scholarly journals Impact of volcanic and post volcanic activity on fluvial relief

2019 ◽  
pp. 49-66
Author(s):  
E. V. Lebedeva
Keyword(s):  
Explosive Volcanism ◽  
Hydrothermal Activity ◽  
River Network ◽  
Tectonic Activity ◽  
Lava Tubes ◽  
Near Surface ◽  
Volcanic Material ◽  
Mud Volcanism ◽  
High Erosion Rate ◽  
Characteristic Features

The characteristic features of the river network, the structure and functioning of the valleys affected by effusive and explosive volcanism, volcano-tectonic phenomena, gas hydrothermal activity and mud volcanism are revealed. It has been established that within flows and covers of effusives, the formation of new streams channels can occur not only due to backward erosion, but also as a result of the collapse of the roof of the near-surface lava tubes, which are actively used by underground runoff. A high erosion rate, a large volume of solid runoff, and a significant role of deflation in the transformation of the fluvial relief are characteristic for regions of domination of explosive activity. There valleys become zones of accumulation of volcanic material, which is gradually processed by mudflow, alluvial, aeolian and other processes. Volcanic-tectonic activity changes the rivers position, direction of streams and morphology of the valleys, leading to numerous reorganizations of the river network, as a result of which the valleys of modern watercourses often consist of uneven-age fragments. Valleys of hydrothermal zones are characterized by the active development of slope processes, which leads to the formation in them not only of sinter terraces, but also numerous landslide ones. Mud volcanic processes periodically lead to the filling and blocking of the valleys with mud breccia flows, which affects both the composition of the alluvium of watercourses and the morphology of the valleys.

Palaeogene alluvial–volcaniclastic deposits in the Mesta Basin (SW Bulgaria): depositional setting and basin evolution

2009 ◽  
Vol 147 (3) ◽  
pp. 321-338 ◽  
Author(s):  
ANDREAS SIEMES ◽  
TOM McCANN ◽  
ANNE FISCHER
Keyword(s):  
Volcanic Activity ◽  
Drainage System ◽  
Explosive Volcanism ◽  
Late Eocene ◽  
Sediment Supply ◽  
Tectonic Activity ◽  
Density Currents ◽  
Volcanic Material ◽  
Sedimentary Evolution ◽  
Sedimentary Architecture

AbstractThe Mesta half-graben is one in a series of extensional basins in SW Bulgaria that record the onset of extension within the Rhodope Zone in the Late Eocene. Tectonic activity on a continuous detachment along the eastern margin was a major control on subsidence, accommodation space creation, sediment supply and facies distribution in the basin. The sedimentary architecture was complicated by synsedimentary rotation, the presence of intrabasinal faults and the resulting compartmentalization, as well as synsedimentary volcanic activity. Facies and structural analysis of a key transverse section in the central part of the basin, together with supporting observations from other parts of the basin, indicate a pulsed tectono-sedimentary evolution of the basin with three distinct stages. The first stage (Late Eocene) is a phase of rapid extension with an initial alluvial setting. Basin margin fans and an axial fluvial through-drainage system were the major depositional systems in this stage. The second stage (Early Oligocene) marks the onset of volcanic activity within the Mesta Basin and is characterized by the formation of volcanic centres, an intense phase of explosive volcanism and rapid infilling of the previous basin topography with volcanic material deposited from pyroclastic density currents. The third stage (Late Oligocene) represents waning volcanic activity in a mixed alluvial–volcaniclastic environment. This stage is characterized by alternating alluvial and volcaniclastic depositional cycles, as well as partial reworking of volcanic material.

Permafrost, tectonics, and past and future regional climate change, Yukon and adjacent Northwest Territories

1994 ◽  
Vol 31 (1) ◽  
pp. 182-191 ◽  
Author(s):  
C. R. Burn
Keyword(s):  
Northwest Territories ◽  
General Circulation ◽  
Regional Climate ◽  
Gulf Of Alaska ◽  
General Circulation Models ◽  
Yukon Territory ◽  
Early Pleistocene ◽  
Tectonic Activity ◽  
Near Surface ◽  
Late Tertiary

