scholarly journals Influence of basement heterogeneity on the architecture of low subsidence rate Paleozoic intracratonic basins (Ahnet and Mouydir basins, Central Sahara)

2018 ◽  
Author(s):  
Paul Perron ◽  
Michel Guiraud ◽  
Emmanuelle Vennin ◽  
Isabelle Moretti ◽  
Éric Portier ◽  
...  
Keyword(s):  
Normal Faults ◽  
North African ◽  
Subsidence Rate ◽  
Tectonic Events ◽  
Structural Framework ◽  
Vertical Fault ◽  
Central Sahara ◽  
Local Inversion ◽  
Thickness Variations ◽  
Facies Succession

Abstract. The Paleozoic intracratonic North African Platform is characterized by an association of arches (ridges, domes, swells or paleo-highs) and low subsidence rate syncline basins of different wavelengths (75–620 km). The structural framework of the platform results from the accretion of Archean and Proterozoic terranes during the Pan-African orogeny (750–580 Ma). The Ahnet and Mouydir basins are successively delimited from east to west by the Amguid El Biod, Arak-Foum Belrem, and Azzel Matti arches, bounded by inherited Precambrian sub-vertical fault systems which were repeatedly reactivated or inverted during the Paleozoic. Major unconformities are related to several tectonic events such as the Cambrian–Ordovician extension, Ordovician–Silurian glacial rebound, Silurian–Devonian “Caledonian” extension/compression, late Devonian extension/compression, and “Hercynian” compression. The deposits associated with these arches and syncline basins exhibit thickness variations and facies changes ranging from continental to marine environments. The arches are characterized by thin amalgamated deposits with condensed and erosional surfaces, whereas the syncline basins exhibit thicker and well-preserved successions. In addition, the vertical facies succession evolves from thin Silurian to Givetian deposits into thick Upper Devonian sediments. Synsedimentary deformations are evidenced by wedges, truncations, and divergent onlaps. Locally, deformation is characterized by near-vertical planar normal faults responsible for horst and graben structuring associated with folding during the Cambrian–Ordovician–Silurian period. These structures may have been inverted or activated during the Devonian compression and the Carboniferous. The sedimentary infilling pattern and the nature of deformation result from the slow Paleozoic reactivation of Precambrian terranes bounded by vertical lithospheric fault zones. Alternating periods of tectonic quiescence and low-rate subsidence acceleration associated with extension and local inversion tectonics correspond to a succession of Paleozoic geodynamic events (i.e. far-field orogenic belt, glaciation).

scholarly journals Influence of basement heterogeneity on the architecture of low subsidence rate Paleozoic intracratonic basins (Reggane, Ahnet, Mouydir and Illizi basins, Hoggar Massif)

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1239-1275 ◽  
Author(s):  
Paul Perron ◽  
Michel Guiraud ◽  
Emmanuelle Vennin ◽  
Isabelle Moretti ◽  
Éric Portier ◽  
...  
Keyword(s):  
Shear Zones ◽  
Normal Faults ◽  
Late Devonian ◽  
North African ◽  
Subsidence Rate ◽  
Tectonic Events ◽  
Structural Framework ◽  
Local Inversion ◽  
Thickness Variations ◽  
Facies Succession

Abstract. The Paleozoic intracratonic North African Platform is characterized by an association of arches (ridges, domes, swells, or paleo-highs) and low subsidence rate syncline basins of different wavelengths (75–620 km). The Reggane, Ahnet, Mouydir and Illizi basins are successively delimited from east to west by the Amguid El Biod, Arak-Foum Belrem, and Azzel Matti arches. Through the analysis of new unpublished geological data (i.e., satellite images, well logs, seismic lines), the deposits associated with these arches and syncline basins exhibit thickness variations and facies changes ranging from continental to marine environments. The arches are characterized by thin amalgamated deposits with condensed and erosional surfaces, whereas the syncline basins exhibit thicker and well-preserved successions. In addition, the vertical facies succession evolves from thin Silurian to Givetian deposits into thick Upper Devonian sediments. Synsedimentary structures and major unconformities are related to several tectonic events such as the Cambrian–Ordovician extension, the Ordovician–Silurian glacial rebound, the Silurian–Devonian Caledonian extension/compression, the late Devonian extension/compression, and the Hercynian compression. Locally, deformation is characterized by near-vertical planar normal faults responsible for horst and graben structuring associated with folding during the Cambrian–Ordovician–Silurian period. These structures may have been inverted or reactivated during the Devonian (i.e., Caledonian, Mid–Late Devonian) compression and the Carboniferous (i.e., pre-Hercynian to Hercynian). Additionally, basement characterization from geological and geophysics data (aeromagnetic and gravity maps), shows an interesting age-dependent zonation of the terranes which are bounded by mega-shear zones within the arches–basins framework. The old terranes are situated under arches while the young terranes are located under the basins depocenter. This structural framework results from the accretion of Archean and Proterozoic terranes inherited from former orogeny (e.g., Pan-African orogeny 900–520 Ma). Therefore, the sedimentary infilling pattern and the nature of deformation result from the repeated slow Paleozoic reactivation of Precambrian terranes bounded by subvertical lithospheric fault systems. Alternating periods of tectonic quiescence and low-rate subsidence acceleration associated with extension and local inversion tectonics correspond to a succession of Paleozoic geodynamic events (i.e., far-field orogenic belt, glaciation).

