scholarly journals Geodynamic Framework of Saline Systems in Eastern Tunisia: Saline Depressions Inherited from the Triassic Intrusions and/or the Messinian Salinity Crisis

ISRN Geology ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Elhoucine Essefi ◽  
Jamel Touir ◽  
Mohamed Ali Tagorti ◽  
Chokri Yaich
Keyword(s):  
Preferential Orientation ◽  
Tectonic Activity ◽  
Messinian Salinity Crisis ◽  
Geodynamic Evolution ◽  
Geodynamic Model ◽  
Salty Water

Based on the geodynamic context, two hypotheses of origin of salt in the subsurface of the Sahel area are worth being defended. The first suggests that the halokinesis activities, namely, of the Triassic evaporitic sedimentation, may still be until now influencing the functioning of the saline systems in the Sahel. The second integrates the Sahel area geodynamic evolution in the framework of the convergence between African and Eurasian plates. It suggests a link between the blockage of the subduction between African and Eurasian plates in North Tunisia, the Messinian Salinity Crisis, and eventually the concrete opening and evolution of the playa during the Quaternary. Such a suggestion is materialized by a geodynamic model relating successively these events. This scenario suggests that the Messinian Salinity Crisis constituted huge quantities of salt and/or salty water. This saline subsurface reserve is until now influencing the Sahel behavior as a whole. Through groundwater convergence, huge quantities of salt are accumulated within depressions of the Sahel area. Currently, the convergence of the plate between African and Eurasian plates results in a tectonic activity within these saline systems materialized by the formation of fault spring mounds along preferential orientation ensuring the surface-subsurface connectivity.

scholarly journals Geodynamic evolution of the Earth over the Phanerozoic: Plate tectonic activity and palaeoclimatic indicators

2015 ◽  
Vol 4 (2) ◽  
pp. 167-188 ◽  
Author(s):  
Christian Vérard ◽  
Cyril Hochard ◽  
Peter O. Baumgartner ◽  
Gérard M. Stampfli ◽  
Min Liu
Keyword(s):  
Tectonic Activity ◽  
Plate Tectonic ◽  
Geodynamic Evolution ◽  
The Earth

MAGMATOLOGICAL TECTONICS: ALFRED RITTMANN’S PARADIGM

2021 ◽  
Vol 40 (1) ◽  
pp. 266-281
Author(s):  
DANIELE MUSUMECI ◽  
STEFANO BRANCA ◽  
LUIGI INGALISO
Keyword(s):  
Twentieth Century ◽  
Interdisciplinary Research ◽  
Tectonic Activity ◽  
Geodynamic Model ◽  
Geological Processes ◽  
History Of ◽  
Fundamental Law ◽  
Scientific Worldview ◽  
Working Hypotheses

ABSTRACT The aim of this research is to present the life and research of Alfred Rittmann (1893–1980). He was an Earth scientist in the broadest sense: a petrographer, mineralogist, magmatologist, tectonist, geodynamicist, planetologist, volcanologist and, what is more, a philosopher of geosciences. He is considered the founder of contemporary, volcanology by combining in his interdisciplinary research the study of volcanic phenomena at the surface with tectonic activity and magmatology. In his books, Rittmann discussed the first correlations between volcanism and tectonics; his geodynamic model comprises complex studies of geology, volcanology, magmatology and geodynamics. We propose to name his scientific worldview ‘Magmatological Tectonics’ (MT) and to describe it as a Kuhnian paradigm. The leading concept of all geological processes is the fundamental law. Rittmann also made abundant use of Chamberlin’s method, the method of multiple working hypotheses. Some brief interpretations will be proposed regarding the importance of Rittmann in the history of geosciences in the twentieth century and the emergence of some philosophical problems deriving from this research.

Multiple reactivation of the Rennick Geodynamic Belt (northern Victoria Land, Antarctica): insights from inversion of fault slip data 

2021 ◽  
Author(s):  
Michele Locatelli ◽  
Paola Cianfarra ◽  
Laura Crispini ◽  
Laura Federico
Keyword(s):  
Monte Carlo ◽  
Spatial Distribution ◽  
Fault Plane ◽  
Fault Slip ◽  
Tectonic Activity ◽  
Angular Deviation ◽  
Geodynamic Evolution ◽  
Zone Length ◽  
Stress Tensors ◽  
Victoria Land

