scholarly journals Tectonic Controls on Near-Surface Variations in CH4 and CO2 Concentrations along the Northwestern Margin of the Ordos Block, China

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Y. J. Cui ◽  
Y. Li ◽  
X. Y. Si ◽  
L. X. Yang ◽  
Z. F. Liu ◽  
...  
Keyword(s):  
Slip Rate ◽  
Tectonic Stress ◽  
Gas Migration ◽  
Tectonic Structures ◽  
Near Surface ◽  
Migration Pathway ◽  
Ordos Block ◽  
Key Factor ◽  
Northwestern Margin ◽  
History Of

Tectonic controls on near-surface CH4 and CO2 concentrations were investigated by measuring CH4 and CO2 concentrations at the surface and a height of 1.5 m, in the different tectonic units that comprise the northwestern margin of Ordos Block, China, which has a complex tectonic structure and a history of strong earthquakes. CH4 and CO2 concentrations varied from 1905 to 2472 ppb and 397.5 to 458.5 ppm, respectively. Surface CH4 and CO2 concentrations were generally higher than those measured at 1.5 m, but showed similar trends, indicating that the measured CH4 and CO2 predominantly originated from underground gases. The CH4 and CO2 concentrations increased with an increasing strike-slip rate across the faults, and concentrations in the blocks with high internal deformation were much higher than those measured in the stable blocks. Regions of extensional deformation had higher gas concentrations than regions that had experienced compressional deformation. The spatial distribution of CH4 and CO2 at the study site had similar trends to faults associated with the Yinchuan Graben. The results of this study indicated that gas source, gas migration pathway, and tectonic stress were the main factors that influenced gas emission. The key factor is tectonic stress, which controlled the formation of tectonic structures, changed the pathway of degassing, and acted as the driving force for gas migration. The results of this study clarify the mechanism of CH4 and CO2 degassing in faulted regions and suggest that CH4 and CO2 concentrations may be useful precursors in the monitoring of seismic activity. The results may also help inform future assessments of the contribution of geological sources to greenhouse gas emissions.

GPR, TDR, and geochemistry measurements above an active gas vent to study near-surface gas-migration pathways

Geophysics ◽  
2008 ◽  
Vol 73 (1) ◽  
pp. A11-A15 ◽  
Author(s):  
Elena Pettinelli ◽  
Stan E. Beaubien ◽  
Salvatore Lombardi ◽  
A. Peter Annan
Keyword(s):  
Water Content ◽  
High Water ◽  
Time Domain Reflectometry ◽  
High Water Content ◽  
Gas Migration ◽  
Secondary Effects ◽  
Near Surface ◽  
Geologic Storage ◽  
Migration Pathway ◽  
Migration Pathways

The migration of deep gas to the atmosphere along faults and associated structures is important in many fields, from studying the natural contribution of atmospheric greenhouse gases leaking from geothermal areas to ensuring the safety of man-made natural gas and carbon dioxide [Formula: see text] geologic-storage sites. Near-surface geophysical and geochemical techniques were applied to a naturally occurring gas vent located along a deep terrestrial fault to better understand the structure and geophysical response of this gas-migration pathway. A number of ground-penetrating radar (GPR) profiles were first conducted across the vent. Spot samples were then measured along one of these profiles for in situ apparent permittivity (using time-domain reflectometry — TDR), complex permittivity on dried samples (using a capacitivecell), soil-gas composition, and clay and bulk mineralogy. Results show how the migrating gas induces secondary effects that modify the signature of the vent as seen in the GPR profiles. In particular, high flux rates across the vent core (i.e., the central portion of the vent) result in a total lack of vegetation, which in turn leads to high water content that is likely responsible, together with increased bulk conductivity, for GPR signal blanking. In the transition zone surrounding the core, a water-content minimum and other changes contribute to a deeper GPR signal penetration that highlights dipping events. Data show that the structure itself is slightly asymmetrical, which may indicate more fracturing to one side of the feature. This study shows that GPR surveys are capable of imaging secondary effects induced by gas migration in soils above a structural discontinuity, even if the structure itself cannot be imaged.

scholarly journals Pervasive near-surface stratal disruption in an accretionary prism setting: Kaczawa Complex, SW Poland

2016 ◽  
Vol 154 (3) ◽  
pp. 651-660 ◽  
Author(s):  
JOANNA KOSTYLEW ◽  
JAN A. ZALASIEWICZ ◽  
RYSZARD KRYZA
Keyword(s):  
Accretionary Prism ◽  
Burial History ◽  
Tectonic Structures ◽  
Near Surface ◽  
Unconsolidated Sediment ◽  
History Of ◽  
Sw Poland

AbstractThe tectonized and metamorphosed mudrocks within the Variscan accretionary prism of the Kaczawa Mountains in SW Poland comprise sedimentary mélanges together with more coherent stratigraphic units; some represent large olistoliths deposited in a submarine trench. We infer a trend of progressive near-surface stratal disruption in mud-dominated deposits due to dewatering that forms a continuum with subduction-related tectonic structures imposed on unconsolidated sediment during deeper burial. The assemblage of characters suggests that an accretionary prism environment can influence, and leave characteristic traces of, the total burial history of a trench succession.

