     

Paleoecological zoning of Kuznetsk Basin territory in late Paleozoic

In the Kuznetsk basin, south-central Siberia, regression of marine conditions promoted simultaneous existence of many environments during Carboniferous and Permian times. Different sequences of fades in different areas complicate correlation. Floral, faunal and lithologic data have been mapped to determine succession of biologic complexes for four intervals of late Paleozoic time: 1) middle Ostrog suite (maximum marine transgression); 2) middle Alykayeva subsuite of the lower Balakhonikha suite (maximum Balakhonikha coal formation); 3) upper Kuznetsk and lower Il'ya suites (beginning of second stage of coal formation); 4) middle Uskat subsuite of Il'ya suite. These intervals were selected because they correspond to the peak development of conditions typical of their stratigraphic subdivisions, they are most easily correlated, and contain the most information. — Nicholas Hotton, III.     

The impact of technogenic factors on the seismicity of the Kuznetsk Basin region and Lake Baikal

Using the materials from the catalogue of seismic events in the Siberian region, we estimated the impact of man’s activity on natural seismicity. Local man’s intervention into natural processes has been studied by the examples of commercial explosions during the quarry mineral mining in the Kuznetsk Basin and the exploitation of the railroad site along the shore of Lake Baikal. Seismic emission is shown to change with time under the impact of powerful monochromatic vibrators on the environment.     

Petrological and mineralogical features of volcanic rocks from the central Kuznetsk Basin (southern Siberia)

The Kuznetsk Basin volcanic rocks are close in age (from 252.3 ± 0.6 to 246.2 ± 1.4 Ma) to the traps of the West Siberian Plate and Siberian craton, which formed as a result of the Permo-Triassic plume activity. The geologic and petrographic features evidence that the andesitic basalts exposed in the Karakan and Elbak quarries are effusive rocks; most of them are andesitic basalts, and the rest are trachyandesitic basalts. The mineral composition is as follows: olivine Fo_59–66, plagioclase An_47–60, and clinopyroxene En_47–42Fs_25–12Wo_42–33; Mg# = 82–63. Using the COMAGMAT 3.5 program, the magma crystallization conditions during the andesitic-basalt formation were determined: 1109–1105 ºC, buffer QFM-NNO. The studied rocks are enriched in LREE ((La/Yb)_ch = 4.7–7.5) and are depleted in HREE ((Sm/Yb)_ch = 2.0–2.8). A specific geochemical feature of the rocks is strong Nb, Ta, Ti, and Eu negative anomalies ((La/Nb)_PM = 4.5–1.6, (La/Ta)_PM = 3.2–2.0, Eu/Eu? = 0.7) and a positive U anomaly on their normalized element patterns; ?_Nd(T) varies from +2.3 to +3.1. The HREE depletion of the Kuznetsk Basin volcanic rock points to the presence of garnet in the mantle source during their generation. The low Mg# indicates that the parental melts are not of the primary-mantle genesis but are probably the product of differentiation in deep-seated intermediate magma chambers.     

Natural coal fires in the Kuznetsk Coal Basin: Geologic causes,climate, and age

The paper summarizes data on the Pleistocene combustion metamorphic complexes of the Kuznetsk Coal Basin. Paralava and clinker samples are dated by 40Ar/39Ar incremental heating. The 40Ar/39Ar ages of the combustion metamorphic rocks permit reconstructions of the succession of renewed activity of ancient faults in the Salair zone and age estimates for the evolution of the present-day drainage network. Cross sections of burned rocks from the western margin and center of the Kuznetsk Basin are compared. The geologic factors of coal ignition risks are analyzed. On the western margin of the Kuznetsk Basin, paleofires occurred in steeply dipping thick seams with predominant crushed vitrain–clarain coal, which has a high oxygen and methane adsorption capacity. Highly denuded high-temperature combustion metamorphic complexes are most often localized in the arches of slightly broken anticlines. Oxygen was supplied to the coals during the Late Cenozoic renewed fault activity and the subsequent erosion of the sediments. The natural fires in the area were a result of external rather than spontaneous ignition. The depths of the paleofires (up to 200 m) indicate that they occurred in a warm and dry climate. In the center of the Kuznetsk Basin, dispersed fire foci appeared in seams of self-igniting coals with the erosion propagation of the current drainage network. The combustion metamorphic complexes here are partly eroded and consist mostly of clinkers with a low degree of alteration. The 40Ar/39Ar ages and geological data indicate that the earliest large-scale combustion events on the western periphery of the basin occurred in the Eopleistocene (1.3–0.9 Ma).The oldest 40Ar/39Ar age of a coal fire episode (1.7 ± 0.3 Ma) might be the upper age boundary of the altitude differentiation of topography, which corresponds to the renewed activity of the Tyrgan and Afonino–Kiselevsk faults. The later synchronous combustion events on the western margin (0.2 ± 0.1 Ma) and in the center of the basin (0.13–0.02 Ma), most probably, occurred during the Kazantsevian interglacial, which gave rise to the present-day drainage network.     