scholarly journals Pre-Pliocene tectonostratigraphic framework of the Provence continental shelf (eastern Gulf of Lion, SE France)

2016 ◽  
Vol 187 (4-5) ◽  
pp. 187-215 ◽  
Author(s):  
François Fournier ◽  
Aurélie Tassy ◽  
Isabelle Thinon ◽  
Philippe Münch ◽  
Jean-Jacques Cornée ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Sedimentary Cover ◽  
Normal Component ◽  
Fault Reactivation ◽  
Normal Faults ◽  
Seismic Profiles ◽  
Structural Framework ◽  
Sea Bottom ◽  
Marine Surface ◽  
Marine Seismic

AbstractThe seaward extension of onshore formations and structures were previously almost unknown in Provence. The interpretation of 2D high-resolution marine seismic profiles together with the integration of sea-bottom rock samples provides new insights into the stratigraphic, structural and paleogeographic framework of pre-Messinian Salinity Crisis (MSC) deposits of the Provence continental shelf. Seven post-Jurassic seismic units have been identified on seismic profiles, mapped throughout the offshore Provence area and correlated with the onshore series. The studied marine surface and sub-surface database provided new insights into the mid and late Cretaceous paleogeography and structural framework as well as into the syn- and post-rift deformation in Provence. Thick (up to 2000 m) Aptian-Albian series whose deposition is controlled by E-W-trending faults are evidenced offshore. The occurrence and location of the Upper Cretaceous South-Provence basin is confirmed by the thick (up to 1500 m) basinal series downlaping the Aptian-Albian unit. This basin was fed in terrigenous sediments by a southern massif (“Massif Méridional”) whose present-day relict is the Paleozoic basement and its sedimentary cover from the Sicié imbricate. In the bay of Marseille, thick syn-rift (Rupelian to Aquitanian) deposition occurred (>1000 m). During the rifting phase, syn-sedimentary deformations consist of dominant N040 to N060 sub-vertical faults with a normal component and N050 drag-synclines and anticlines. The syn-rift and early post-rift units (Rupelian to early Burdigalian) are deformed and form a set of E-W-trending en echelon folds that may result from sinistral strike-slip reactivation of N040 to N060 normal faults during a N-S compressive phase of early-to-mid Burdigalian age (18–20 Ma). Finally, minor fault reactivation and local folding affect post-rift deposits within a N160-trending corridor localized south of La Couronne, and could result from a later, post-Burdigalian and pre-Pliocene compressive phase.

scholarly journals Extensional Messinian basins in the Central Mediterranean (Calabria, Italy): new stratigraphic and tectonic insights

2018 ◽  
Vol 73 ◽  
pp. 45 ◽  
Author(s):  
Alfonsa Milia ◽  
Maurizio M. Torrente
Keyword(s):  
Water Environment ◽  
Sedimentary Basins ◽  
Normal Faults ◽  
Seismic Profiles ◽  
Rift Basins ◽  
Central Mediterranean ◽  
Tectonic Events ◽  
Basin Subsidence ◽  
Basement Deformation ◽  
Two Stages

The direction of extension and the architecture of the Messinian basins of the Central Mediterranean region is a controversial issue. By combining original stratigraphic analysis of wells and seismic profiles collected offshore and onshore Calabria, we reassess the tectonic evolution that controlled the sedimentation and basement deformation during Messinian times. Three main deep sedimentary basins in the Calabria area record a Messinian succession formed by two clays/shales-dominated subunits subdivided by a halite-dominated subunit. The correlation with the worldwide recognized stratigraphic features permit to define the chronology of the stratigraphic and tectonic events. Three main rift basins that opened in a N-S direction have been recognized. On the contrary a fourth supradetachment basin opened toward the East. We found that the basin subsidence was controlled by two stages of activity of normal faults and that Messinian rift basins evolve in a deep-water environment. The overall pattern of extensional faults of the Central Mediterranean corresponds to normal faults striking parallel to the trench and normal faults striking at an oblique angle to the trench (Fig. 14). In particular in Campania and Calabria regions are present two rifts parallel to trench and an intervening rift orthogonal to the trench. We maintain that the recognized Messinian rift basins can be interpreted according to the “Double-door saloon tectonics”.