Using UAV and drilling to detect Quaternary activity of the Zhuozishan West Piedmont Fault, provides insight into the structural development of the Wuhai Basin and Northwestern Ordos Block, China

2020 ◽  
Author(s):  
Kuan Liang ◽  
Baoqi Ma ◽  
Qinjian Tian
Keyword(s):  
Hanging Wall ◽  
Slip Rate ◽  
Normal Fault ◽  
Fault System ◽  
Structural Development ◽  
Slip Rates ◽  
Ordos Block ◽  
Elevation Data ◽  
Northwestern Margin ◽  
Regional Tectonic

<p>The Wuhai Basin is in the northwestern corner of the Ordos Block. Analyzing the geometry, and kinematic and dynamic characteristics of the boundary fault, the Zhuozishan West Piedmont Fault (ZWPF), will elucidate the regional tectonic environment and guide earthquake prevention and disaster reduction projects. Six presentative sites were selected for topographic measurements, from northern, middle and southern parts. Displacements of the ZWPF were calculated by measuring the top surface elevation of a widely distributed lacustrine layer in the footwall from outcrops at the sites (using UAV), and in the hanging wall from boreholes. The vertical slip rate of the ZWPF was then calculated based on the displacement and age of the lacustrine layer. Three to four normal fault-controlled terraces have developed on the footwall of the ZWPF, and the top surface of the lacustrine layer is at 1092–1132 m elevation. Data from boreholes showed that the top surface of the lacustrine layer is at an elevation of 1042–1063 m in the hanging wall. Vertical slip rates since 70 ka were estimated as 0.5±0.2 to 1.0±0.2 mm/a. The highest rate of vertical slip was observed at Fenghuang Ridge, in the central part of the fault system, and the vertical slip rate reduced to the south. In the northern Wuhai Basin, normal faulting still controls the piedmont landscape. However, NW-SE trending reverse faults and secondary folding have resulted from dextral strike-slip movement of the fault. The Wuhai Basin developed as a dextral-tensional negative flower structure. This study indicated that stress conditions of the northwestern margin of the Ordos Block include NE–SW compression and NW–SE extension, and an S-shaped rift zone has dominated the scale, structure, and evolution of the Yinchuan, Wuhai and Hetao Basins, and the active mode of faulting in these basins.</p>

scholarly journals North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Alexis P. Rodriguez ◽  
Kenneth L. Tanaka ◽  
Ali M. Bramson ◽  
Gregory J. Leonard ◽  
Victor R. Baker ◽  
...  
Keyword(s):  
Katabatic Wind ◽  
Spiral Pattern ◽  
Near Surface ◽  
Valuable Source ◽  
History Of ◽  
North Polar ◽  
Human Exploration ◽  
Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

scholarly journals Dilation of subglacial sediment governs incipient surge motion in glaciers with deformable beds

2020 ◽  
Vol 476 (2238) ◽  
pp. 20200033 ◽  
Author(s):  
B. M. Minchew ◽  
C. R. Meyer
Keyword(s):  
Pore Water ◽  
Flow Model ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slip Rate ◽  
Effective Pressure ◽  
Ice Flow ◽  
History Of ◽  
Glacier Surges ◽  
Geographical Clustering

Glacier surges are quasi-periodic episodes of rapid ice flow that arise from increases in slip rate at the ice–bed interface. The mechanisms that trigger and sustain surges are not well understood. Here, we develop a new model of incipient surge motion for glaciers underlain by sediments to explore how surges may arise from slip instabilities within a thin layer of saturated, deforming subglacial till. Our model represents the evolution of internal friction, porosity and pore water pressure within the till as functions of the rate and history of shear deformation, and couples the till mechanics to a simple ice-flow model. Changes in pore water pressure govern incipient surge motion, with less permeable till facilitating surging because dilation-driven reductions in pore water pressure slow the rate at which till tends towards a new steady state, thereby allowing time for the glacier to thin dynamically. The reduction of overburden (and thus effective) pressure at the bed caused by dynamic thinning of the glacier sustains surge acceleration in our model. The need for changes in both the hydromechanical properties of the till and the thickness of the glacier creates restrictive conditions for surge motion that are consistent with the rarity of surge-type glaciers and their geographical clustering.