Permo-Triassic plume magmatism of the Kuznetsk Basin,Central Asia: geology,geochronology, and geochemistry

The Kuznetsk Basin is located in the northern part of the Altai–Sayan Folded Area (ASFA), southwestern Siberia. Its Late Permian–Middle Triassic section includes basaltic stratum-like bodies, sills, formed at 250–248 Ma. The basalts are medium-high-Ti tholeiites enriched in La. Compositionally they are close to the Early Triassic basalts of the Syverma Formation in the Siberian Flood basalt large igneous province, basalts of the Urengoi Rift in the West Siberian Basin and to the Triassic basalts of the North-Mongolian rift system. The basalts probably formed in relation to mantle plume activity: they are enriched in light rare-earth elements (LREE; La_n = 90–115, La/Sm_n = 2.4–2.6) but relatively depleted in Nb (Nb/La_PM = 0.34–0.48). Low to medium differentiation of heavy rare-earth elements (HREE; Gd/Yb_n = 1.4–1.7) suggests a spinel facies mantle source for basaltic melts. Our obtained data on the composition and age of the Kuznetsk basalts support the previous idea about their genetic and structural links with the Permian–Triassic continental flood basalts of the Siberian Platform (Siberian Traps) possibly related to the activity of the Siberian superplume which peaked at 252–248 Ma. The abruptly changing thickness of the Kuznetsk Late Permian–Middle Triassic units suggests their formation within an extensional regime similar to the exposed rifts of Southern Urals and northern Mongolia and buried rifts of the West Siberian Basin.     

Neotectonics of the Manych Trough

The general (regional) and local neotectonic features of the Manych Trough have been discussed. It has been shown that the trough’s bottom was generally immersed at a slow but stable rate of 0.1 mm/year with an amplitude of 40–50 m. Additionally, migration of portions of the maximal and minimal immersion has been identified. All the local tectonic rises in the Manych Trough were thresholds during the existence of the strait in the past and various evidence for their neotectonic activity, with the maximums in Early and Late Khazarian epochs, has been found.     

Neotectonics of the upper Mississippi embayment

Although the upper Mississippi embayment is an area of low relief, the region has been subjected to tectonic influence throughout its history and continues to be so today. Tectonic activity can be recognized through seismicity patterns and geological indicators of activity, either those as a direct result of earthquakes, or longer term geomorphic, structural, and sedimentological signatures. The rate of seismic activity in the upper Mississippi embayment is generally lower than at the margins of tectonic plates; the embayment, however, is the most seismically active region east of the Rocky Mountains, with activity concentrated in the New Madrid seismic zone. This zone produced the very large New Madrid earthquakes of 1811 and 1812.

Geological and geophysical evidence of neotectonic activity in the upper Mississippi embayment includes faulting in the Benton Hills and Thebes Gap in Missouri, paleoliquefaction in the Western Lowlands of Missouri, subsurface faulting beneath and tilting of Crowley's Ridge in northeastern Arkansas and southeastern Missouri, subsurface faulting along the Crittenden County fault zone near Memphis, Tennessee, faulting along the east flank of the Tiptonville dome, and numerous indicators of historic and prehistoric large earthquakes in the New Madrid seismic zone.

Paleoearthquake studies in the New Madrid seismic zone have used trenching, seismic reflection, shallow coring, pedology, geomorphology, archaeology, and dendrochronology to identify and date faulting, deposits of liquefied sand, and areas of uplift and subsidence. The cause of today's relatively high rate of tectonic activity in the Mississippi embayment remains elusive. It is also not clear whether this activity rate is a short term phenomenon or has been constant over millions of years. Ongoing geodetic and geological studies should provide more insight as to the precise manner in which crustal strain is accumulating, and perhaps allow improved regional neotectonic models.     