Late Tertiary changes in the general circulation of the atmosphere, regionally enhanced by uplift of the Wrangell – Saint: Elias and Coast mountains, were sufficient to promote permafrost development in the western Arctic. Permafrost developed in Yukon Territory and adjacent Northwest Territories during early Pleistocene glacial periods, after continued tectonic activity led to further modification of regional climate, but degraded in the interglacials. Permafrost has been present in northern parts of the region since the Illinoian glaciation, but most ground ice in central Yukon formed in the Late Wisconsinan. The present interglacial is the only one with widespread evidence of permafrost, which is maintained in the valleys of central and southern Yukon by the Saint Elias Mountains blocking continental penetration of maritime air from the Gulf of Alaska. This reduces snow depth in winter, while cold-air drainage in the dissected terrain of the Yukon Plateaus enhances the near-surface inversion, leading to continental minimum temperatures. General circulation models used to simulate climate represent the physiography of northwest Canada crudely. As a result, the simulations are unable to reproduce conditions responsible for the development and preservation of permafrost in the region.

Delineating active faults across the Narmada-Son Lineament (NSL), India using the technique of Fracture Induced Electromagnetic Radiation (FEMR)

2021 ◽  
Author(s):  
Shreeja Das ◽  
Jyotirmoy Mallik
Keyword(s):  
Electromagnetic Radiation ◽  
Process Zone ◽  
Active Faults ◽  
Central India ◽  
Earthquake Forecasting ◽  
Tectonic Activity ◽  
Eurasian Plate ◽  
Near Surface ◽  
Crustal Stresses ◽  
Tectonically Active

<p>The Fracture Induced Electromagnetic Radiation (FEMR) technique has gradually progressed in the past decade as a useful geophysical tool to determine the direction and magnitude of recent crustal stresses, visualize the modification and realignment of stresses inside tunnels thus proving to be an important precursor for geohazards, earthquake forecasting, as well as delineate landslide-prone slip planes in unstable regions. Its working principle is based on the generation of geogenic electromagnetic radiation emanating from the brittle rock bodies that are fractured being subjected to an incremental increase of the differential stress in the near-surface of the Earth’s crust. The “Process zone” at the fractured crack tip contains numerous microcracks which subsequently creates dipoles due to the polarization of charges on such microcrack tips which rapidly oscillates emitting FEMR waves of frequencies between KHz to MHz range. The coalescence of the microcracks eventually leads to a macro failure dampening the amplitude of the FEMR pulses. The attenuation of FEMR pulses is comparatively lesser than seismic waves making it a more efficient precursor to potential tectonic activities indicating an upcoming earthquake a few hours/days before the actual event. In the current study, we have attempted to exploit this technique to identify the locations of the potential active faults across the tectonically active Narmada-Son Lineament (NSL), Central India. Although the first tectonic stage involved rifting and formation of the NSL during the Precambrian time, the rifting continued at least till the time of Gondwana deposition. Later, tectonic inversion took place as a result of the collision between the Indian and the Eurasian plate resulting in reverse reactivation of the faults. Episodic reverse movement along NSL caused recurrent earthquakes and linear disposition of the sediments that were deposited at the foothills of the Satpura Horst. Although the origin of East-West trending NSL dates back to the Precambrian time, it is very much tectonically active as manifested by recent earthquakes. The study has been conducted by taking linear FEMR readings across 3 traverses along the NSL which on analysis provides an idea about the potential active faults, their locations, and frequency of occurrence. The accumulation of strain in the brittle rocks that can eventually lead to a macro failure is demarcated as an anomalous increase in the amplitude of the FEMR pulses indicative of an upcoming tectonic episode in the region. To further corroborate the analysis, we have attempted to determine the neo-tectonic activity in the region by calculating the morphometric parameters across the Khandwa-Itarsi-Jabalpur region, Central India. Finally, we attempt to comment on the tectonic evolution of Central India in the recent past. We also encourage researchers to adapt the novel technique of FEMR which is swift, affordable, and feasible compared to conventional techniques deployed to survey the active tectonics of a region.</p>

scholarly journals The stratigraphy and deformation of the Precambrian rocks of the Grænseland area, South-West Greenland

1970 ◽  
Vol 86 ◽  
pp. 1-210
Author(s):  
E Bondesen
Keyword(s):  
Sedimentary Basins ◽  
Explosive Volcanism ◽  
Tectonic Activity ◽  
Carbonaceous Shale ◽  
Pillow Lavas ◽  
Carbonate Sedimentation ◽  
Carbonaceous Shales ◽  
Basic Volcanics ◽  
Thrust Zone ◽  
Orogenic Cycle