Age, evolution and tectonic history of the Highland Border Complex, Scotland

1984 ◽  
Vol 75 (2) ◽  
pp. 113-133 ◽  
Author(s):  
Gordon B. Curry ◽  
B. J. Bluck ◽  
C. J. Burton ◽  
J. K. Ingham ◽  
David J. Siveter ◽  
...  
Keyword(s):  
Regional Scale ◽  
Plate Boundary ◽  
North American Plate ◽  
Tectonic History ◽  
Lower Ordovician ◽  
Northwestern Margin ◽  
Comprehensive Survey ◽  
History Of ◽  
Early Palaeozoic ◽  
Western Ireland

I. ABSTRACT: Research interest in the Highland Border Complex has been pursued sporadically during the past 150 years. The results and conclusions have emphasised the problems of dealing with a lithologically disparate association which crops out in isolated, fault-bounded slivers along the line of the Highland Boundary fault. For much of the present century, the debate has centred on whether the rocks of the complex have affinities with the Dalradian Supergroup to the N, or are a discrete group. Recent fossil discoveries in a wide variety of Highland Border rocks have confirmed that many are of Ordovician age, and hence cannot have been involved in at least the early Grampian deformational events (now accurately dated as pre-Ordovician) which affect the Dalradian Supergroup. Such palaeontological discoveries form the basis for a viable biostratigraphical synthesis. On a regional scale, it is apparent that the geological history of the Highland Border rocks must be viewed in the context of plate boundary tectonism along the entire northwestern margin of Iapetus during Palaeozoic times.II. ABSTRACT: Silicified articulate brachiopods from the Lower Ordovician (Arenig) Dounans Limestone are extremely rare but the stratigraphically diagnostic generaArchaeorthisSchuchert and Cooper, andOrthidiumHall and Clarke, have been identified. In addition, three specimens with characteristic syntrophiid morphology have been recovered. Inarticulate brachiopods are known from Stonehaven and Bofrishlie Burn near Aberfoyle, and have also been previously recorded from Arran.III. ABSTRACT: Micropalaeontological investigation of the Highland Border Complex has produced a range of microfossils including chitinozoans, coleolids, calcispheres and other more enigmatic objects. The stratigraphical ranges of the species lie almost entirely within the Ordovician and reveal a scatter of ages for different lithologies from the Arenig through to the Caradoc or Ashgill, with a pronounced erosional break between the Llandeilo and the Caradoc.IV. ABSTRACT: A Lower Ordovician (Arenig Series) silicified ostracode fauna from the Highland Border Dounans Limestone at Lime Craig Quarry, Aberfoyle, Central Scotland, represents the earliest record of this group of Crustacea from the British part of the early Palaeozoic ‘North American’ plate.V. ABSTRACT: Palaeontological age determinations for a variety of Highland Border rocks are presented. The data are based on the results of recent prospecting which has demonstrated that macro- and microfossils are present in a much greater range of Highland Border lithologies than previously realised. Data from other studies are also incorporated, as are modern taxonomie re-assessments of older palaeontological discoveries, in a comprehensive survey of Highland Border biostratigraphy. These accumulated data demonstrate that all fossiliferous Highland Border rocks so far discovered are of Ordovician age, with the exception of the Lower Cambrian Leny Limestone.VI. ABSTRACT: The Highland Border Complex consists of at least four rock assemblages: a serpentinite and possibly other ophiolitic rocks of Early or pre-Arenig age; a sequence of limestones and conglomerates of Early Arenig age; a succession of dark shales, cherts, quartz wackes, basic lavas and associated volcanogenic sediments of Llanvirn and ? earlier age; and an assemblage of limestones, breccias, conglomerates and arenites with subordinate shales of Caradoc or Ashgill age. At least three assemblages are divided by unconformities and in theirmost general aspect have similarities with coeval rocks in western Ireland.The Highland Border Complex probably formed N of the Midland Valley arc massif in a marginal sea comparable with the Sunda shelf adjacent to Sumatra–Java. Strike-slip and thrust emplacement of the whole Complex in at least four episodes followed the probable generation of all or part of its rocks by pull-apart mechanisms.

MODERN PERFORMANCE ON THE KAZAKH KOBYZ

2020 ◽  
Vol 1 (2) ◽  
pp. 176-180
Author(s):  
T. Zh. Yeginbayeva ◽  
Keyword(s):  
Cultural Development ◽  
Ancient History ◽  
Musical Culture ◽  
The Past ◽  
Ensemble Performance ◽  
Natural Tendency ◽  
New Development ◽  
Key Factor ◽  
History Of ◽  
Ancient Times

Global processes in the musical culture of Kazakhstan are the result of the numerous events that have taken place in the country over the past 20 years. The independence of the state has become a key factor that has had a decisive impact on the economic, socio-political and cultural development of the country. We have entered a new life, which has a rich cultural heritage and was carefully preserved by our ancestors. One of the proofs is the history of Kazakh kobyz art from ancient times to the present day. Modern kobyz art is closely connected with ancient history and has a rich natural tendency for new development, based on centuries of experience. Therefore, kobyz music of the XXth–XXIst centuries absorbed the traditions of European genres and styles, and is widely used in mass music, in various directions of ethnorock, art-rock, folk and others. Two lines of development of music for kobyz and music on kobyz existed in ancient times and nowadays. From here comes the divergence of creative direction among modern composers and in ensemble performance.