Geodesy and geodynamics

Man's interest in the dynamics of the earth's crust goes back several centuries. Ekman recently pointed out the theory of post-glacial uplift in Fennoscandia. In the 15th century, towns along the Baltic-Sea experienced receding of the sea. In this century, Bowie had started a program for repeating surveys in seismically active regions. Wegeners' hypothesis of Continental Drift aroused the interest of scientists. In January 1985, Walter Sullivan traced the evolution from Wegener's continental drift through plate tectonics to the latest suggestion of the formation of continents from “terranes”. Spatial techniques. Laser Ranging, VLBI, GPS have given geodesists the ability to monitor continental drift, intracontinental deformations and other phenomena.

Along faults, such as the San Andreas Fault, the conventional geodetic approach to deformation has been to use a linear concept, except for episodic events such as earthquakes and so on.

Wayne Thatcher's model on the declining strain rate is justified if sufficient geodetic data, well distributed, are available. Strain components can be computed from distortion patterns which might develop when an earlier survey is adjusted to be made consistent with a later survey. There exists a correlation of the movement of the instantaneous pole of rotation with the energy release of all earthquakes.     

Geology,geodynamics and orogenic gold prospectivity modelling of the Paleoproterozoic Kumasi Basin,Ghana, West Africa

This paper describes the geology and tectonics of the Paleoproterozoic Kumasi Basin, Ghana, West Africa, as applied to predictive mapping of prospectivity for orogenic gold mineral systems within the basin. The main objective of the study was to identify the most prospective ground for orogenic gold deposits within the Paleoproterozoic Kumasi Basin. A knowledge-driven, two-stage fuzzy inference system (FIS) was used for prospectivity modelling. The spatial proxies that served as input to the FIS were derived based on a conceptual model of gold mineral systems in the Kumasi Basin. As a first step, key components of the mineral system were predictively modelled using a Mamdani-type FIS. The second step involved combining the individual FIS outputs using a conjunction (product) operator to produce a continuous-scale prospectivity map. Using a cumulative area fuzzy favourability (CAFF) curve approach, this map was reclassified into a ternary prospectivity map divided into high-prospectivity, moderate-prospectivity and low-prospectivity areas, respectively. The spatial distribution of the known gold deposits within the study area relative to that of the prospective and non-prospective areas served as a means for evaluating the capture efficiency of our model. Approximately 99% of the known gold deposits and occurrences fall within high- and moderate-prospectivity areas that occupy 31% of the total study area. The high- and moderate-prospectivity areas illustrated by the prospectivity map are elongate features that are spatially coincident with areas of structural complexity along and reactivation during D4 of NE–SW-striking D2 thrust faults and subsidiary structures, implying a strong structural control on gold mineralization in the Kumasi Basin. In conclusion, our FIS approach to mapping gold prospectivity, which was based entirely on the conceptual reasoning of expert geologists and ignored the spatial distribution of known gold deposits for prospectivity estimation, effectively captured the main mineralized trends. As such, this study also demonstrates the effectiveness of FIS in capturing the linguistic reasoning of expert knowledge by exploration geologists. In spite of using a large number of variables, the curse of dimensionality was precluded because no training data are required for parameter estimation.     

Neotectonics at the Arabian plate margins

Opening of the Red Sea is accompanied by convergence between the Arabian plate and Eurasia. Regional topography and structure favour gravity glide as the main driving force of plate translation. At the leading edge of the plate, the Zagros Mountains undergo coseismic serial folding which is equivalent to Holocene shortening by ∼20 mm/year and which has led to major episodes of coastal uplift of which the last was ∼1700 years BP. At the Jordan Rift transform, which bounds the Arabian plate on the west, a recurrence interval of ∼1600 years is reported for events of M_L≥5.5. The palaeomagnetic record for the last 3.2 Ma indicates an average spreading rate for the Red Sea of ∼20 mm/year; there is some evidence that hydrothermal activity in the Red Sea is pulsatory, with a period of ∼2000 year, and that it reflects discontinuous spreading. The Holocene neotectonic records of the Zagros, the Jordan Rift and the Red Sea are the product of complex plate interactions and of the accumulation and release of strain in the crust along the plate margins. But they also reflect elastic strain energy storage and release within the Arabian plate, whence parallels in the period of major deformation episodes in the three deforming zones and the apparent discrepancy between the seismic moment predicted by plate kinematics and that recorded in the Zagros. Any associated intraplate deformation, if detected geodetically, would thus help the assessment of seismic hazard.     