Tectonic controlled sedimentary features at the NE marigin of the Sorgenfrei-Tornquist Zone (STZ), southern Sweden

2020 ◽  
Author(s):  
Yaocen Pan ◽  
Elisabeth Seidel ◽  
Christian Hübscher ◽  
Christopher Juhlin ◽  
Daniel Sopher
Keyword(s):  
Border Zone ◽  
Coarse Grained ◽  
Inversion Tectonics ◽  
Sea Level Changes ◽  
Tectonic Events ◽  
Basement Faults ◽  
Local Inversion ◽  
Multichannel Seismic Data ◽  
Shelf Margin ◽  
Topographic Relief

<p>The Hanö Bay basin was formed during Late Cretaceous transgression as a sedimentary trough on the NE margin of the Sorgenfrei-Tornquist Zone (STZ), a narrow NW-SE striking intraplate inversion zone within the Fennoscandian Border Zone. Sedimentation within the basin was primarily controlled by inversion tectonics, resulting in a coarse-grained syn-inversion clastic wedge forming adjacent to the basin-bounding fault in the Santonian-Maastrichtian. Previous studies have highlighted the deposition of contourite sediments associated with topographic relief of the chalk sea created by such local inversion-induced uplift. Imaged upper Cretaceous clinforms in the marginal trough show a NE-ward progadational character, that is, away from the uplifted and eroded inversion zone. These extend along the inversion axis all the way to NE of the Mid-Polish trough.</p><p>To gain detailed stratigraphic constraints and to better understand the interaction of these syn-sedimentary features that developed during inversion tectonics, we use a combination of high-resolution multichannel seismic data (MCS) from the 2019 AL526 cruise and a number of key profiles from reprocessed 70-80’s legacy industry MCS. Preliminary results suggest a drift-moat system developed during a stepwise uplift of the SW shoulder of the STZ, with the uplift driven by transpressional reactivation of basement faults. The resultant aggradational wedge formed a shelf-margin extending fairly far into the basin. The overlying clinoform depositional successions clearly demonstrate several depositional stages; including highstand-progradation, highstand-aggradation and distinct transgression-retrogradation, during which an overall landward migration of the paleo-shoreline position is revealed. The results constrain relative sea-level changes in this area that were primarily related to tectonic events during the Santonian-Campanian.</p>

The structural evolution of the Falkland Plateau

2020 ◽  
Author(s):  
Roxana Mihaela Stanca ◽  
Douglas Paton ◽  
Estelle Mortimer ◽  
David Hodgson ◽  
Dave McCarthy
Keyword(s):  
Seismic Reflection ◽  
Normal Faults ◽  
Falkland Islands ◽  
The South ◽  
Clockwise Rotation ◽  
Transform Faults ◽  
Stress Regime ◽  
Seismic Reflection Data ◽  
Western Margin ◽  
Structural Framework