Constraining the slip rate of Jurassic rift faults through the drowning history of a carbonate platform

Terra Nova ◽  
2021 ◽  
Author(s):  
Santantonio Massimo ◽  
Cipriani Angelo ◽  
Fabbi Simone ◽  
Meister Christian
Keyword(s):  
Carbonate Platform ◽  
Slip Rate ◽  
History Of

“Russian” Spengler and the Destiny of World History in Russian Philosophy in the Beginning of the 20th Century

2020 ◽  
Vol 65 ◽  
pp. 115-128
Author(s):  
Vladimir A. Kudryavtsev ◽  
Alexandra I. Vakulinskaya
Keyword(s):  
The United States ◽  
Russian Philosophy ◽  
Cultural Revival ◽  
The Enlightenment ◽  
Ideological Influence ◽  
Key Factor ◽  
History Of ◽  
Religious Factor ◽  
In The Beginning

This article deals with the history of Russian philosophers ‘acquaintance with the ideas of O. Spengler, set forth in his work “The Decline of the West”. The authors point out that the initial orientation of Russian thought towards Historiosophy, problems of history and ontology became the key factor of Spengler’s popularity in Russia. The article considers and analyzes critical and methodological approaches to the theory of cultural and historical types by O. Spengler and N. Ya. Danilevsky within the framework of Russian philosophical thought. The authors pay attention to the ideological influence of the United States as the country which adheres to the ideas of the Enlightenment, as well as to German thinkers, who visited this country in the early twentieth century. It is concluded that the global scenario of the human civilization development, that used to be the mainstream of its formation before the events of the beginning of this year, is unsuitable and untenable. The authors insist on the important role of the theory of cultural and historical types supported and developed by Russian emigration representatives, and focus on the importance of the religious factor in the process of cultural revival.

The Pikwitonei Granulite Domain, Manitoba: a giant Neoarchean high-grade terrane in the northwest Superior ProvinceThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.N. Machado, T.E. Krogh, and W. Weber are deceased.

2011 ◽  
Vol 48 (2) ◽  
pp. 205-245 ◽  
Author(s):  
L. M. Heaman ◽  
Ch. O. Böhm ◽  
N. Machado ◽  
T. E. Krogh ◽  
W. Weber ◽  
...  
Keyword(s):  
Granulite Facies ◽  
Superior Province ◽  
High Grade ◽  
Metamorphic Zircon ◽  
Special Issue ◽  
Metamorphic History ◽  
Zircon Growth ◽  
The World ◽  
Northwestern Margin ◽  
History Of

The Pikwitonei Granulite Domain located at the northwestern margin of the Superior Province is one of the largest Neoarchean high-grade terranes in the world, with well-preserved granulite metamorphic assemblages preserved in a variety of lithologies, including enderbite, opdalite, charnockite, and mafic granulite. U–Pb geochronology has been attempted to unravel the protolith ages and metamorphic history of numerous lithologies at three main localities; Natawahunan Lake, Sipiwesk Lake, and Cauchon Lake. The U–Pb age results indicate that some of the layered enderbite gneisses are Mesoarchean (3.4–3.0 Ga) and the more massive enderbites are Neoarchean. The high-grade metamorphic history of the Pikwitonei Granulite Domain is complex and multistage with at least four episodes of metamorphic zircon growth identified: (1) 2716.1 ± 3.8 Ma, (2) 2694.6 ± 0.6 Ma, (3) 2679.6 ± 0.9 Ma, and (4) 2642.5 ± 0.9 Ma. Metamorphic zircon growth during episodes 2 and 3 are interpreted to be regional in extent, corresponding to M1 amphibolite- and M2 granulite-facies events, respectively, consistent with previous field observations. The youngest metamorphic episode at 2642.5 Ma is only recognized at southern Cauchon Lake, where it coincides with granite melt production and possible development of a major northeast-trending deformation zone. The timing and multistage metamorphic history recorded in the Pikwitonei Granulite Domain is similar to most Superior Province high-grade terranes and marks a fundamental break in Archean crustal evolution worldwide at the termination of prolific global Neoarchean greenstone belt formation.

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