<p>The Rennick Geodynamic Belt (RGB, East Antarctica) is a regionally sized, ca N-S trending, deformation zone (length > 100 km) where a dense fault network separates tectonic units of northern the Victoria Land, to the W from the East Antarctic Craton, to the E.</p><p>The RGB is long known to have been active since Cambrian-Ordovician times up to recent, but its framework and geodynamic evolution is still debated and partially investigated. The long-lived tectonic activity led to a great structural complexity, due to the superposition and polyphasic reactivation of regional faults. Such complexity is reflected by the numerous (in some cases contrasting) tectonic reconstructions of the RGB area.</p><p>In this contribution we explore the present-day tectonic framework of the RGB, investigating the stress field that possibly characterised the last geodynamic events in the area. We base on selected datasets of fault-slip data and fractures density (collected by the Authors in various PNRA Italian Antarctic expeditions) and combine fault-slip data inversion with the azimuthal orientation of faults and the spatial distribution of fractures intensity across the RGB.</p><p>To obtain a more robust portrait of the RGB geodynamic evolution, two different software based on different fault-inversion methods were used in this study: DAISY (Windows, version 3.5) and FSA (MAC, version 36.5x7i). The software DAISY implements the multiple Monte Carlo convergent method and provides the best orientation of the principal paleostresses with an estimate of the error quantified by the factor MAD (Mean Angular Deviation, corresponding to the average angular deviation between the measured pitch of the kinematic vector on the fault plane and the predicted one by applying to the fault the computed paleostress). At each step, faults are uniquely associated to the stress tensor that provides the lowest MAD. Differently, the FSA software combines a random grid search of the stress tensors following a Monte Carlo approach, under the univocal condition of fulfilment of the frictional constraint (i.e. the fault plane must form with an orientation that satisfies the Mohr-Coulomb yield criterion, i.e. t/s<sub>n</sub> = tgf with t = shear stress, s<sub>n</sub> = normal stress and f = angle of internal friction). Additionally, this software allows a direct examination of the reduced Mohr circle of the calculated stress tensors, so that we can select the one with the largest number of faults showing a high t/s<sub>n</sub> ratio.</p><p>The paleostress tensors were computed from 373 fault-slip data collected in 34 structural stations on site. Results from this multi methodological approach revealed:</p><p>(i) the existence of two, N-S oriented geotectonic provinces (namely the Bowers Mts province to the W and Usarp Mts to the E) characterized by the different spatial distribution of brittle deformation, more intense in the Bower Mts domain.</p><p>(ii) The superposition of two recent (Meso-Cenozoic) major tectonic events, with prevalent strike-slip kinematics and characterized by faults reactivation with right-lateral movement overprinting a previous left-lateral one.</p>

Clay mineralogy of the Tertiary sediments in the Internal Subbetic of Málaga Province, S Spain: implications for geodynamic evolution

Clay Minerals ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 615-620 ◽  
Author(s):  
F. J. Alcalá-García ◽  
M. Martín-Martín ◽  
A. López-Galindo
Keyword(s):  
Mixed Layer ◽  
Marine Sediments ◽  
Sedimentary Environment ◽  
Clay Mineralogy ◽  
Tectonic Activity ◽  
Mineral Association ◽  
Geodynamic Evolution ◽  
Time And Space ◽  
External Zone ◽  
Layer I

AbstractThe clay mineralogy of a set of Tertiary marine sediments from the Internal Subbetic of the Betic External Zone was examined. Two types of sedimentary environment were distinguished: a platform environment consisting of limestones, marls, organogenic limestones, conglomerates and silexites distributed heterogeneously in time and space; and deep environments, where the sedimentation consisted of marls, marly limestones, marly clays and silexites, with no sedimentary gap. A third group of sediments studied belongs to the Águila Complex, with mineralogical and stratigraphic characteristics very similar to the platform sediments. This third type of sediment is found in the sediments of the Campo de Gibraltar Complex as large, disperse blocks resulting from tectonic activity. A very similar mineral association was observed in all three domains, consisting of smectite, illite, mixed-layer I-S, kaolinite and lesser amounts of palygorskite and chlorite. Materials mainly derive from the erosion of Mesozoic sediments, and sedimentation was controlled by the compressive tectonics of the region.

PRE-SALT CARBONATES DEFINE A NEW STRATIGRAPHIC MODEL FOR THE MESSINIAN SALINITY CRISIS IN THE CENTRAL MEDITERRANEAN (CALCARE DI BASE Fm, SOUTHERN ITALY)

2020 ◽  
Author(s):  
Mario Borrelli ◽  
Edoardo Perri
Keyword(s):  
Sea Level ◽  
Southern Italy ◽  
Carbonate Platform ◽  
Wide Spectrum ◽  
Tectonic Activity ◽  
Turbidity Currents ◽  
Messinian Salinity Crisis ◽  
Central Mediterranean ◽  
Relative Sea Level ◽  
Stratigraphic Model