The Grænseland area exhibits a middle Precambrian (Ketilidian) succession of unusually well preserved sediments, basic volcanics, and intrusives. A Ketilidian type lithostratigraphy is established and the evolution of the sedimentary basins is reconstructed. The sedimentation began on a weathered gneiss surface with residual gravel and arkoses. An early carbonate sedimentation led to a severe alteration of the gneiss substratum. Varved pelites and a magnetite-conglomerate with chert pebbles transgressed the earlier deposited sediments and the gneiss substratum; orthoquartzites were thereafter deposited in two basin structures. The deposition of dolomitic shales and pelites appears to indicate progressively increasing depth. Large amounts of graded greywackes, interpreted as turbitides, bear witness of unstable tectonic conditions and a subaqueous tallus indicates nearby fault activity. Filled with greywackes the basins appear to have stabilized, and a comparatively uniform euxenic facies of carbonaceous shales and dolomites with preserved organic remnants prevailed independent of the earlier basins in a period of tectonic quiescence. A considerable thickness of pillow lavas then appears to have been extruded under conditions of quiet subsidence during the euxenic conditions shown by the existence of an anthracite-carbonaceous shale layer and the local facies relations on top of the pillow lavas. A new phase of sedimentation appears to have taken place under conditions of tectonic activity and explosive volcanism. The total thickness of the Ketilidian strata in Grænseland is approximately 4400 m. This succession is compared with other areas of Ketilidian deposits in SouthWest Greenland. The Ketilidian deposits were deformed in two periods of folding, accompanied by thrusting and metamorphism under low greenshist facies conditions. The first deformation is a local drag in incompetent horizons and is possibly related to the tilting and twisting of the basement surface. The second deformation is of regional importance but of very different development depending on the material affected and its position in relation to the sedimentary basins and earlier formed structures. Some areas are virtually undeformed. The basement reacted to the deformations by brecciation and faulting. An analysis of lineations in a thrust zone indicates that the initially formed lineations were twisted and bent towards the direction of tectonic transport. A correlation, based on deformation of metadykes, is attempted with other areas of Ketilidian activity and it is suggested that the second deformation occurred close to 1635 m.y. and corresponds thus to the Sanerutian plutonic episode. The Ketilidian (1800 m.y.? -1500 m.y.) is envisaged as an orogenic cycle of deposition, folding and metamorphism beginning at and ending with major uncomformities. The basement gneisses are shown to contain evidence for two older (pre-Ketilidian) orogenic cycles.

scholarly journals GENETIC MODEL OF MUD VOLCANISM OF THE KERCH PENINSULA (SCIENTIFIC AND APPLIED ASPECTS)

2021 ◽  
Vol 14 (1) ◽  
pp. 57-74
Author(s):  
V.A. Nesterovskyi ◽  
N.O. Hryshchanko ◽  
M.A. Deiak
Keyword(s):  
Genetic Model ◽  
Thick Layer ◽  
Volcanic Eruptions ◽  
Ore Deposits ◽  
Geological History ◽  
Mud Volcanoes ◽  
Near Surface ◽  
Kerch Peninsula ◽  
Mud Volcanism ◽  
History Of

The work is devoted to the results of many years of research and observations of mud volcanoes on the Kerch Peninsula. It aims to reveal the most important factors and aspects related to their origin, activity and impact on the geological history of the region. About 50 fossil and modern mud volcanoes have been defined on the Kerch Peninsula and the adjacent part of the water area. Their activity is consistent with the phases of activation of the alpine tectogenesis of the Crimean-Caucasian segment and is intermittent and impulsive. In the geological history of the peninsula, four main bursts of mud volcanic activity are clearly recorded: in the Upper Maikop, Chokrak-Karagan, Sarmatian and Cimmerian. Its greatest activity is manifested in the late Miocene and early Pliocene. Favorable factors for the development of mud volcanoes within the peninsula are the presence of a thick layer of plastic clays enriched in water and gas fluids, the widespread development of brachyanticlinal folds in the Neogene structural surface and a network of deep faults and fractures. The activity of mud volcanoes is associated with the formation of specific compensation structures – depressed synclines, which have become widespread on the Kerch Peninsula. The latter, depending on the paleogeographic conditions (sea, land) and the structural position of volcanoes in the anticlines, have acquired different specifics of structure and filling. Some depressed synclines are associated with iron ore deposits, which differ from typical iron ores of the mulde type by significant capacity, structural and textural features and material composition. Components of hydrothermal and exogenous origin have been defined in the products of mud volcanism: mud gases, mud waters, mud breccias, which indicates the genetic connection of this phenomenon with deep and near-surface processes. In addition, liquid, solid and gaseous hydrocarbons are often detected in volcanic eruptions. The latter are a criterion for searching for oil and gas at depth. Mud volcanoes of the Kerch Peninsula are a unique testing ground for monitoring the processes of modern mineral formation, the dynamics of deep processes and seismic activity in the region.