<p>The palaeogeographic reconstruction of the Falkland Plateau transform margin in a Gondwana pre-break-up configuration has been the subject of debate for years. This is mainly due to the uncertainty in the position of the Falkland Islands microplate. The islands were an extension of the south-east coast of South Africa, being either i) part of a rigid Falkland Plateau fixed to the South American plate or ii) undergoing a vertical-axis clockwise rotation of between 80° to 120° along the transform faults generated during the initial stages of fragmentation of south-western Gondwana. The absence of documented evidence of this rotation within the sedimentary infill of the basins surrounding the Falkland Islands represents an ongoing issue. Furthermore, a structural framework of the eastern continental shelf of the islands that takes into account the most recent seismic reflection surveys has not been published yet.</p><p>This study presents an updated description of the structural configuration of the Falkland Plateau Basin, focusing on the Volunteer and Fitzroy sub-basins. This structural framework, based on extensive 2D and 3D seismic reflection data and aided by seismic attribute mapping, provides new insights into the evolution of the Falkland Islands microplate and the Falkland Plateau Basin.</p><p>Three main structural trends were identified across this section of the Falkland Plateau. WNW-ESE trending half-grabens were mapped north-west of the Volunteer sub-basin; these correlate laterally with linear gravity anomalies following the same trend north of the Falkland Islands. NNE-SSW to N-S normal faults are predominant west of the Volunteer sub-basin and are believed to control the western margin of the Falkland Plateau Basin. Locally, the NNE-SSW trend is subdued by NNW-SSE striking en-échelon normal faults suggestive of left-lateral movement along a NNE-SSW direction. A similar trend is interpreted in the southern part of the Fitzroy sub-basin, supporting sinistral wrenching along the western margin of the Falkland Plateau Basin.</p><p>These results suggest intra-plate deformation that is consistent with a clockwise rotation of the Falkland Islands microplate along the transform faults that accommodated the initial fragmentation of Gondwana. The interpreted fault network allows us to understand the temporal variation in the orientation of the minimum horizontal stress across the Falkland Islands microplate. By comparing this variation with the regional stress regime in south-western Gondwana, the timing and mechanism of the rotation of the islands can be better constrained.</p>

scholarly journals Filling Materials in Brittle Structures as Indicator of Cenozoic Tectonic Events in Southeastern Brazil

2020 ◽  
Vol 43 (2) ◽  
Author(s):  
Salomão Silva Calegari ◽  
Thaís Ruy Aiolfi ◽  
Mirna Aparecida Neves ◽  
Caroline Cibele Vieira Soares ◽  
Rodson De Abreu Marques ◽  
...  
Keyword(s):  
Manganese Oxides ◽  
Southeastern Brazil ◽  
Normal Faults ◽  
Mineral Formation ◽  
Mineral Precipitation ◽  
Geological Structures ◽  
Weathering Processes ◽  
Mineralogical Association ◽  
Filling Materials ◽  
Tectonic Events

The filling materials in brittle structures can provide useful information about the Cenozoic evolution developed over proterozoic terrains. When these materials are affected by faults, they record deformation phases that can be determined chronologically and, in the occurrence of lateritic materials, it is possible to infer the paleoenvironmental conditions during the mineral formation. This work aimed to identify crystalline phases of brittle structure filling materials and to propose evolutionary interpretations for Cenozoic tectonic reactivation based on literature data. The study area is located in the Southern part of the Espírito Santo State, near the Brazilian Southeastern Continental Margin, where proterozoic geological structures have been reactivated since the mesozoic rift phase, up to the Holocene. The mineral assemblage found in the filling materials includes primary minerals such as quartz, muscovite, microcline, rutile, titanite, and bannisterite; and the weathering minerals such as kaolinite, illite, hematite, goethite, hydrobiotite, lithiophorite and, birnessite. The mineralogical association found in the filling materials denotes the action of fluid phases with mineral precipitation at the brittle discontinuities during the weathering processes that occurred during the Cenozoic, probably between the Miocene and the Pleistocene. The faults, which striations are marked on the filling materials, originated after (in the case of the manganese oxides) or during (in the case of the illite) the mineral formation, indicating that the maximum age of these faults is in the Miocene. The origin of the brittle structures that affected the filling materials studied here is linked to the uplifting of the Continental Brazilian Margin, when ancient geological structures were reactivated as normal faults due to the local action of an extensional regime.

scholarly journals Ammonoids from the Dalle des Iridet of the Mouydir and Ahnet (Central Sahara) and the Formation d'Hassi Sguilma of the Saoura Valley (Late Tournaisian–Early Viséan; Algeria)

Fossil Record ◽  
2010 ◽  
Vol 13 (1) ◽  
pp. 203-214 ◽  
Author(s):  
D. Korn ◽  
V. Ebbighausen ◽  
J. Bockwinkel
Keyword(s):  
New Species ◽  
Early Carboniferous ◽  
North African ◽  
The North ◽  
Two New Species ◽  
Western Algeria ◽  
Central Sahara ◽  
North Western