<p>The Calcare di Base Formation (CdB) mostly (but not exclusively) represents a microbial-mediated carbonate body formed during Messinian and extending for more than 500 km across the Southern Italy, along the accretionary wedges of Calabria and Sicily Apennine chain. In these areas, the microbial carbonates, frequently associated with evaporites, are stratigraphically positioned at the onset of the Messinian Salinity Crisis, pre-dating the massive basinal sulphates and halite deposition in the Mediterranean Circum.</p><p>The CdB highlights a wide spectrum of different facies positioned along a prograding carbonate platform to slope system. The inner platform environments are characterized by sabkhas, flood-influenced salinas and peritidal mudflats, rich of planar to domal laminated microbial boundstones associated with evaporites, solution breccias and local cross-laminated detrital carbonates. Megabreccias with plarform-derived clasts and a local siliciclastic input prevail in the upper slope, whereas debris flows and high-density turbidity currents occurred in the lower slope. Basinward, thinly laminated clay and marlstones associated to low-density turbidites characterize the outer-platform.</p><p>In a newly-proposed general sequential stratigraphic model of the Messinian Salinity Crisis, the carbonate platform systems represent a high-stand phase of at least two depositional cycles that follow one another. Each cycle begins with a relative sea-level fall responsible for the emplacement of prograding wedges composed of terrigenous and evaporitic deposits that, subsequently, evolve in the deposition of huge deposits of primary basin-fill evaporites. This latter phase is followed by open marine transgression due to relative sea-level rise that predates the development of another carbonate platform.</p><p>Despite the intense syn-sedimentary tectonic activity, responsible for huge basinward sediments exportation and fast decreasing in the accommodation space, the defined systems tracts succession has been mainly controlled by eustatic sea-level variations.</p>

The northernmost record of the Messinian salinity crisis (Piedmont basin, Italy)

2016 ◽  
Vol 8 (2.1) ◽  
pp. 1-58 ◽  
Author(s):  
Francesco Dela Pierre ◽  
Marcello Natalicchio ◽  
Francesca Lozar ◽  
Sabrina Bonetto ◽  
Giorgio Carnevale ◽  
...  
Keyword(s):  
Messinian Salinity Crisis

Preferential Orientation of Photochromic Gadolinium Oxyhydrides

2020 ◽  
Author(s):  
Elbruz Murat Baba ◽  
Jose Montero ◽  
Dmitrii Moldarev ◽  
Marcos V. Moro ◽  
Max Wolff ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Rare Earth ◽  
Preferential Orientation ◽  
Reactive Magnetron ◽  
Flow Ratio ◽  
Deposition Pressure ◽  
Step Process ◽  
Oxidation In Air ◽  
Key Parameter

<p>We report preferential orientation control in photochromic gadolinium oxyhydride (GdHO) thin films deposited by a two-step process. Gadolinium hydride (GdH<sub>2-x</sub>) films were grown by reactive magnetron sputtering, followed by oxidation in air. The preferential orientation, grain size, anion concentrations, and photochromic response of the films are strongly dependent on the deposition pressure. GdHO films show preferential orientation along the [100] direction and exhibit photochromism when synthesized at deposition pressures up to 5.8 Pa and. The photochromic contrast is larger than 20 % when the films are deposited below 2.8 Pa with 0.22 H<sub>2</sub>/Ar flow ratio. We argue that the degree of preferential orientation defines the oxygen concentration which is known to be a key parameter for photochromism in rare-earth oxyhydride thin films. The experimental observations described above are explained by the oxidation-induced decrease of the grain size as a result of the increase of the deposition pressure of the sputtering gas. </p>

Morphotectonic Analysis of Tanjung Bungo Area Based on Geological Structure Control, Central Sumatera Basin

2020 ◽  
Author(s):  
D., A., L., A. Putri
Keyword(s):  
Natural Resources ◽  
River Flow ◽  
Measurement Data ◽  
River System ◽  
Flow Patterns ◽  
Source Rocks ◽  
Aerial Photographs ◽  
Morphological Data ◽  
Tectonic Activity ◽  
Geological Structures

Tectonic activity in an area could result in various impacts such as changes in elevation, level of slope percentages, river flow patterns and systems, and the formation of geological structures both locally and regionally, which will form a new landscape. The tectonic activity also affects the stratigraphic sequences of the area. Therefore, it is necessary to study morphotectonic or landscape forms that are influenced by active tectonic activities, both those occur recently and in the past. These geological results help provide information of the potential of natural resources in and around Tanjung Bungo area. Morphological data are based on three main aspects including morphogenesis, morphometry, and morphography. The data are collected in two ways, the first is field survey by directly observing and taking field data such as measuring geological structures, rock positions, and outcrop profiles. The second way is to interpret them through Digital Elevation Model (DEM) and aerial photographs by analyzing river flow patterns and lineament analysis. The field measurement data are processed using WinTensor, Dips, and SedLog Software. The supporting data such as Topographic Maps, Morphological Elevation Maps, Slope Maps, Flow Pattern Maps, and Lineament Maps are based on DEM data and are processed using ArcGis Software 10.6.1 and PCI Geomatica. Morphotectonically, the Tanjung Bungo area is at a moderate to high-class level of tectonic activity taken place actively resulted in several joints, faults, and folds. The formation of geological structures has affected the morphological conditions of the area as seen from the development of steep slopes, structural flow patterns such as radial, rectangular, and dendritic, as well as illustrated by rough surface relief in Tanjung Bungo area. This area has the potential for oil and gas resources as indicated by the Telisa Formation, consisting of calcareous silts rich in planktonic and benthonic fossils, which may be source rocks and its contact with the Menggala Formation which is braided river system deposits that could be good reservoirs. Further research needs to be done since current research is only an interpretation of surface data. Current natural resources being exploited in Tanjung Bungo region are coals. The coals have thicknesses of 5-7 cm and are classified as bituminous coals.

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