scholarly journals Geoelectric heterogeneities of the Kerch iron ore basin

2021 ◽  
Vol 43 (5) ◽  
pp. 165-180
Author(s):  
I. Yu. Nikolaev ◽  
T. K. Burakhovych ◽  
A. M. Kushnir ◽  
Ye. M. Sheremet
Keyword(s):  
Electrical Conductivity ◽  
Upper Mantle ◽  
Iron Ore ◽  
Earth’S Crust ◽  
Crust And Upper Mantle ◽  
Near Surface ◽  
Low Resistivity ◽  
Kerch Peninsula ◽  
Mud Volcanism ◽  
Earth's Crust

The three-dimensional geoelectric model of the Earth’s crust and upper mantle of the Kerch Peninsula has been built for the first time based on the results of experimental observations of the Earth’s low-frequency electromagnetic field, carried out in 2007—2013 by the Institutes of the National Academy of Sciences of Ukraine. Its physical and geological interpretation and detailing of the near-surface part were carried out according to the data of the audiomagnetotelluric sounding method to study the deep structure of the Kerch iron ore basin. To the east of the Korsak-Feodosiya fault along the southern part of the Indolo-Kuban trough (in the north of the South Kerch and almost under the entire North Kerch zones), a low-resistance anomaly (ρ=1 Ohm∙m) was found at depths from 2.5 km to 12 km about 20 km wide. Its eastern part is located in the consolidated Earth’s crust and is galvanically connected with surface sedimentary strata, while the western part is completely in sedimentary deposits. The anomaly covers the territory of the Kerch iron ore basin and occurrences of mud volcanism. The characteristics of the upper part of the layered section of the Kerch Peninsula in the interval of the first hundreds of meters were obtained from the results of one-dimensional inversion of the audiomagnetotelluric sounding data (frequency range 8—4000 Hz). It is shown that the first 15 m of the section, corresponding to Quaternary deposits, have resistivity values up to 1 Ohm∙m. Below, in the Neogene sediments, the electrical resistance increases to values of 5 Ohm∙m and more. Both horizontally and vertically, the distribution of resistivity values has a variable character, manifesting as a thin-layered structure with low resistivity values. Possibly, such areas have a direct connection with the channel for transporting hummock material and gases. A connection is assumed between the low-resistivity thin-layered near-surface areas, a deep anomaly of electrical conductivity in the upper part of the Earth’s crust, and the likely high electrical conductivity of rocks at the depths of the upper mantle with iron ore deposits, as well as the manifestation of mud volcanism. The heterogeneity of the crustal and mantle highly conductive layers may indicate a high permeability of the contact zones for deep fluids.

scholarly journals 2D Geoelectric Imaging of the Uneme-Nekhua Fracture Zone

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Muslim B. Aminu ◽  
Tunde M. Akande ◽  
Olubukola A. Ishola
Keyword(s):  
Fracture Zone ◽  
Tectonic Activity ◽  
Recent Sediment ◽  
Stream Data ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Array Configuration ◽  
The North ◽  
Electrode Separation ◽  
Dipole Length

We have employed 2D geoelectric imaging to reveal the geometry and nature of a fracture zone in Uneme-Nekhua, southwestern Nigeria. The fracture zone is discernable from an outcropping rock scarp and appears to define the course of a seasonal stream. Data were acquired using the dipole-dipole survey array configuration with electrode separation of 6 m and a maximum dipole length of 60 m. Three traverses with lengths varying between 72 m and 120 m were laid orthogonal to the course of the seasonal stream. 2D geoelectric images of the subsurface along the profiles imaged a north-south trending fracture zone. This fracture zone appears to consist of two vertical fractures with more intense definition downstream. The eastern fracture is buried by recent sediment, while the western fracture appears to have experienced more recent tectonic activity as it appears to penetrate through the near surface. Perhaps at some point, deformation ceased on the eastern fracture and further strain was transferred to the western fracture. The fracture zone generally defines the course of the north-south seasonal stream with the exception of the downstream end where the fracture appears to have died out entirely. Two associated basement trenches lying parallel to and east of the fracture zone are also imaged.