Four ammonoid species are described from the Early Carboniferous (Mississippian) Iridet Formation of the Ahnet and Mouydir (Central Sahara, Algeria); three of which are new: <i>Eurites temertassetensis</i> n. sp., <i>Trimorphoceras teguentourense</i> n. sp., and <i>Trimorphoceras azzelmattiense</i> n. sp. The species can be attributed to the North African <i>Ammonellipsites-Merocanites</i> Assemblage (<i>Fascipericyclus-Ammonellipsites</i> Genus Zone; Late Tournaisian to Early Viséan). Additionally, the two new species <i>Ammonellipsites sguilmensis</i> n. sp. and <i>Muensteroceras beniabbesense</i> n. sp. are described from the time equivalent Hassi Sguilma Formation of the Saoura Valley (north-western Algeria). <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200900012" target="_blank">10.1002/mmng.200900012</a>

scholarly journals From widespread Mississippian to localized Pennsylvanian extension in central Spitsbergen, Svalbard

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1535-1558
Author(s):  
Jean-Baptiste P. Koehl ◽  
Jhon M. Muñoz-Barrera
Keyword(s):  
Sedimentary Rocks ◽  
Fault Zones ◽  
Normal Faults ◽  
Late Devonian ◽  
Growth Strata ◽  
Tectonic Events ◽  
Basement Rocks ◽  
Field Evidence ◽  
History Of ◽  
Tectonic Settings

Abstract. In the Devonian–Carboniferous, a rapid succession of clustered extensional and contractional tectonic events is thought to have affected sedimentary rocks in central Spitsbergen, Svalbard. These events include Caledonian post-orogenic extensional collapse associated with the formation of thick Early–Middle Devonian basins, Late Devonian–Mississippian Ellesmerian contraction, and Early–Middle Pennsylvanian rifting, which resulted in the deposition of thick sedimentary units in Carboniferous basins like the Billefjorden Trough. The clustering of these varied tectonic settings sometimes makes it difficult to resolve the tectono-sedimentary history of individual stratigraphic units. Notably, the context of deposition of Mississippian clastic and coal-bearing sedimentary rocks of the Billefjorden Group is still debated, especially in central Spitsbergen. We present field evidence (e.g., growth strata and slickensides) from the northern part of the Billefjorden Trough, in Odellfjellet, suggesting that tilted Mississippian sedimentary strata of the Billefjorden Group deposited during active (Late/latest?) Mississippian extension. WNW–ESE-striking basin-oblique faults showing Mississippian growth strata systematically die out upwards within Mississippian to lowermost Pennsylvanian strata, thus suggesting a period of widespread WNW–ESE-directed extension in the Mississippian and an episode of localized extension in Early–Middle Pennsylvanian times. In addition, the presence of abundant basin-oblique faults in basement rocks adjacent to the Billefjorden Trough suggests that the formation of Mississippian normal faults was partly controlled by reactivation of preexisting Neoproterozoic (Timanian?) basement-seated fault zones. We propose that these preexisting faults reactivated as transverse or accommodation cross faults in or near the crest of transverse folds reflecting differential displacement along the Billefjorden Fault Zone. In Cenozoic times, a few margin-oblique faults (e.g., the Overgangshytta fault) may have mildly reactivated as oblique thrusts during transpression–contraction, but shallow-dipping, bedding-parallel, duplex-shaped décollements in shales of the Billefjorden Group possibly prevented substantial movement along these faults.

The evolution of the Lansarine–Baouala salt canopy in the North African Cretaceous passive margin in Tunisia

2013 ◽  
Vol 150 (5) ◽  
pp. 835-861 ◽  
Author(s):  
AMARA MASROUHI ◽  
OLIVIER BELLIER ◽  
HEMIN KOYI ◽  
JEAN-MARIE VILA ◽  
MOHAMED GHANMI
Keyword(s):  
Geological Mapping ◽  
Passive Margin ◽  
Normal Faults ◽  
North African ◽  
The North ◽  
Extensional Tectonic ◽  
Two Factors ◽  
Salt Structure ◽  
Differential Sedimentation ◽  
Cretaceous Period

AbstractDetailed geological mapping, dating, and gravimetric and seismic data are used to interpret the Lansarine–Baouala salt structure (North Tunisia) as a salt canopy emplaced during the Cretaceous Period. The extensional tectonic regime related to the Cretaceous continental margin offered at least two factors that encouraged buried Triassic salt to extrude onto the sea floor and flow downslope: (i) extension induced normal faults that provided routes to the surface, and led to the formation of sub-marine slopes along which salt could flow; (ii) this structural setting led to differential sedimentation and consequently differential loading as a mechanism for salt movement. The present 40-km-long Lansarine–Baouala salt structure with its unique mass of allochthonous Triassic salt at surface was fed from at least four stems. The salt structure is recognized as one of the few examples worldwide of a subaerial salt canopy due to the coalescence of submarine sheets of Triassic salt extruded in Cretaceous times.

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