Satellite geodesy and geodynamics

A short review of the fundamental techniques of satellite geodesy for the determination of the (timevarying) coordinates of a global set of geodetic reference points as well as the gravity field of the earth is given. The last results of modern observation techniques, especially the high accuracies obtained in the last few years, may show the relevance of this particular data source for the investigation of geodynamical phenomena in the near future.

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Zusammenfassung Eine kurze Übersicht stellt die wesentlichen Techniken der Satelliten-Geodäsie für die Bestimmung der (zeitabhängigen) Koordination eines globalen Satzes geodätischer Referenzpunkte und des Schwerefeldes der Erde vor. Die neuesten Ergebnisse moderner Beobachtungsverfahren, vor allem die hohen Genauigkeiten, die in den letzten Jahren erreicht wurden, zeigen die Bedeutung dieser speziellen Datenquelle für die Untersuchung geodynamischer Phänomene in naher Zukunft.

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Résumé L'auteur expose en un court aperçu les techniques essentielles de la géodésie par satellites pour la détermination (en fonction du temps) des coordonnées d'une série globale de points de référence géodésiques et le champ de gravité de la Terre. Les tout derniers résultats des techniques d'observation modernes, et avant tout la haute précision atteinte au cours de ces dernières années, montrent la portée de cette source particulière de données pour l'étude des phénomènes géodynamiques dans le prochain avenir.

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Neotectonics and seismicity in southern Patagonia

Research for evaluation of geologic hazards involving earthquakes and volcanic eruptions in southern Argentina seems to have historically received little attention. Nevertheless, the relatively small work done indicates a Neogene tectonic architecture in the area with capability of generating potential hazardous earthquakes in a growing population region. Seismicity and some morphotectonic evidences of Quaternary activity of the Magallanes–Fagnano left‐lateral fault system in the transform boundary between South America and Scotia plates, are analysed in this paper. This fault system is considered to be an important seismogenic source, responsible for large earthquakes that have occurred in southern Argentina. Some examples from the South and Austral Andean Volcanic Zones are also examined in order to show recent volcanic activity which also generated crustal seismicity. Preliminary hazard estimation clearly shows the presence of both potentially active volcanic centres in southern Patagonia that may also trigger seismicity and the high probability for large crustal earthquake generation. Copyright © 2015 John Wiley & Sons, Ltd.     

Neotectonics and intraplate continental topography of the northern Alpine Foreland

Research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity. Current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues. The accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years, which, on geological time scales, is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity. More reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling on-going intraplate deformation.The Alpine Orogen and the intraplate sedimentary basins and rifts in its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed. Seismicity and stress indicator data, combined with geodetic and geomorphologic observations, demonstrate that deformation of the Northern Alpine foreland is still on-going and will continue in the future. This has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area. We examine relationships between deeper lithospheric processes, neotectonics and surface processes in the northern Alpine Foreland, and their implications for tectonically induced topography.For the Environmental Tectonics Project (ENTEC), the Upper and Lower Rhine Graben (URG and LRG) and the Vienna Basin (VB) were selected as natural laboratories. The Vienna Basin developed during the middle Miocene as a sinistral pull-apart structure on top of the East Alpine nappe stack, whereas the Upper and Lower Rhine grabens are typical intracontinental rifts. The Upper Rhine Graben opened during its Late Eocene and Oligocene initial rifting phase by nearly orthogonal crustal extension, whereas its Neogene evolution was controlled by oblique extension. Seismic tomography suggests that during extension the mantle-lithosphere was partially decoupled from the upper crust at the level of the lower crust. However, whole lithospheric folding controlled the mid-Miocene to Pliocene uplift of the Vosges–Black Forest Arch, whereas thermal thinning of the mantle–lithosphere above a mantle plume contributed substantially to the past and present uplift of the Rhenish Massif. By contrast, oblique crustal extension, controlling the late Oligocene initial subsidence stage of the Lower Rhine Graben, gave way to orthogonal extension at the transition to the Neogene.The ENTEC Project integrated geological, geophysical, geomorphologic, geodetic and seismological data and developed dynamic models to quantify the societal impact of neotectonics in areas hosting major urban and industrial activity concentrations. The response of Europe's intraplate lithosphere to Late Neogene compressional stresses depends largely on its thermo-mechanical structure, which, in turn, controls vertical motions, topography evolution and related surface processes.