scholarly journals Volcanic hydrothermal systems as potential analogues of Martian sulphate-rich terrains

2015 ◽  
Vol 95 (2) ◽  
pp. 153-169 ◽  
Author(s):  
A. Rodríguez ◽  
M.J. van Bergen
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Systems ◽  
Geothermal Systems ◽  
Ambient Conditions ◽  
Flow Paths ◽  
Near Surface ◽  
Mineral Associations ◽  
The Status ◽  
History Of ◽  
Active Processes

AbstractRemote sensing observations and rover missions have documented the presence of sulphate-rich mineral associations on Mars. Many of these minerals are paleo-indicators of hydrous, acidic and oxidising environments that must have prevailed in Mars´ distant past, contrary to the present conditions. Furthermore, occurrences of silica together with high Cl and Br concentrations in Martian soils and rocks represent fingerprints of chemically atypical fluids involved in processes operating on the surface or at shallow depth. From field observations at representative active volcanoes in subduction settings, supported by geochemical modelling, we demonstrate that volcanic hydrothermal systems are capable of producing Mars-like secondary mineral assemblages near lakes, springs and fumaroles through the action of acidic fluids. Water–gas-rock interactions, together with localised flow paths of water and fumarolic gas emitted from associated subaerial vents, lead to deposition of a range of sulphates, including gypsum, jarosite, alunite, epsomite and silica. Evaporation, vapour separation and fluid mixing in (near-) surface environments with strong gradients in temperature and fluid chemistry further promote the diversity of secondary minerals. The mineralogical and chemical marks are highly variable in space and time, being subject to fluctuations in ambient conditions as well as to changes in the status of volcanic-hydrothermal activity. It is concluded that active processes in modern volcanic-geothermal systems may be akin to those that created several of the sulphate-rich terrains in the early history of Mars.

Iron and silica enrichments in the middle Albian neptunian dykes from the High-Tatric Unit, Central Western Carpathians: an indication of hydrothermal activity for an extensional tectonic regime

2016 ◽  
Vol 155 (1) ◽  
pp. 1-19 ◽  
Author(s):  
KRZYSZTOF BĄK ◽  
JOANNA KOWALCZYK ◽  
ANNA WOLSKA ◽  
MARTA BĄK ◽  
LUCYNA NATKANIEC-NOWAK
Keyword(s):  
Hydrothermal Vents ◽  
Sea Water ◽  
Hydrothermal Activity ◽  
Western Tethys ◽  
Carbonate Sedimentation ◽  
Sea Bottom ◽  
Neptunian Dykes ◽  
Post Archean Australian Shale ◽  
Characteristic Features ◽  
Central Western Carpathians

AbstractStudies dealing with the response of subaqueous volcanic and hydrothermal activities to carbonate sedimentation in hemipelagic environments affected by tectonic processes are comparatively rare. Here, a microfacies record with combined chemical data from the neptunian dykes found at an intrabasinal ridge (Tatric Ridge; Carpathian domain of the Western Tethys), close to a source of alkaline volcanism with possible hydrothermal vents (Zliechov Basin), is presented. The characteristic features of the neptunian dykes, up to 20 cm thick, in the middle Albian echinoderm-foraminiferal limestones (Tatra Mountains, Inner Carpathians) are their red fillings. Microprobe and x-ray diffraction analyses show that this reddish material, partly mixed with sparitic clasts coming from the host limestone, consists mainly of hematite crystals which are associated with low crystalline silica and quartz. The microfacies data suggest that the reddish infillings of the dykes is partly related to dissolution processes inside the fissures that could have taken place during the transport of FeCl3 fluids together with silica gel. The fluids could have been derived from hydrothermal vents occurring along the extensional faults in the neighbouring Zliechov Basin. Rare Earth element (REE) signatures of the reddish infill (i.e. low values of total REE content, chondrite- and Post-Archean Australian Shale-normalized REE + Y patterns with negative Ce anomaly) and a high Y/Ho ratio suggest authigenic removal of REEs from the water column. This suggests that the fissures were open to the sea bottom and were in contact with sea water during their filling.

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